View original document

The full text on this page is automatically extracted from the file linked above and may contain errors and inconsistencies.

UNITED STATES DEPARTMENT OF LABOR
FRANCES PERKINS, Secretary

BUREAU OF LABOR STATISTICS
ISADOR LUBIN, Commissioner

BULLETIN OF THE UNITED STATES1 .
XI
r-A Q
BUREAU OF LABOR S T A T I S T I C S /................... IlO e OU O
E M P L O Y M E N T AND U N E M P L O Y M E N T S E R I E S

TECHNOLOGICAL CHANGES
AND EMPLOYMENT IN THE
ELECTRIC-LAMP INDUSTRY
By WITT BOWDEN
of the
United States Bureau of Labor Statistics.

UNITED STATES
GOVERNMENT PRINTING OFFICE
WASHINGTON : 1933

For sale by the Superintendent of Documents, Washington, D.C.




Price 10 cent»




Contents
Letter of transmittal________________________________________________
Summary__________________________________________________________
Origin and growth of the industry____________________________________
The electric lamp of today__________________________________________
How lamps are made_______________________________________________
General description----------------- -------------------------------------------------The making of filaments________________________________________
Lead-in wires__________________________________________________
Tubing and cane_______________________________________________
Bulbs__________________________________________________________
Bases__________________________________________________________
Large lamps of standard types___________________________________
Miniature lamps_______________________________________________
Chronology of principal technological changes_________________________
Production and employment in lamp-assembly plants__________________
Problems in estimating the effects of technological changes on employment.
Nature of technological changes_________________________________
Unit of measurement___________________________________________
Technological reduction of labor time____________________________
Base year or period for comparison______________________________
Effects of changes in volume of production_______________________
Technological displacement in lamp-assembly plants___________________
Year-to-year changes___________________________________________
Changes in successive years as compared with 192D________________
Production and employment in plants making parts___________________
Glass bulbs for large lamps______________________________________
Glass tubing and miniature bulbs________________________________
Lead-in wires__________________________________________________
Bases__________________________________________________________
Changes in employment in all branches of the industry________________
A p p e n d ix A . — Outline of the history of lighting_______________________
A p p e n d ix B.—Length of life and efficiency of electric lamps___________
in




Page
v
1
2
3
8
8
12
14
16
18
23
25
28
30
32
36
36
36
37
37
38
38
38
41
44
44
47
49
51
52
54
60




LETTER OF TRANSMITTAL
U n it e d S t a t e s D e p a r t m e n t o f L a b o r ,
B u r e a u o f L a b o r S t a t is t ic s ,

,

Washington, October 1 1988.
Hon. F r a n c e s P e r k in s ,

Secretary of Labor.
I have the honor to transmit herewith the
results of a study of technological changes and employment in the
manufacture of electric lamps. This is one of a series of studies made
by the Bureau for the purpose of determining to what extent techno­
logical changes in industry are affecting the output per worker and
the opportunity for employment.
The Bureau takes this opportunity to acknowledge the cordial
cooperation of representatives of the electric-lamp industry. Through
the courtesy of M r. A. E. Allen, M r. J. L. Thomas, and various other
officials, both the technical and the statistical staffs connected with
the industry devoted much time and effort to the inquiry.
Respectfully submitted.
M adam S e c r e ta r y :




I s a d o r L u b in ,

Commissioner.




BULLETIN OF THE

U. S. BUREAU OF LABOR STATISTICS
WASHINGTON

OCTOBER 1933

TECHNOLOGICAL CHANGES AND EMPLOYMENT IN THE
ELECTRIC-LAMP INDUSTRY

Summary
In 1920 approximately 362,140,000 electric lamps were made in
the United States. The number fell off sharply m 1921, then in­
creased to 643,957,000 in 1929, and thereafter declined to 503,350,000
in 1931.
In 1920 about 59 percent of all labor engaged in the industry was
employed in assembly plants, in which are combined the filament,
the lead-in wires, the glass parts of the mount, the bulb, the base,
and the other parts. In 1920 the average number of workers in
lamp-assembly plants was 17,283; by 1931 the number had declined
to 5,817.
On account of a reduction in the average number of hours per
employee, the total number of man-hours declined somewhat more
sharply than the average number of workers— from 36,145,000 in
1920 to 11,448,000 in 1931. This was a reduction of 68.3 percent.
On account of the increased production the amount of labor required
per lamp declined more rapidly than the total number of man-hours.
The time required per lamp in 1920 was 0.099809 man-hour, and in
1931, 0.022743 man-hour— a reduction of 77.2 percent. Stated
reciprocally, in terms of the number of lamps produced per man-hour,
the number in 1920 was 10.019 lamps, and in 1931, 43.968 lamps.
W ith 1920 as the base, or 100, the index of productivity of labor
increased to 438.9 in 1931.
In plants for making parts (the filament, the lead-in wires, the
bulb, the base, etc.) the amount of labor employed was less than
one fourth of all labor engaged in the industry. There have been
varying increases in the productivity of labor in plants for making
parts. In the case of bulbs for large lamps, as distinguished from
miniature bulbs, the increase in productivity exceeded the increase in
lamp-assembly plants, but for all of the parts plants combined the
estimated index of productivity was lower.
For the entire industry, including the nonmanufacturing divisions,
the index of productivity ranged from 100 in 1920 to approximately
340 in 1929 and 329 in 1931.




I

2

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

The changes in the total volume of employment in terms of manhours were due in part to changes in the number of lamps produced,
a decrease or an increase in production being accompanied by a
similar change in the amount of labor, especially in the lamp-assembly
and the parts-manufacturing plants. The other principal factor
affecting volume of employment was the saving of labor by means
of technological improvements. During the period from 1920 to 1931
earlier technological researches were continued and even intensified.
Among hundreds of innovations there were two outstanding changes.
One of these was the development of the group or unit system of
coordinating, and when possible synchronizing, the various related
operations of a production unit. An illustration is a high-speed
lamp-assembly machine in five sections, for (1) stem making, (2)
stem inserting (placing the filament-support wires in the stem), (3)
filament mounting, (4) sealing the mount in the bulb and exhausting
the air, and (5) attaching the base. A second outstanding change
was the perfecting and extensive adoption of cam-operated mech­
anisms for performing a large proportion of the operations formerly
requiring manual labor. An instance of the intricate and delicate
operations made possible in this way is the automatic mounting of
the filament of both large and miniature lamps on the lead-in wires
and the support wires of the stem.

Origin and Growth of the Industry
The first commercially successful incandescent electric lamp was
the carbon filament lamp invented by Thomas A. Edison in 1879.
This was the beginning of the incandescent electric-lamp industry,
but its growth depended primarily on the development of economical
sources of current. Edison realized this, and it was largely through
his efforts that the first central station for the supplying of electric
current was constructed in New York in 1882. The success of this
station led to the installation of similar power stations in other
cities, and the central-station industry developed rapidly. The
transition from direct current to alternating current resulted from
the successful use of the latter by George Westinghouse in lighting
the World’s Fair at Chicago in 1893.
The carbon-filament-lamp industry grew with the central-station
industry until nearly 50,000,000 carbon-filament lamps were sold in
the United States during 1906. The rapid growth of the industry
since that time is traceable to other inventions. One of these was
the pressed-tungsten-filament lamp invented by Just and Hanaman
and introduced in 1907. This was followed in 1910 by the drawntungsten-filament lamp developed by Dr. W . D . Coolidge, and in
1915 by the gas-filled drawn-tungsten-wire filament lamp invented
by Dr. Irving Langmuir. These and many other inventions, together
with the further development of central power stations since 1906,
have so stimulated the growth of the incandescent-lamp industry
that more than half a billion incandescent lamps were sold in the
United States during the year 1931.
Inventions often have far-reaching results. The electric lamp is
an outstanding example of this. This lamp was largely responsible
for the early development of the central-station industry, because
the first central staticwas depended almpgt entirely upon the revenue




THE ELECTRIC LAMP OF TODAY

3

which they obtained from the sale of current for the operation of
electric lamps. It is possible that there would have been no centralstation development if it had not been for the invention of the electric
lamp; and it is certain that there would have been no extensive
electric-lamp industry if it had not been for the development of the
central station. The great central-station industry, which thus
owed its origin to the electric lamp, has become more important in
employing labor and in changing our modes of living and working
than the lamp industry itself.
Thus the electric-lamp industry has contributed indirectly to
employment in central power stations. On the other hand, the use
of electric power has restricted the development of other sources
of power; and the use of the electric lamp has limited the develop­
ment of lighting by other agencies, such as kerosene and gas. A
specialized investigation of a limited field, such as the present study
of technological changes and employment in the electric-lamp indus­
try, must eliminate these intangible factors while recognizing that
they qualify in a measure the conclusions reached in the more limited
field of inquiry.
The activities of industrial organizations seem naturally to divide
into two main phases: (1) The manufacturing and marketing of a
product which meets present-day needs and existing demands; and
(2) the development of the industry so as to enable it to anticipate
the needs and possibilities of the future. The electric-lamp industry
has been distinguished by unusual emphasis on the second phase.
The organization of the industry has provided large sums and en­
gaged the services of many of the foremost engineers and scientists for
carrying on research and for putting into effect new knowledge and
new ideas. The industry has exhibited an emphatic trend toward
continuous improvement of lighting facilities.
These policies of the industry have had a number of important
results. For most purposes, ana where current is available at moder­
ate cost, the incandescent electric lamp provides the most efficient
and most economical form of lighting. The light output of the
tungsten-filament lamp in 1920 was 10.6 lumens per watt, and in
1931 was 13.4 lumens per watt. These figures apply only to the
ordinary large lamps operating on standard central-station circuits.
Between 1920 and 1931 the list prices of the more widely used types
of electric lamps, ranging in size from 10 to 60 watts, were reduced
about 43 percent, and the prices of larger sizes were reduced even
more.1 The increasing efficiency and adaptability and the decreasing
cost of the electric lamp have increased the demand for lamps. This
in turn has helped to counteract a decline in volume of labor
accompanying the introduction of remarkable labor-saving methods.

The Electric Lamp of Today
There are two main types of electric lamps— large and miniature.
The definition is not absolute. “ Although the miniature-lamp
class designates broadly those lamps fitted with other than medium
and mogul bases, the final determination as to whether a lamp is listed
as a large or miniature lamp depends upon the service rather than the
i National Electric Light Association. Report of the Lamp Committee, June 1932. New York,
pp. 2-4.




TECHNOLOGICAL CHANGES— ELECTRIC-LAM P INDUSTRY

construction; for example, railway signal lamps and lamps for decora­
tive service are classified as large lamps, even though fitted with
bayonet candelabra or candelabra screw bases.” Another distinction,
which again is not absolute, is in the making of the bulbs. Bulbs
for large lamps of standard types are blown from glass direct from
the furnace by continuous automatic process. Bulbs for miniature
lamps are for the most part made from tubing.
The structure and parts and also the materials of ordinary large
lamps are shown in figures 1, 2, and 3. The materials are drawn
from practically world-wide sources.
The filament is the central part of the lamp— the light-giving ele­
ment. The way in which the filament is mounted and connected
efficiently with the source of current becomes apparent from the dia­
grams presented in figures 1 and 2. The filament wire, usually coiled,
is mounted on support wires and lead-in wires. The support wires
are anchored in a glass rod or stem, which is usually merely an exten-

MATERIALS
TUNGSTEN
SAND
SODA
NITRE
MANGANESE
ARSENIC
FELDSPAR
LIME
LEAD
COBALT (BLUE)
POTASH
LITHARGE
TUNGSTEN
OR MOLYBDENUM
NICKEL
COPPER
IRON
NICKEL
COPPER
ALCOHOL
MARBLE DUST
v PINE RESIN
SHELLAC
CHALK
BAKELITE
GLYPTAL
MALACHITE GREEN
COPPER
ZINC
LEAD
TIN

PARTS
BULB
FILAMENT
SUPPORTS
BUTTON
BUTTON ROD
LEAD-IN WIRES
STEM SEAL
EXHAUST TUBE
BASE
GLASS INSULATOR
BASE CONTACT

F ig u r e 1.—D ia g ra m of a n electric la m p .

sion of a glass tube used for exhausting air from the bulb. The
lead-in wires are for the purpose of connecting the filament with the
wires extending from the central station (or source of current) to the
socket. A lead-in wire consists of three parts— an outer lead, an
inner lead, and a seal wire (a weld). It is at this central point, the
seal wire, that the lead-in wires are fused with the glass of the stem.
A t the same point the exhaust tube is fused with the flare. These
portions combined (the exhaust tube and the flare, the lead-in wires,
the support wires, and the filament) form the mount, the mount minus
the filament being called the stem. The mount is sealed to the neck
of the bulb at the flange or enlarged portion of the flare. When the
mount and the bulb have been sealed together by fusion of the glass
the air is exhausted from the lamp, and if it is a gas-filled lamp,
gas is inserted and the exhaust tube is sealed off by fusion of the
glass. The base is then cemented on the neck of the bulb with one
lead-in wire extending through the eyelet of the base, the other
lead-in wire being soldered on the outside of the base.







THE ELECTRIC LAMP OF TODAY

F igure 2.—Eleetric-lamp parts.

O

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

There are two standard types of miniature lamps. The larger
sizes of miniature lamps are known as flange-seal lamps and are for
the most part similar in essential parts to the standardized large
lamps. The smaller sizes of miniature lamps are known as butt-seal
lamps. These call for an additional descriptive note. The principal
differences will be apparent from a comparison of the diagrammatic
sketches in figure 3 with those in figures 1 and 2. Instead of a flared
glass tube for holding and sealing the lead-in wires and for sealing
the mount to the bulb a tiny bead or ring of synthetic glass is used.
A 1-piece lead-in wire is used in place of the 3-piece lead or weld of
the larger lamps. No support wires are necessary, the filament being
mounted only on the lead-in wires. The base is more commonly of
the bayonet type than of the screw type, being held by pins inserted
in the base and fitted into grooves in the socket in a manner suggestive
of the bayonet.
In addition to the standard mass-production types of large and
miniature lamps there are many special types for which the demand is
• W a td e d le a d
S in g le le a d
L E A D W IR E S
Stem b e a d
Filament •
S te m bead
L e a d w ir e s *
H -S T E M

ST E M
BEAD

U -S te m —
J
tu b e
FLARE

'S u p p o r t
E x H a u s t ^ S t c m J I ^-Stcm p r e s s
tu b e
tu b e
'— O r i f i c e
S T E M FOR T I P L E S S L A M P

F ig u r e 3.—P a r ts u s e d in ste m s for m in ia tu r e electric la m p s.

comparatively small, and the production of these lamps is therefore
not so largely mechanized. The variety and aggregate importance
of special types is indicated by the fact that a single company
announces the production of 9,000 kinds and sizes of lamps.
The sizes of lamps in practical use range from the 10,000 watt
lamps for lighting airports and for special theatrical uses to the
“ grain of wheat” lamp for surgical purposes. In addition to the
ordinary familiar pear-shaped lamp for general lighting there is a
great variety of shapes, such as the tubular small-base lamps for show
cases, panels, etc., and the candle-shaped and flame-shaped decorative
lamps. There are numerous colors, such as the blue-green daylight
lamp, furnishing a whiter light than the ordinary lamp provides;
photographic blue lamps for absorbing red and yellow rays; and lamps
with decorative colors, usually applied to the bulb in the form of a
spray coating.
Special types of lamps include lamps for ordinary lighting use but
applied under exceptional conditions. For mechanics, repair men.




THE ELECTRIC LAMP OF TODAY

7

and others, there are rough-usage lamps with sturdy structure and
operated usually from a drop cord. For resisting vibrations there is
a lamp with ring-shaped coiled filament mounted on a sturdy stem.
For country homes, trains, etc., low-voltage and variable voltage
lamps are provided. The exacting conditions of service and length
of me necessary in the case of lamps for miners are met by special
handling in the making and testing of such lamps. Where a light
with a minimum of heat is important, water-cooled lamps are avail­
able. There is also a variety of under-water lamps for such purposes
as marine rescue work; under-water work around docks, piers, etc.;
study of under-water formations, flora, and fauna (as in the Beebe
expeditions); under-water decorative uses, as in streams and foun­
tains; illumination of swimming pools; and inspection of liquids.
Special lamps include those with special functions beyond ordinary
lighting. Among these are projection lamps for such purposes as
picture projection, beacons, floodlights, headlights, and spotlights.
Among their special features are highly concentrated filaments, often
“ coiled-coil filaments” ; and special handling in the manufacturing
processes for the exact alining of the parts, testing, etc. Other
special-purpose lamps are used in photography. There is, for in­
stance, a ribbon-filament lamp used in taking microphotographs
and for other purposes. Another lamp used in photography is the
photo-flash lamp. In the bulb of this lamp is a very thin aluminum
foil in an atmosphere of pure oxygen. A very small specially treated
filament for a 1.5 voltage is used in starting the flash.
Among the most interesting of the special lamps are the so-called
gaseous-conductor lamps for various purposes. Their main features
mclude electrodes either alone or in connection with a filament; and
a gas or vapor conductor of current between the electrodes. These
lamps are in a sense a reversion to the carbon-arc lamp which was
successfully used in series for street lighting before the development
of the Edison incandescent lamp.
One of the most widely used of the gaseous-conductor lamps is the
tube lamp (“ luminous tube” ) for electric signs. This tube contains
neon gas and frequently other gases which are made luminous by
electrical discharge between electrodes. High voltages and trans­
formers are used. These tubes are not lamps in the ordinary sense,
and neither the output nor the labor of the neon-electric sign industry
is included in the present study.
Other gaseous-conductor lamps include neon-glow lamps used, not
for ordinary illumination, but as indicators and for testing purposes,
etc. They are orange-red in color. There is a neon atmosphere in a
bulb with metal electrodes. These lamps are used with ordinary
bases and on ordinary voltages, and have the advantages of long life
and low wattage.
There are also special lamps of the gaseous-conductor type for
the purpose of ultraviolet radiation with or without ordinary
light-giving facilities. One lamp of this type has a special bulb,
a pool of mercury in the bowl of the bulb, two tungsten electrodes, and
a tungsten filament connecting the electrodes. An electric arc is
created in the mercury vapor between the electrodes. M ost of the
light is from the filament and the tungsten electrodes, and most of the
ultraviolet radiation is from the arc. Transformers make possible




8

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

the use of ordinary light-socket voltages. Such lamps are used for the
maintenance of nealth in connection with ordinary illumination
needs; for the treatment of certain diseases, such as rickets; and
in poultry husbandry in brooders for winter hatching and under
conditions of limited sunlight.
In connection with the special types of lamps mention must be
made of the photoelectric cell. This is often called a lamp, and it is
made in connection with lamp manufacturing; but it is really a Ughtconcentration tube or bulb for converting light into electricity—
not electricity into light. Perhaps most intimately associated with
the development of the photoelectric cell is Dr. Harvey C. Rentschler.
Although the device is in a sense still in the experimental stage, its pos­
sibilities have already been demonstrated in a remarkable manner.
One of its uses is in connection with the photometer for testing the
light output of lamps. It has doubled the speed and also doubled
the accuracy of this testing process. It records ultraviolet rays in
the sunlight. It can be made to count passing objects, as for example
the number of vehicles passing a given point, by registering the num­
ber of interceptions of a light beam. It may be made to actuate
relay switches for various purposes, such as the setting off of a burglar
alarm. Although it is one of the most remarkable and significant of
recent scientific developments, it is merely an incidental phase of the
electric-lamp industry.

How Lamps Are Made
General Description
The various parts of an electric lamp are produced in separate
plants or at least in separate departments. In the wire plant
tungsten ore is reduced and made into filament wire, and wire for
use in supporting the filament and for other auxiliary purposes is also
manufactured. Welds are made in the plant or department commonly
called “ the welds department.” Welds consist of outer and inner lead
wires and the seal wire, only the latter being manufactured ordinarily
in the welds plant. Other wire, such as that used for mandrels on
which filaments are coiled, is either made or adapted to appropriate
uses in the same department. Glass tubing and cane for the glass
parts of the mount and for smaller bulbs are made in tubing plants.
Miniature bulbs are usually made from tubing in separate plants or
departments. Large bulbs and some miniature bulbs are made in
separate plants and are blown from molten glass drawn directly from
a tank. There are also separate plants for the making of bases.
Various other elements, such as cement, acids, gases, tools, and ma­
chines, are in part produced in separate departments by the lamp
companies and in part purchased by them from other manufacturers.
Most of the labor required in the manufacturing divisions of the
lamp industry is employed in what are known as “ lamp-assembly
plants.” In these plants, however, the processes are more than those
of merely assembling the parts. Various essential changes are made
in the nature of the parts in the process of combining them into a
completed lamp. From the point of view of manufacturing proc­
esses, lamps are of three main varieties: Large lamps of standard
types, miniature lamps of standard types— both made in such large




F

igure

4.—G

eneral

V iew

o f

Bu

lb

-

m aking

M

a c h in ery

.

Glass furnace (cold) with arched m outh; Ohio machine (in front of furnace); hot-belt conveyor (left); tractor (a round segmented feeder plate not shown); burn-off machine (center
foreground); conveyor (between burn-off machine and rectangular leer to the right); rectangular annealing leer; cooling conveyor.




HOW LAMPS ARE MADE

9

quantities as to be adapted to mass-production methods— and
special lamps not adapted to mass-production methods, mainly
because of the limited demand. In the making of these special
lamps the methods are more largely either manual or semiautomatic
than in the case of lamps of standard types. Because of the great
variety of types of special lamps and the relatively slight effects of
technological changes on the volume of labor in their manufacture,
the methods of making them will not be further discussed.
In the making of the various parts and also in the assembling of
the parts, there have recently been hundreds of technological changes
affecting employment. Two developments are of outstanding im­
portance. One of these is the group or unit system of manufacture.
A conception of what is meant by the group system may be gained
from a photographic illustration of bulb-making machinery (fig. 4).
In the left background is the arched mouth of the glass tank or furnace.
In front of the furnace is the so-called Ohio machine for making bulbs.
To the left is one form of hot-belt conveyor, which in turn connects
with a tractor, the mechanism of which is not shown. B y means of
the hot-belt conveyor and the tractor the bulbs are transferred to the
circular bum-off machine shown in the center foreground. From
this the bulbs are conveyed to the rectangular annealing leer in the
right foreground. From this they are in turn transferred to a cooling
conveyor, which takes them to the inspection department. The
same tank may supply other similar units. The underlying principle
is the coordination and synchronized operation of the various related
parts of a production unit, and it is extensively applied throughout
the industry.
The second outstanding technological development is the perfecting
of a widely used mechanism for performing a large proportion of the
operations formerly requiring manual labor. This mechanism is
extremely adaptable and assumes many forms. In general it may
be described as a turret or spider rotating on a vertical axis operated
by electrical motive power and usually indexing from one operating
position to another. In some cases, however, there is a continuous
tractor movement instead of an intermittent indexing arrangement,
and in some cases the machine is oblong instead of circular.
The Ohio bulb-making machine and the burn-off machine shown in
figure 4 are both of the general type described. The important
features of this type of mechanism are shown in figures 5 to 7. Figure
5 illustrates the way in which such a mechanism rotates and indexes
to successive operating positions. The machine illustrated is known
as the finishing machine, and is used for attaching the base to the neck
of the bulb containing the sealed-in mount.
Figure 6 illustrates the mechanical principles by which a rotating
turret machine is operated (in this case a large-lamp stem-making
and support-inserting machine). The diagram includes the main cam
shaft and the indexing and operating mechanism. The main cam
shaft, with the driving cams mounted thereon, actuates all the
mechanisms on the machine.
Figure 7 shows in detail the manner in which one of the driving
cams on a main cam shaft automatically operates a number of
mechanisms (in this case the flare feeding fingers, the stem jaws for
the flare feed, the stem jaws for the exhaust tube feed, and the exhaust
tube nonfeed mechanism).




10

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

In general, such a machine is operated by a revolving main cam shaft.
On this shaft is a series of driving cams varying in number, size, and
shape, and adjusted by means of a master cam dial for maintaining
exact time and space relations between the different operating mecha­
nisms at the different indexing or working positions. The main cam
shaft with its series of cams operates the indexing device for rotating
the turret or spider; various levers, fulcrums, elbows, conveyors,
fingers, pincers, and other operating devices; secondary cam shafts;

F ig u r e 5.—Operation of a rotating turret type machine.

and in some cases a chain device for operating a second cam shaft
containing a similar series of driving cams, which in turn control
another series of operating devices of various kinds.
The cam-operated turret machines vary widely in size, and their
adaptability ranges from the heavier to the most delicate operations.
Thus there is the 48-head Ohio bulb-making machine (fig. 4) which
indexes at 48 positions and turns out finished bulbs (except for frost­
ing). In contrast there is the small filament-mounting machine per­
fected after about 10 years of study and experiment. The mechanical




HW
O
LAM
PS
AE
R
MADE




12

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

principles are similar, but in such delicate operations as mounting a
coiled filament on the ends of lead-in wires and support wires there is
required, in preparing the specifications, a minute and painstaking
knowledge of the qualities of the materials to be used (for example,
the coefficient of expansion of metals when subjected to heat under
operating conditions); and there is necessary also a remarkable pre­
cision in making the various delicate and intricate mechanisms
according to specifications in order that the unit may operate through­
out in synchronism. The development of this particular type of
mechanism has revolutionized many industries in recent years by
making it possible to perform automatically a constantly increasing
number of operations which formerly required manual labor.
The Making of Filaments
Before the introduction of the tungsten filament, carbon was
generally used, and some carbon filaments are still made. The pre­
vailing method involves a reduction of cellulose material to liquid

form, the squirting of this material through nozzles into a solidifying
fluid (a method now used extensively in manufacturing rayon), the
coating of the carbon filament thus made with graphite, and firing
for reduction of the cellulose to carbon, the best results being obtained
by firing in an electrical-resistance furnace.
In 1910, 77.2 percent of large lamps and 86.4 percent of miniature
lamps contained carbon filaments. In 1931 the estimated proportion
of large lamps containing carbon filaments was only 0.7 percent as
contrasted with 99.3 percent of tungsten-filament lamps; and the
proportion of miniature lamps with carbon filaments was only 0.5
percent as contrasted with 99.5 percent tungsten-filament lamps.
The making of tungsten filaments resulted from long-continued
experimentation, and its success forms one of the notable achieve­
ments in the application of science to industry. Following is an
outline of the main steps in the process of transforming the crude ore
(usually wolframite) into the filament as it appears on the mount of
an electric lamp: (1) Chemical purification of the raw tungsten
oxide to pure tungsten oxide; (2) “ doping” with a chemical to in­




HOW LAMPS ARE MADE

13

crease the nonsag quality of the metal; (3) hydrogen treatment for
eliminating the oxide; (4) sifting of the purified powdered metal; (5)
pressing into slugs; (6) a partial furnace sintering; (7) final sintering
by electrical treatment for converting the pressed powder in the slug
into a solid bar comparable to pig iron; (8) swaging (automatic
hammering); (9) rough drawing through steel or carboloy dies; (10)
final drawing through diamond dies; and (11) coil winding and cutting
into filament form.
The ore is usually imported from China or Australia, because the
finer grade of ores comes from these countries. It is first put through
a chemical process for separating or precipitating the pure tungsten
oxide from the ore. For this purpose it is placed in tanks, and later
the dross elements are drained off through a screen which retains the
tungsten oxide. In appearance and general consistency this resembles
sulphur.
The tungsten oxide is reduced to a powder and mixed with a
chemical “ dope. ” This chemical, in the later processes to which the
tungsten is subjected, changes the structure of the metal in a manner
which helps to keep the filament wire in the lamp from sagging.
The next stage eliminates the oxide from the tungsten. The tung­
sten oxide, “ doped” as already indicated, is placed in small elongated
troughs. These troughs are conveyed slowly through tubes which are
heated by gas. Pure dry hydrogen gas is passed through the same
tubes from the opposite direction. The hydrogen combines with the
oxide, and since the troughs of tungsten oxide are forced through the
tubes against the hydrogen current, the latter drives off the oxide,
leaving pure tungsten.
The pure tungsten after it comes from the hydrogen furnace is put
through a fine-mesh silk screen-. These screens are operated in units
by a mechanical device. The result is a very fine and extremely
pure tungsten powder.
The tungsten powder is carefully measured and weighed and a
predetermined quantity (as 600 grams) is put into a metal compress
and subjected to a pressure of 15 tons per square inch. The result is
the compression of the powder into a slug, 600 grams being reduced
to a slug 24 by % inches. The slug is very brittle, and is held
together merely by the compactness of the particles.
The slug is put on a molybdenum slab and the slab is then placed
in a roasting or sintering furnace for a partial sintering. The parti­
cles are not melted but are only slightly fused together to impart
additional strength to the slug.
The slug is then put into a copper bell jar and sintered by subjec­
tion to electrical treatment by the passing of 2,000 amperes through
it at 40 volts pressure. The jar is filled with pure dry hydrogen to
prevent odixation of the tungsten while hot. The temperature
approaches the melting point, and the use of an ordinary crucible is
impossible because of the high melting point of tungsten. B y means
of this electrical treatment the slug is completely sintered and the
particles are fused into a solid metal bar. It is in a state resembling
that of pig iron and is not ductile.
For imparting ductility the bar is swaged or hammered. The
sintered bar or rod, as it comes from the electrical treatment, is placed
in an electrical furnace in which hydrogen is burning to avoid oxida­




14

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

tion. The mechanic who handles the operation places a heated end
of the bar in a swaging machine having two hammers which together
resemble a die. These hammers operate on an angular cam. The
rod is forced through the center of the machine and then withdrawn,
while the rotating hammers reduce the size and increase the length
of the rod. The other end of the rod is then heated and put through
the same process. (See fig. 8.) There are about 15 swaging machines
in a unit and the rod is subjected to a large number of passes through
these machines until it is reduced to ordinary wire (as size 14). As
the rod is elongated into a wire in passing through the machines, the
process becomes increasingly automatic.
The hammered wire is next subjected to a rough-drawing process
through steel or carboloy dies. These dies are operated substantially
according to standard wire-drawing practices. They not only reduce
the size of the hammered wire, but impart to it the uniformity of
size and the smoothness of surface necessary for further drawing
through diamond dies (fig. 9).
These latter dies are necessary because of the extreme exactness
and uniformity required of all filaments and the minute sizes necessary
for small lamps. The dies are drilled mechanically in the wire­
drawing department. For the finest filament wire (about one fourth
the diameter of a human hair) the wire is drawn as many as 400 times.
The dies are mounted on drawing machines and the machines are
arranged in units. As a spool of wire is automatically fed through
one die it is automatically wound on another spool. The manual
parts of the drawing process consist of transferring the spools from
one die to another, threading the dies and keeping the automatic
mechanism properly adjusted and in running order.
In addition to the making of tungsten wire the wire department
makes molybdenum wire. This is used for support hooks (the wires
extending from the glass stem and used for mounting the filament)
in lamps other than those burning at a very high temperature.
Molybdenum has a melting point of about 2,500° C. For lamps
burning at a higher temperature tungsten supports are used.
Molybdenum is purified by a much simpler process than is necessary
in the case of tungsten, which requires about a week for refining as
compared with about 18 hours in the case of molybdenum. After
the two metals are reduced to pure powder form, the processes
already described for tungsten apply almost without modification to
molybdenum.
The coiling and winding and final preparation of the filament wire
for mounting on lamp stems are operations which are performed in
lamp-assembly plants,
Lead-in Wires
The nature of lead-in wires is indicated in figures 2 and 3. Their
purpose, in general, is to establish connection between the filament
wire inside the lamp and the wires carrying the electric current from
its source to the filament. The lead-in wires must pass through a
nonconducting medium and for this reason, as well as for holding
them in proper position, they pass through the glass portions of the
mount. When glass is subjected to heat such as results from the
burning of the lamp the result is an expansion. In order to maintain
a perfect seal of the lamp against the entrance of air or the escape of







F

igu re

8.—S w

aging

T

ungsten

Ro

d s

to

st r e n g t h e n

m eta l

fo r

M

aking

F

ila m en ts

.

F

igure

9.— D




iamond

D

ies

for

D

raw ing

T

un gsten

W

ire

HOW LAMPS ARE MADE

15

gases from the lamp it is necessary, therefore, that the coefficient of
expansion of those portions of the lead-in wires which are sealed in
the glass should be the same as the coefficient of expansion of the
glass itself.
An early solution of this problem of equalizing the expansion was
the use of platinum for the sealed-in part of the lead-in wires. From
1911 to 1913 the use of nickel iron was introduced. Since 1913 dumet
wire has come into general use for the sealed-in part of the lead-in
wire. For the outer lead copper is generally used. In the case of
filaments which are too small to warrant the welding of the sealed-in
part to the inner and outer parts, the entire filament is made of dumet
wire. In some lamps with very hard glass in the seal tungsten
lead-in wires are used, but in general dumet wire is used for the
seal and nickel and copper for the inner and outer leads. W ith the
introduction of gas-filled lamps, nickel was used for the inner lead.
Dumet wire is composed of (1) a copper-plated nickel-iron core or
rod, (2) a brass spelter in the form of a ribbon wrapped around the
core rod, and (3) a copper tube which is slipped over the spelter and
the core rod. The copper tube is shorter than the core rod. This
composite rod is put on a large drawbench and drawn down until the
copper tube completely covers the central core rod.
This process is merely mechanical. In order to solder the outer
tube to the core rod the composite rod is placed in a hydrogen furnace
at a predetermined temperature which melts the brass spelter, and
thus a complete soldering is effected.
The composite soldered rod (about 5 feet long and 450 millimeters
in diameter) is then put on a large drawbench and drawn down to
250 millimeters in diameter. Rods are then butt-welded together
end to end so as to form one long piece. This piece, after being
annealed, is put on a standard wire-drawing machine and drawn
down to 120 millimeters. Then it is put on an upright wire-drawing
machine and drawn down to 50 millimeters. The wire is then
annealed and transferred to a diamond die wire-drawing machine.
Here it is drawn from 50 millimeters in diameter to the finished sizes,
as, for example, 10 millimeters. A t this stage the wire is passed
through a gas flame, through a borax solution, and then through a
gas flame again. This produces a red coating on the wire which
protects it from oxidation.
The wire is then inspected and the joints which were made by the
butt-welding of the rods are cut out. The wire is then ready for use
in the manufacture of leads or for other purposes.
The welding of the seal to the inner and outer leads was originally
done by hand. The operator picked up a piece of copper wire, the
outer lead, with the left hand and a piece of the seal wire (formerly
platinum) by means of tweezers in the right hand. The copper wire
was then held in a gas flame until the copper melted, when the seal
wire was inserted into the melted ball on the end of the copper wire.
This made what was called the first fused lead. These leads were
then given to another operator who performed a similar operation.
The first step toward mechanical operation was by means of the
single electric welder, which welded 6nly one copper wire to the dumet
wire, the other copper wire being welded to the other end of the dumet
wire by hand. B y the addition of another mech&mcal unit at the




16

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

right end of the machine, the two units forming the double electric
welder, all three parts of the lead-in wire were welded mechanically.
The next development was the miniature percussive machine.
W ith the introduction of gas-filled lamps it was necessary to use some
other metal than copper for the inner lead. Nickel wire was used
for this purpose and the miniature percussive machine was developed
for the purpose of welding the three parts— the nickel inner lead, the
dumet seal, and the copper outer lead. For making welds for
larger gas-filled lamps a large percussive machine was developed,
which in addition to the operations performed by the miniature
machine makes a hook on the end of the nickel inner lead, the hook
being used for draping the filament wire.
Miniature lamps of the flashlight type do not use welds, but have
1-part dumet wire leads which extend from the base of the lamp to
the filament. The end of the lead that connects with the filament is
flattened by a machine, producing a knoblike enlargement. The
wire is then drawn through a die and the knob is formed into a
microscopic tube, into which the end of the filament is inserted, the
two ends being clamped together. The inserting and clamping of
the filament is, of course, done in the lamp-assembly plant.
The machines used in the welds department have not only become
increasingly automatic but have been so perfected as to make it
possible to increase the speed of operation by degrees until the
output per operator has been multiplied many times.
In addition to the making of welds the welds department makes
mandrel wire on which the filament is wound, the mandrel being
later dissolved by acid. The department also makes nickel tubing
for supports in larger lamps; nickel straights (pieces of straight nickel
wire for specialized uses); and pieces 01 nickel ribbon used in large
lamps for supports for the mica disks which are fitted above the neck
to keep the heat from the base.
The materials used for these various parts are manufactured in
other plants. The principal manufacturing processes in the welds
department are connected with combining the nickel iron, the brass,
and the copper parts of the dumet wire; wire drawing; welding the
dumet wire to the other parts of the lead-in wire; and the making of
the auxiliary parts such as mandrel wire.
Tubing and Cane
Glass tubing and cane are used principally for the glass parts of
the mount (see fig. 2), for the making of miniature bulbs, and for
luminous tubes. The processes are virtually the same without regard
to the uses to which the tubing is to be put. The old method of
making tubing was a method of hand drawing and blowing. A brief
but unusually clear description of this earlier process may be quoted.2
Standing in front of the pot of molten glass, the gatherer inserts his long and
heavy pipe into the molten mass, and by skillful manipulation accumulates at
the end of the pipe the first bit of glass. He then withdraws the pipe and shapes
the glass into a round ball by first marvering it on a flat and smooth surface and
then blocking it in a wooden receptacle filled with water to cool the outer surface
of the ball. He then returns it to the pot and makes a second gathering of glass
over the formed ball, again marvers and blocks it, and then turns it over to the
ball maker. The latter makes a third and final gathering of glass, at which
*U.S. Bureau of Labor Statistics Bui. No. 441: Productivity of Labor in the Glass Industry.
Washington, 1927, p. 137.




HOW LAMPS ARE MADE

17

time the ball on the end of the pipe weighs on the average from 30 to 40 pounds.
After swinging the pipe several times forward and backward, at the same time
blowing ligntly into the pipe, the ball maker hands it over to the marverer, who,
by repeated blowing, marvering, and blocking the glass, puts it into shape to be
drawn.
In the meantime the punty boy has heated his punty, consisting of a large
iron disk attached to an iron rod. The gaffer, to whom the carry-over boy has
brought the pipe with the ball of glass ready to be drawn, lifts it over the punty,
allowing the outer surface of the glass ball to become attached to the disk of the
punty. The drawing boy then lifts the punty from the floor and begins to move
away from the gaffer, pulling with him the glass, which has become firmly
fastened to the punty. The gaffer, while continuously blowing into his pipe to
keep the inside of the tube hollow, walks slowly in the opposite direction from
the drawing boy, thus drawing out the glass to the required thinness. When
the drawing is finished, the cutting boy, with the help of a file, cuts the usable
part of the tubing into required sizes and throws the waste into a cullet recep­
tacle. It is estimated that only 25 to 30 percent of the tubing thus drawn by
hand is good tubing, the rest going back into the melting pot as cullet.
The present method of making tubing, except in the case of small
quantities of special types, is by the so-called “ Danner process.”
Patents covering it were issued in 1917. Since then many improve­
ments have been made, which account for a progressive increase in
productivity of labor. Variations in methods of applying the
process naturally occur, but the following account is characteristic
of the industry.
The raw materials come into the mixing house adjacent to the main
plant on a private railway spur on the opposite side of the plant from
the track for outgoing shipments in order to facilitate a constant
flow. Bulk materials such as sand and cullet (broken glass) are lifted
mechanically from cars to the second floor and placed in silos (storage
and feed tanks). Cullet is ground by a crusher with a magnetized
conveyor for removing metal. From the silos and the cullet crusher
the bulk materials are dumped into the mixer by levers. The mixer
is drawn by a tractor into position under each storage tank in turn,
and as the material pours by gravity into the mixer it is weighed, the
tank being closed by a lever when the right amount is emptied into
the mixer, which is then moved to a new position under another tank.
Thus these materials, and various others such as lead oxide, niter,
and potash, are handled by means of mechanical devices, and in a
carefully coordinated manner so as to avoid waste motion and to
reduce the amount of labor to a minimum. Similar mechanical
methods and coordination of movements are utilized in the transfer
of the materials to the furnace. A typical furnace installation consists
of a feeder through which the “ batches” of raw materials are emptied,
the melting end of the furnace, the throat (an opening through which
the molten glass flows), the working end, the reheater, and the man­
drel or spool from which the fused glass is transformed into a line of
tubing. As the materials are fused into molten glass of proper tem­
perature and consistency the glass is allowed to flow to the rotating
clay mandrel or spool. When ready to begin drawing a workman
takes a long hooked piece of steel and drives the hook into the molten
glass on the end of the rotating mandrel. He then withdraws the
hook, to which a portion of the molten glass adheres, and as he moves
away from the mandrel the drawing process begins. The “ gob” of
glass on the hook, with the crude tubing extending from it to the
rotating mandrel, is drawn away from the mandrel and toward the
drawing machine more than a hundred feet away (the distance




18

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

varying). Air is supplied through the mandrel to form a tube instead
of a rod. A t the proper moment the “ gob” , or rough end attached
to the hook, is broken off. A man wearing asbestos mittens then
seizes the tube and draws it out by hand along the runway over rollers
covered with asbestos cloth until he reaches the drawing machine,
when he feeds the tube into the machine. Thereafter the drawing
process is automatic.
Various factors are involved in the regulation of the size of the
tubing and the thickness of its walls, and exact ratios are worked out
for such phases of the operation as the size of the mandrel, the amount
of glass fed to it, the speed of its rotation, and the speed of the draw.
The rate of drawing for smaller tubing rims as high as 7 miles an hour,
with higher speeds attainable by means of recent improvements.
Kemarkable as is the efficiency of the Danner machine in its opera­
tion in recent years, improvements now make possible a far greater
productivity of labor. Among the more recent improvements are a
die connected with the furnace for additional feeding control; a method
of rotating the tubing for securing more perfect roundness instead
of depending exclusively on the rotation of the mandrel; and an
arrangement for taking advantage of the force of gravity by placing
the drawing machine on a level below that of the furnace, thereby
allowing the molten glass to flow by gravity from the mandrel so that
the tubing is formed without being drawn or pulled, and therefore
with a minimum of strain and with a much higher speed.
The tubing is passed on by the drawing mechanism to a cutting
section, the two operating synchronously. A revolving disk saw
nicks one side of the tubing and a slight mechanical pressure breaks
it smoothly at the point of the nick. As the tubing passes through
the drawing and cutting processes it is inspected, a check inspection
being made of a certain percent of the output. The tubing thus
inspected and cut to measure is passed through a gaging machine,
which automatically sorts it by outside diameter. Tne sorted tubing
is then put through packing machines which weigh, wrap, bind,
and transfer it from one section to another in preparation for removal
by elevators to the storage and shipping room below.
Bulbs
The making of miniature bulbs from tubing is a process radically
different from the making of large bulbs from molten glass direct from
the furnace.
In the making of miniature bulbs the tubing is transferred from
the stockroom to the blowing department on hand trucks. The
principal operations are by means of machines of the rotating vertical
turret type.
The ordinary blowing machine revolves around a
vertical axis and assumes 12 indexed operating positions during the
revolution. The same type of machine is used for all sizes of minia­
ture bulbs, the sizes varying with the sizes of tubing. The tubes are
placed upright in a circular row in chucks in the 12 operating posi­
tions. Six positions are required for making a bulb, so that there
are two sets of six indexed positions and two bulbs are made by one
complete rotation of the machine. The machine, which is automatic,
indexes through a series of fires playing upon the lower end of the
tubing in successive positions.




HOW LAMPS ARE MADE

19

After being inspected, the bulbs are transferred to the cutting
department and placed in hot-cut machines. As they come from the
blowing machines, they are sealed by the fusion of the glass at the
neck. It is necessary to open the bulb, and this is done by a process
known as “ cracking.” There are two types of hot-cut machines.
One of these, that for the larger miniature bulbs, is an indexing ma­
chine similar in operation to the blowing machine. After the bulb is
“ cracked” (opened by the removal of the lower fused end of the neck)
it passes to another indexed position where the final cut is performed.
On the outside a knife of the circular-saw type operates on the neck
of the bulb, and a small inside knife, moving upward into the neck
operates in synchronism with the outside knife. In the case of larger
miniature bulbs a monogram is applied, and they are then subjected
to final inspection and packing. In the case of smaller miniature
bulbs a hot-cut machine has recently been developed which has a
tractor or continuous operation instead of an indexing arrangement.
The smaller miniature bulbs are not monogrammed. They are fed
automatically into the hot-cut machine, and this automatic feed
combined with the continuous tractor movement greatly speeds up
the operation. Smaller bulbs are annealed, largely for the purpose
of cleaning them.
Some miniature bulbs are blown from glass direct from the furnace,
as in the case of large bulbs.
Large bulbs of standard sizes, shapes, and materials are made by
automatic processes which illustrate in a remarkable manner the
developments in the field of automatic machinery, although special
types for which the demand is relatively small are made by semi­
automatic or even manual methods.
In the handling of the raw materials mechanical methods have been
developed resembling those used in the manufacture of tubing and
cane. The principal ingredient, sand, is produced from sandstone
rock. The sand is transported in tank cars and is handled in a manner
similar to the method of handling liquids. The various processes of
storing, assembling, weighing, and mixing the ingredients and of
transferring the “ batch” from the mixing house to the furnace have
been developed in such manner as to eliminate most of the manual
labor. The force of gravity is used extensively, as, for instance, in
the unloading of sand from the tank cars.
M any improvements have been made in the melting furnaces.
A typical furnace holds about 200 tons of molten glass and is large
enough to contain a large reserve of glass beyond the amount needed
for a single day’s production of bulbs. A rectangular furnace con­
taining 200 tons of molten glass feeds 4 bulb-making units, which may
be operated independently.
A typical bulb-making unit (illustrated in fig. 4) fed by the melting
furnace consists of: (1) A bulb-making machine; (2) a hot-belt
conveyor; (3) a tractor conveyor for feeding bulbs from the hot-belt
conveyor into (4) a round segmented feeder plate which feeds the
bulbs into (5) a bum-off machine; (6) a conveyor for transferring the
bulbs to (7) an annealing leer; (8) a cooling conveyor; and (9) in­
specting and loading tables.
In the typical unit illustrated by figure 4 a 48-spindle bulb-making
machine of the Ohio type has a ram operated by compressed air.
The ram, to which are attached four holders, is automatically extended




20

TECHNOLOGICAL CHANGES— ELECTRIC-LAM P INDUSTRY

into the molten glass inside the furnace and each of the four holders,
by suction, lifts out an exact quantity of molten glass, the quantity
being determined by keeping the level of glass in the furnace constant
within one thirty-second of an inch. The ram then withdraws the
holders and they deposit their loads of soft glass on four spindles
extending upward from the machine. The indexing mechanism of
the machine then moves clockwise into position for allowing the next
four spindles to be supplied by the ram holders. Thus in succession
the 48 spindles on the rotating machine are fed. While the spindles
rotate, for the purpose of securing a uniform distribution of glass, the
entire indexing mechanism of the machine revolves on its vertical axis.
Following a set of four spindles around the machine from the
furnace mouth one finds that at predetermined times they auto­
matically change their position from upright or vertical to an outward
or horizontal and finally to a downward position between the vertical
and the horizontal. A cavity in the solid ball of glass is started by a
plunger, and as the spindles rotate and change their position puffs of
air are blown into the cavity through cam-operated valves. For
each spindle there is a mold. A t a certain position the two halves of
the mold close about the glass. A final blow of air is then turned on
and retained until the mold is ready to open and discharge the formed
bulb from the machine. The jaws of the mold then open, releasing
the bulb, and the spindle moves outward and drops the bulb onto an
asbestos conveyor. The four spindles, having thus completed the
circuit of the revolving mechanism, are then ready to take their turn
once more at the furnace mouth. Eleven other units of 4 spindles
each (48 in all) are simultaneously in operation in various stages of
forming the bulb.
The process is almost entirely automatic, but one part of the
operation is supervised. As the molten glass hangs on the spindle
its weight elongates it, and its length before the mold closes about it is
regulated by jets of air. It is necessary for an attendant to watch the
process of elongation in order to regulate the amount of cooling air.
As the bulbs move automatically from the spindles to the inspecting
and loading tables they pass through a bum-off machine. The pur­
pose of this machine is to remove the surplus portion of the bulb that
has been held by the spindle jaw. This is accomplished by feeding
the bulb into horseshoe-shaped burners, where a sharp flame of
artificial gas and air blows on the neck of the bulb. This flame
softens the glass sufficiently to allow the weight of the undesired part
to pull this portion away from the rest of the bulb.
When the bulbs reach the inspecting tables each bulb is inspected
for various defects in glass or manufacture. Bulbs which do not
require frosting are packed for shipment in hampers at the inspecting
tables. Those which are to receive what is known as inside frosting
are put up in trays, which are assembled in trucks and taken to the
frosting department. The purpose of inside frosting is to diffuse
the light and to reduce the glare from the filament. The process
was introduced about 1925, and it required an additional labor force.
Into each bulb is injected an acid solution which dissolves glass from
the inner surface of the bulb, but the indentations thus formed
weaken the bulb wall, and another acid solution is therefore injected
for the purpose of reducing the sharpness of the angles etched by the
first acid. The bulbs are finally washed with hot clean water for




yFORE HEARTH OF TANK
/FLOW REGULATOR
^GLASS LINE
.BLOWHEADS ON CONVEYOR
>fclVE TO 6LOWHEAO CONVEYOR

CULLET CONVEYOR

HW
O

ANETARY SPEED REDUCING GEAR

LAMPS
AE
R
MADE

DRIVE SHAFT
RIVE TO MOLD CARRIER BELT
IMOLDS ON CONVEYOR

DRIVE TO CONVEYOR BELT

\CHAIN DRIVE SYNCHRONIZING
FORMING ROLLS WITH CONVEYOR




F ig u r e 10.—Side elevation of Coming bulb machine (working side).

(Reproduced from The Glass Industry, August 1931.)

to

22

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

removing the residual material. They are then discharged from the
machine and passed through a hot-air drier to the inspectors. The
inside frosting process was at first largely manual but has been almost
entirely mechanized.
A recent mechanical development of unusual interest and impor­
tance is a bulb-making machine essentially different in principle from
the Ohio machine above described. This is the so-called “ Corning
bulb machine/7 Its essential principle has been described as a major
illustration of a “ vital engineering concept, a concept so vague and
generalized as to be more like a metaphysical concept than an engi­

neering principle. This idea is that for maximum results, the motion
of machinery must be absolutely continuous, and the product should
flow in a straight line, not in circles.” 3
Important features of this machine are illustrated diagrammatically
in figures 10 and 11. Instead of being a rotating turret indexing
machine with ram-operated arms moving back and forth from the
furnace to the spindles, it is a tractor-operated continuously moving
mechanism, which is fed by a continuous flow of glass from the furnace.
The glass flows by gravity from the tank and passes through rollers*
forming a continuous ribbon of glass. Moving in synchronism with
* The Glass Industry, August 1931, p. 160: New Lamps for Old, by F. W. Preston.




HOW LAMPS ARE MADE

23

the glass ribbon and the blow-head conveyor is a conveyor containing
the molds for shaping the segments of the glass ribbon into bulbs.
The completed bulbs are automatically conveyed through the various
succeeding processes to the inspecting and packing section. This
truly marvelous mechanism can produce as many as 440 bulbs per
minute; and since the machine runs continuously day and night when
production from the tank is begun, the daily capacity is far beyond
the half million mark.
Bases
Before 1900 there were extensive variations in bases with regard
to style, shape, and modes of contact with circuit wires. Standardi­
zation was undertaken about 1900, and as a result the number of
sizes has been much reduced, and the modes of contact with circuit
wires have been restricted to natural adaptations determined by the
uses to which the lamps are put. There are three main types of
bases: (1) The screw base with a screw thread formed in the shell
of the base and a corresponding thread in the socket; (2) the bayonet
base with pins or finlike projections in the shell of the base for fitting
into corresponding slots in the socket; and (3) prong bases with metal
prongs for fitting into corresponding openings in the socket. The
principal sizes are miniature, candelabra, intermediate, medium, and
mogul.
A base of the ordinary type consists of the shell (the cylindrical
metal part which fits into the socket), with a thread formed in it or
with inserted pins; the eyelet (the small metal tip of the base through
which a lead-in wire extends for making contact with the socket
wire); the glass portion connecting the shell and the eyelet; and
cement which is inserted in the base at the lamp-assembly plant.
The brass shell of the bases was formerly made by five different
machines, one for each of five main processes: (1) Cutting the blank
or disk and cupping or indenting it; (2) drawing out the cup or inden­
tation; (3) trimming and stamping; (4) threading; and (5) piercing
and forming. These processes are now combined on two machines,
the first making the unthreaded shell and the second adding the
thread.
Both shells and eyelets are made on what is commonly called an
eyelet machine. For ordinary shells this machine is a transfer slide
machine with six or seven rams or plungers operated vertically. A t
the first position a plunger cuts the blank disk from roll strip brass.
A t the second position the disk is cupped, or compressed in the
center into a cuplike shape, by pressure of the die and the plunger on
the malleable blank. A t the third position the cup is drawn or elon­
gated. The fourth plunger pierces the cup at the base. The fifth
plunger forms the dome by rounding out the cup about the pierced
base. A t the final position the upper edge of the cup is cut or trimmed.
The shells are discharged from the shell-making machine and
dropped onto a conveyor belt, and by means of cross conveyors, airconveyor posts, and an electrically controlled mechanical device are
distributed to the threading-machme hoppers in such a manner as to
keep a constant level in the hopper. Each shell is automatically
placed between threaded cylinders and these revolving cylinders press
the threads into the malleable brass shell. A typical machine threads




24

TECHNOLOGICAL CHANGES— ELECTEIC-LAMP INDUSTRY

150 shells per minute, within a variation limit of six thousandths of
an inch. When threaded the shells are dropped through an opening
in the floor onto a belt conveyor and from this belt they are blown by
air jets to the second floor above, and automatically weighed and
barreled.
The bayonet type of base goes through a process known as “ pin­
ning” instead of threading. The shells are automatically fed mto
the pinning machine by means of a pin hopper, horizontal dials, turn­
over chutes, and transfer fingers, for the purpose of placing them
uniformly and synchronously in position for the automatic operations
of the machine. A transfer finger places the shell on a piercing
stud or anvil and two plungers, operating horizontally, pierce the
shell on opposite sides. It is then raised from the piercing anvil by a
stripper and two transfer fingers convey it to a riveting anvil. The
wire for the pins is fed from two sides, and two steel fingers seize the
ends of the two wires while shearing knives cut off short measured
lengths for the pins. The fingers then place the pins in position and
hold them until two riveting plungers drive them into the holes made
by the piercing plungers and rivet them against the riveting anvil.
The eyelet of a base is essentially a brass disk embedded in the
glass of the base and pierced in the center for threading one of the
lead-in wires. The eyelet is made on a so-called “ eyelet machine”
similar to the machine used for the making of shells. The operations
are similar. The first plunger cuts the blank, a tiny disk of brass, from
a ribbon of brass; the second plunger makes an indentation in the
center of the disk. A t the third and fourth positions the disk is
slightly cupped and formed preparatory to piercing. The next
plunger pierces the center. Finally comes the crimping or shaping
of the brass where pierced for the anchoring of the eyelet in the
glass.
The shell and the eyelet are combined in the glass-base machine.
A rotating indexing machine with 36 positions is the type of machine
used for making medium screw bases. Its movement is clockwise.
The eyelets and shells are fed automatically from hoppers, feed dials,
and transfer fingers into operating position. There is a die or cavity
for each of the 36 positions. In each die an eyelet and a shell are placed
automatically and from the glass tank beyond and above the ma­
chine a glass string or stream of molten glass flows onto the dies of
the machine. This glass stream is automatically controlled. The
three parts (shell, eyelet, and glass connection) are joined together
and formed by means of cam-operated plungers. A t the end of the
processes the die is raised and an air jet blows the shell into an annealer for giving the proper temper and hardness to the glass and for
cooling the base.
From the glass department the bases are trucked by hand to the
inspection department. Ingenious arrangements have been devised
for subjecting them to inspection, and an even more remarkable
system is projected. As the bases are moved along a conveyor each
inspector examines a portion, putting the faulty bases into a small
chute leading to a container and dropping the good ones through an
opening onto the lower part of the endless belt. The supply of bases
fed to the conveyor is gaged by the capacity of the 12 inspectors,
but if for any reason there is a surplus of bases not inspected the
surplus is automatically diverted from the main belt to an auxiliary




HOW LAMPS ARE MADE

25

belt, which returns them to the head of the main belt where they are
merged with the bases from the main supply hopper.
The inspected bases are taken to the finishing department. Here
they are thoroughly cleaned and treated to give them a bright finish.
They are poured into a feed hopper supplying a dipping machine.
This machine is a hollow sectional revolving drum or cage, in which
the bases are subjected to a succession of chemical solutions and
rinses. They are finally passed through a gas-fired drum for heat
drying; sawdust is mixed with the bases as the drum revolves, the
sawdust absorbing the moisture in order to avoid spots.
In*addition to the making of bases and the other parts already de­
scribed, the manufacture of acids, gases, machines, and tools, and
specialized lamps, and the carrying on of experimental work involve
many distinctive processes. As there is no adequate means of corre­
lating the amount of labor with the volume of output, and as these
processes are relatively insignificant as affecting a statistical com­
parison of changes in volume of labor with changes in volume of
output, they are omitted from further consideration.
Large Lamps of Standard Types
The description of lamp-making processes in assembly plants will
be limited to standard types of lamps. It should be noted in this
connection, however, that the term “ standard lamp” has more than
one meaning. From the technician’s point of view a standard lamp
is determined by photometric measurements and is “ a lamp of known
lumens or candlepower (spherical or horizontal) at a certain voltage
used as a basis of comparison in the photometry of other lamps” .
As the term “ standard type of lamp” is here used it applies to lamps
that are most widely used and that are produced in quantities large
enough to make possible large-scale or mass-production methods.
A lamp-assembly plant does more than merely put together the
parts of a lamp. It makes essential changes in the parts and performs
with marvelous exactness the operations required to combine the
parts of the lamp. There is a considerable degree of specialization in
these assembly plants. There are plants exclusively for standard
types of large lamps, for standard types of miniature lamps (though
now large and miniature lamps are usually made in the same factory),
for special types of lamps, and for experimental work.
Among the principal steps in the making of large lamps are: (1)
Making the filament coil; (2) making the mount; (3) sealing the
mount in the bulb, exhausting the air, and (in the case of gas-filled
lamps) filling with gas; (4) inserting cement in the base; and (5) basing
and finishing.
The filament wire after it comes from the wire plant must be sub­
jected to a large number of operations in a centralized coiling depart­
ment. The wire is received in spools and is wound on bobbins previous
to being put on coiling machines for coiling the filament on mandrels.
The coiled filament must be cut to the lengths desired for different
lamps, except in the case of certain types of filaments which are auto­
matically cut in connection with coiling. With certain exceptions the
mandrel around which the filament is coiled must be removed by a
separate process. This includes a series of heated acid baths for dis­
solving the mandrel wire and also for cleaning the filament. After­




26

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

ward the filaments are put through hydrogen furnaces for annealing,
in order to complete the cleaning process and to relieve any strain
remaining from coil winding. Samples of the filaments are then spottested in an atmosphere of hydrogen to reveal any variations in
diameter. The coils are projected through a series of mirrors and
lights onto a screen and highly magnified for inspection. The final
inspection is for length, uniformity, and color.
One of the most interesting processes connected with the prepara­
tion of the filament for mounting is called gettering. A large number
of coils (perhaps 3,000) are put into a funnel-shaped cup over which a
glass vessel is lowered. The coils are then whirled about in this vessel
by means of high-pressure air. This creates a vacuum which sucks
up the gettering fluid through a nozzle from a glass below the vessel
and sprays it over the coils. This particular method is used for vac­
uum lamps but not for gas-filled lamps. A getter has been defined as
a chemical substance introduced in the incandescent lamp bulb to
improve the vacuum during the process of manufacture, in the case
of certain types of lamps, and to maintain a more constant output of
light during the life of the lamp.
In addition to the work on the filament in preparing it for the mount,
the lamp-assembly plants do supplementary work on other parts as
they come from the parts manufacturing plants. In the case of the
bulb, for instance, some lamp-assembly plants have machines for in­
side frosting and out.side spraying of bulbs. These machines are of the
familiar rotating turret indexing type. In the case of the inside bowl
frosting process the spray is, of course, applied to the bulb before the
mount is sealed in. In case of the outside spraying process the spray
is applied to the bulb after the mount has been sealed in and the base
attached. In both cases the processes are almost entirely automatic.
Another operation performed in connection with the preparation
of parts for final assembly is the inserting of cement in bases. This
is done by a separate machine which is highly automatic, and the
process is carried on in the lamp-assembly plant in order that the
cement may retain its freshness until the base is cemented to the
neck of the bulb.
After the filament has been made ready for draping on the stem,
and after the various other parts have been assembled, the process
of combining them into a lamp illustrates the working out of the unit
system of manufacture. This is particularly true of the lamp-assembly
plants for the making of standard types of lamps. Variations in
procedure are, of course, numerous. The general principles of the
procedure may be illustrated by the case of a high-speed unit lampmaking machine or group of machines in five sections.
The first section of this group is the stem-making section. It
includes a 24-head turret indexing machine for joining together the
lead wires, the flared glass tubing used for sealing the stem to the
base, and the exhaust tubing which serves to exhaust the air and
inject the gas in gas-filled lamps and anchor the support wires to the
filament. One flare, two lead wires, and one exhaust tube are assem­
bled and sent through a series of heating positions till the flare and the
tube are fused with the lead wires, the fusion occurring at the exact
portion of the lead wires which is made of dumet wire. All of these
processes are synchronized and the operations are carried on by means
of a series of cams as previously described.




HOW LAMPS ARE MADE

27

The stem is then automatically conveyed to the second or inserting
section of the machine, where a button is formed on the end of the
exhaust tubing and where support wires are measured, cut off, inserted
in the soft-glass button, and bent to proper pitch for receiving the
filament.
In the third section the filament is mounted on the stem. This
has usually been done by hand, the filament wire being draped around
the support wires, each end being fastened to one of the lead-in wires.
When the filament is thus mounted on the stem the mount is put in a
tray, and the tray when filled is conveyed by a gravity slide to the
next section.
The fourth section consists of a sealing-in and exhaust machine.
This is a turret indexing machine with two tiers of heads. Each head
on the upper tier has a mount pin for holding the mount. A bulb
turret (a circular rotating bulb container) moves over in sytfchronism
with the main machine to a position which places the bulb above and
in line with the mount in the mount pin. As the bulb is moved into
this position it is stamped on the top with a monogram in acid and
etching ink which is later burned into the glass. An automatic bulb
loader takes the bulb from the turret, and as the mount indexes in
the proper position the bulb is dropped over it. As the machine
rotates, the bulb with the mount thus inserted passes through a series
of heating positions, the bulb itself revolving for uniform heating, until
at the proper position the flared glass tubing of the mount is sealed
to the neck of the bulb and the surplus glass (cullet) below the seal
drops into a receptacle. When the bulb with the sealed-in mount
has completed the circuit of the upper tier the exhaust tubing still
extends through the neck of the lamp, and this tubing is put into a
rubber stopper on one of the heads in the lower tier of the same
machine. This lower tier is the exhaust deck. As the machine
rotates the air is exhausted, and in the case of gas-filled lamps gas is
injected. The final process on this machine is known as “ tipping off ”
or sealing of the exhaust tube after exhausting and filling.
The lamp is then automatically ejected onto a conveyor, where it
is momentarily retained by a finger device for testing, and then
removed by the conveyor.
The fifth section of the unit is the basing and soldering section, to
which the lamps are automatically conveyed. A typical basing
machine is a 48-head turret indexing machine. The bases, which
are made in another factory and which have been filled with cement
on a separate machine, are placed on the neck of the lamp by hand
with one lead wire through the eyelet of the base and the other lead
wire on the outside of the base. The lamp with the base thus attached
goes through the various operating positions where the base is
cemented on, and the lead wires are trimmed and soldered into place.
A more highly developed instance of the unit system consists of
three sections. In the first section of each unit there are two auto­
matic mounting machines for making the stem, inserting the support
wires in the stem, and mounting the filament. Each of these ma­
chines has a capacity of 1,500 per hour. The second section consists
of three sealing-exhaust machines, each of which has a capacity of
1,000 per hour. The third section consists of three base-finishing
machines each with a capacity of 1,020 per hour. The total output
of a unit is 3,000 per hour. It is to be noted that the different sections
1762°—33-----3




28

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

are coordinated on the basis of approximately equal capacity. The
entire unit is synchronized and adapted to maximum capacity of the
machines and to a minimum amount of labor. In addition to the
automatic mounting of the filament by a recently developed machine
various other hand operations that have survived earlier mechaniza­
tion are being transferred to machines, as, for instance, a bucket
conveyor for transferring the lamps from the sealing-exhaust machines
to the base-finishing machines.
Miniature Lamps
From the point of view of methods of manufacture miniature lamps
are of two main types— flange-seal and butt-seal lamps. The flangeseal type is similar to the large lamp insofar as the bulb is sealed
around the flange of the mount. In the butt-seal lamp the lead wires
are sealed in a glass bead to make the stem, and this bead is combined
with an exhaust tube or top tube for sealing the mount in the bulb.
Flange-seal miniature lamps include headlight lamps, most of the
miniature sign and decorative lamps, the larger Christmas tree lamps
for outside use, and part of miner’s lamps. Butt-seal lamps include
lamps for flashlights, toy trains, radio panels, cowl and instrument
lamps for automobiles, small low-voltage Christmas tree lamps, and
a part of miner’s lamps. There are various lamps for special uses of
both types.
In the making of flange-seal miniature lamps the processes are not
so radically different from those used in making large lamps as to call
for detailed treatment. There are numerous variations, as, for in­
stance, special handling of the filament in focusing lamps, and a modi­
fied stem-making process in connection with double-contact lamps
using three lead-in wires. The main processes may be summarized
as follows: (1) The glass parts, including the flange and the lead-in
wires and support wires (where support wires are necessary), are
assembled and combined into the stem. (2) In a large proportion
of flange-seal miniature lamps there is a process known as “ terminal
spacing.” The lead-in wires are trimmed to a predetermined length
and the ends are bent. Terminal spacing is for the purpose of pre­
paring the wires for mounting the filament and also for controlling
the light source. (3) The filament is mounted on the stem either
manually or automatically. (4) The mount is sealed in the bulb by
fusing the flange with the neck of the bulb. (5) The bulb is ex­
hausted, ordinarily filled with an inert gas, automatically tipped off,
and unloaded. (6) Next come basing, soldering, and cleaning.
(7) The final stages include marking, inspecting, and packing.
In the case of the butt-seal lamps the essential difference, as already
stated, is in the use of a glass bead for making the* stem, which is
combined with the top tube for sealing the mount to the bulb. The
bead for the mount is made in a glass factory. It consists of powdered
glass mixed with a binder. This mixture is punched out under pres­
sure into beads and not fused in the process of manufacture. In the
lamp-assembly plant the bead is fused around the lead wires in making
the stem, the stem consisting of the bead and the lead wires fused
together.
In place of separate processes for stem making, terminal spacing,
and mounting, as in flange-seal lamps, the mount for butt-seal lamps




HOW LAMPS ARE MADE

29

is made by a single set of operations on an automatic beading and
mounting machine. The lead-in wires are automatically fed from
two spools of dumet wire, the entire lead-in wires being made of dumet
instead of the dumet wire being limited to the sealed-in portion. The
wire is automatically cut at a predetermined length. The bead is
automatically dropped over the two lead-in wires and fused around
them to make the stem. As the machine rotates to successive operat­
ing positions the lead-in wires are flattened in preparation for bending
the ends into hooks, hooks are formed on the ends, the wires are
properly spaced, and they are heat-cleaned in preparation for the
mounting of the filament. The filament wire is coiled on the stem
machine, being automatically wound around the mandrel, cut,
stripped off the mandrel, and transferred to a position under the hooks
of the lead-in wires, the wires already having been attached to the
bead by the fusion of the bead around them to form the stem. Next
the filament coil is clamped to the hooked ends of the lead-in wires.
The position of the filament in relation to the lead-in wires, as the
amount of bend or curvature in the filament, is automatically adjusted
and is made to vary with different types and sizes of lamps. Finally
the mount is automatically ejected from the machine.
If gettering is required the operator getters the mount and places
it in the bulb. The bulbs with mounts inserted are placed on trays
for transfer to the sealing machine.
One method of sealing the mount to the bulb is embodied in the
operations of a 48-head automatic sealing machine. An operator
loads a bulb containing the mount into the first position on the
machine. Successive operations include the following: (1) The top
tube— that is, the exhaust tube— is conveyed from the machine and
sealed to the bulb. (2) A restriction is drawn in the tube (the tube
is made smaller) at the place where the bulb is to be tipped off or
sealed on the exhaust machine. (3) The mount is adjusted and
centered in the bulb while the glass is still plastic, and the mount
and bulb are fused together. (4) The sealed lamp is then removed
from the machine, either automatically or manually, and is ready for
the exhaust machine.
The process of exhausting the air is essentially the same as in the
case of flange-seal lamps. For vacuum-type lamps a machine is now
in use (a mercury condensation machine) for exhausting. Lamps
are loaded manually, automatically tested under high pressure for
leaks, exhausted, tipped off, and automatically ejected. The speed of
operation has been greatly increased.
Basing is also similar to the corresponding process in the making of
flange-seal lamps.
This account indicates a departmentalized arrangement in contrast
with the unit system of manufacture. Much progress has been made
toward the introduction of the unit system in the making of miniature
lamps, but there are problems which limit the efficiency of the system.
One of these problems lies in the fact that the machines used in the
different stages do not have the same speed of operation. Unless the
slower machines can be speeded up, or unless an appropriate combina­
tion of slow and fast machines can be made, as in the case of the largelamp unit system described above, some of the machines will neces­
sarily be idle a part of the time, and the advantages of synchronous
continuous operation will not be realized.




30

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

Chronology of Principal Technological Changes
Technological changes which affect the amount of labor time re­
quired per unit of output have two main aspects. In the first place,
there are changes in the physical facilities and materials of industry,
and these are characteristically mechanical, though not exclusively so.
Secondly, there are changes in the managerial technique of using the
physical facilities and materials of industry. There is, of course, no
absolute distinction between the two. Among the managerial changes
may be classed the group or unit system of manufacture heretofore
described,4 although this arrangement might, perhaps, be classed as a
combination of managerial technique and changes in the physical
facilities.
M any of the technological changes which have occurred in the
electric-lamp industry are too intangible or too gradual to be placed
in exact time sequence. This may be illustrated by the effects of the
automatic weighing and gaging of glass tubing in speeding up the
making of miniature bulbs from tubing. There has been a gradual
increase of the speed of the machines due to the exact size of the
tubing, and there has also been a reduction of the loss in process, so
called— that is, a reduction of the percentage of imperfect bulbs— and
this of course in turn increases the output of bulbs per man-hour or
reciprocally reduces the amount of time required per bulb. Formerly
a bulb-making machine requiring 1 operator and 1 inspector produced
5,000 bulbs a day, but with the making of more perfect tubing and
with a more exact regulation of the gas and air, and blowing air, 1
operator supervises 3 machines producing 26,000 bulbs a day, the
inspection of the output requiring the time of 1 inspector and half the
time of another. Another bulb-blowing machine was designed to
produce 5,000 per day with 1 operator and 1 inspector. W ith the
development and perfecting of tubing, gaging, and weighing, and gas
regulation, it is now possible for 1 operator to supervise 6 machines
producing 66,000 bulbs per day, 2 inspectors taking care of the output.
Following is a list of technological changes in the electric-lamp in­
dustry since 1907. Only outstanding changes are included, and par­
ticularly those that have tended to reduce the amount of labor time
per unit of output. The dates given are in some cases approximate.
1907
(1) Mechanical mixing and control of “ batch” for glass furnace.
(2) Electric welding machine for making lead-in wires.
1910
(3) Standardization of formulas for bulbs and tubing.
(4) Tungsten made ductile.
(5) Regenerative pot furnaces.
1912
(6) Empire semiautomatic bulb-blowing machine.
(7) Westlake bulb machine.
1913
(8) Dumet wire for welds.
(9) Double electric welding machine.
(10) The gas-filled lamp.
« See pp. 2, 19-20,26-28.




CHRONOLOGY OP TECHNOLOGICAL CHANGES

31

1914
(11) The first automatic indexing machine (for sealing).
(12) Automatic miniature beading and mounting machine.
(13) Automatic support-wire inserting machine.
1915
(14)
(15)
(16)
(17)

Lime glass for bulbs (facilitating automatic bulb making).
Automatic base-filling machine (for inserting cement).
Metal dies for drawing tungsten and molybdenum.
Automatic exhaust machine.
1916
(18) Danner tube-drawing machine.
1917

(19) Magnetic separator for automatically removing iron from glass.
1918
(20) Development of standard machine parts for glass manufacture.
(21) Continuous mandrel coiling machine.
(22) Automatic miniature-bulb blowing machine.
(23)
(24)
(25)
(26)
(27)

1919
Tipless lamp.
Automatic glass-tube-sorting machine.
Tank furnace for automatic bulb production.
Tank cars for shipping sand.
Mixing of tungsten ores.
1920

(28) Spray coating process.
(29) Automatic safety stop, Westlake bulb machine.
(30) Burn-off machine for automatically removing surplus glass from necks of
bulbs.
(31) Hot-cut flare machine.
1921
(32) Miniature percussive welder.
(33) Large percussive welder.
(34) Development of group or unit system of manufacture.
(35) Printing of monograms and labels on bulbs.
(36) High-production tipless stem machine.
1922
(37) High-production support-wire inserting machine.
(38) Tungsten wire annealing.
(39) Bulb annealing furnace (as high as 600,000 a day).
1923
(40) Elimination of trays in bulb works.
(41) Coiling machine for miniature-lamp filaments.
1924
(42) Use of natural gas in cutting-off and burning-off processes.
(43) Basing and soldering machine.
(44) Photoelectric cell applied to photometry (measuring the light output of
lamps).
(45) Sealex machine (for sealing, exhausting, and gas filling).
1925
(46) Automatic “ batch” (glass) feeder.
(47) Inside frosting machine.
(48) Improved type of steel for cams.




32

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

(49)
(50)
(51)
(52)
(53)

Simplified and standardized line of bulbs, facilitating mass production.
Improved mandrels for use in making glass tubing.
Mercury pumps.
Combination miniature coiling and coil-mounting machine.
Standardization of lamps, facilitating mass production (6 standard lamps
replacing 45 types and sizes for ordinary lighting).

(54)
(55)
(56)
(57)

Improved packing of glass tubing.
The 48-spindle bulb machine.
Elimination of bulb washing.
Automatic miniature butt-sealing machine.

1926

1927
(58)
(59)
(60)
(61)
(62)
(63)
(64)

The Corning ribbon bulb machine.
Improved method of mixing tungsten powders.
Mechanical temperature indicator for exhaust.
High-frequency testing device.
Cutting of glass tubing to predetermined length.
Elimination of tissue-paper bulb wrapping.
Improved dimension gages.
1928
(65) Tubular bulb machine.
(66) Tank furnace for tubing.
1929
(67)
(68)
(69)
(70)
(71)
(72)
(73)
(74)
(75)
(76)
(77)
(78)
(79)
(80)
(81)
(82)
(83)
(84)
(85)
(86)

Electric bulb annealing.
Automatic weighing of glass tubing.
Use of the photoelectric cell for sorting.
Machine for coiling filament wire without a mandrel.
Automatic mounting machine for mounting filaments in large lamps.
Centering of filament in focusing type miniature lamps by beam-of-light
method.
1930
The Ohio bulb machine.
Improved methods of coil production and coil cleaning.
Extension of automatic mounting of filaments.
Improved lamp conveyor on sealex machine.
Multiple dip gettering machine.
Stem-making and sealing machine for 5,000- and 10,000-watt lamps.
Mechanical cullet (waste glass) pull-down device for sealex machine.
Development of butt-lamp sealing machine to seal automobile headlight
lamps of the fiange-seal type.
Development of conveyor and other units to allow continuous progressive
operations in making automobile headlight lamps.
Improved soldering devices.
1931
Automatic cutting, sizing, and glazing of tubing for butt sealing.
Improved gas burners for glass cracking and burning operations.
Rivet soldering on basing machines.
Improved miniature-bulb hot-cut machine.

Production and Employment in Lamp-Assembly Plants
The lamp-assembly plant, as has already been indicated, is for the
purpose of combining the filament, the glass tubing, the bulb, the
base, and the various other parts into a finished product. The com­
parative importance of lamp-assembly plants in respect to the amount
of labor employed is indicated by the fact that in 1920 they employed
about 59 percent of the total labor (including nonmanufacturing
labor) employed in the lamp industry. In 1931 the labor in the
assembly plants was only about 42 percent of the total.




33

PRODUCTION, ETC., IN LAMP-ASSEMBLY PLANTS

In the tables which follow, the figures of the volume of output and
of labor are estimates derived from the best available sources. For
relatively small portions of the industry, only the production figures
are available, but manufacturing methods are known and the approxi­
mate amounts of labor can be apportioned. For other small portions
of the industry, records of labor are not available for some of the years
1920 to 1931, but for these years reasonably close approximations can
be made. In some of the minor details, the figures are not comparable
for the entire period. For example, in the volume of labor employed
in lamp-assembly plants there is included a small amount of labor
used in making miniature bulbs before this work was completely
transferred to separate plants. On the other hand, a counterbalancing
illustration is the extension of dining-room facilities in lamp-assembly
plants, which tended to increase the volume of labor in these plants
during the later years of the period from 1920 to 1931.
While the basic figures given in the tables are not to be regarded as
exact transcriptions of records, and while there is undoubtedly a
margin of error, at the same time it is believed that the actual trends
in lamp-assembly plants of the industry as a whole are shown with an
unimportant margin of error.
The figures of unit time requirement and of the productivity of
labor are meticulously extended, not with the idea of conveying an
unwarranted impression of exactness, but for the purpose of narrow­
ing the margin of error in using these as factors for computing the
columns derived from the basic data of hours and output.
The changes in the volume of output in assembly plants from 1920
to 1931 are indicated in table 1. The number of so-called large lamps,
including the ordinary sizes for household use, etc., varied between
1920 and 1931 from 161,665,000 in 1921 to 362,826,000 in 1929, the
number declining, as might be expected, during the depression years
1921 and 1922 and 1930 and 1931. The number of miniature lamps,
such as automobile lamps and flashlights, varied during the period
1920 to 1931 in a similar manner. The smallest number was
80,850,000 in 1921 and the largest number was 281,131,000 in 1929.
The changes may readily be visualized by reference to the columns
of index numbers for each of the two types and for their total in
table 1.
T able

1.— Estimated changes in volume of output in electric-lamp-assembly
factories, 1920 to 1981
[1920=100]
Large lamps

Miniature lamps

Total

Year
Number
1920.........................................
1921.........................................
1922.........................................
1923.........................................
1924.........................................
1925............. ...........................
1926.— ................... — ..........
1927_........................................
1928.........................................
1929........................................
1930.........................................
1931.........................................




234,770,000
161,665,000
206,019 000
248,347,000
251,752,000
274,087,000
281,588,000
340,545,000
313,475,000
362,826,000
335,001,000
326,613,000

Index
100.0
68.9
87.8
105.8
107.2
116.7
119.9
145.1
133.5
154.5
142.7
139.1

Number
127,370,000
80,850,000
105,246,000
155,879,000
183,420,000
185,188,000
200,867,000
203,967,000
243,478,000
281,131,000
218,198,000
176,737,000

Index
100.0
63.5
82.6
122.4
144.0
145.4
157.7
160.1
191.2
220.7
171.3
138.8

Number
362,140,000
242,515,000
311,265,000
404,226,000
435,172,000
459,275,000
482,455,000
544,512,000
556,953,000
643,957,000
553,199,000
503,350,000

Index
100.0
67.0
86.0
111.6
120.2
126.8
133.2
150.4
153.8
177.8
152.8
139.0

34

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

Estimated changes involving labor employed in electric-lampassembly plants during the same period 1920 to 1931 are included in
table 2. The average number of hours per employee per year varied
from a maximum of 2,213 to a minimum of 1,968. The reduction in
number of man-hours was somewhat greater than the reduction in
average number of employees. In order to visualize the change in
number of man-hours in terms of workers the average number of
hours per worker per year for the entire period has been computed
(2,105 hours). Dividing the total number of hours worked in each
year by the average number of hours per employee per year gives the
number of employees if the number of hours per worker had remained
constant. On this equated basis, the number of workers would have
ranged from 17,171 in 1920 to 5,438 in 1931. The index of change
in the last column of table 2 (ranging from 100 in 1920 to 31.7 m
1931) is the same as the index of change in number of man-hours.
T a b l e 3 . — Estimated changes in volume of labor in electric-lamp-assembly factories,

1920 to 1981
[1920=100]
Large lamps

Year

Total

Miniature lamps

Employees on
basis of average
number of
Average
Average Average hours, 1920-.
Average
number Man-hours number Man-hours number number 31, per em­
Man-hours of em­
of em­ of hours ployee (2,105)
of em­
ployees per em­
ployees
ployees
ployee
Num­ Index
ber

1920...............
1921............. ......
1922___________
1923............... —
1924___________
1925___________
1926...............
1927. _____ _____
1928.......... .........
1929___________
1930....... .........1931.......... .........

25,194,000
15,764,000
16,484,000
18,459,000
14,240,000
13,055,000
11,498,000
12,064,000
9,902,000
10,097,000
8,521,000
7,520,000

12,196
7,826
8,387
8,844
6,574
5,915
5,383
5,442
4,564
4,425
3,987
3,753

10,951,000
5,946,000
8,065,000
8,362,000
7,839,000
6,698,000
6,078,000
5,858,000
6,074,000
5,906,000
4,903,000
3,928,000

5,087
3,103
3,737
3,989
3,639
3,147
2,907
2,657
2,689
2,833
2,473
2,064

36,145,000 17,283
21,710,000 10,929
24,549,000 12,124
26,821,000 12,833
22,079,000 10,213
19,753,000 9,062
17,576,000 8,290
17,922,000 8,099
15,976,000 7,253
16,003,000 7,258
13,424,000 6,460
11,448,000 5,817

2,091
1,986
2,025
2,090
2,162
2,180
2,120
2,213
2,203
2,205
2,078
1,968

17,171
10,314
11,662
12,742
10,489
9,384
8,350
8,514
7,590
7,602
6,377
5,438

100.0
60.1
67.9
74.2
61.1
54.7
48.6
49.6
44.2
44.3
37.1
31.7

Table 3 contains estimates of changes in the productivity of labor
and in the amount of time required per lamp in electric-lamp-assembly
plants, 1920 to 1931.
The productivity of labor is computed on the basis of the total
number of man-hours and the total number of lamps. The average
number of lamps produced per man-hour increased continuously even
during years of declining production from 10.019 in 1920 to 43.968
in 1931. The index of productivity shows a corresponding increase
from 100 in 1920 to 438.9 in 1931.
From the point of view of the employee the productivity of his
labor naturally has primary interest, but for the statistical analysis of
the effects of changes in productivity on employment, its reciprocal,
namely, the amount of time required per lamp, is a more logical fac­
tor. Changes in time requirement per lamp are also shown in table 3,
and these figures are used in most of the subsequent tables dealing
with electric-lamp-assembly plants.




35

PRODUCTION, ETC., IN LAMP-ASSEMBLY PLANTS

T a b l e 3 . — Estimated changes in productivity of labor and in time required per unit

of output in electric-lamp-assembly plants, 1920 to 1931
[1920=100]
Production of
lamps

Employment

Year
Number
1920.........................................
1921.............................. ..........
1922............. ...........................
1923.........................................
1924................................... .
1925........................................
1926.........................................
1927............. ...........................
1928........ ................................
1929............. ............ .........
1930.........................................
1931................ ........................

362,140,000
242,515,000
311,265,000
404,226,000
435,172,000
459,275,000
482,455,000
544,512,000
556,953,000
643,957,000
553,199,000
503,350,000

Lamps pro­
duced per
man-hour

Average
Index Man-hours Index number Index
100.0
67.0
86.0
111.6
120.2
126.8
133.2
150.4
153.8
177.8
152.8
139.0

Time require­
ment per lamp
Manhours

Index

36,145,000 100.0 10.019 100.0 0.099809
21,710,000 60.1 11.171 111.5 .089520
24,549,000 67.9 12.679 126.6 . 078868
26,821,000 74.2 15.071 150.4 .066351
22,079,000 61.1 19.710 196.7 . 050736
19,753,000 54.7 23.251 232.1 .043009
17,576,000 48.6 27.450 274.0 .036430
17,922,000 49.6 30.382 303.2 .032914
15,976,000 44.2 34.862 348.0 .028685
16,003,000 44.9 40. 240 401.6 . 024851
13,424,000 37.1 41. 210 411.3 .024266
11,448,000 31.7 43.968 438.9 .022743

100.0
89.7
79.0
66.5
50.8
43.1
36.5
33.0
28.7
24.9
24.3
22.8

In order to visualize more readily the principal changes indicated
by the previous tables, these changes are reduced to an index form,
with 1926 as the base (table 4), and presented graphically in figure 12.

F igure 12.—Employment, production, and productivity in electric-lamp assembly plants, 1920 to 1931.
T a b l e 4 . — Estimated changes in volume of output and of labor and in productivity

of labor in electric-lamp-assembly plants, 1920 to 1981
[1926=100]
Production of lamps
Year

1920 ........................... -.......... ......
1921..............................................
1922 ..............................................
1923 ................................. ........
1924 ................................. ............
1925 ..............................................
1926 .............................................
1927 ...................................-....... 1928 ........ — ............................. —
1929 ..............................................
1930 ..............................................
1931...............................................




Number
362.140.000
242.515.000
311,265,000
404.226.000
435.172.000
459,275,000
482.455.000

544.512.000
556.953.000
643.957.000
553.199.000
503.350.000

Index
75.1
50.3
64.5
83.8
90.2
95.2
100.0
112.9
115.4
133.5
114.7
104.3

Employment
Man-hours
36,145,000
21,710,000
24.549.000
26.821.000
22,079,000
19,753,000
17,576,000
17,922,000
15,976,000
16.003.000
13.424.000
11,448,000

Index
205.6
123.5
139.7
152.6
125.6
112.4
100.0
102.0
90.9
91.1
76.4
65.1

Productivity
Number
of lamps
per hour
10.0
11.2
12.7
15.1
19.7
23.3
27.4
30.4
34.9
40.2
41.2
44.0

Index
36.5
40.9
46.4
55.1
71.9
85.0
100.0
110.9
172.4
146.7
150.4
160.6

36

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

Problems in Estimating the Effects of Technological Changes
on Employment
Nature of Technological Changes
Technological changes are perhaps most commonly associated
with machines. Processes not primarily mechanical in nature
should, however, also be included. Methods of economizing space,
materials, and time are also essentially technological, even though
there is no mechanical innovation. There are a few major techno­
logical changes, such as, for example, the introduction of the Ohio
bulb-making machine, and the group or unit system of manufacturing
in electric-lamp-assembly plants, but minor changes are occurring
much more frequently, in fact almost continuously, and in the aggre­
gate are probably more important than the relatively few major
changes. “ Scientific management ” is often more effective than
scientific mechanism.
There are also technological changes which are indirect in their
operation so far as a particular industry is concerned. The various
improvements in transportation, for example, such as road construc­
tion and the use of trucks and airplanes, are made without specific
reference to any particular industry such as the electric-lamp industry,
but they may considerably increase the productivity of certain
phases of labor in the electric-lamp industry.
Unit of Measurement
Whenever applicable, the unit of measurement of the effects of
technological changes on labor is the amount of time required per
unit of output, or, reciprocally, the amount of output per unit of
labor time. If the unit time requirement decreases (or the produc­
tivity of labor increases), this change may or may not be due to
technological changes. In order to determine whether or not such
a change in the amount of time required per unit of output is a result
of technological changes it is necessary to understand the operating
conditions of the industry in question.
The effects of technological changes on labor are not adequately
expressed by the change in unit time requirement unless the volume
of labor is flexible in response to changes in volume of output. If,
for example, production declines to a point ’where the minimum
number of workers necessary for maintaining operations can produce
more than the demand for output justifies, the productivity of labor
will decline and the amount of labor time per unit of output will rise,
due to declining production. Some industries, and some branches
of most industries, are of such nature that the amount of labor does
not readily fluctuate with changes in volume of output, and the unit
time requirement will vary, therefore, in such instances not merely
with technological changes but with changes in volume of output.
The unit time requirement must be regarded as an adequate measure
of the effects of technological changes on employment only when
nontechnological factors are so unimportant in causing changes in
unit time requirement that the margin of error due to their inclusion
is not excessive. It is never a perfect unit of measurement, but
ordinarily it is the best available method.




EFFECTS OF TECHNOLOGICAL CHANGES

37

If an employer can increase the total number of man-hours of labor
in proportion to increases in production and can reduce the total
number of hours of labor in proportion to any falling off of business,
the amount of time required per unit of output will remain constant
unless there are changes in his methods which require an increase or
decrease of labor. If there are such changes, their influence on
employment will be measured approximately by any change in unit
time requirement.
Technological Reduction of Labor Time
If there is a reduction in the amount of labor time per unit of output
in a given year or period as compared with an earlier year or period,
this reduction in labor time is likely to be viewed by the employer,
who is interested in lowering the cost of production, as a “ saving”
of labor time. From the point of view of the employee, who is in­
terested in keeping or finding a job, the reduction is a “ loss” of labor
time.
Ordinarily, in the major industries the employer estimates in ad­
vance the probable demand for his product, and the actual production
of a given year is determined primarily by the actual or estimated
demand of that year. The demand, in turn, is likely to be entirely
unaffected by any changes in the productivity of labor during the
year. In other words, if during a particular year an employer is able
to make a reduction or saving in the average amount of time per unit
of output, his total reduction or saving will be the unit saving multi­
plied by the number of units of output. Similarly, from the point of
view of the employees the total loss of labor time or reduction of
employment opportunities consists of the product of the reduction in
the amount of time per unit of output times the total number of units
produced. The only exception is an increase of production which is
attributable to lower prices to consumers based on reduction of labor
cost— in other words, an increase in production which would not have
occurred had it not been for the reduction in unit time requirement.
Base Year or Period for Comparison
Any effort to ascertain the effects of technological changes on em­
ployment necessarily involves a comparison of one period with another.
It is likely that employers and employees are primarily interested in
the saving or loss of labor time of the current year, month, week, or
cycle of production as compared with the similar period immediately
preceding it. Ordinarily, therefore, a year-to-year comparison is per­
haps of primary interest. But in order to discover long-time trends
an earlier year or period must be compared with the present. W hat­
ever the object in view, this point of departure should be made clear
and the limitation of the result attained to the particular object in
view should be kept in mind. Obviously, the amount of reduction of
labor time in the current year as compared with the previous year will
not be the same as the amount of reduction of labor time in the current
year as compared with some earlier year. If the productivity of labor
is an approximate measure of technological change in a given industry,
then each result is valid for the particular object in view; but its
limitation to this object must be made apparent.




38

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

Effects of Changes in Volume of Production
An increase in the productivity of labor tends to reduce the amount
of employment. An increase in production tends to increase the
amount of employment. The combined effect of these two factors
on total volume of employment is readily ascertainable. The amount
of saving of labor time (or from the employee's point of view, the
amount of loss of employment opportunity) tends to increase not
only with a rise in productivity of labor, but also with an expansion
in the volume of production, up to a point where any additional vol­
ume of production is itself a result of declining labor cost. Up to
that point the volume of production is a condition which determines
the extent to which the rate of productivity of labor is effective in
the saving (or loss) of labor time.

Technological Displacment in Lamp-Assembly Plants
Year to Year Changes
Changes in the total volume of employment are measured by
(1) changes in total production and (2) changes in the production rate
in terms of time required per lamp (or reciprocally, the number of
lamps produced per unit of labor). Changes in the net volume of
employment, and the significance of the change in the production
rate in years of increasing production, are analyzed in tables 5 and 6.
Table 5 contains the basic data of production, employment, and pro­
duction rates. Table 6 analyzes the changes in employment as
measured by changes in production and in production rates for each
year as compared with the preceding year and for each year as com­
pared with 1920. Since the volume of labor in electric-lamp-assembly
plants fluctuates readily with changes in volume of production, the
changes in production rates are approximate measures of technological
change.5
If production should remain constant, the operation of the tech­
nological factor as measured by change in the production rate
would be simple and obvious, but variations in production introduce
complications.
If production declines, the technological reduction of labor time is a
net reduction, to which is added the amount of labor displaced by the
decrease in production. Thus, the technological reduction in 1921
amounted to 2,495,000 man-hours (table 6, col. 2), this sum being the
product of the number of lamps manufactured and the average reduc­
tion, as compared with 1920, in the time required per lamp (table 5).
But because of the fact that 119,625,000 fewer lamps were made in
1921 than in 1920, 11,940,000 fewer man-hours were needed (table 6,
col. 1). The total change in employment is the sum of these reduc­
tions, or 14,435,000 man-hours (col. 6).




39

CHANGES IN LAMP-ASSEMBLY PLANTS

T a b l e 5 .— Production, employment, a n d production rates in electric-lamp-assembly

plants, 1920 to 1981, estimated year-to-year changes, and changes as compared
with 1920
Production

Production rates

Employment

Reduction
as com­
Year-toChange as
Year-toYear Number of year change compared Number of year change pared with
with 1920 man-hours
(manlamps
1920
(lamps)
(lamps)
hours)
(manhours)
6
1920..
1921
1922_.
1923-.
1924..
1926..
1926..
1927..
1928..
1929-.
1930..
1931..

362.140.000
242.616.000 -119,625,
311.265.000 +68,750,
404.226.000 +92,961,
435.172.000 +30,946,
459.275.000 +24,103,
482.455.000 +23,180,
544.512.000 +62,057,
556.953.000 +12,441,
643.957.000 +87,004,
553.199.000 -90,768,
603.350.000 -49,849,

-119, 625.000
-50, 875.000
+42, 086.000
+73, 032.000
+97, 135.000
120 315.000
+182, 372.000
+194, 813.000
+281, 817.000
+191, 059.000
+141, 210.000

+ ,

36.145.000
21.710.000 -14,435,000
24.549.000 +2,839,000
26.821.000 +2,272.000
22.079.000 -4,742,000
19.753.000 -2,326,000
17.576.000 -2,177,000
17.922.000 +346,000
15.976.000 -1,946,000
16.003.000
+27,000
13.424.000 -2,579,000
11.448.000 -1,976,000

ManReduc­
hours Year-to- tion as
com­
re­
year re­ pared
quired duction
with
per
1920
lamp
7
0.099809

.010289 0.010289
. 010652 .020941
.012517 . 033458
.015615 .049073
.007727 .056800
.006579 . 063379
.003516
.004229 .071124
.024851 .003834 . 074958
.024266 .000585 . 075543
. 022743 .001523 .077066

14,435,
11,596,
9,324,
14,066,
16,392,
18,569,
18,223,
20,169,
20,142,
22,721,
24,697,

.078868
.066351
.050736
.043009
.036430
.032914

T a b l e 6 . — Analysis of changes in employment in electric-lamp-assembly plantst

1920 to 1931 1
Reduction in employment (man-hours) -

Year

Total reduction in
man-hours as
In years of decreasing In years of increasing Increased
measured by
production as meas­
production as meas­
change in pro­
ured by change in employ­
duction rate 2
ured b y ment in Net change
production rate2
making
additional in manhours
Equiv­
output
alent
(manChange in On output On addi­
num­
equal to tional out­ hours)
Man-hours ber of
in produc­ produc­ base year’s
tion
put
tion rate2 production
work­
ers 3

Each year as compared with preceding year
1921..
1922..
1923..
1924..
1926..
1926..
1927..
1928..
1929..
1930..
1931..

11,940,000 2,495,000

*2,255,000
1,209,000

324.000
767.000

2.583.000
3.896.000
6.312.000
3.363.000
3.022.000
1.696.000
2.303.000
2.135.000

732.000
1,164,000
483.000
186.000
153.000
218.000
53,000
334,000

-14,435,000
5.422.000 +2,839,000
6.168.000 +2,272,000
1.570.000 -4,742,000
1.037.000 -2,326,000
844.000 -2,177,000
2.042.000
+346,000
357.000 -1,946,000
+27,000
2.162.000
-2,579,000
-1,976,000

495.000
315.000
060.000
795.000
649.000
175.000
914.000
356.000
469.000
324.000
767.000

1,185
1,575
2,404
3,228

2.495.000
6.518.000
13.524.000
21.355.000
26.087.000
30.577.000
36.425.000
39.613.000
48.269.000
41.790.000
38.791.000

1,185
3,096
6,425
10,145
12,393
14,526
17,304
18,819
22,931
19,853
18,428

1,686

1,508
909
1,119
1,173
154
364

Each year as compared with 1920
1921..
1922..
1923..
1924..
1925..
1926..
1927..
1928..
1929..
1930..
1931-

11,940,000 2.495.000
5,078,000 6.518.000

12,116,000 1.408.000 2.792.000
17.771.000 3.584.000 3.705.000
20.570.000 5.517.000 4.178.000
22.952.000 7.625.000 4.383.000
24.225.000 12,200,000 6.002.000
25.757.000 13.856.000 5.588.000
27.145.000 21.124.000 7.003.000
27.357.000 14.433.000 4.636.000
27.909.000 10.882.000 3.212.000

1 For basic data see table 5.
J Primarily technological. See pp. 36-37.

435.000
596.000
324.000
066.000
392.000
569.000
223.000
169.000
142.000
721.000
697.000

8 Based on the average number of hours per employee per year (2,105). See table 2.




40

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

If production increases, as in 1922 as compared with 1921, the
technological reduction of labor time, amounting to 3,315,000 manhours (col. 7), is not a net reduction in employment, for employment
increased as compared with 1921. This increase of 2,839,000 manhours (col. 6) was because of the fact that the labor used in the pro­
duction of 68,750,000 m om lamps than in 1921 more than counter­
balanced the technological reduction, in spite of the lower production
rate. In this case the technological reduction of labor time did not
mean, therefore, a net falling off in the amount of employment as
compared with 1921, but it did mean that employers, because of the
lower production rate, were able to produce the output of 1922 by
employing 3,315,000 fewer man-hours than would have been required
if the production rate had not fallen. Stated in another way, the
net increase in employment in 1922 was only 2,839,000 man-hours,
but if there had been no change in the production rate, the increase
would have been 2,839,000 man-hours plus the technological reduction
of 3,315,000 man-hours, or a total of 6,154,000 man-hours.
A similar situation existed in 1923 as compared with 1922. But in
1924, as compared with 1923, there was a net decline of employment
as well as a technological reduction of labor time. In making
404.226.000 lamps, equaling the number made in 1923, lamp-assembly
plants were able to reduce employment to the extent of 6,312,000 manhours (col. 3). In making the 30,946,000 additional lamps produced
in 1924, they were able to effect a further technological reduction of
483.000 man-hours (col. 4)— a total of 6,795,000 man-hours. But in
making the added 30,946,000 lamps at the lower production rate of
1924 they required 1,570,000 man-hours (col. 5). Therefore, because
of the increased output made at the lower production rate of 1924, the
technological reduction was counterbalanced to the extent of 1,570,000
man-hours, so that the net decline in employment was 4,742,000 manhours (col. 6).
In the larger industries, such as the electric-lamp industry, the
volume of production in any given year is determined primarily, not
by any decrease in labor cost during the year, but by the actual or
estimated demand for the product. The 30,946,000 additional lamps
manufactured in 1924 as compared with 1923, for example (table 5,
col. 2), were produced, not because there was a decline in unit time
requirement, but because expanding demand warranted the additional
output. Improvements in methods of production, however, made
possible the reduction in unit time requirement, and employers thereby
effected a saving of labor time in manufacturing during 1924 not only
a quantity of lamps equal to the production of 1923, but also the
additional output of 1924. The total amount of labor saved, there­
fore, by virtue of technological changes as measured by changes in
unit time requirement was the reduction in time requirement per unit
(0.015615 man-hour) times the total number of lamps produced in
1924 (435,172,000), or 6,795,000 man-hours. Since the average num­
ber of hours per worker per year was 2,105, the equivalent number of
workers was 3,228.
The total technological effect on labor time in each of the years
1920 to 1931 as compared with the preceding year ranged from 324,000
man-hours, equivalent to 154 employees, in 1930, to 6,795,000 manhours, equivalent to 3,228 employees, in 1924 (table 6, cols. 7 and 8).
These estimates represent, to lamp-assembly plants, a saving of labor,




CHANGES IN LAMP-ASSEMBLY PLANTS

41

and to workers, a shrinkage of employment opportunities in each
year as compared with the preceding year resulting from technological
changes as measured by changes in the production rate.
Changes in Successive Years as Compared with 1920
The first section of table 6 analyzes the year-to-year changes in
employment in electric-lamp-assembly plants from 1920 to 1931 by
comparing each year with the preceding year. Ordinarily the em­
ployer and the employee alike are primarily interested in comparing
each year or cycle of production with the similar period immediately
preceding it. But it is also desirable to analyze the long-term
trends, and for this purpose a modification of the method used in
the first section of table 6 is necessary. Such a modification is em­
bodied in table 5 and the second section of table 6 (p. 39), in which
the employment in lamp-assembly plants analyzed in each year from
1920 to 1931 is compared, not with the preceding year, but with
192° .
There was a decrease in total volume of employment in each of
the years from 1921 to 1931 as compared with 1920. The decline
ranged from 9,324,000 man-hours in 1923 to 24,697,000 man-hours in
1931. The only years in which there was a decrease in production as
compared with 1920 were 1921 and 1922. In 1929 the additional
production beyond that of 1920 was greatest and amounted to
281.817.000 lamps— an increase of 78 percent. In each year, as
compared with 1920, there was a reduction in the production rate in
terms of unit time requirement.
In years when production was less than in 1920 (the years 1921
and 1922), the declining production rate was reinforced by the reduced
output in causing a decline in total employment. Thus, in 1922,
5.078.000 fewer man-hours were required than in 1920 because of
the fact that 50,875,000 fewer lamps were made; and in the making
of the 311,265,000 lamps of 1922 there was an additional reduction of
6.518.000 man-hours because of the lower production rate, bringing
the total reduction of man-hours to 11,596,000 (table 6, second section,
cols. 1, 2, 6).
In 1923 and later years the quantity of lamps made increased
beyond that of 1920. The lower production rate of 1923 enabled
employers to produce a quantity of lamps equal to that of 1920 with
12.116.000 fewer man-hours. But 42,086,000 additional lamps were
made in 1923 beyond the quantity made in 1920, and the making of
these additional lamps, at the lower production rate of 1923, required
2.792.000 additional man-hours. Therefore, the net reduction in
man-hours was only 9,324,000 (cols. 3, 5, 6). Similarly, in succeeding
years, the additional output beyond that of 1920 counteracted in
part the effect of the declining production rate in its effect on the net
reduction of employment.
But if there had been no reduction in the production rate, the addi­
tional output of 1923 could have been produced only by the employ­
ment of 1,408,000 additional man-hours (col. 4). In other words,
lamp-assembly plants were able to produce the output of 1923 with
13.524.000 fewer man-hours (col. 7), equivalent to 6,425 workers
(col. 8), because of the change in the production rate; and workers
consequently experienced an equivalent shrinkage in employment




42

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

opportunities. A similar analysis for each of the succeeding years
reveals a progressive increase in the amount of labor saved, as com­
pared with 1920, and as measured by changes in the production rate,
ranging from 21,355,000 man-hours in 1924 to 48,269,000 man-hours
in 1929. Stated in another way, the output of 1929, the peak year,
if produced on the basis of the 1920 production rate, would have
given employment to 22,931 additional workers. Thereafter the
amount declined to 38,791,000 man-hours, equivalent to 18,428
workers, in 1931.
These figures are overestimates of the effects of technological
changes as measured by changes in unit time requirement, because
they are based on the assumption that the number of lamps produced
in each of the years would have been produced even if the amount of
time required per lamp had remained the same as in 1920. There
were extensive reductions in prices during the period since J920,6 and
these reductions, which were partly due to the declining cost of labor,
undoubtedly had some effect in stimulating the demand for lamps
and thereby in causing an increase in production. In the making of
any portion of the increased output which would not have been made
if there had been no reduction of labor time per lamp, there is no
saving of labor by the employer or no loss of opportunity for employ­
ment from the worker’s point of view. The increased production of
1929, for example, as compared with 1920 was probably due in part
to the decrease in unit time requirement from 0.099809 man-hour in
1920 to 0.024851 man-hour in 1929. But the increased production
of 1929 as compared with 1928 was essentially unaffected by the
reduction in unit time requirement in 1929 as compared with 1928.
The purpose of table 7 is to correct the overestimate of the long­
term effects of technological changes shown in the second section of
table 6. This overestimate is due to the fact that the reduction in
time required per lamp in each successive year is based on the unit
time requirement of 1920, and thus fails to take into account the
probability that increased production was in part dependent on
declining labor cost. In table 7 the unit time requirement of each
year is compared with that of the preceding year, with the exception
of years of declining production. Since the purpose of using each
preceding year as the base is to discount the effects of declining unit
time requirement on volume of production when production is in­
creasing, the unit time requirement of 1922 and of 1923 is compared
with that of 1920, and similarly, the 1931 unit time requirement is
compared with that of 1929.
The total reduction of labor time in 1921 as compared with 1920,
as measured by the change in unit time requirement, was 2,495,000
man-hours, equivalent to about 1,185 workers. The total production
in 1922 remained below that of 1920, and a direct comparison is
therefore made with 1920, with an indicated total reduction in labor
time, as measured by reduction in unit time requirement, of 6,518,000
man-hours, equivalent to about 3,096 employees. The first year to
show an increase in production over 1920 was 1923, and it may be
assumed that this increase was a result not of reduction in labor cost
but of the general revival of business. Therefore there is still a direct
comparison with 1920, indicating that the total reduction of labor time
•See p. 3.




CHANGES IN LAMP-ASSEMBLY PLANTS

43

in 1923 as compared with 1920, and as measured by the reduction in
unit time requirement, amounted to the equivalent of 6,425 workers.
T a b l e 7. — Reduction of labor time in electric-lamp-assembly plants, 1920 to 1981,

estimated on basis of reductions in unit time requirement
[Except in years of declining output, each preceding year is used as base]
Man-hours

Year

In making total number of
lamps

Number of
lamps
Total
number

1920..................................
1921_______________
1922__________________
1923__________________
1924________ __________
1925__________________
1926_______________— .
1927..______ __________
1928______________ ____
1929______________ ____
1930....... - _____________
1931. __________________

Reduction of labor time, based on time
required per lamp in each preceding
year

362,140,000
242,515,000
311,265,000
404,226,000
435,172,000
459,275,000
482,455,000
544,512,000
556,953,000
643,957,000
553,199,000
503,350,000

Per lamp Per lamp

Manhours

Equiv­ Annual
alent saving
Man-hours number as com­
pared
of
workers1 with
1920

36,145,000 0.099809 0
0
21,710,000 .089520 0.010289
2,495,000
24,549,000 .078868 a.020941 2 6,518,000
26,821,000 .066351 2 .033458 2 13,525,000
22,079,000 .050736 .015615
6,795,000
19,753,000 .043009 . 007727
3,549,000
17,576,000 . 036430 .006579
3,174,000
17,922,000 . 032914 . 003516
1,915,000
2,355,000
15,976,000 . 028685 .004229
16,003,000 .024851 .003834
2,469,000
13,424,000 . 024266 .000585
324,000
.
11,448,000 . 022743 < 002108 * 1,061,000

Workers

0
0
1,185
1,185
3,096
3,096
6,425
6,425
3,228
9,653
1,686 11,339
1,508 12,847
910 13,757
1,119 14,876
1,173 16,049
154 3 13,941
504 «13,054

1 Based on average number of hours per employee per year (2,105).
2 Unit time requirement in 1920 used as base, because output of 1922 was smaller than that of 1920, and
therefore the decrease in unit time requirement obviously resulted from technological changes and was
independent of changes in output.
3 The reduction in labor for 1929 (16,049) applies to 1930 only in the ratio of 1930’s output to that of 1929
(85.9 percent).
* Unit time requirement of 1929 used as base, because of declining output. See note 2.
« The reduction in labor for 1929 (16,049) applies to 1931 only in the ratio of 1931’s output to that of 1929
(78.2 percent).

In 1924, production continued to increase, and unit time require­
ment continued to decline. It is possible that none of the increased
production is attributable to the reduced amount of time required
per lamp since 1920. But the long-term downward trend of unit
time requirement probably had some effect on the rising production
curve even as early as 1924. Therefore, the 1920 unit time require­
ment is no longer used as the base, and that of 1923 is substituted.
The reduction in unit time requirement of 0.015615 man-hour in 1924
as compared with 1923 is multiplied by the number of lamps produced
in 1924 (435,172,000), and the result indicates a total reduction of
6,795,000 man-hours, equivalent to 3,228 workers in 1924 as compared
with 1923.
But it is desired to estimate the effects of technological changes in
each year as compared not with the preceding year but with 1920.
If it is assumed that in 1924 the output and the unit time requirement
remained the same as in 1923, there would still be a saving of labor in
1924 equal to that of 1923, that is, 6,425 employees. But because of
the change in the volume of output and in the unit time requirement
there was a saving in 1924 as compared with 1923 of 3,228 employees.
Therefore, by adding 3,228 to 6,425 there is obtained a conservative
indication (9,653) of the saving in labor time in 1924 as compared with
1920, due mainly to technological changes, after discounting the effects
1762°—33----- i




44

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

of technological changes in adding to the volume of output in 1924.
In a similar manner it may be assumed that if in 1925 the output and
the unit time requirement had remained the same as in 1924 the labor
saved in 1925 as compared with 1920 would have amounted to 9,653
employees. By adding the saving in 1925 as compared with 1924
due to the changes in output and unit time requirements in 1925 the
total saving in number of workers in 1925 as compared with 1920
becomes 11,339. The same method is used for each year in turn
except for the years 1930 and 1931. Because of the decline in output
during these years the reduction in amount of labor for 1929 as com­
pared with 1920 (16,049 employees) applies to 1930 and 1931 only in
the ratio of the output of each of these years to that of 1929. The
amount of labor saved in 1931 as compared with 1920 is computed
on this basis at 13,054 workers.

Production and Employment in Plants Making Parts
An account of the processes of manufacturing the more important
parts used in lamp-assembly plants has already been presented.7
The main parts, as has already been seen, are the filament, the lead-in
wires, glass tubing, bulbs, and bases. In compiling information re­
garding the volume of output and volume of labor in the manufac­
ture of lamp parts during the years 1920 to 1931 a number of diffi­
culties make exact and complete analysis impossible. Some of the
parts are made in plants which are not a part of the lamp industry.
Especially is this true of glass tubing and bulbs. In the case of the
lamp companies, there have been changes in the extent to which
they have made their own parts instead of purchasing them. There
has also been a difficulty connected with the separate classification
of labor devoted to the making of parts for electric lamps and parts
for other uses, as, for instance, radio tubes.
Glass Bulbs for Large Lamps
The case of bulbs is particularly interesting because of popular
confusion regarding changes in methods of manufacturing bulbs and
the effects of these changes on volume of labor. In this connection
the following is a widely quoted statement: “ An electric-lamp
machine, recently installed, has a production of 531,000 lamp globes
a day, an increase per man of 9,000 times the method previously
employed.” 8 This statement, as it has been popularly interpreted,
involves a number of confusions. In the first place, the terms “ globe ” ,
“ bulb” , and “ lamp” have been confused, and the statement has been
applied to the finished lamp, whereas in the process of manufacture
the bulb is merely the outer glass part in which the lamp is sealed.
In the second place, the figure 9,000 should be regarded as an index
number with 100 as the base, and this 90-fold (not 9,000-fold) increase
in productivity results not from the introduction of a single machine
but from a large number of technological changes extending over
more than a decade. In the third place, this indication of change in
the productivity of labor applies not to the entire lamp industry,
and not even to most of the labor required for the making of bulbs,
but only to that portion of the labor which is required for the actual
*O C pp. l^ U .
C
8Statement attributed to the group known as Technocracy, in the New York Times, Aug. 21,1932,




45

PRODUCTION, ETC., IN PLANTS MAKING PARTS

operation of machines for making bulbs for large lamps as distinguished
from miniature lamps.
The effects of improved machinery in multiplying the produc­
tivity of labor are illustrated in a remarkable manner by the data
shown in table 8 9 for the making of glass bulbs for large electric
lamps. The table deals only with 25- and 40-watt bulbs, but these
may be regarded as typical of the standardized types. The effects of
the more important steps in the transition from hand production to
automatic production are clearly shown by means of typical samples of
output. The index of output per man-hour from 1916 to 1932 runs
from 100 to 8645.5— more than an 86-fold increase— in the case of 25watt bulbs, and from 100 to 7171.3— nearly a 72-fold increase— in the
case of 40-watt bulbs. These indexes do not reveal the full extent of
the transition, for the reason that comparable figures relating to the
most recent improvement, the so-called ribbon bulb machine,1 are not
0
available. The output of a single unit for 24 hours runs beyond
half a million bulbs, but the exact number of man-hours is not known
and therefore the index of man-hour output is omitted.
The figures for man-hour output presented in table 8 apply only to
labor used in the actual operation of the machines named in the
table. Labor required for preparing the materials, for feeding the
furnace, for inspecting the bulbs, and for various other operations is
not included.
T a b l e 8 . — Estimated changes in the productivity of hand and machine labor in

selected plants in making glass bulbs for 25- and 40-watt electric lamps

Method of production

Year

Num­
ber of
workers
per unit

Num­
ber of
unithours

Output per manhour
Num­ Number of Output
ber of bulbs pro­ per unitIndex
manhour
(output
duced
hours
Bulbs in plant
A =100)

25-watt bulbs

Hand production: Plant A—. 1916-19
Hand production: Plant B— 19231
.
Semiautomatic machine
(Empire E )........................ 1925 *
Automatic machine (Empire
F)__................................... 1925 i
Automatic (24-spindle West­
1925
lake, old type).......... -.......
Automatic (24-spindle West­
lake, new type).................. 1925 3
D o._....................... ....... 1931-32 <
Automatic (48-spindle Ohio). 1931-32 5
Ribbon bulb machine______ 1932 «

2H 63,946 143,879
2H 1,573 3,539
3

7,556,500
198,941

Bulbs

118.2
126.5

52.5
56.2

100.0
107.0

912

3,192

370,492

406.2

116.1

221.1

2M 1,898

4,428

3,550,427

1,870.6

801.8

1527.2

11,302 14,514,503 2,139.5

1,284.2

2446.1

2,336.9 1,699.3
3,537.7 2,573. 7
6,242.2 4,538.9
20,762.0

3236.8
4902.3
8645.5

m

6,784

lH

2,596
558
1,908
653

m

lH

3,570 6,066,484
767 1,974,031
2,624 11,910,157
13,557,900

40-watt bulbs

Hand production: Plant A „ . 1916-18
Hand production: Plant B „ . 1923 «
Semiautomatic machine
(Empire E )_____ _____
1925«
Automatic machine (Empire
F)_____________________ 1925 8
Automatic (24-spindle West­
1925
lake, old type)----- ------ ----Automatic (24-spindle West­
1925
lake, new type)— ............
Do— ....................-....... 1931-32 7
Automatic (48-spindle Ohio). 1931-32»
Eibbon bulb machine
___ 1932 6
» 7 months.
24 months.

M 205,686 462,794
2H 2,463 5,544

24,361,352
309,143

118.4
125.5

1,324,494

52.6
55.8

100.0
106.1

3M 3,247

11,364

407.9

116.6

221.7

2M 3,010

7,022

5,530,679 1,837.4

787.6

1497.3

m

9,058

15,091

19,915,140 2,198.6

1,319.7

2508.9

m
m
m

5,244
1,157
939
379

7,211
1,591
1,291

2,342.5 1,703.5
3,341.8 2,430.2
5,186.1 3,772.1
19,633.0

3238.6
4620.2
7171.3

311 months.
414 months.

12,283,960
3,866,497
4,869,767
7,440,800

•16 months.
66 months.

713 months.
815 months.

9 Table 8 has been compiled in part from material contained in U.S. Bureau of Labor Statistics Bui. No.
441: Productivity of Labor in the Glass Industry, Washington, 1927, pp, 127-131, and in part from later
material furnished by manufacturers.
» See pp. 21-23.




46

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

The productivity of labor as a whole used in the manufacturing of
glass bulbs for large electric lamps during the years 1920 to 1931 is
computed in table 9. For certain minor portions of the industry
direct figures were not available, but on the basis of available informa­
tion the estimates contained in the table are a close approximation for
the entire industry. On the basis of changes in the number of bulbs
and changes in the number of man-hours the index of productivity of
labor (100 in 1920) ranges from 82.7 in 1921'to 487.6 in 1931. It will
be noted that this change in the rate of productivity for the entire
labor force used in the manufacturing of bulbs for large lamps is
radically different from the indexes of the productivity of machine
labor in table 8. The change in the productivity rate from 100 to
487.6, applying to all labor in the large bulb plants, corresponds
closely to the changes in the productivity of all labor in the lampassembly plants as presented in table 3, where the index runs from
100 to 438.9. Table 9 also includes changes in the number of workers
actually employed, estimated changes in number of workers equated
on the basis of average hours worked, the number which would have
been required if the productivity rate of 1920 had continued, and the
number which would have been required if the output had remained
constant from 1920 to 1931.
T able

9.— Estimated changes in output and employment in plants for making glass
bulbs for large 1 electric lamps, 1920 to 1931
Employees

Year

1920................................
1921................................
1922................................
1923................................
1924................................
1925................................
1926................................
1927................................
1928................................
1929.^................ ............
1930...............................
1931............................. .

Number of em­
ployees required
on basis of—

Index of
Equated on basis of
produc­
numberof hours per
Number of Number of tivity of
bulbs made man-hours labor Average employee in 1920 Pro­
(1920= number
ductiv­ Output
100)
Index ity rate of 1920
Num­
(1920= of 1920
ber
100)
255,815,000
199,989,000
257,892,000
308,707,000
244,218,000
299,517,000
327,649,000
377,910,000
334,915,000
388,159,000
360,726,000
348,203,000

6,587,400
6,226,700
3,352,200
2,886,400
2,537,600
1,942,800
2,466,500
2,346,400
2,031,700
2,005,000
2,077,400
1,840,000

100.0
82.7
198.2
275.8
247.9
397.4
342.3
415.2
424.7
499.0
447.4
487.6

2,892
2,873
1,485
1,288
1,093
863
1,092
1,042
905
836
919
968

2,892
2,733
1,472
1,267
1,114
853
1,083
1,030
892
880
912
808

100.0
94.5
50.9
43.8
38.5
29.5
37.4
35.6
30.8
30.4
31.5
27.9

2,892
2,260
2,918
3,494
2,762
3,390
3,707
4,277
3,788
4,391
4,080
3,940

2,892
3,497
1,459
1,049
1,167
728
845
697
681
580
646
593

i As distingushed from miniature lamps, the bulbs for which are usually made from tubing.

An incidental phase of the manufacture of glass bulbs is the develop­
ment of the process known as inside frosting.1 This recently de­
1
veloped process involves an additional amount of work in the making
of bulbs. Effects of the changes in methods of carrying on the process
in typical units are shown in table 10. The index of output per manhour increased from 100 in 1927, when the process was largely manual,
to 175.9 in 1929, when mechanical control had been introduced.
The later use of electrical control was largely responsible for the in­
crease of the index of productivity to 264.6 in 1932.
See pp. 20-22,




47

PRODUCTION, ETC., IN PLANTS MAKING PARTS
T able

10.— Changes in productivity of labor in inside-frosting department of a
glass-bulb factory (24-hours’ operation) , 1927, 1929, and 1932
Number Number Number
of em­
ployees of hours of bulbs
(3 shifts) worked frosted

Year

51
42
33

1927 (hand method)____________________________
1929 (mechanical method)_______________________
1932 (electrical control)_________________________

408
336
264

Output per manhour
Bulbs

245,351
355,104
419,688

601
1,057
1,590

Index
100.0
175.9
264.6

Glass Tubing and Miniature Bulbs
The making of glass tubing 1 has been marked by radical innova­
2
tions, but complete statistics covering indirect as well as direct labor
are not available. Changes in the productivity of hand and machine
labor in selected plants in making tubing are analyzed in table l l . 1
3
T able

11.— Estimated changes in the productivity of hand and machine labor in
selected plants for making glass tubing

Method of production

Year

Sizes 19-21 (1,100 to 890 inches per
pound):
Hand production.................... 1917-18
19251
Danner machine_____ _____
Improved Danner process
1929
1931
Do____________ _______
Sizes 32-34 (270 to 216 inches per
pound):
Hand production___________ 1917-192
1925
Danner machine.....................
1929
Improved Danner process___
1931
Do.— ..............................

Num­
ber of
work­
ers
per
unit

Num­
ber of
unithours

Output per
Num­
Output
man-hour
ber of Tubing
per
man- produced unithours
hour Pounds Index

8
4
3M
3X

10,309 82,472
4,000 16,000
2,231 7,809
1,108 3,878

Pounds

Pounds

79.7
235.7
394.8
368.4

10.0 100.0
58.9 589.0
112.8 1128.0
105.3 1053.0

8
4
2M
2M

18,900 151,200 1,522,152
6,579 26,316 1,978,281
6,766 16,915 2,378,797
2,073 5,183 661,359

80.5
300.7
351.6
319.0

10.1
75.2
140.6
127.6

821,176
942,968
880,900
408,226

100.0
744.6
1392.1
1263.4

19 months.
2 January 1917 to June 1919.

On the basis of the operation of machines during selected periods,
the output of specified sizes of tubing and the number of man-hours
used in the actual operation of the machines are compared for the
purpose of showing changes in the productivity of labor. These
changes with respect to tubing of sizes 19 to 21 run from 100 in 1917
to 1053 in 1931— more than a tenfold increase in productivity. In
the case of tubing of sizes 32 to 34 the productivity index runs from
100 in 1917 to 1263.4 in 1931— almost a thirteenfold increase, but in
this case, as in the case in table 8, relating to direct labor in the
making of large bulbs, the changes in the rate of productivity for all
labor used in the making of tubing are very much smaller.
As has already been stated in connection with the description of
the making of miniature bulbs,1 most of the bulbs of this description
4
For description of the processes see pp. 16-18.
1 Table 11has been compiled in part from data contained in U.S. Bureau of Labor Statistics Bui. No. 441:
3
Productivity of Labor in the Glass Industry, Washington, 1927, pp. 143, 144, and in part from data fur­
nished by manufacturers.
i* See pp. 18-19..
12




48

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

are made from glass tubing. The estimated changes from 1920 to
1931 in output and employment in all plants for making bulbs for
miniature lamps are analyzed in table 12.
T able

12.— Estimated changes in output and employment in plants for making
glass bulbs for miniature electric lamps, 1920 to 1931
Number of
Index of productivity Employees (total) employees
of labor (1920= 100)
required on
basis of—

Man-hours

Year

Direct Indirect
labor
labor

1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931

Total
labor

Equated on
basis of
number of Pro­
hours per
Aver­ employee duc­ Out­
In­
Direct direct Total age
tivity put
in 1920
labor labor labor num­
rate of
ber
of
1920
Index 1920
Num­ (1920=
ber
100)

622,700
342,100
309,500
371,400
459,900
404,600
349,700
330,600
347,000
335,400
296,100
209,800

100.0
188.9
205.8
566.6
592.8
699.4
720.1
764.0
859.2
895.4
903.4
915.3

Number
of bulbs
made

117,170,000
71,850,000
95,646,000
145,979,000
173,400,000
175,030.000
188,891,000
194,135,000
232,459,000
269,711,000
205,740,000
168,143,000

232,900
75,600
92,400
51,200
58,100
49,800
52,200
50,500
53,800
59,900
45,300
36,500

389,800
266,500
217,100
320,200
401,800
354,800
297,500
280,100
293,200
275,500
250,800
173,300

100.0
89.7
146.5
151.5
143.5
163.8
211.0
230.2
263.5
325.2
272.4
322.3

100.0
111.7
164.4
209.0
200.5
230.3
287.2
312.2
356.4
427.7
369.7
426.1

259
330
226
214
193
161
142
155
202
204
196
140

259 100.0
142 54.8
129 49.8
154 59.5
191 73.7
168 64.9
145 56.0
138 53.3
144 55.6
140 54.1
123 47.5
87 33.6

259
159
212
322
383
387
416
431
513
599
455
371

259
232
158
124
129
112
90
83
73
61
70
61

It has been found possible to divide the labor used in the making
of miniature bulbs into direct labor and indirect labor. These terms
are not always used consistently, and the number of man-hours
assigned to each class of labor is approximate. One definition of
direct labor, widely but not universally accepted, describes it as labor
which modifies the physical conditions or appearances of products or
which is concerned with the inspecting or handling of products. From
this definition it is apparent that direct labor includes some labor in
addition to what is required for the actual operation of machines.
In miniature-bulb plants the number of man-hours of direct labor
is much more variable than the number of man-hours of indirect labor.
In other words, direct labor is much more flexible, and can be made to
conform in volume much more readily to changes in methods and to
changes in volume of output. The productivity index of direct labor
tends consistently upward from 100 in 1920 to 915.3 in 1931. (See
table 12.) The index of productivity of indirect labor, on the other
hand, fluctuates widely and in 1921, with the falling off of volume of
production, the productivity rate declines to 89.7. A slight decline
in the productivity rate appears also in 1930 and 1931, and is to be
accounted for by the fact that the volume of indirect labor is not so
readily adaptable to changing volume of output as is the volume of
direct labor. In consequence the index of productivity of direct and
indirect labor combined also shows a decline in 1930 and 1931. The
index for the aggregate of both classes of labor runs from 100 in 1920
to 427.7 in 1929 and then tends downward to 369.7 in 1930, but rises
again to 426,1 in 1931.




PRODUCTION, ETC., IN PLANTS MAKING PARTS

49

In connection with the making of miniature bulbs it should be noted
that the transition to automatic methods had already been effected
very largely by 1920. In a typical plant, for instance, in 1920, only
3,650,000 bulbs were produced by hand methods while 87,550,000
bulbs were produced by automatic methods. The principal technical
changes accounting for the increased productivity of labor since 1920
were connected with the perfecting and speeding up of automatic
machines.
Lead-in Wires
In the making of lead-in wires 1 only a small percent of total labor
5
is used. The portion of the lead-in wire which is sealed in the glass
is made of dumet wire. In the making of dumet wire there have been
no essential technological changes since 1920. In table 13 are shown
the production in meters, the number of employees, and the average
output per employee from 1920 to 1931. The productivity of em­
ployees engaged in making dumet wire fluctuated widely, ranging as
low as 63 in 1922 (from 100 in 1920) and as high as 305 in 1929. In
so small a group of workers the variations in volume of output do not
readily find proportionate effect on volume of employment.
T able

13.— Changes in productivity of labor in a plant for making dumet wire,
1920 to 1931

Year

1920.......................................... ........... ......................
1921________________ ___________________________
1922___ _________ _____________________ _________
1923........ ............................-....... ..................................
1924.................................................. ............ ...............
1925— ................................. .........................................
1926— __________ ________________ _____________
19271
____ _______ ___ __________________________
1928...............................................................................
1929.............................................. ..................................
1930 2
________ ___________ _____________________
1931 3 _ ____________________ ___________________
_

Production
of wire

Meters

5,474,773
3,414, 236
2,779,375
4,782,627
7,204,775
6,873,878
6,879,484
16,883,280
23,258,129
31,760, 287
16,889,999
11,618,108

Number
of em­
ployees

10
7
8
9
9
9
13
17
19
19
15
11

Average output of wire
per employee
Meters

547,477
487,748
347,422
531,403
800,531
763,764
529,191
993,134
1,224,112
1,671, 594
1,126,000
1,056,192

Index
(1920=
100)

100
89
63
97
146
140
97
181
224
305
206
193

1Production of plating core rods was increased by dipping 140 instead of 10 at a time.
2Number of rods annealed in 1 operation was increased from 105 to 140.
* Decreased productivity was partly due to retention of surplus labor beyond production requirements.

The sealed-in portion of the lead-in wire (the part made of dumet
wire) is welded to the other portions by machines which have not
undergone any fundamentally important change since 1920. One of
the earlier automatic devices was the double electric machine for
making welds, and changes in the productivity of labor in the opera­
tion of this machine are shown in table 14. From 1919 to 1931 the
productivity of labor used in the direct operation of these machines
increased from 100 to 255. This increase was due in part to the per­
fecting of the machine in such manner as to make higher speeds and
w See pp. 14-16.




50

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

increased output practicable. This is indicated by figures for each
year for average production per machine and. for speed shown in
table 14.
T able

14.— Changes in 'productivity of labor in operation of double electric machine
for making welds, in selected plants, 1919 to 1931
[1919=100]

Year

1919.
1920.
1921.
1922.
1923.
1924.
1925.
1926.
1927.
1928.
1929.
1930.
1931.

Number
Index of productivity per
Number of workers
of ma­
worker
Average
Speed
chines production (revolu­
(includ­
per ma­ tions per
ing idle
minute) Machine Inspec­ Machine Inspec­
chine
Total
ma­
tion
tion
labor
labor
labor
chines)
labor
labor
35.000
40.000
43.000
44.500
44.500
44.500
44.500
47.700
46.700
47.500
48.700
50,600
49.500

74
92
92
92
92
92
92
106
106
106
106
106
106

100
122

154
159
159
159
158
164
137
140
250
260
255

100

107
119
124
124
124
123
127
125
127
130
135
132

100

111

128
132
132
132
131
136
128
130
152
158
154

The increase in productivity of machine labor is also due in part
to an increase in the number of machines without a proportionate
increase in the number of employees to operate the machines, as is
indicated by figures in table 14. The increase in the productivity
of inspection labor was much smaller, ranging from 100 in 1919 to
132 in 1931.
Among the other machines used for the making of welds (welding
the dumet wire to the other portions of the lead-in wire) are the
miniature percussive machine and the large percussive machine. The
changes in the productivity of machine labor and inspection labor
used in the operation of these machines are estimated in tables 15 and
16. In these cases, as in the case of the double electric machine, the
productivity of machine labor increased much more rapidly than the
productivity of inspection labor. In the case of the miniature per­
cussive machine, productivity of machine labor increased from 100
in 1921 to 277 in 1931, due in part to an increase in the number of
machines and in part to more efficient operation of the machines,
leading to increased output per machine (table 15). In the case of
the large percussive machine the increase in the productivity of
machine labor from 100 in 1922 to 305 in 1931 is attributable to the
same causes and also to an increase in speed of the machine (table 16).
These statistics relating to the making of lead-in wires involve
such small numbers of workers as to be of no special significance;
but they illustrate the difference between the effects of technological
changes on direct machine labor as compared with other labor such
as is used in the inspection of the output. They illustrate also the
comparative difficulty of maintaining flexibility in the volume of
labor in proportion to changes in the volume of output when, as in
this case, the volume of labor is already small and highly specialized.




51

PRODUCTION, ETC., IN PLANTS MAKING PARTS
T able

15.— Changes in productivity of labor in operation of miniature percussive
machine for making welds, in selected plants, 1921 to 1981
[1921=100]
Number of workers

Year

Number
of ma­
chines

1921.......................
1922_____________
1923_____________
1924_____________
1925_____________
1926_____________
1927_____________
1928_____________
1929_____________
1930_____________
1931— ____ _____

T able

8
8
8
9
8
12
17
17
17
17
17

Average
produc­
tion per
machine

. Welds
41,500
41,500
41.500
49.500
49,500
49,500
47,400
55,400
55,600
55,200
54,100

Speed
(r.p.m.)

Index of productivity per
worker

Machine
labor

Inspec­
tion la­
bor

Machine
labor

Inspec­
tion la­
bor

3
3
3
3
3
3
3
3
3
3
3

8
8
8
9
8
12
17
17
17
17
17

100
100
100
134
119
179
243
284
285
283
277

100
100
100
119
119
119
114
133
134
133
130

138
138
120
120
120
120
120
120
120
120
120

Total
labor

100
100
100
123
119
131
133
156
157
155
152

16.— Changes in productivity of labor in operation of large percussive machine
for making welds, in selected plants, 1922 to 1981
[1922=100]
Number of workers

Year

Number
of ma­
chines

Average
produc­
tion per
machine

Welds

1922_____________
1923_____________
1924____________
1925_____________
1926_____________
1927_____________
1928_____________
1929_____________
1930____________
1931_____________

5
6
9
9
33
54
39
28
35
35

31.000
30.000
32,600
33,600
35,900
35,900
38,300
38.700
39.700
40,500

Speed
(r.p.m.)

Index of productivity per
worker
i

Machine
labor

Inspec­
tion la­
bor

Machine
labor

Inspec­
tion la­
bor

2
2
3
3
8
11
8
5
6
6

5
6
9
9
33
54
39
28
35
35

100
116
126
130
191
227
241
280
299
305

100
97
105
108
116
116
124
125
128
131

74
74
74
74
83
83
86
86
86
86

Total
labor

100
102
110
114
130
135
144
148
153
156

Bases
Table 17 contains estimates of the changes from 1920 to 1931 in
the number of bases produced, in the average number of employees,
in the number of man-hours, and in the average output per manhour. The figures are in part derived from actual records and in
part computed on the basis of ratios which are believed to be con­
servative. W ith the exception of the year 1921, when an abnormal
decline in output occurred, the index of the average output per manhour has been higher than in 1920 and has increased materially even
during the years 1930 and 1931 when the output was declining. The
estimated number of man-hours declined from 1,023,900 in 1920 to
619,300 in 1921 and then increased by 1929 to 1,006,300, after which
occurred a decline to 641,700. The index of productivity declines
from 100 in 1920 to 72 in 1921 and then rises for the most part
consistently to 189 in 1931.




52

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

Some of the most important of the machines used in the making
of bases were developed before 1920. The changes in the produc­
tivity of labor in the making of bases are attributable in large degree
to more efficient operation of machines and to improvements of a
secondary nature in the handling of materials and of the bases in
the various stages of manufacture, as for instance the development
of more efficient conveyor systems.
T able

17.— Estimated changes in 'productivity of labor in making of bases for
electric lamps, 1920 to 1931

Year

1920................................................................
1921................................ ..............................
1922. .............................................................
1923_______________ _____ ___________
1924....... ......................................... .............
1925...............................-.........—............... .
1926__________ _______ _________ _____
1927__________________________________
1928-____ _____________ _________
1929. ...................................... -.........-....... —
1930............ .................. -.........- ...........-.......
1931____________ ___________ ____ _____

Estimated Estimat­ Estimated
ed
number of age aver­ number of
num­
bases pro­ ber of em­ man-hours'
duced
ployees

432.068.000
187.648.000
348.932.000
442.751.000
435.901.000
463.571.000
488.024.000
565.616.000
573.129.000
713.849.000
559.017.000
513.001.000

455
275
314
375
389
352
330
350
361
405
348
317

i

1,023,900
619.300
706.300
843.000
875.300
788.700
786,200
803,400
806.000
1,006,300
797,500
641.700

Average output per
man-hour

Number

422
303
494
525
498
588
621
704
711
709
701
799

Index
(1920=
100)
100
72
117
124
118
139
147
167
168
168
166
189

Changes in Employment in All Branches of the Industry
In the entire electric-lamp industry it is possible to classify the
labor used under the following four heads:
(1) Labor used in lamp-assembly plants;
(2) Labor devoted to the manufacturing of parts;
(3) Workers in the equipment divisions, which are concerned with
the development and testing of machinery and other equipment
used in the manufacturing of lamps and parts; and
(4) Nonmanufacturing labor connected with sales, home offices,
and warehouses.
Information is less adequate regarding the number of workers
outside of lamp-assembly plants than in them, especially for the earlier
years of the period from 1920 to 1931. For a large portion of the
industry available information makes possible accurate estimates,
but for the industry as a whole these estimates must be regarded as
indicating only the trends.
The most radical change in number of workers between 1920 and
1931 occurred in lamp-assembly plants. In 1920 the proportion of
total labor employed in these plants was about 59 percent; by 1931
it had declined to about 42 percent. The proportion of labor used
in the manufacturing of parts, 23 percent in 1920, declined somewhat
thereafter, but by 1931 it had risen to approximately the same percent
of the total. Labor devoted to the development and testing of equip­
ment rose from about 3 percent in 1920 to about 6 percent in 1931.
Nonmanufacturing labor increased from about 15 percent in 1920 to
about 29 percent in 1931.




53

CHANGES IN EMPLOYMENT IN INDUSTRY

The rate of productivity of labor in each of the four main classifica­
tions and in all classifications combined may be estimated by dividing
the total number of lamps produced by the number of workers in each
classification, and by the total number of workers. The basic figures
are approximations with regard to certain portions of the industry,
and the results must therefore be viewed, when applied to the entire
industry, as indicating merely the trends. On the basis of available
data the changes in rates of productivity of labor, as compared with
1920, are estimated as follows:
T able

18.— Rate of productivity of labor in the main classifications of the electriclamp industry, 1920 , 1929, and 1931
Classification

1920

1929

1931

Lamp-assembly plants______________________________________
Manufacturing of parts_____________________________________
Equipment divisions_______________________________________
Nonmanufacturing divisions_________________________________

100
100
100
100

i 448
349
166
192

1457
324
167
175

Total___________________________________ ____________

100

340

329

1 These estimates of productivity differ from those given in table 6 because they apply only to portion
of the industry for which full information is available regarding employment outside of lamp-assembly
plants and because they are based on average number of employees instead of man-hours.

In the nonmanufacturing divisions important technological changes
occurred alike in office equipment and in managerial technique. But
supervisory work, sales, and general overhead activities are naturally
less affected by labor-saving innovations. This is due in part to the
nature of the work and in part to the more stable tenure of positions
in these phases of the industry. Employees are more commonly
engaged on a monthly or annual basis, and separations from employ­
ment follow less readily any downward trend of output than in those
divisions where hourly or daily rates of pay prevail. Similarly, when
the volume of production is increasing, employees in the nonmanu­
facturing divisions are able to handle any additional work with a
minimum increase in numbers. Because of these conditions, the
volume of nonmanufacturing labor fluctuated with changes in output
less readily than in the case of manufacturing labor, especially in
lamp-assembly plants. This is indicated by a comparison of the rates
of productivity for 1929 and 1931 in table 18, the rate falling in the
nonmanufacturing divisions and continuing to rise in assembly plants.
In the divisions devoted to the making of parts, many vital techno­
logical changes were made, as in the manufacturing of bulbs, but
many phases of parts manufacturing were slightly affected by laborsaving innovations, especially after 1920. Furthermore, in these
plants and in the equipment divisions the number of employees was
too small, and the proportion of supervisory labor was too large, to
make possible a facile adjustment of the volume of labor in response
to changes in the volume of output.
In lamp-assembly plants, on the other hand, conditions facilitated
a flexible adaptation of employment to changes in production. The
number of workers in these plants was comparatively large, the
stability of tenure of the supervisory force was a relatively insig­
nificant factor, and the use of automatic machinery and of new mana­
gerial technique was more extensively feasible. The outstanding
effects of technological changes on volume of labor were therefore
experienced in lamp-assembly plants.




Appendix A.—Outline of the History of Lighting
Earlier Methods of Lighting
Early methods of lighting consisted mainly of open fires and primi­
tive sources of illumination involving lighting as an incidental function
or involving a minimum of fabrication or adaptation of materials
found in nature. Camp fires gave light as well as heat. Signal fires
were mainly for communicating intelligence., “ Brands from the
burning” in the form of unfabricated torches and rush lights were no
doubt widely used. Among the earliest arts and crafts appeared the
manufacturing of torches in the form of rosin splinters, rushes, stalks
of flax soaked with grease, etc.; and primitive peoples e a r t y learned to
fabricate torch holders as well as torches. Another primitive method
of lighting consisted of the use of fire baskets containing glowing coals
or inflammable material.
Among the more civilized groups of early times, as well as among
present-day peoples, the principal lighting device aside from the
electric lamp is the basin lamp in its various forms. Materials for
basins included natural stone, shells, pottery, metals, and glass.
Materials used for burning in basin lamps have ranged so widely as
to include animal oils derived from game and domestic animals, seal
oil, whale oil, lard, tallow, vegetable oils derived from various sources
such as nuts, rape seed, olives, and resinous woods (as camphene, a
purified oil of turpentine freed by distillation from rosin), and mineral
oils, particularly “ coal oil” or kerosene derived from petroleum.
Basin lamps have also included various auxiliary devices for con­
trolling the flame or for increasing its lighting power, such as wicks,
wick holders and chimneys. Wicks have been made of porous natural
fibers, such as moss, reeds, etc., but mainly from spun or woven
textiles. In connection with the control of the wick, of the flow of oil,
and of the burning process, the most primitive method is simply the
floating of the wick. A somewhat more ingenious device consisted of
a wick trough or channel or basin mouth (in some cases a series of
them) through which the wick protruded. The final development in
this connection consisted of separate wick holders or burners. These
were introduced in the latter part of the eighteenth century. There
are movable devices for adjusting the wick as it burns, snuffers for
removing the carbonized portion, and arrangements for controlling
the air currents to aid combustion. For the latter purpose tubular
air chambers were introduced below the flame and chimneys or
globes were added for enclosing the flame. The most highly devel­
oped basin lamp consists of the modern kerosene lamp with a glass
basin or bowl, a textile wick, an adjustable metal wick holder or
burner with air passages, and a glass chimney or globe. An obvious
modification of the ordinary basin lamp is the portable lamp or
lantern.
54




APPENDIX A .— HISTORY OF LIGHTING

55

Rivaling the basin lamp in antiquity and in extent of use is the
candle. Candles have been made of solidified oil or wax (ranging
from the ancient beeswax candles to the modernistic bayberry or wax
myrtle candles), of spermaceti (a fatty substance from sperm oil), of
tallow, and most recently and extensively of paraffin derived from
petroleum. The manufacture of candles with string wicks and of
candlesticks was long one of the leading industries. The primitive
method of making the candle was by dipping the string in the oil or
wax, but the use of molds operated first by hand and later by machin­
ery supplanted the primitive method.
Before the development of the electric lamp, gas lighting made
rapid headway against the more primitive lamps and candles. The
pioneer in gas lighting was William Murdock, who was connected
with the firm of Boulton & W att, at Birmingham, England, in the
latter part of the eighteenth century. He developed a process for
deriving gas from coal, and a method of using it in the Soho factories
near Birmingham. Murdock's first successful experiment was in
1792. Its use in the Soho plants passed beyond the experimental
stage in the early nineteenth century. It was used for lighting some
of the streets of London as early as 1807. Other materials besides coal
gas include natural gas, vaporized gasoline, and acetylene derived
from calcium carbide and water.
There have been two main types of gas burners. One type consists
of luminous or flame burners, the light coming directly from the com­
bustion as in basin lamps and candles. Burners of the second type
are incandescent and are commonly called gas mantles. Platinum
gauze was used, but was short-lived and uneconomical. The W elsbach mantle was patented in 1885, and in its various modifications
came into wide use.
In addition to the ordinary gas lamps there are what are known as
gaseous-conductor electric lamps, in contrast with electric-arc lamps
and electric-filament lamps. Recent developments in this field of
lighting have been particularly significant.1
6
The development of gas lighting, which before the ascendency of
electric lighting was a most promising phase of the Ughting industry,
has been severely restricted by the nse of the electric-lighting indus­
try. The most important remaining field in which gas lighting pre­
dominates is found in isolated places where electricity is not available
and where a better mode than the kerosene lamp can be afforded.
Early Control of Electric Phenomena
Among the most important incidents in the scientific and technical
background of electric lighting was the development of the battery
for generating electricity. This was derived primarily from the vol­
taic pile of Volta in 1799. Somewhat later came Farraday’s experi­
ments, from which is traceable the dynamo for converting electrical
energy into mechanical energy or into light. Generations of experi­
ment and invention and scientific study in all of the leading countries
contributed innumerable important elements. Particularly signifi­
cant was the discovery of the laws of electrical currents flowing
through wires. These are indicated by the terms in everyday use
in the industry. One of these is the term “ volt” , the unit for meas­
WSee pp. 7-8.




56

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

uring electromotive force. Another is the ampere, for measuring the
current. A third is the ohm, the unit of measurement of resistance.
Ohm’s law, which was propounded in 1825, is to the effect that a
current measured in amperes equals the electromotive force in volts
divided by the resistance in ohms. A fourth term in everyday use
is the watt, the unit of measurement of work done over a circuit.
It is not without significance to note that these four terms are from
the names of four outstanding scientists and inventors— one an
Italian, one a Frenchman, the third a German, and the last an
Englishman.

Jncandesce/itJ-am /t-.

A : Cbcrbtnfitamertt.
CC: TvuiwejiMgatinelftres.
J): JSaOny.

dire £ac.m.?L-.
AB: CarPoTtfflechvtttS.
CC'i Cojiduetcr#.
J): B attery.

Vozraicj&C‘

F ig u r e 13.—D ia g ra m s of in c an d escen t a n d a rc lamps.

The Electric-Arc Lamp
In a recent history of the electric lamp 1 there are illustrations of
7
19 electric lamps invented befori
”
1
)f 1879. The first
electric-arc lamp
successful electric lamps were
includes an open circuit between two electrodes, usually of carbon,
the electric discharge being accompanied by the ionizing of gas or
vapor between the electrodes. The light comes either from the
heated electrodes or from the gas or vapor between them or from
both. The incandescent lamp, on the other hand, has a closed cir­
cuit with a filament which evaporates very slowly and which is heated
so intensively as to give light.
1 Howell, J. W., and Schroeder, H. History of the Incandescent Lamp. Schenectady, 1927, pp. 25-44.
7




APPEND IX A .— HISTORY OF LIGHTING

57

The discovery of the electric arc is attributed to Sir Humphry
D avy in the first decade of the nineteenth century. Carbon sticks
or electrodes were attached to the two terminals of a battery. The
carbon or charcoal became white-hot. Upon the withdrawal of the
electrodes there was “ a constant discharge” between the points of
carbon, “ producing a most brilliant ascending arch of light”— an
electric arc.
The successful use of the electric arc in arc lamps in series, especially
for street lighting, dates from the late seventies. A t first the arc was
an open arc, but during the last decade of the century the enclosed
arc came into use. This furnished less light per watt, but the carbons
lasted much longer, the light was much steadier, and the lamps gave
less trouble. There was developed a self-adjusting double-carbon
arc lamp which automatically placed a second pair of electrodes in
operation when the first pair burned out.
In the early electric-arc lamps the source of light was mainly the
electrodes. The positive electrode or carbon furnished about 85 per­
cent of the light. Toward the end of the century there was developed
the enclosed flame arc, the arc itself having light-giving power due to
the impregnation of the carbons with such metallic salts as calcium
fluoride. B y such means there was about a threefold increase in the
amount of light per watt. There was also developed the luminous arc
produced by noncarbon electrodes, as, for example, the magnetite
arc lamp with one copper electrode and one hollow iron electrode
containing magnetite and titanium oxide. In still later developments
the source of light has included the gases used in the gaseous-conductor
electric lamps already mentioned.
Among the limitations of the electric-arc lamp were its relatively
large size and its use in series only. The development of an electric
lamp, small, compact, and adaptable to individual use as well as use in
series, awaited the genius of Thomas A. Edison.
The Carbon-Filament Lamp
A preliminary to the development of the individual electric lamp
in the form of the carbon-fllament lamp was Edison's multiple dis­
tribution system devised in 1878. The problem which he undertook
to solve was the problem of tapping the current for a single lamp as
distinguished from a series, as was necessary in the case of the arc
lamps then widely used, especially for street lighting. His solution
of the problem had three essential features. He developed a dynamo
with drum-wound armature having large wires for low resistance in
the armature. He made possible a constant voltage of about 110
between the brushes of the armature, the voltage remaining constant
in spite of variations in the consumption of current. He devised a
wiring arrangement for tapping current for any lamp desired. This
arrangement consisted at first of a 2-wire system, but in 1882 he
substituted a 3-wire system which effected a saving of 60 percent in
the amount of copper used.
Edison’s new dynamo theoretically made possible the supply of
current to any individual lamp desired; but in practice it was neces­
sary for him to develop a lamp with a much higher resistance in the
filament than that of any lamps then in existence. This necessity
he deduced from his application of Ohm’s law to the problem— the




58

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

rate of flow of current in amperes equals the force of the current in
volts divided by the resistance of the conductor in ohms. By trans­
posing the terms, the resistance in ohms equals the force in volts
divided by the rate in amperes. In a wire conductor resistance is
low in a large wire and high in a small wire, somewhat as is true of
the resistance to the flow of water in a pipe. That is to say, for a
given wattage (consisting of volts times amperes), low voltage means
high amperage requiring large wire, and high voltage means low
amperage with small wire. Edison’s conclusion was that he should
use high voltage and low amperage in order to attain the economy of
the use of small wire. The necessary conditions included a dynamo
of high voltage with suitable small high-resistance wire, and a cor­
responding high-resistance-filament lamp to be burned singly, as
compared with the carbon arc series lamps. The first condition was
met by his 110-volt dynamo and multiple distribution system for
burning lamps singly; but the second condition he had yet to meet
for existing lamps had a low resistance. The best available lamp was
a 110-watt lamp of 10 amperes and 11 volts. Its resistance, there­
fore, was 1.1 ohms, or 11 volts divided by 10 amperes. The remain­
ing problem, therefore, was the development of a high-resistance
lamp.
Edison’s aim was the development of a 110-watt lamp which would
compete with prevailing gas lamps to be used on a 110-volt circuit.
W hat must be the resistance of such a lamp? Its wattage is 110; its
voltage 110. Its amperage, therefore, would be 110 divided by 110,
or 1. Its resistance would be the quotient of the voltage divided by
the amperage, or 110 divided by 1, that is 110. It was necessary,
therefore, for Edison to make a change from the existing lamp of
1 ohm resistance to a lamp of 110 ohms resistance.
In order to achieve this end he undertook a quest for materials
which would enable him to develop a high-resistance filament. He
experimented with platinum, then generally used, but abandoned it
because it was too costly and too short-lived. •He then undertook a
prolonged study of carbon filaments. After absorbing available exist­
ing knowledge he carried out a series of experiments. The material
used would need resistance not only to the high voltage of the lamp
which he had in mind but to combustion, vaporization, and fusion.
It must also have suitable light-giving qualities. As the outcome of
his experiments he developed a cellulose thread which he carbonized
by extreme refinements of the methods used for carbonizing wood into
charcoal and coal into coke.
The lamp which he completed in 1879, and for which a patent was
granted in 1880, has been described as having four main features:
“ (1) A high resistance filament of carbon, in (2) a chamber made
entirely of glass and closed at all points by fusion of the glass, which
contained (3) a high vacuum and through which (4) platinum wires
passed to carry current to the filament.” 1
8
In addition to these primary features of the lamp itself there were
several secondary developments, mainly Edison’s work, which were
essential to the extensive use of the new lamp. Among these were
sockets, switches, lead fuses to protect the dynamo and the trans­
mission system, meters, and underground cables. An outstanding
development was the central power station. A temporary station
is Howell, J. W., and Schroeder, H. History of the Incandescent Lamp. Schenectady, 1927, p. 61.




APPENDIX A .— HISTORY OF LIGHTING

59

was built in lower New York in 1880. The first permanent station
was completed in 1882. It contained six large direct-current dynamos
and it served 58 customers using 1,284 sockets. The establishment
of this central power station is of utmost importance in the history
of other electrical industries as well as lighting. Although a consid­
erable development of commercial electric lighting was possible by
means of direct current, the successful use of an alternating-current
system by George Westinghouse at the Chicago World's Fair in 1893
had a revolutionary effect on the electric-lighting industry.
The Tungsten-Filament Lamp
Many improvements were made in the carbon-filament lamp. From
the mechanical point of view, perhaps the most notable improvement
was the squirted cellulose-carbon filament of 1888. From the point
of view of the light-giving efficiency of the filament a most important
improvement was the gem or metallized-carbon filament, which came
into use, however, only a short time before the development of the
tungsten filament.
In connection with the tungsten filament, which came into extensive
use as early as 1907, there have been three principal developments.
The first was the pressed-tungsten filament which was devised after
prolonged experiments in the reduction of the extremely difficult
tungsten ores. The pressed-tungsten filament, although extremely
efficient with respect to light-giving qualities, was fragile and could
not be used except in limited fields. W ith the development of the
drawn-tungsten-wire filament, however, the fragility was remedied,
and the light-giving efficiency also was increased. A third important
development in connection with the tungsten-filament lamp was the
substitution of the gas-filled lamp for the vacuum lamp. The gasfilled lamp came gradually into use after 1913.
Increase in Efficiency (Large Lamps)
The efficiency of the electric lamp is measured in terms of lumens
per watt. This expression “ represents the quantity of light (in a
practical sense) obtained from an incandescent lamp (or other source)
per unit of electrical power supplied to the source.” The watt, of
course, is the unit of current used, and consists of volts times amperes.
Available statistics of efficiency apply for the most part only to
large lamps. The efficiency of miniature lamps under actual operating
conditions— on automobiles, and under various other conditions—
cannot readily be ascertained. The following figures apply, therefore,
only to large lamps. The carbon-filament lamps of 1881 are estimated
to have had an efficiency of 1.68 lumens per watt, and those of 1906
an efficiency of 3.4 lumens per watt.1 The tungsten-filament lamps
®
of 1920 are estimated to have risen in efficiency to 10.6 lumens per
watt, and in 1931 to 13.4 lumens per watt.2
0
if Howell, J. W., and Schroeder, H. History of the Incandescent Lamp. Schenectady, 1927, pp. 83-84.
Electric Light Association. Keport of the Lamp Committee, June 1932. New York, p. 2.

2®
National




Appendix B.—Length of Life and Efficiency of Electric
Lamps
W ith most consumed products the length of time the product will
last in use is generally the most important element of its value. A
better tire, for example, is usually one which will last for a greater
number of miles, and progress in the art of making tires has been
largely a matter of making them last longer and cost less.
Because length of life is so commonly the correct criterion of value
in other products, it is a frequent error to consider the value of a
lamp as being based solely upon its length of life. In so doing the
consumer fails to give consideration to other fundamental elements of
lamp value and may frequently arrive at a conclusion which works
to his disadvantage.
The electric incandescent lamp is a device whose function is to
transform electric energy into light. The passage of the current
through the fine wire which forms the filament of the lamp heats
this filament so that it glows brightly. The high temperature, how­
ever, causes a gradual evaporation of the metal, so that the filament
becomes thinner and thinner, and after some hundreds of hours, it
usually burns through at some point and the lamp fails.
The life of the lamp— that is, the number of hours it will burn
before failure— depends upon two factors. The first is the tempera­
ture at which the filament is operated. A lower temperature
lengthens the life but reduces disproportionately the light output. A
higher temperature shortens the life but increases the light output.
The second factor is the inherent quality of the lamp; that is, the
value which the manufacturer has built into it. This factor is
influenced by the relative excellence of all the materials and the
precision of all the processes used in the fabrication of the lamp. If
a lamp of superior quality and a lamp of inferior quality are operated
so as to give the same amount of light and consume the same amount
of power, the lamp of superior quality will have the longer life. By
taking advantage of the longer life to be obtained through low fila­
ment temperature, a comparatively poor lamp can be made to last
for a comparatively long life, but long life obtained in this way is not
due to, nor evidence of, good value. On the contrary, that additional
life is obtained only by accepting low efficiency of light output which
is inevitably the penalty of low filament temperature.
A manufacturer of lamps could, if it seemed desirable, design lamps
for a very long life, actually 100 years or more, or for a very short life,
one day or less. The long-life lamp would produce a very small
amount of light for the electricity consumed; the other would produce
a large amount of light for the electricity used, but the expense for
lamp replacements would be high. Neither extreme would produce
light at the lowest cost.
60




APPEN D IX B .— LIFE, ETC., OF ELECTRIC LAMPS

61

It is not possible to tell what the designed life of a lamp should be
for the lowest unit cost of light until the price to be paid for electric
energy is known. Obviously, where the rate for energy is very low,
one can afford to use longer-lived lamps which consume relatively
more power for the amount of light they give. Where the rate for
electric energy is higher, it pays to use lamps that give as much light
as practicable for the power they use, even though the lamps them­
selves must be replaced more frequently. For any rate paid for
electric energy there is a corresponding expenditure for lamps which
will result in a minimum over-all cost for lighting. It was first
established by Thomas Edison and confirmed by many later investi­
gators that to secure the minimum cost for lighting the amount paid
out for lamps must be approximately one sixth of the amount paid out
for electricity to operate lamps. A few examples will illustrate this
relationship.
(1) Assuming we have paid 20 cents for a 60-watt lamp and are
burning this on energy costing 2 cents per kilowatt-hour, then, at the
end of 1,000 hours we will find that we have used $1.20 worth of elec­
tricity. If the lamp we purchased has been designed for a 1,000hour life, then we are very close to the point of getting the most
economical lighting, because 20 cents (the price paid for the lamp)
is exactly one sixth of $1.20 (the amount spent for energy). This is
not quite a typical illustration because nearly everyone who is able
to purchase energy at the very low rate of 2 cents is a large wholesale
consumer who can also purchase his lamps at a substantial discount;
such a consumer should use a lamp designed for a higher filament
temperature and a shorter life than the foregoing illustration indicates.
(2) If energy costs 5 cents (which is nearer the usual household
rate), then $1.20 worth of energy will be used up by a 60-watt lamp
in 400 hours of burning rather than in 1,000 hours. To obtain the
most for his money, the consumer, paying 5 cents for electricity,
must get more light out of his 60-watt lamp than where energy costs
2 cents. A lamp designed for a 400-hour life will give materially
more light than a 1,000-hour lamp and in 400 hours will cost for
lamp renewals 20 cents, or just one sixth of the cost of the energy
consumed. A 400-hour lamp is, therefore, the economical 60-watt
lamp to use on 5-cent current.
(3) If a 60-watt lamp were purchased for 10 cents, then its most
economical life on 5-cent electricity would be 200 hours.
In general, it may be said that the manufacturer in designing lamps,
and the consumer in buying them, should be guided by the cost of
electric energy and by the prices to be charged or paid for the lamps.
High rates for electric energy call for lamps designed for comparatively
short life with high light output, because they are more economical
than lamps of equal or higher prices designed for longer life with
lower light output.
There is another factor which influences the length of time a lamp
should bum to obtain maximum economy. This factor is the cost
involved in the effort required to replace lamps which have burned
out. Obviously, a lamp which burns 500 hours will have to be
renewed twice as often as a lamp which burns 1,000 hours; therefore,
the labor cost of changing 500-hour lamps will be twice as great as
the cost of changing 1,000-hour lamps, However, this cost is usually




62

TECHNOLOGICAL CHANGES— ELECTRIC-LAMP INDUSTRY

low, and for the lamps regularly used in the home it is practically
negligible, as, on the average, such lamps are burned less than 500
hours annually. The cost of lamp replacement may become an im­
portant factor, however, in some industrial and commercial uses
where lamps are located in places not easily accessible, and this is
frequently of sufficient moment to justify a longer life, and therefore
a higher rate for lighting than would otherwise be economical.
It is evident that different lamp wattages, different kilowatt-hour
rates, and different lamp prices all require different lamp lives to
obtain the minimum cost for a unit of light. If the lamp manufac­
turer attempted to make all of these varieties, the cost of lamps
would be prohibitive and the confusion intolerable. The only prac­
tical solution of this problem is to design each type of lamp for maxi­
mum economy at average kilowatt-hour rates, with a reasonable
allowance for the effort expended in replacing burned-out lamps. A t
the prices which now prevail for lamps and energy, the life of lamps
of a given quality and price may vary a hundred or two hundred
hours from the optimum value without greatly increasing or decreas­
ing the cost of light, because the shorter-lived lamp, giving more light,
will in this way usually fully balance the additional cost of lamp
renewals. If, however, the snorter-lived lamp is materially lower in
price than the longer-lived lamp, and is of the same high quality,
there will usually be a substantial economy in using the short-r-lived
lamp.
Since the most economical lamp is necessarily one designed for a
length of life based on the relative cost of energy, it is obvious that
110 specifications requiring a particular length of life, as 1,000 hours,
can be valid except for the limited conditions in which the ratio of
cost of energy to cost of lamps calls for the specified length of life.




LIST OF BULLETINS OF THE BUREAU OF LABOR STATISTICS
The following is a list of all bulletins of the Bureau of Labor Statistics published since
July, 1912, except that in the case of bulletins giving the results of periodic surveys of the
bureau only the latest bulletin on any one subject is here listed.
A complete list of the reports and bulletins issued prior to July, 1912, as well as the bulletins
published since that date, will be furnished on application. Bulletins marked thus (*) are
out of print.
Conciliation and arbitration (including strikes and lockouts).

*No. 124. Conciliation and arbitration in the building trades of Greater New Yorkj [1913.]
♦No. 133. Report of the industrial council of the British Board of Trade on its inquiry into industrial
agreements. [1913.]
♦No. 139. Michigan copper district strike. [1914.]
♦No. 144. Industrial court of the cloak, suit, and skirt industry of New York City. [1914.]
♦No. 145. Conciliation, arbitration, and sanitation in the dress and waist industry of New York City.
[1914.]
•No. 191. Collective bargaining in the anthracite-coal industry. [1916.]
♦No. 198. Collective agreements in the men's clothing industry. [1916.]
No. 233. Operation of the industrial disputes investigation act of Canada. [1918.
No. 255. Joint industrial councils in Great Britain. [1919.]
No. 283. History of the Shipbuilding Labor Adjustment Board, 1917 to 1919.
No. 287. National War Labor Board: History of its formation, activities, etc. [1921.]
♦No. 303. Use of Federal power in settlement of railway labor disputes. [1922.]
No. 341. Trade agreement in the silk-ribbon industry of New York City. [1923.]
No. 402. Collective bargaining by actors. [1926.]
No. 468. Trade agreements, 1927.
No. 481. Joint industrial control in the book and job printing industry. [1928.]
Cooperation.

No. 313.
♦No. 314.
No. 437.
No. 531.

Consumers’ cooperative societies in the United States in 1920.
Cooperative credit societies (credit unions) in America and in foreign countries. [1922J
Cooperative movement in the United States in 1925 (other than agricultural).
Consumers', credit, and productive cooperative societies, 1929.

Employment and unemployment.

♦No. 109. Statistics of unemployment and the work of employment offices [in the United States], [1913.]
•No. 172. Unemployment in New York City, N. Y. [1915.]
♦No. 183. Regularity of employment in the women's ready-to-wear garment industries. [1915.
♦No. 195. Unemployment in the United States. [1916.]
♦No. 196. Proceedings of Employment Managers’ Conference, held in Minneapolis, Minn., Ja mary
19 and 20,1916.
♦No. 202. Proceedings of the conference of Employment Managers’ Association of Boston, Mass.,
held May 10,1916.
No. 206. The British system of labor exchanges. [1916.]
♦No. 227. Proceedings of Employment Managers' Conference, Philadelphia, Pa., April 2 and 3, 1917.
♦No. 235. Employment system of the Lake Carriers’ Association. [1918.]
♦No. 241. Public employment offices in the United States. [1918.]
♦No. 247. Proceedings of Employment Managers’ Conference, Rochester, N. Y., May 9-11, 1918.
♦No. 310. Industrial unemployment: A statistical study of its extent and causes. [1922.]
No. 409. Unemployment in Columbus, Ohio, 1921 to 1925.
No. 542. Report of the Advisory Committee on Employment Statistics. [1931.]
No. 544. Unemployment benefit plans in the United States and unemployment insurance in foreign
countries. [1931.]
♦No. 553. Fluctuation in employment in Ohio, 1914 to 1929.
No. 555. Social and economic character of unemployment in Philadelphia, April, 1930.
Foreign labor laws.

♦No. 142.
No. 494.
No. 510.
No. 529.
No. 549.
No. 554.
No. 559.
No. 569.

Administration of labor laws and factory inspection in certain European countries. [1914.]
Labor legislation of Uruguay. [1929.]
Labor legislation of Argentina. [1930.]
Workmen’s compensation legislation of the Latin American countries. [1930.]
Labor legislation of Venezuela. [1931.]
Labor legislation of Paraguay. [1931.]
Labor legislation of Ecuador. [1931.]
Labor legislation of Mexico. [1932.]

Housing.

♦No. 158.
No. 263.
No. 295.
No. 545.

Government aid to home owning and housing of working people in foreign countries. [1914.]
Housing by employers in the United States. [1920.]
Building operations in representative cities, 1920.
Building permits in principal cities of the United States in [1921 to] 1930.




[I]

Industrial accidents and hygiene.

*No. 104. Lead poisoning in potteries, tile works, and porcelain-enameled sanitary ware factories.
[1912.]
No. 120. Hygiene of the painters’ trade. [1913.]
♦No. 127. Dangers to workers from dusts and fumes, and methods of protection. [1913.]
*No. 141. Lead poisoning in the smelting and refining of lead. [1914.]
♦No. 157. Industrial accident statistics. [1915.]
♦No. 165. Lead poisoning in the manufacture of storage batteries. [1914.]
*No. 179. Industrial poisons used in the rubber industry. [1915.]
No. 188. Report of British departmental committee on the danger in the use of lead in the painting of
buildings. [1916.]
♦No. 201. Report of the committee on statistics and compensation insurance costs of the Internationa
Association of Industrial Accident Boards and Commissions. [1916.]
No. 209. Hygiene of the printing trades. [1917.]
*No. 219. Industrial poisons used or produced in the manufacture of explosives. [1917.]
No. 221. Hours, fatigue, and health in British munition factories. [1917.]
No. 230. Industrial efficiency and fatigue in British munition factories. [1917.]
♦No. 231. Mortality from respiratory diseases in dusty trades (inorganic dusts). [1918.]
♦No. 234. The safety movement in the iron and steel industry, 1907 to 1917.
No. 236. Effects of the air hammer on the hands of stonecutters. [1918.]
♦No. 249. Industrial health and efficiency. Final report of British Health of Munition Workers’
Committee. [1919.]
♦No. 251. Preventable death in the cotton-manufacturing industry. [1919.]
No. 256. Accidents and accident prevention in machine building. [1919.]
No. 267. Anthrax as an occupational disease. [1920.]
No. 276. Standardization of industrial accident statistics. [1920.]
*No. 280. Industrial poisoning in making coal-tar dyes and dye intermediates. [1921.]
♦No. 291. Carbon monoxide poisoning. [1921.]
No. 293. The problem of dust phthisis in the granite-stone industry. [1922.]
No. 298. Causes and prevention of accidents in the iron and steel industry, 1910-1919.
No. 392. Survey of hygienic conditions in the printing trades. [1925.]
No. 405. Phosphorus necrosis in the manufacture of fireworks and in the preparation of phosphorus%
[1926.]
No. 427. Health survey of the printing trades, 1922 to 1925.
No. 428. Proceedings of the Industrial Accident Prevention Conference, held at Washington, D. C.,
July 14-16,1926.
No. 460. A new test for industrial lead poisoning. [1928.]
No. 466. Settlement for accidents to American seamen. [1928.]
No. 488. Deaths from lead poisoning, 1925-1927.
No. 490. Statistics of industrial accidents in the United States to the end of 1927.
No. 507. Causes of death, by occupation. [1930.]
No. 582. Occupation hazards and diagnostic signs: A guide to impairments to be looked for in hazard­
ous occupations. (Revision of Bui. No. 306.) [1933.J
Industrial relations and labor conditions

No. 237.
8No. 340.
1
*No. 349.
*No. 361.
No. 380.
No. 383.
No. 384.
No. 399.
No. 483.
No. 534.

Industrial unrest in Great Britain. [1917.]
Chinese migrations, with special reference to labor conditions. [1923.]
Industrial relations in the West Coast lumber industry. [1923.]
Labor relations in the Fairmont (W. Va.) bituminous-coal field. [1924.] •
Postwar labor conditions in Germany. [1925.]
Works council movement in Germany. [1925.]
Labor conditions in the shoe industry in Massachusetts, 1920-1924.
Labor relations in the lace and lace-curtain industries in the United States. [1925.]
Conditions in the shoe industry in Haverhill. Mass., 1928.
Labor conditions in the Territory of Hawaii, 1929-1930.

Labor laws of the United States (including decisions of courts relating to labor)

*No. 211.
*No. 229.
No. 285.
No. 321.
No. 322.
No. 343.
No. 370.
No. 408.
No. 581.
No. 590.
No. 592.

Labor laws and their administration in the Pacific States. [1917.]
Wage-payment legislation in the United States. [1917.]
Minimum-wage laws of the United States: Construction and operation. [1921.]
Labor laws that have been declared unconstitutional. [1922.]
Kansas Court of Industrial Relations. [1923.]
Laws providing for bureaus of labor statistics, etc. [1923.]
Labor laws of the United States, with decisions of courts relating thereto. [1925.]
Laws relating to payment of wages. [1926.]
Laws relating to employment agencies in the United States, as of January 1,1933.
Labor legislation, 1931 and 1932. (In press.)
Decisions of courts and opinions affecting labor, 1931 and 1932. (In press.)

Prison labor

No. 372. Convict labor in 1923.
Proceedings of annual conventions of the Association of Governmental Officials in Industry of the United
States and Canada. (Name changed in 1928 from Association o f Governmental Labor Officials of the
United States and Canada.)

*No. 266.
No. 307.
♦No. 323.
♦No. 352.
♦No. 389.
♦No. 411.
♦No. 429.
♦No. 455.

Seventh, Seattle, Wash., July 12-15,1920.
Eighth, New Orleans, La., May 2-6,1921.
Ninth, Harrisburg, Pa., May 22-26,1922.
Tenth, Richmond, Va., May 1-4,1923.
Eleventh, Chicago, 111., May 19-23,1924.
Twelfth, Salt Lake City, Utah, August 13-15,1925.
Thirteenth, Columbus, Ohio, June 7-10,1926.
Fourteenth. Paterson, N. J., May 31 to June 3, 1927.




fill

*No. 480.
No. 508.
No. 530.
*No. 563.

Fifteenth, New Orieans, La., May 21-24,1928.
Sixteenth, Toronto, Canada, June 4-7, 1929.
Seventeenth, Louisville, Ky., May 20-23,1930.
Eighteenth, Boston, Mass., May 18-22, 1931.

Proceedings of annual meetings of the International Association o f Industrial Accident Boards and
Commissions.

No. 210.
No. 248.
No. 264.
*No. 273.
No. 281.
No. 304.
No. 333.
*No. 359.
No. 385.
No. 395.
No. 406.
No. 432.
*No. 456.
No. 485.
No. 511.
No. 536.
No 564.
No. 577.

Third, Columbus, Ohio, April 25-28,1916.
Fourth, Boston, Mass., August 21-25,1917.
Fifth, Madison, Wis., September 24-27,1918.
Sixth, Toronto, Canada, September 23-26,1919.
Seventh, San Francisco, Calif., September 20-24,1920.
Eighth, Chicago, 111., September 19-23,1921.
Ninth, Baltimore, Md., October 9-13,1922.
Tenth, St. Paul, Minn., September 24-26,1923.
Eleventh, Halifax, Nova Scotia, August 26-28,1924.
Index to proceedings, 1914-1924.
Twelfth, Salt Lake City, Utah. August 17-20, 1925.
Thirteenth, Hartford, Conn., September 14-17,1926.
Fourteenth, Atlanta, Ga., September 27-29,1927.
Fifteenth, Paterson, N.J., September 11-14,1928.
Sixteenth, Buffalo, N.Y., October 8-11,1929.
Seventeenth, Wilmington, Del., September 22-26, 1930.
Eighteenth, Richmond, Va., October 5-8,1931.
Nineteenth, Columbus, Ohio, September 26-29,1932.

Proceedings of annual meetings of the International Association of Public Employment Services.

No. 192. First, Chicago, December 19 and 20,1913; second, Indianapolis, September 24 and 25,1914;
third, Detroit, July 1 and 2,1915.
Fourth, Buffalo, N.Y., July 20 and 21,1916.
Ninth, Buffalo, N.Y., September 7-9,1921.
Tenth, Washington, D.C., September 11-13,1922.
Eleventh, Toronto. Canada, September 4-7, 1923.
Twelfth, Chicago, 111., May 19-23,1924.
Thirteenth, Rochester, N.Y., September 15-17, 1925.
Fifteenth, Detroit, Mich., October 25-28,1927.
Sixteenth, Cleveland, Ohio, September 18-21,1928.
Seventeenth, Philadelphia, Pa., September 24-27,1929; eighteenth, Toronto, Canada, Sep­
tember 9-12, 1930.

*No. 220.
No. 311.
No. 337.
No. 355.
No. 400.
No. 414.
No. 478.
♦No. 501.
No. 538.

Productivity of labor and technological unemployment

No. 356. Productivity costs in the common-brick industry. [1924.]
No. 360. Time and labor costs in manufacturing 100 pairs of shoes. 1923
No. 407. Labor cost of production and wages and hours of labor in the paper box-board industry.
[1926.]
*No. 412. Wages, hours, and productivity in the pottery industry. 1925.
No. 441. Productivity of labor in the glass industry. [1927.]
No. 474. Productivity of labor in merchant blast furnaces. [1928.]
No. 475. Productivity of labor in newspaper printing. [1929.]
No. 550. Cargo handling and longshore labor conditions. [1932.]
No. 574. Technological changes and employment in the United States Postal Service. [1932.]
No. 585. Labor productivity in the tire industry. [1933].
Retail prices and cost o f living.

♦No. 121.
*No. 130.
*No. 164.
*No. 170.
No. 357.
No. 369.
No. 4C5.

Sugar prices, from refiner to consumer. [1913.]
Wheat and flour prices, from farmer to consumer. [1913.]
Butter prices, from producer to consumer. 11914.1
Foreign food prices as affected by the war. 11915.J
Cost of living in the United States. [1924.]
The use of cost-of-living figures in wage adjustments. [1925.]
Retail prices, 1890 to 1928.

Safety codes.

♦No. 336.
No. 350.
*No. 351.
No. 375.
♦No. 382.
No. 410.
♦No. 430.
No. 447.
No. 451.
No. 463.
No. 509.
No. 512.
No. 519.
No. 527.
No. 556.
No. 562.

Safety code for the protection of industrial workers in foundries.
Rules governing the approval of headlighting devices for motor vehicles.
Safety code for the construction, care, and use of ladders.
Safety code for laundry machinery and operations.
Code of lighting school buildings.
Safety code for paper and pulp mills.
Safety code for power presses and foot and hand presses.
Safety code for rubber mills and calenders.
Safety code for forging and hot-metal stamping.
Safety code for mechanical power-transmission apparatus-first revision.
Textile safety code.
Code for identification of gas-mask canisters.
Safety code for woodworking plants, as revised 1930.
Safety code for the use, care, and protection of abrasive wheels, as revised 1930.
Code of lighting: Factories, mills, and other work places. (Revision of 1930.)
Safety codes for the prevention of dust explosions.




[m]

Vocational and workers* education

*No. 159.
*No. 162.
*No. 199.
No. 271.
No. 459.

Short-unit courses for wage earners, and a factory school experiment. 11915.]
Vocational education survey of Richmond, Va. [1915.]
Vocational education survey of Minneapolis, Minn, f1917.]
Adult working-class education in Great Britain and the United States. [1920.]
Apprenticeship in building construction. [1928.]

Wages and hours of labor

*No. 146. Wages and regularity of employment and standardization of piece rates in the dress and
waist industry of New York City. [1914.]
*No. 147. Wages and regularity of employment in the cloak, suit, and skirt industry. [1914.]
No. 161. Wages and hours of labor in the clothing and cigar industries, 1911 to 1913.
*No. 163. Wages and hours of labor in the building and repairing of steam railroad cars, 1907 to 1913.
*No. 190. Wages and hours of labor in the cotton, woolen, and silk industries, 1907 to 1914.
*No. 204. Street-railway employment in the United States. [1917.]
*No. 225. Wages and hours of labor in the lumber, millwork, and furniture industries, 1915.
No. 265. Industrial survey in selected industries in the United States, 1919.
No. 297. Wages and hours of labor in the petroleum industry. 1920.
No. 356. Productivity costs in the common-brick industry. [1924.]
No. 358. Wages and hours of labor in the automobile-tire industry, 1923.
No. 360. Time and labor costs in manufacturing 100 pairs of shoes, 1923.
No. 365. Wages and hours of labor in the paper and pulp industry, 1923.
No. 407. Labor cost of production and wages and hours of labor in the paper box-board industry.
[1926.]
♦No. 412. Wages, hours, and productivity in the pottery industry, 1925.
No. 416. Hours and earnings in anthracite and bituminous-coal mining, 1922 and 1924.
No. 484. Wages and hours of labor of common street laborers, 1928.
No. 499. History of wages in the United States from colonial times to 1928.
No. 502. Wages and hours of labor in the motor-vehicle industry, 1928.
No. 514. Pennsylvania Railroad wage data. From Report of Joint Fact Finding Committee im
wage negotiations in 1927.
No. 516. Hours and earnings in bituminous-coal mining, 1929.
No. 523. Wages and hours in the manufacture of airplanes and aircraft engines, 1929.
No. 525. Wages and hours of labor in the Portland cement industry, 1929.
No. 532. Wages and hours of labor in the cigarette-manufacturing industry, 1930.
No. 534. Labor conditions in the Territory of Hawaii, 1929-1930.
No. 539. Wages and hours of labor in cotton-goods manufacturing, 1910 to 1930.
No. 547. Wages and hours of labor in the cane-sugar refining industry, 1930.
No. 557. Wages and hours of labor in the men’s clothing industry, 1911 to 1930.
No. 566. Union scales of wages and hours of labor, May 15,1931.
No. 567. Wages and hours of labor in the iron and steel industry, 1931.
No. 568. Wages and hours of labor in the manufacture of silk and rayon goods, 1931.
No. 570. Wages and hours of labor in foundries and machine shops, 1931.
No. 571. Wages and hours of labor in the furniture industry, 1910 to 1931.
No. 573. Wages and hours of labor in metalliferous mining, 1924 to 1931.
No. 575. Wages and hours of labor in air transportation, 1931.
No. 576. Wages and hours of labor in the slaughtering and meat-packing industry, 1931.
No. 578. Wages and hours of labor in gasoline-filling stations and motor-vehicle repair garages, 1931.
No. 579. Wages and hours of labor in the boot and shoe industry, 1910 to 1932.
No. 580. Wages and hours of labor in the baking industry—bread and cake departments, 1931.
No. 584. Wages and hours of labor in woolen and worsted goods manufacturing, 1932.
No. 586. Wages and hours of labor in the lumber industry, 1932.
No. 587. Wages and hours of labor in the rayon and other synthetic yarn manufacturing, 1932.
No. 588. Wages and hours of labor in the dyeing and finishing of textiles, 1932;
No. 589. Wages and hours of labor in the leather industry, 1932. (In press.)
No. 591. Wages and hours of labor in the hosiery and underwear industry, 1932. (In press.)
Welfare work

*No. 123.
No. 222.
*No. 250.
No. 458.

Employers’ welfare work. [1913.J
Welfare work in British munition factories. 11917.]
Welfare work for employees in industrial establishments in the United States. [1919.]
Health and recreation activities in industrial establishments, 1926.

Wholesale prices

*No. 284. Index numbers of wholesale prices in the United States and foreign countries. 11921.]
*No. 453. Revised index numbers of wholesale prices, 1923 to July, 1927.
No. 572. Wholesale prices, 1931.
Women and children in industry

*No. 116. Hours, earnings, and duration of employment of wage-earning women in selected industries
in the District of Columbia. [1913.]
*No. 117. Prohibition of night work of young persons. [1913.]
*No. 118. Ten-hour maximum working-day for women and young persons. [1913.]
*No. 119. Working hours of women in the pea canneries of Wisconsin. [1913.]
*No. 122. Employment of women in power laundries in Milwaukee. 11913.]
*No. 160. Hours, earnings, and conditions of labor of women in Indiana mercantile establishments
and garment factories. [1914.]
*No. 175. Summary of the report on condition of woman and child wage earners in the United States.
[1915.]
*No. 176. Effect of minimum-wage determinations in Oregon. [1915.]
*No. 180. The boot and shoe industry in Massachusetts as a vocation for women. [1915.]
*No. 182. Unemployment among women in department and other retail stores of Boston, Mass. [1916.]
No. 193. Dressmaking as a trade for women in Massachusetts. [1916.]
*No. 215. Industrial experience of trade-school girls in Massachusetts. [1917.]
*No. 217. Effect of workmen’s compensation laws in diminishing the necessity of industrial employ­
ment of women and children. [1917.]
*No. 223. Employment of women and juveniles in Great Britain during the war. [1917.]
No. 253. Women in the lead industries. [1919.]
No. 467. Minimum-wage legislation in various countries. [1928.]
No. 558. Labor conditions of women and children in Japan. [1931.]




[IV]

Workmen’s insurance and compensation (including laws relating thereto).

*No. 101.
*No. 102.
No. 103.
No. 107.
*No. 155.
*No. 212.
♦No. 243.
No. 301.
No. 312.
*No. 379.
No. 477.
No. 496.
No. 529.

Care of tuberculous wage earners in Germany. [1912.]
British national insurance act, 1911.
Sickness and accident insurance law in Switzerland. 11912.]
Law relating to insurance of salaried employees in Germany. [1913.]
Compensation for accidents to employees of the United States. 11914.]
Proceedings of the conference on social insurance called by the International Association of
Industrial Accident Boards and Commissions, Washington, D.C., December 5-9,1916.
Workmen’s compensation legislation in the United States and foreign countries, 1917 and 1918.
Comparison of workmen’s compensation insurance and administration. [1922.]
National health insurance in Great Britain, 1911 to 1921.
Comparison of workmen’s compensation laws of the United States as of January 1, 1925.
Public-service retirement systems, United States and Europe. [1929.]
Workmen’s compensation legislation of the United States and Canada as of January 1,1929.
(With text of legislation enacted in 1927 and 1928.)
Workmen’s compensation legislation of the Latin American countries. 11930.]

Miscellaneous series.

*No. 174. Subject index of the publications of the United States Bureau of Labor Statistics up to May
1,1915.
No. 208. Profit sharing in the United States. [1916.]
No. 242. Food situation in central Europe, 1917.
No. 254. International labor legislation and the society of nations. [1919.]
*No. 268. Historical survey of international action affecting labor. [1920.]
No. 282. Mutual relief associations among Government employees in Washington, D.C. [1921.
No. 319. The Bureau of Labor Statistics: Its history, activities, and organization. [1922.]
No. 326. Methods of procuring and computing statistical information of the Bureau of Labor Statis­
tics. [1923.]
No. 342. International Seamen’s Union of America: A study of its history and problems. [1923.]
No. 346. Humanity in government. [1923.]
No. 386. Cost of American almshouses. 11925.]
No. 398. Growth of legal-aid work in the United States. [1926.]
No. 401. Family allowances in foreign countries. [1926.]
No. 461. Labor organizations in Chile. [1928.]
♦No. 465. Beneficial activities of American trade-unions. [1928.]
No. 479. Activities and functions of a State department of labor. [1928.]
*No. 489. Care of aged persons in United States. [1929.]
No. 505. Directory of homes for the aged in the United States. [1929.]
No. 506. Handbook of American trade-unions. 1929 edition.
No. 518. Personnel research agencies. 1930 edition.
No. 541. Handbook of labor statistics. 1931 edition.
No. 561. Public old-age pensions and insurance in the United States and in foreign countries. [1932.]
No. 565. Park recreation areas in the United States, 1930.




M