ELE CTRI C L IGHTING

I N C A N D E S C E N C E ,

APPLICATION TO INTERIOR ILLUMINATION .

A PRA C T I C A L TRE A 7TS E .

WITH 96 ILLUSTRATION S .

WI L L I A M E D WA RD SAWY E R.

N EW Y O RK

D . VA N N O S TRAN D , PUB L I S H ER,

MURRAY S TRE E T AN D 27WARRE N S rmr.

1881 .

PRE FA C E .

TH E subject of electric lighting by incandescence is one

of general interest . Its brillia nt premises have ex

cited the curiosity and the an ticipations of the public

to a degme almost unprecedented in the history of inven;tion . B ut beyond the threshold of the laboratory its

processes are unknown,and information which would be

of service to experimehtalists is withheld .

My purpose in preparing this work is not alone to

show the state of the art in its practical applications,

but also to indicate the direction in Which the laborer in

science is most likely to attain success,and to impart an

accumte co nception of the principles underlying the employment of electricity for interior illumination .

Special description of lighting by the voltaic arc is

omitted,for the reason that the subject is fully dis

cussed in numerous text-books readily obtainable , and

because there are few cities in which this formof lighting may not now be seen in operation ;while to the

subject of electric generators, which constitute the be

ginning and the end of any system of lighting , consider

able space is giveh .

6 PRE FACE .

Those who expect tofind these pages the vehicle of atheory Will be di sappointed . Those who expect tofindthem devoted to criticism of the labors of other experi

mentalists will be equall y disappointed .

In the position of an impartial student and observer

I have sought less to indicate defects than to exhibit

accomplishments .

W I L L IAM EDWARD SAWY E R.

N EW Y ORK, January 1 5

,1881 .

C O N T E N T S .

I N TRODUCTORY

C HAPTER I .

G enerators of E lectricity,

C H APTER I I .

G enerators of the G ramme Type,C H A PT ER III .

G enerators of the N ew S iemens Type

C H APTER IV .

I ncandescent L amps ,C HAPTE RV .

Carbons for I ncandescent Lighting ,

C H A FT ERVI .

N ew Forms of Lamps,CH APTE RVl I .

N ew Forms of L amps (C ontinued)C H APTERVI I I .

Preservation of Incandescent C arbons ,

CH APTER IX .

D ivision ofCurrent and L ight,

CH APTERX .

Regulators and S witches.

CH APTERXI .

G eneral D istribution ,

C H A PTERXI I .C ommercial Aspects,

I N TRO D UC T I O N .

HEN the free ends of two conducting wires con

nected with the terminal s of a galvanic battery,or other generator of electricity, are brought together,the circuit of the generator is completed, and a cur

rent of electricity more or less powerful , according to

i ts quantity and electro -motive force, traverses the ele

ments of the generator and the conductor uniting its

terminals . This conductor offers a certa in resistance to

the pa ssage of the current Which may generally be

disregarded . The generator offers a considerable resist

ance , and the current appears as heat in its elements,for the reas on that the current is divided between

the generator and the conductor in proportion to their

respective resistances and the calorific effects of current

in any conductor are pmportional to its value in that

conductor . I t,now

,we separate the ends of the con

ducting wires, the movement of separation involves pri

marily a poor connection at the points of contact, and

a poor connection means resistance ;henc e the former

relations of the generator and the conductor are dis

ta thed, and the current being distributed exactly in

proportion to the resistance of any part. of the circuit,

a less proportion is found in the generator and the

remainder is concentrated at the imperfect points of9

10 IN TROD UCTION .

contact,where it produces heat sufficient to fuse and

then to vaporize them and as the vapor of a conductor

is also a conductor of electricity, the current traverses

the break between the points of contant, as they are

drawn apart,to a distance commensurate with the in

tensity or electro-motive force of the current . The va

porized conductor uniting the points of contact con

stitntes the voltaic arc, the most brilliant and dazzling

of all artificia l lights . In the Serrin, Siemens. Jablochkofl, Brush, and other lamps, the arc is formed between

the ends of carbon rods or pencils ;and the light ismoreintense and economical when the distance between the

carbons is slight and the curren t great in quantity than

when the reverse is the case .

The voltaic arc is the most economies! of electric

lights ; and in the illumination of large open spaces,and for all purposes requiring much penetrative power,it Will doubtless maintain its supremacy . In many

cases of experimental test it has developed a light of

from to candles per horse power of force

expended in driving the generator. the cost of which in

large steam -engines is less than one cent per hour.

In both the voltaic arc and the incandescent forms

of lighting the dynamo. or the magneto-electric, type of

generator is now universally employed . Each type of

machine is designed to tra nsform mechanical for ce into

electricity . The magneto electric machine is that in

which the magneticfield is derived from a permanentmagnet . The dynamo-electric machine is that in which

the permanent is replaced by an elecn'

o -magnet . Both

opmte upon the same principle— that the cutting of a

IN TROD UCTION . 1 1

line of magnetic force by an endl ess conductor of electri

city, constituting a closed circuit, induces in the latter a

current whose direction is determined by the directionof motion of the conductor, or the direction of polarity of

the magneticfield . The machines of Pixii,C larke, Nol

let and Van Malderen, Ladd, Wilde, and others are ex

amples of both magneto and dynamo-electric generatorsbut they have all succumbed to the superior appara tus

of the present day. O f these old machines we shall con

sider the genera tor of Wilde as embodying a principle

Which is destined to play an important part in theutilization of electricity for the purposes of domestic

ill umination .

ELECTRICLIGHTINGBYINCANDESCENCE.

CHAPTER I .

om aarons or E L E C TRIC ITY .

H E value of a pound of coal inmechanica l energy is

about foot-pounds the val ue of a pound

of zinc is about foot -pounds . The cost of a

pound of zinc is about twenty -hye times the cost of a

pound of coal . With this great discrepancy between

the energy and co st of the one and the energy and cost

of the other,and aftermaking due allowance for all the

facts favorable to zinc, it is clear that in electric lighting,at least

,the period of usefulness of the gal vanic battery

has passed, not to return . The discovery by Faraday ,in 1831 , of magneto-electric induction, and the construc

tion by Pixii, a year later, of thefirst magneto-electricmachine

,mark the beginning of the era of conversion of

mechanical power into electricity but we shall not at

tempt to describe the efforts of the earlier experimenters,who, al though far in ad vance of their times, made little

progress toward the real izations of the present day . A f

ter Pixii came Saxton, in 1833 ;Clarke, in 1836 ;Nollet

and Van Malderen,in 1849 and Holmes

,in 1852

,all of

whom employed the magneto electric principle . In13

14 E LE CTRIC LIGHTIN G B Y I N C A N D B S C E N C E .

1857 the Siemens armature was invented, and sabse

quently, in 1866 , Wilde constructed his remarkable

The Wilde machine con sists of a Siemens armature

whose electro magneticfield of force is sustained by anexciting machine of the magneto-el ectric type. It is ,

omu roas on ELE CTRI C ITY . 15

therefore,a double machine

,each part of which is pro

vided with a Siemens armature, whose advantages arethat it occupies but little spa ce, and may therefore be

rotated in a magnetic neld of maximum intensity ; and

whose disadvantages are the high speed of

necessary,and excess ive heating by reason

of the rapid changes in its molecular struc

ture co nent upon the rapidi ty of its ro .

tation while cutting the z: of mmetic

force . B a ween the opposite of a com

pound per ent horseshoe magnet the ar

mature is planed,and its rotah

'

on is efiectedby ma ; n of a belt passing over the pulley

shown in Fig. 2 . The Siemens armature

has not gone out of use, for its simplicity

and c t m of construction continue to

commend it. In electro-plating and labora

tory work itfinds constant employment .Primarily

,the Siemens armature consists

of a rol ler of wrought or cast iron in which

deep,longitudinal grooves are cut, whereby

its section is reduced to a form similar to

that of the letter B . Lengthwise in these

grooves the induction helix of insulated wire

is wound . In Fig . 3 we have a section of

the s and thefield magnet polar extensions ofIn the upper or magneto-electric machine. the induc

tive action is derived from the permanent magnets M,

whose u ties are in conta ct with the soft~ iron pola r

extensions, mn , forming the sides of a socket within

16 ELECTRI C L IG H T lN G B Y IN C AN D E SC E N C E .

which the armature rotates . The curren t generated in

the an nature-coil flows from the commutator to the

binding-screws p g, Which are the termina ls of the large

electro magnet coils, A B , through which the current

circulates . The lower extremities of the large

Fig. 8. S ection of 8 1 . Armature and Field.

are in contact with two iron polar extensions, T T ,

rated by a mass of diamagnetic metal, 23 and the second

S iemens armature, of large size, furnishes the currentuse . F is the bmring of the armature-s

AB,MN (Fig. 3) represent the socket within which the

t; revolves,the portions A B being of iron and

M N of bras s or other diamagnetic material . B y em

ploying the current induced l n the armature of the super

posed magneto~machine to excite the electro-magnet of

the lower dynamo-machine, there is es tablished in the

lower machine a much more powerful magneticfield A.

that of the compound permanent magnet of the mmachine

,and from the lower armature a current ofmuch

grw ter power than that induced in the upper armature

is obtained . The polarity of the armature is reversed

at each half-revolution, and the alternately opposite

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18 mec'mwmea '

rmc B Ymu s nescnncn.first a weak current in the armature-coils, and this, beingreturned to themagnet-coils

,increases the power of the

magnet, and induces in the armature a correspondingly

powerful current, which is again returned to the magnet

coils and this action progresses until a point of mag

netic saturation is attained . The principle of accumulation by mutual action is employed in the HamerAJteneck, the Gramme, Brush , Hochhausen , and other

generators in general use and where a single lamp,or a

limited number of lamps,is to be operated

,it does not

appear advisable to employ an exciting machine, the

practical use of the latter being in the lighting of build

ings or sections of a city requiring a large number of

lamps and a common source of supply .

In all accumulative machines increase of resistance in ,

or interruption of, the external circuit at once cuts

down or destroys thefield of force‘ for thefield of forceis dependent entirely upon the resistance of the circui t

,

and we ha ve the most effective work when the resistance

external to themachine is sensibly equal to its internalresistan ce

,although it is often possible to obta in satis

factory results when the external is greatly in excess of

the internal resistance . As thefield of force must becrea ted by the charging~up of the magnet upon its own

circuit, it is clear that when we increase the external re

sista nce thefield of force is weakened, and very soon apoint is reached at which the magnet will not appre

ciably charge . Thus it is that a dynamo-machine may

successfully operate a single lamp, or a limited number

of lamps,while it will produce no good effect when two or

a greater number of lamps are connected in circuit, and

GEN ERATORS O F E L E C TRI C I T Y . 19

in order to obtain the best resul ts the maximum

of light with the minimum expenditure of poweH ub

stantiallyfifty per cent, of the curren t generated is ordinarily expended in exciting the machine, andfifty percent. in the production of light . Compensating for in

cm d res istance in the externa l circuit by increasing

the speed of the generator above its normal velocity is

T ho D e Metitens l tachlne.

The permanentfield magnet of the machines

generally given way to the more compact and power

fm°

electro-magnet, but in the recent invention of De

20 suscrmcmon'

rtxc B Ymeannescmtcs .

Meritens (Fig. 5) the original form of magnet is revived .

For this machine great efficiency has been claimed ;andthat within certain limits it is an economical generator

of electricity we have no reason to doubt . The saving

of the power expended to sustain thefield of force ofdynamo-electric machines is, of course, advantageous ;but the cost of construction, multiplication of parts, and

cumbersomeness of large generators designed upon this

plan will probably operate aga inst them , as they have

operated against the similarly-designed Alliance and

Holmes machines . In construction the De Meritens

machine consists of a series of grooved m atures, likethe letter H , joined side by side and mounted upon the

periphery of a diamagnetic wheel,so as to constitute an

iron ring in sectiens , provided with as many projections

as there are distinct pieces . In the bottom of the

grooves the armature coils are wound ; and the whole is

rotated within thefiel ds of force of a series of powerfulsteel magnets

,built up of thin plates and supported in a

circular frame . The methods of adjustment of parts

employed by De Meritens are simple and eifective.

The Lontin distributor (Fig . 6 ) is one of several

new forms of generators, embodying the principle of

Wilde,designed to operate a considerable number of

lamps from a single source . The exciting machine is

of the dynamo-electric type, and consists of an electremagnet between the poles of which revolve a number of radially-arranged bar electro-magnets consti

tuting the atmatm'

es . The current produced is em

ployed in sustain ing thefields of force of the distributor,which co nsists of a large, stationary, soft-iron ring, F, to

GEN ERATO RS or ELECTRICITY.21

which are secured equidistantly a series of short electro

magnets, B ,equal in number to the electro-magnets, M,

of the inner revolving wheel. The revolving magnets,which are connected in multiple circuit, are charged

by the exciting machine and constitu te thefields ofAs the ends of the revo lving magnets present

Pig . 6 . L ontin”

; Machine .

al tern ately opposite poles to the poles of the stationary

magnets, alternating currents are induced in the latter,

and as many separate lamps may be worked from a

s ingle distributor as there are electremagnets B .

Regarding the performance of the Lontin distributor,

i t is stated that in the smal l machine the light obtained

per horse power of mechanical force expended is from

400 to 600 candles, while in a larger machine, having a

E LECTRIC LIGH TIN G B Y I N C AN D E S C E N C E .

capacity of 12 lights,and consuming twelve horse power,

the light obtained per horse-power is from600 to 750candles . A generator used at the railway station at

Lyons fed 31 separate lamps, each having an illumina t

ing power of 340 candles, but the value of themechanical energy expended is not known .

Fig. 7 . T he S awyer D istributor.

The Sawyer distributo r (Fig . 7) bears a certain resem

blance to the Lontin machine, but is based upon a dif

ferent pri nciple of action .

GE N ERATORS os E LE CTRI C ITY . 23

It is a wel l-known fact that far every magnet there

is a point of maximum sustaining power. Taxed be

yond that point, the magnet will no longer sustain its

armature . Suppose that we have a magnet, N S (Fig.

whose armature or armatures,A

,re

quire all its power to sustain them . If,

n ow,we bring to the magnet a third

a rmature, B (Fig. greater in mass

than either of the armatures A , both

armatures A Will fall off, because armatnre B ,

of greate r mass, operates to

magnetically short -circuit them. If we

have,surrounding armature A

,a coil of Fig, at M et and

insulated wire, when we approach the

magnet with armature B a current of electricity is in ~

duced in that coil and when we move armature B away,armature A being within the mag

neticfield,a current of opposite

direction is induced in the co iL

In the Sawyer distributor both

thefield magnets and their induction armatures are stationary . To

the inner periphery of an iron ring

arefixed a series of electro-magnets whose coils, joined together,are fed by an exciting machine .

B olted to the sides of the polar

extensions of the magnets by mea ns

of brass screws,and prevented

frommagnetic contact by brass plates, 0 ,are the soft

iron armatures B , whose coils are connected with the

34 ummc LIGH TIN G B Ymcmsscs sca

signed to short-circui t the magnetic force of thefieldmagnets

,is rapidly rotated, its projections approaching

almost to contact with the polar faces of thefield magnets. The cross-section of D is much in excess of the

cross -section of B consequently, when the former is in

the position shown, the magnetic force is almost entire

Fig. 10 . T he Geek y Machine.

ly short ' circuited from B . As the position of the pro

jections of D is changed, the magnetic force of thefieldmagnet is directed through the armatures B ,

and a cur

rent of electricity of one direction is induced in theircoils ;as the projections assume the position shown a

current of the opposite direction is induced . B y means

of this generator a large volume of electricity is obtain

able,but in effective action it seems to be inferior to

some other generators .

The Seeley machine (Fig. which appeared in

the year 1880, contemplates an armature entirely of

copper wire or ribbon (the iron core being discarded),

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26 E LE CTRIC LIGHTIN G B Y I N CAN D E S CE N CE .

The shaft of the machine is rota ted by means of pulley

E . In practice there are six magnets on each side of

the armature-disk,and twelve arma tures .

A form of alterna ting-current machine,the same in

principle as the Seeley machine,was devised by S ie

mens and H alske in 1878,and consists in one form of

a central disk carrying coreless Wire helices (Fig.

This disk is rapidly rotated between two sets of electro

magnets whosefields of force are sustained by a smallS iemens continuons-cnrrent machine.

C HAPT ER I I .

GE N ERATORS O F T H E GRAMME TY PE .

OF dynamo~electrio generators none are better known ,or more extensively employed, than those of M.

Gramme, whose invention has excited the intea'

est of

scientific since itsfirst to the

Flg. 18. T he G nmme hh chine.

28 ELECTRIC LIGHTIN G B Y IN CAN D ES CE N CE.

French Academy of Sciences in 1871 . The essential fea~

ture of the Gramme machine (Fig. 13) is a soft-iron ring

wound throughout, in the same direction, with a con

tinuous insula ted copper wire, the terminals of which

are joined together, so that the whole constitutes

endl ess wire helix (Fig.

Fig. 14. Principle of the G rammeMachine .

In order to arrive at an understanding of its O pera

tion,let us suppose that the wire is denuded upon the

periphery of the helix, thus forming a band, composed

of bared sections of the wire, running around the outer

circumference of the ring. In this we have one element

of the commutator, the other of which is composed of

the collecting brushes,M M’

,which make connection

with the barecl sections of the helix . When the ring is

placed between the poles,S N

,of any magnet

,the ring

constitutes the arma ture of that magnet, and there occur

in the ring two co nsequent poles, S'

N'

. If the ring is

now revolved the poles developed in the ring remain in

variably in the same relation with respect to the magnet

poles,N 8 . Whatever may be the rapidi ty of rota tion .

the ring poles, N'

S’

, remainfixed in space and ea ch part

GE N ERATORS cs res GRAMME TYPE . 29

of the copper helix successively traverses them . It is

apparent, therefore, that the helix will be the seat of a

curren t of (me direction when traversing the path M S M'

,

and of the inverse direction When traversing the path

M ’N M ; and the part of the helix above the line M M’

will be a by a current of one direction, and al l

th the line by a current of inverse direc'

tion,

t; sf an equal s,

u of elements, conpled in

or O pposition . The two currents are equal and

purpose of esta blishing

but is divided into short

den revemels of polarity in the ring,but a continuous

premeivemovememof the consequent poles, whichsubject to N- ment in respect of the poles of themagnet inmomrtion to the velocity of rota tion of the

39 E LECTRIC LIGHTIN G B Y wcmnsscsscs .

To produce a successful Gramme machine, it is ne»

overlapping fromtwo-thirds tofive-sixths of the outer

periphery of the ring,and the distance bemen the

presented to its outer periphery should in no case ex

esed one and a half inches,and in sma ll machin es

should not exceed one-half inch . The helix must be

wound so as to bring the layers of wire within this

space, and the pola r faces should be in as close proz i

mity to the outer periphery of the helix as may be compatible with safety in mechanical construction .

In the Gramme,as in all other machines provided With

iron induction-cores,the heating of the armature

coils is often a serious defect,especially when the veins

city of rota tion is great and the resistance of the axe

ternal circuit low : and in some machines the heat dew

veloped is so great as frequen tly to be des tructive of

ing have been made,attended wi

ing the number of armatures in re spectmagnets, as inmnltisectional machines .is to run a stream of water through the shaft of the

armature ; or, as in the H ochhansen electro-platingmachine, to run the entire armature in a water-box, the

armature helix being carefully insulated ;or, as in theSawyer machine

,to cause the water to flow throughout,

the interior mass of the iron . A third method is to so

construct the armature as to subject it to the free circa

lation of currents of air.

GEN ERATORS O F THE GRAMME TYPE .

In the Maxim machine (Fig. the lastd escribed me

thod is employed . This generator, which has recent

ly been introduced and successfully operated in N ew

York and other cities , is based upon the Gramme

as to its armature, with some changes in

Fig. no. T hemumMachine.

is composed of

a largemember of thin flanges of soft iron arranged

side by side so as to form a tube or hollow cylinder

the air is M to circulate . The electro-magnet is sien

ilur in mstmction to the compound magnet of Dr.

32 E LE CTRIC LIGHTI N G B Y I N CAN D E S CE N CE .

Siemens . N o comparisons of the efficiency of theMaxim machine with other generators have been made ;but unless the resistance of the external circuit is low,

the armature is not hea ted so highly that the hand

may not be placed upon it.

In some respects similar t o the Gramme is the Brush

machine (Fig . whose extensive employment through

out the United States has demonstrated its efficiency inthe production of a series of voltaic arcs . The Brush

armature consists of a fla t ring of soft cas t-iron revo lv

ing in its own plane . This ring is composed of two or

more parts,insulated from each other, and each provided

wi th a series of grooves designed

tion of currents in the iron of thefine the action of thefield ofcurrents in the eight helice

wound . The sta tionary electro

of the armature in the plane of

whose poles,fixed in space, are constan

respect of.the mass of the ring. In the

the armature helices, however, the Brushessentially from the Gramme . They are not cod

together to form a continuous circuit, but ea ch pair of

diametrically opposite helices is connected with diame

trically opposite segments of the commutator, which

segments are not connected with any other helices .

Thus each pair of helices is entirely independent of the

others . The object of this arrangement is to remove

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34 ELECTRI C LIGHTI N G B Y IN C A N DmC E N O E .

which, at the neutra l point, not only contributes nothing

in useful etfect, but adds to the internal resistance of the

machine . Thus in the Brush machine three-fourths of

the armature-helices onl y are included in the circu it at

any one time.

hotels,and facto ries . The resis tance of the useful ar

mature~ coils is from four to six ohms, and the resistance

of the magnet-coils from six to eight ohms,making the

ten to fourteen ohms . The resistance of the external cir

cuit is the sum of the resistance of all the lamps, the ih

ternal res istance of each of which varies from one tofive ohms . It is sta ted by the manufacturers that thesixwen-light machine (the diameter of whose armature is

twenty inches, and length of base sixty-eight'

inches),driven at a speed of 750 revolutions per minute, absorbs

about one horse power per lamp . In his statement of the

efficiency of hi s system,Mr. Brush says that as many as

33 lamps have been operated simultaneously in the cir

cuit of this machine at a speed of 800 revolutions , with

an arc of appreciable length in each lamp ;but the total

light produced was less than ha lf that l obtained when

sixteen or seventeen lamps were employed.

The investigations of the Franklin Institute as to the

relative efficiency of the Gramme and Brush machines

(1877 in mainta ining the voltaic arc,resulted in the

following detennina tions

osnmwrons O F TH E cum TYPE .

The Gramme machine is the most economical, con

sidered as a means for converting motive power into elec

trica l cnrrent, giving in the arc a nseful result equal to

38 per cen t . , or to 41 per cent . after deducting friction

and the resistance of the air. In this machine the loss of

power in friction and local action is the least . The large

Brush machine comes next in order of efficiency, givingin the are a useful efl'ect equal to 31 per cent . of the total

power used, or 37§ per cent . after deducting friction.

”

As the resul t of the Frankhn Institu te experiments it

was shown that the Brush machine,at a speed of

developed a light of sta ndard candles, or 377 can

dles per horse-power ;while the Gramme machine, run at

a speed of 800 revolutions and consuming horse

power, produced a light of 705 candl es, or 383 candles per

horse power. In running 25 minutes the Brush machine

increased in temperature from 73? to 88° Fahr. The

in tema l resistance of the machine was .483 of an ohm,

and the resistance of the lamp . 54 of an ohm . The ih

ternal resis ta nce of the Gramme machine was ohms,

and the resistance of the are ohms .

Underlying the principle of the Gramme generator;

bnt coming to general notice subsequent to the inven

vised by Dr. Antonio Pacinotti in 1860,and described in

the June number of the Italian scientific journal , I lN uoco G imcnto

,four years later. The Pacinotti ma

chine (Fig . 18) was thefirst machine to produce a currentat electricity continuous in character and constant in

direction and intensity and it differs from the Gramme

33 E LECTRIC LIGHTI N G B Ymcmsscmtcs .

in principle solely in that the revolving ring is pro

vided with projections,as in the Brush machin e,

between which the endless helix is wonnd . Although

the design of Pacinotti was to produce an electro-mgnetic engine, he clw ly described its conversion into a

capable of producing, in combination a

Fig. l8. T hemutant KingM

permanent or an electro magnet, a continuous current

of constan t direction . The chief improvement of Grammecons istedmomitting the projections . upon the O ring,

a

nd

struction is not known . In general construction, how

ever, the Gramme genera tor is new, and superior to the

Pacinotti ring machine .

CHAPTER III.

GE N ERATO RS or T H E N E W smm s TY PE .

FOLLOWING the generator of M. Gramme comes the

(Fig. generally known as the N ew Siemens machine,the command electromagnet of which has the hat shape

Fig. 10. T he N ew S iemens Machine.

of the Wilde machine . In this generato rthe armature consists of a long, soft-iron . hollow drum

87

38 ELECTRIC LIGHTIN G B Y IN C AN DM C E .

rotating between the curved polar faces A of the electro»

magnet B . This drum is wound longitudinally, andmapeculiar manner

,with insulated wire

,covering al l parts

of the same,and connected, at different points, with the

insulated commutator segmen ts,in such a manner that

the coil is a continuous one, endl ess as in the Gramme

machine, but not wound or connected in the same manner. When the armature is caused to rotate

,a current

is induced in the armature coils, and the magnet iscited, upon the principle of mutual action al ready de

The small est-sized Hamer~ A l teneck machine is 698m

in length, 572

“ wide,and 233mm high ; the drum is

388m long, and carries 28 wire coils and a commutator

divided into 56 parts . Its weight amounts to 115 kilo

grammes ; the maximnnrvelocity of the drum ,900 re

volutions per minute and the intensity of the light pro

duced,

standard candl es . One and a half horse

power is required to run it. The medium-sized ma

chine differs in construction but sl ightly from the above .

It is 757mmin length,7o0"m wide

,and 284" high ; the

drum has a length of 456m,and is also wound with 28

coil s . The commutator is, therefore, al so composed of

56 pieces, upon which wire collecting brushes are made

produces, at its maximum velocity of 700 revolutions

per minute, a light of candles,and absorbs three

and one-half horse-power.

In the South Foreland lighthouse experiments, comdncted by Prof . Tyndall , the re lative eficiency of theGramme and the Hafner-A lteneck machines was made

GE N ERA TORS O F THE N E W S IEMEN S TYPE . w

at a speed of revolutions per minute, absorbing

horse power, the Gramme machine developed a light of

758 candl es per horse power. The largest Hainer-Alte

power, developed 9 1 1 candles-light per horse power ;while a smaller machine, at 850 revolutions per minute,

per horse power. A second small machine developed

for a brief period candl es- light per horse power.

In another form of the New Siemens machine (Fig .

Pig . ao. N ew S iemens Machine, S tationary Armnmle C ore.

armature core is stationary,and the

and rotate with a cylinder

but not touching, the core . In

of this form of generator,which is most complete, he illustrates the fact that when

moves in a magneticfield, such motionor so o called Foucaul t, currents, which,away

,become tran sformed into heat,

.

40 ELE CTRIC LIGHTIN G B Y iscmsscs scn.

rise to a considerable heating of the metallic bodies in

motion . As long,therefore, as the iron core revolves

with the coiled drum through the magneticfield, t these

currents are not to be avoided , though they may be di

minished to some extent by constructing the arma ture

of coils of iron wire instead of massive iron . It was,therefore

,determined to secure the iron armature inside

t he drum,and so prevent it from taking part in the mo

tion of the latter. As a matter of course, this renders

the construction of the drnmmuch more complicated,especially when it is considered that the long drum

,

with its surrounding coils of wi re,has to be moved

through the narrowest possible space between the pclar

faces of the electro-magnet and the stationary iron core .

In the engraving,which is composed from Dr . S chel i

len’s work,we have a horizontal section of the machine

,

showing the thin German-silver drum upon which the

wire is wound . Each terminal face of the drum carries

a short tube,which tubes form the trunnions of the

drum and lie in boxes provided with oil-cnps . A h iron

shaft,secured by mean s of screws in its supporting pil

lars,passes through these tubes into the interior of the

iron armature, where, by means of two disks bolted to

each other, the armature is fastened to the shaft . The

drum is surrounded on the outside,at two oppod te

plams,for about two-thirds of its circumference and

over its entire length,by the two curved polar faces of

the magnet . These are placed as closely as possible to

the wire surrounding the German-silver drum,and form

,

wi th the stationary hollow iron interior core,a narrow

annular space, constituting the magneticfield, through

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a mmo L IG HT IN G BY IN O A N D E S C E N‘

C E .

and in constructing the armature the hollow

In efficiency the E dison

constructed, would seem to be equal to any

of the H i fner-Altenach form, although we have no da taupon which to base a conclusion . T he

GE N E RATO RS 0 9 T H E N EW snms s TYPE . 43

m min two ways . In thefirst, of which F‘

ig. 22

is a sectional end view, a helix of iron wire, wound like

thrwd upon a spool, surrounds a wooden

or other diamagnetic roll . This helix con

M nees the core of the armature . O ver it

RM VM M AMIn the second form of an armature, m

it is composed of a large number of thin, softaro n flanges ,similar to those used in the r 3 1 1 4 machine

,and a free

to 3V0 id s h

In the

which Fig is an illnstmtionthe compound magw t of Sie m’m’ 8k“W " “Am'm'

and a simple Wilde electm-magnet of

cas t-iron is substituted therefor. To secure the maxi

mum of magnetic power, thelimbs O f the magnet in in

thickness as they approach the

ends of the magnet limbs cas t

T he genemtor shown in the il

machine, the armature being 2

inches in diameter, and, as in mmmmmmsize, the arma ture core consists of a substantially solidroll ofmallw ble iron . In large machines the arma ture,

GE N E RATO RS O F THE N EW S IEMEN S TYP& 45

l ike tha t of the Hfifner-A lteneck machine, is in the form

T o prevent hea ting, the malleable iron roll is con

F ig . 26 . Around a series of wrought-iron tubes, B ,the

mm. M a dm a n .

iron caps, D . The 811m0 is hollowed out a portion of

its length from each end, and provided with ope n-

‘

s

into the spaces enclosed by caps D . All the joints m

strew nof water is let into one end

in the dimtion of the arrow into

46 ELECTRIC LIGHTIN G B Y I N O A N D E S O E N CE .

In brineiple the same asthe H i fner-A lteneck ma

chine,it is not surprising

that this generator should

have yielded as good te

sults ;but the temperatures

maintained while doing

work have been of an un

expected character. In in

chine varies from . 25 of an

ohmto 5 . ohms,according

to the work to be done

and the distance between

the periphery of the iron of

the armature and the polar

faces of the magnet is fromfives ixteenths of an inch toone and one-eighth inches

,

machine . Each polar face

covers one-third of the peri

phery of the armature when

wound with the induction

helices .

The N o . 1,or smallest

size of machine,driven at a

speed of revolutions

per minute by a belt one

inch in width, yields a light

by the voltaic arc of 500 candl es,and incandesoenoe

Fig . 81

G E N E RATO RS on T HE N EW snsmss s TYPE. 47

276 candles . N o deduction is made for the element

the percentage of which in smal l

Fig ” . End Secfion of lmge Amtm-o .

The following table, compiled from a series of tests

machine, in of chm'

in Waning of cad et

oh-l . char mu, Fahd“ inm in:

f .

i

Reduction of the temperature of the arma tm'

e below

that of the surrounding air was so entire ly unexpected

tha t on November 22 a prolonged test of the No. 2 ma

chine,wound with a different size of wire, was made.

The internal resistance of the machine was found to be

49 E LE CTRICmomma B Ymcmnsscascs .

ohms,and the resistance of the external circuit . 9

ohm,making the total resistance ohms . The dura

tion of the tes t was from A .M . until 9 P. M . O bser

va tions were carefully made both at the beginning and

end of the run , and at intermediate intervals, with the

following result

wa ter on potature oflore en tering leaving anna

731° F. F.

In every case the temperature of the armature is found

to decrease, al though the larger sizes of machines have

not been subjectedto thermometric measurement .

There is some diversity of opinion regarding the bestmethod of winding the H iifner-A lteneck arma ture . Very

Fig . 29 . Method ofWinding Armature.

l ittle is generally known about the subject, except that

there are several methods,none of which have ever been

made very clear. A method of winding,substantiall y as

good as any, and one that has been used in both the Edi

son and the Sawyer machines, is illustrated in Fig. 29 .

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50 ELECTRIC LIGHTIN G B Y IN CAND ES CE N CE .

coil. Covering of the drumwith asbestos-paper to en

sure proper insulation is advisable, and in order to facili

tate the winding it is useful to insert temporary guiding

pins at the ends and middle of the drum,on the lines

the sections . Accurate laying of the wire is

Fig . 81 . S uperman! C onn and C onnections

essential. After winding, the coils are bound to the

dmmbyfine brass wires wound so as to form a bandaround it, and soldered . There should be several

such bands at different points along the length of the

GEN E RATORS O F THE N EW S IEMEN S TYPE. 5 1

by interposed bands of mica. To the free ends of the

coil s,through a sleeve on the shaft of the machine, the

fourteen commutato r segments are connected as shown

in Fig. 30, in which A is the shaft, B insulating disk,C C commutato r segmen ts, and D D col lecting brushes .

In some cas es it is preferable to superpose coil No . 2

upon coil No . 1 , etc . , as shown in Fig. 31,in which case

the drumis divided into fourteen sections . The connections of the commutator segments, as will be seen, re

main the same .

The collecting brushes bea r seriatim upon commutator

segments !,8 ;2, 9 ;3, 10 ;4, 1 1 ;5, 12 ; 6 , 13 ;

1 ; 1 1,4 ; 13

,6 ; 14, 7 ; and in each

of the respective positions the circuit of the armature

coils,the sections of which now constitute a continuous

,

endless conducto r,is as shown on page 52 :

Fig. 82. HerrFrBlichWinding.

BrégnétWinding.

to divide the armature-coil

into as many sections as may be consistent with the .

practical mechanical construction of the armature and

commutator, in order that the coil may cut the lines of

52 E LE CTRIC LIGHTIN G B Y I N CAN D E S CE N CE .

magnetic force the greatest possible number of times in

a single revolution of the armature .

i S egment of S egment ofcommuta tor in D irection and division of themultiple circuit frombrush commuta tor incontact w ith t st to brush.

contact wath cdbrush. brush.

— u — l o 7 6 3

5_ 8 9

— 1 2— 1 3 2 +

4+ — n — xo 7 6

5 8 9— 1 2 — 1 3 2 + 3+

5+ 4+ 1 + I 4— n — ro 78 9

— 1 2 — 1 3 2 + 3+ 6 +

8+ 5+ 4+ — n — 1 0

9— 1 2 — 1 3 2 + 3+ 6 + 7+

9 + 8+ 5+ 4+ — n

1 2 — 1 3 2 + 3+ 6 +

8

{iii 21 31: 21 ?i xéi ihrs+ xz+ 9 + 8+ 5+ 4+ 1 +2 + 3 + 6 +

2 9 + 8+ 5 4+3+ 6 + 7+ I o + u + 14 1

6 3 2 9 + 8+1 4 s

7 6 3 2 9 +I o + 1 1 + 14+ I 4 5 8

1 1 — 1 0 6 3 2 — 1 3+14+ I 5 8 9

— 1 2

14— 1 1 7 6 3

1 4 8 9— 1 2

The method of winding the armature devised by Herr

Frc'

ilich (Fig . 32) comprises sixteen vertical conductorsarranged in pairs at the point of a regular octagon, and

crossing the octagon by the diagonals at one end of the

armature, and by long chords, crossing in the form of an

GE N ERATORS O F T HE N EW S IEME N S TYPE. 53

e ight-pointed star, at the other. In the method dis

covered by M. B régnét (Fig the portions of the

co ils which cross the ends of the armature to unite

the sixteen vertica l wires cross the octagon along short

CHAPTER IV .

I N O A N D E S C E N T L AMPS .

PRODUCING l ight by heating a poor conductor of

electricity to incandescence is a favorite conception

and numerous attempts have been

made toward its practical realization . In nearly every

much bemuse of any inherent defect of principle as be

cause of imperfections in the details of construction

Lighting by incandescence involves a principle as simple asfighting by the voltaic arc . The conductor ren c

dered luminous is of poor conductivity,or

,in other

terms, of high resistance . The resistance of the wires

connecting it with the generator of electricity may be

disregarded . Therefore the current generated is“

5

between the generator and the poor conductor e s j“

in proportion to their respective resistances ;and as the

latter is contained in small compass,the cnrmnt is cou

centmted at a small . point and there proda ca lori'fie

efiects snficient to yield light .5 6

IN CAN D E S CE N T LAMPS . 55

When a body is at the temperature of C . we

have the heat-rays :

A t we have the orange rays .

yellow rays .

blue rays .

indigo rays .

violet rays .

Above C . we have all the rays of the sun. In

incandescent carbon lighting the conductor is raised to a

temperature much in excess of

Many conductors may be employed in the production

of l ight by incandescence ;and it is a curious fact that

experimentalists have almost invariably followed a beat

eu course,passing from one metal to another : from pla

tinum to iridium and iridio-platinum ; from the metd sto carbon-coated and intermixed asbestos and other re

tractory materials ; andfinally to carbon alone . As

carbon,pure and simple, has been clearly determined to

be the only suitable substance,we shall leave out of con

sideration all other conducto rs of electricity .

There are two types of incandescent lamps in use,those which burn in the air and those in which the 111

minous conductor is enclosed in a globe exhausted ofair or containing an atmosphere of nitrogen or other gas

high temperatures has no chemica l

air lamp is subject to so many ob

jactions that it is doubtful whether it will ever be

mesmfully employed ; but the efforts of Renier andWerdermann have done much towards reducing it tometical form . The Renier lamp (Fig. 34) consists of a

long pencil of carbon continuously fed between an elas

56 E LECTRIC mca '

rms BY IN CAN D ES CEN CE.

tic con tact to a bearing upon a carbon roller at a point

between the vertical and the horizontal . The upper or

elastic conta ct compresses the pen

cil laterally, and one terminal of

the conducting wire is connected

with this contact . The other ter

minal is connected with the carbon

roller. The pencil , being consumed

at the lower extremity more rapid

ly than at any other place, di

minishes in length,and this di

mina tion is compensated by the

continuous downward feeding of

the pencil . Ro tation of the car

bon roller to carry away dead

fra gments of carbon is obtained

from the tangential component of

the pressure of the pencil on theperiphery of the roller.

The \Verdermann 1amp (Fig . 35)is the reverse of the Renier lampin construction and operation . In

this lamp the carbon pencil is fed

upward,through an elas tic con

tact,by means of a weight or

spring,against a solid stationary

block of carbon .

B oth the Renier and the Wer

dermann lamps, under proper conditions, should yield a higher percentage of light per

horse power than lamps in which the carbon is prowcted

Fig . 34. W i n s.

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58 E LE CTRIC LIGHT I N G B Y I N CAN D E S CE N CE .

36 ) consists of a conducting wire, D ,sealed in the glass

of a T oricellian vacuum-tube,and co nnecting with a car

bon rod, A ,whose lower extremity is in contact with a

second conductor resting in the quicksilver. The bar

B,of porcelain

,serves as a support for the apparatus .

For several reasons this lamp could not have been a

successful one, as will bemade clear in another chapter.

”r

In 1873, nearly thirty years later, came the invention

of LodyguinenL a Russian physicist, who was awarded ,

during the subsequent year, the grea t prize of the S t .

Petersburg Academy of Sciences . The L odygnine

burner consisted of a single rod of carbon diminishing

in section at the incandescent part and two or more of

these rods were placed in a globe provided with an ex

terior rheotome, in order that the current might be

T he S tarr-King systemof lighting included a generator of electri

city some of the devices of which are variously used at the present day.

T he following summary of the leading points of S tarr’s E nglish patent,

taken out by King in 1846 (N o . and entitled Improvements inthe Production of Magneto-E lectricity, ” is of interest

1 . T he principle of the machine consists in revolving between the polesof permanent magnets, arranged mdia lly, a disk having near its edgebobbins with their axes parallel to the axis of rotation .

2 . Winds around the iron some a continuous hat s trip of 00pper, ir1

serting cotton between each layer to insulate.

8. Collects the current fromthe separate bobbins with separate springs ,to allow of subdivision

, if necessary.

4. T o prevent neutralizing currents being induced in the brm or

other meta llic plate which forms the wheel carrying the armatures, a

saw-cut ismade fromthe edge to the hole in which the armatune is ia

5 . Attaches a soft-iron bar to the inducingmagnets , so that theymayeach set a second time on any armature during each revolution .

{Meanwhile both S hepard in 1850, E nglish patent N o . and

Roberts in 1852 , E nglish patent N o. invented and experimentedwith incandescent carbon lamps.

I N CAN D ES CEN T LAMPS . 59

been des troyed . Unasconntably, L odyguine has

sevemcriticised by many writers,who have pro

the least

studied of all ; it the most practical and

the most studied of all that had preceded it, for Lody

Q the value of a perfect connection with

t portion,such as results from enlarge

mentof the w rbon at the points of contact with the

60 ELECTRI C LIGHTI N G B Y I N O A N D E S O E N C E .

conductors lead ing to it, and he provided for the insv

itable destruction of the rod by arranging another to

take its place.

After Lodyguine came Konn and Koslofi, whose inventions do not differ essentiall y, although the Konn

lamp of 1875 (Fig . 37) was perhaps the more practicable .

This lamp consists of a base, A ,in copper, on which arefixed two termina ls to which the conductors are fas

tened two bars,C D ,

in copper ;and a small valve, K ,

opening only from within outwards . A globe, B , ex

pended at its upper part, is clamped to the bas e by

means of a collar, L , pressing on soft rubber washers .

O ne of the vertica l rods, D , is insulated from the bas e,and communicates with a terminal, also insulated . The

o ther rod, C ,is constructed in two parts : (1 ) of a tubefixed directly upon the base and in electrical connec

tion therewith and (2) of a copper rod split for a part

of its length , whereby is obtained sufficient elas ticity topermit the rod to slide freely and yet be held in place in

the tube . Carbon pencils,E

,are placed between two

small plates which crown the rods . Each pencil is intro

dnced into two small blocks, 0 ,also of carbon

,which

receive the copper rods F G at their extremities . The

rods G are equal in length , and the rods F are of hue

qnal length . A hammer, I , is hinged on the bar C ,and

makes connection only with a single pencil of carbon at

once .

When the lamp is placed in circuit,a pencil of carbon,

E , is traversed by the current ; and when this pencil

is consumed and drops out of place,the hammer

,I,

makes connection with another pencil ;when all the car

mcw nsscsm‘ LAMPS . 61

!b one have been consumed the hammer rests upon the

0 0 p rod H,and the circuit is not interrupted . A o

co rding to M. Fontaine, the maximum light obtainable

from a Kenn burner is equal to about 175 candles . The

Pk. as. T he“mm Ponh lne’s Imp.

f e it from further change—eu error in

mlmflanon which it is dificult to understand, and thefaM y of which is proved by the results . The average

duration of thefirst pencil is about twenty minutes .

62 E L E CTRIC LIGHTIN G B Y IN CAN D E S CE N CE .

The succeeding pencils have each an average life of two

hours .

Next in practical order comes the B oul iguine lamp

(Fig. inWhich a long pencil of carbon is fed upwards,as in theWerdermanu lamp, through an elastic contact,in this case controlled electro-magnetica lly . The sea ling

Fig . 40 . Farmer’s L amp, 1879 .

of the globe is effected, as in the Konn lamp, by the

lateral pressure of soft rubber washers .

*

T he last of these old lamps of Which there is record

is the invention of M . Fontaine (Fig. in which the

carbon pencils,A A

,are held in rigid contacts . N o

Carbon-holders,made in the formof long tubes andfilled with longcarbons, werefirst employed by S ta ite (E nglish patent N o . of

who ,with his associate, E dwards, was much in advance of the day in

which he worked .

IN C A N D E S O E N T LAMPS. 63

allowance is made for eirpansion or contraction of the

conductors . In this lamp, as in‘

L odyguine’

s . a fresh

pencil is brought into circuit by an exterior rheotome

when one has been consumed .

Among all these lamps that of Konn mainta ins its su

premecy and it must be confessed that, considering the

time and means devoted to the solution of this problem

in European countries, the product is insignificant.The lamp il lustrated in Fig . 40, which was patented

by Farmer, March 25 , 1879 , has not progressed beyond

the stage of laboratory experiment . It is perhaps less

practical than the lamps of Konn and others, in these

respects : that the incandescent rod or pencil is held

between large blocks of carbon in such a manner as to

grea tly obscure the light ; and that the sealing is si

fected by means of a rubber stopper through which pass

the conducting supports, which, being good conductors

of heat, must inevita bly cause the lamp to unseal .

CHAPTER V .

C ARB O N S FO R I N O A N D E S O E N T L IGH TI N G.

BEFORE entering upon a further survey of thefield ofincandescent lighting

,it is well that we should

pause to consider the primal element of all incende

luminous carbon conductox. Its te

it must be uniformand in homogeneity perfect . The1 and harder the carbon the more lasting it proves

to be ; and density, hardness, and homogeneity in the

v aretherefore the elements, or a part of them , of

Before the time of Foucault,who substituted

carbon for wood charcoal , the voltaie arcwas

little more than a laboratory toy and thus with incan a»

descent lighting, so long as the luminous conductor is

confined to the product of the gas -retort its uses must

be confined to the laboratory .

One of the earliest methods of preparing i n car

bons,and that in most general use at the present day,

cons ists in reducing coke to afine powder and thorough »

ly inco rporating it with molas ses or other glutinous hy o

drocarbon substance . The resultant mixture is pressed

into moulds and baked,and afterwards placed in a con

centrated solution of the same hydrocarbon. and, when

thoroughly saturated, again baked ; and so on64

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66 ELECTRIC LIGHTI N G B Ymmmsscas cs .

the paste is compressed and passed through a die plate,whereby the pencil is formed . Subsequently the pen cil

is subjected to a high temperature in a crucible, and by

va rious operations and repetitions of the hea ting the

requisite density and hardness are obtained . The ar

rangement of the pencil for baking,after forming

,while

yet in a pliable condition and without permitting it totwist or bend, is one not full y understood ;and all at

tempts in this country towards duplicating the manu~

facture have signally fail ed . Pencils of one thirty-see

ond of an inch in diameter and nine inches in length,made expressly for us , are as absolutel y straight and te

gular as a wire under tension .

The drawn or moulded pencils are primarily placed in

a horizontal position on a bed of coke-dust in crucibles,

each layer being separated from its neighbor by an

intervening sheet of paper. Secondly,a layer of coke

dust is spread over the carbons;and, lastly, the whole is

covered by silicious sand. Having been kept at a cher

ry-red heat for four orfive hours

,the carbons are reo

moved to a vessel of boiling-hot,concentrated caramel

or sugar-cane, and there left for two or three hours, the

syrup being alternately cooled and heated several times,in order that it may completely permeate the pores of

the carbons . Subsequen tly the syrup is drawn 03 , and

any sugar adhering to the surface of the carbons is re

moved by immersion in boiling water. Finall y, aiter

drying in an oven,whose temperature attains to 80° C .

only in the course of twelve tofifteen hours, the bakingoperation is repeated Upon the number of repetitions

of this process,to a certa in extent, depends the value of

cannons FORmcmm mL IGHTIN G . 67

the ca rbons, which, specially manufactured, are marvels

of purity, tenacity, density, and homogeneity .

’

T he M ov ing synopsis of old E nglish patents relating to electric-light

carbons, taken fromCol. Bolton’

s report, will doubtless prove of interest :G l en n umSu n

'

s .“ Certain Improvements in Ignition

and I llumination.

"

Uses lamp-black, charcoal. or coke. already purified hemsulphurand metallicmixtures by the application of electricity in accordance with the process patented by Jabez Church in 1845 ; digests innitromuriatic acid;washes several times in water or in aome weakalkaline solutioa , or carburetted alkaline solution,finallywith distilled water; then drics and presses with hydraulicscrew, orfly-press .into cylinders , and when necessary exposes to intense heat in a fur

me for twmty-four hours .

1846 . 8 1m" , Takes equal (mantities 01 005 1 of a mediumquality(neither too rich nor too poor) and 0 1 that purified description of

coke known as Church'

s Patent Coke "

;powders andmm i n

close sheet-iron moulds until so lid . then plunges hito concentratedsolution of sugar. and when sufficiently dry subjects it for several

hours in l cloee veesel conta ining charcoal at an intense white heat.

3mm In addition to prewing, also heat. and when hot

plunge into sugarmelwd by heat without the aid of any liquid.Then cool and piace in a closed vessel conta ining pieces of charcoa l

heated to a white heat, and keep there formany hours, or even two orthmdayozor thc whole mass may be a seooad timo immcrwd inun ited sugar and the proemrepeated .

He says. also . that electrodesmade of gas-retort carbon frequentlycontain iron, whichmakes themsplit and not give out somuch light.Theymay bemuch improved by heating to a white heat in a closedvessel for some days .

M n, Prefers to use, l at, plumbago powder having iron,eta , extracted by washing and warming in acids ;2d. lamp-black8d. charcoa l powder;4th, powder of carbonaceous concwte which is

deposited inW ;or. sth, sifted grains of this materia l . Mix

any one of those with brown sugar,melt and boil (without water)until atifl, pm when hot in iron moulds lined inside with paper.chalk, or plaster-of-Paris to preven t adherence and to allow {or cc

cape of the gas . themoulds having ho les for the same purpose. B eat

slowly until a red heat is obtained, at which temperature keep them( 0? some time, then take out and put in upright crucible. with lute;gently raise to a white hea t. at which temperature keep them(or

some time. and then al low themto cool .

dry in the shade. hea t gradua lly in a nearly closed reto rtto a red hea t, a t which temperature keep the retort

hours, when cool slowly.

Makes the carbon disks used by himin his electric laretort carbon , cut into the right shape, and purified bymixture of nitric andmuriatic acids for tfluoricacid for twelve hours.Ros t ers . Improvements in the productionrents in obtaining Light, " etc .

Mixesfive per cent. of lime withma teria ls of e

crease the brilliancy of the light.J1 0 1130 11, Impmvements in producingetc.

H ollows out t0 p of lowercarbon and introduces mercury or platinuminto the recess .

B ums , 119 .

“ Improvements in producing Electric Light. ” Pro

visional protection only .

S ubjects lignite to destructive distillation in closeu vessels.

Covers metal with ta r, pitch. bitumen. asphalt, and rosin , or

tures offineiy-pulverized charcoal or lamp-hlack,material . which on being dried or strongly heatedsolid or compact carbon .

O r drills holes in carbon and insertsmeta l rods . or attaches a va

neering of charcoal tometa l .S un

's , 684. B oils carbon in oil or other fatty substance. and bakes .

HARRISON , 588.

gas carbon . O r a combination ofmetalother formof carbon ,may be formed intoProposes to insert other substances in the powder inthe light.

HUN T, 282 . Improvements in Means for ProducinLight.T he residuumfromthe distillation of tar or pitch is

impalpable powder, and mixed with ta relectrodes are then moulded, heated red hot, immersed in tar

again heated , and so on until the required density is obtained.

cansoxs FO Rmcmsscsm‘ms arms . 69

in the granting of Letters-Patent to Sawyer

annary,1879 , for a process believed to be new in

In many experiments previously made, incan

to arresting consumption of the carbon

und that the globe soon blackened, and

commensurate with the amount of the

ut otherwise suffered no change . It

that the deposi t which blackened the

have proceeded from the pencil and ih

wed that the hydrocarbon atmosphere

11 set free,and the car

it appeared that the

the mecha nical com

dissociated carbon .

upon the pencil from any given

uld be a greater deposit from a.

and that the greater the heat

and the slower the deposition,ould be the carbon . These

subsequently verified . It was found

of hydrocarbon gas or vapor an imcarbon was rendered perfect

,the ori

imperfection, being of proportionate

es and heating proportionately to 9.

than the perfect portions,receiving a de

70 E LECTRICmcarmc B Ymcaansscs sca

posit which compensated for such imperfection . Thus

pencils of carbon of any desired diameter up to one

eighth of an inch, and of a density and homogeneity be

fore unthought-of, and capable of taking a polish like jet ,were formed of and upon a merefilamentary conductor.The originalfilamen t appealed to be unchanged, the deposit carbon being in the form of a cylinder surrounding

it and possible to be broken oil?from it.

It was found also that the pencil could be as veritably

welded or joined to the connecting carbon blocks as

two pieces of metal are welded or joined together, and

the Sawyer-Man carbon horseshoe,whichwas perfected

and exhibited in the winter of 1878—9,was trea ted by

this process,the ends of the horseshoe being welded to

the supporting blocks in order to secure perfect elec

tricel contact .

From obtaining a cylindrical deposit of carbon upon afilament of ordinary carbon,the manufacture of pencils

entirely of deposit carbon was attempted . The cylinder

was sawed through lengthwise by means of a rapidl y

revolving,smooth

,thin disk of steel, and the originalfilament removed . The two portions, semicylindrical

in shape,remaining, were then subjected to trea tmen t .

The most perfect of all these carbons were prepared by

taking sticks offine willow charcoal, and first saturatingthe same with syrup and subjecting to heat as in the

Carré process, in order to increase their conductivity .

The sticks were then divided into pieces one-half an inch

in length and three sixty-fourths of an inch in diameter, and placed between carbon-holders for treatment .

Heated to extreme iucandescence and surrounded by an

caasos s sonmcas nsscmmcarmc. 71

a tmosphere of hydrocarbon, the deposit described immediately formed The pencil,

was thenfiled on one side untilthe original will ow was ex

posed, but leaving the ends of

the pencil untouched . The wil

low being next removed, a pen

cil of boat shape and remark

able durability was obtained .

The Sawyer-Mau lamps,as ex

hibited in New York, were all

furnished with carbons of this

character, and to the perfection

of these boat shaped, electri

cally-f'

ormed carbons was due

their comparative success . To

the necessity of frequent re

newal,and the time and skill

requimd to produce the carbons

,was due the commercial

failure of these lamps .

In preparing long pen'

cils of

carbon,allowance must be made

for the expansion of the origi

nalfilament. The Sawyer de

positing apparatus (Fig.

which holds thefilament, is eutitely immersed in a hydrocar

bon bath . The decomposing current,entering by way or

the metal lic uprightsfixed to a soapstone base, passes

72 E LE CTRIC LIGHT IN G BY IN CAN D ES CE N CE .

through thefilament by way of its carbon-clamps . T he

upper clamp,balanced on a knife-edge, is removable . In

this,when removed, one end of thefilament is secured

and the clamp is then put in position . N ext the lower

end of thefilament is swung between the jaws of thelowerfixed clamp

,and

,this having been tightened, the

cam -lever above is thrown up, and thefilament thusplaced under tension . When the current is applied

there ensues violent ebullition of the liquid composing

the bath,due to the rapid disengagement of hydrogen ;

dense volumes of smoke arise,and in fromfifteen to

thirty seconds thefilament is covered with a shell of deposit carbon from one sixty-fourth to one thirtys econd

of an inch in thickn ess . Olive-oil is the best hydrocar

bon for this treatmen t . Next in order of eficiency,among common hydrocarbons

,are the following :

Refined sperm oilAbsolute alcohol

Naphtha and gasoline

T urpentine .

In using the last-named hydrocarbons,great

must be taken not to overheat the bath,and to see tha t

thefilament is wholly immersed before applying thecurrent, otherwise there is danger offire and explosion .

The carbonizing of live will ow twigs, with a View to

obtaining a suitable bent carbon,by Sawyer Man, and

the carbonizing of paper and bamboo by Edison,subs tan

tially close the account of incandescent carbons. Recently, an attempt to better the texture of thefilamenthas been made by Mr. J W. Swan, of N ewcastlem»

Tyne,who forms it from cotton thread

,which is sub

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CHAPTER VI .

N E W FO RMS O F L AMPS .

IT was in 1875 , after some desultory work, that we htat

took an active interest in the subject of incandescent

lighting. Subsequent years devoted to the perfection

of apparatus in connection therewith have greatly aug

men ted the stock of knowledge originally possessed.

The theories upon which experimentalists had labored,and the probable causes of their failures, were given care

ful consideration, and in all matters of doubt the results

of practical experiment were made the basis of conelet

sions .

It did not atfirs t appear that when a carbon conductoris excluded from contact with combining matter, it is

nevertheless,in the sense of changing form

,destructible ;

otherwise speaking,the destructibili ty of all matter sub

jected to constant and varying tension did not primarily 4

present itself with the convincing force that is born of ex

perience. Many experimenters in incandescent light

ing had failed because they had overlooked the fact

that nothing is indestructible,or undisintegratable, or

unchangeable . Additionally, the Starr-King lamp had

failed because there was present in the T oricellian ?a

cuumthe vapor of quicksilver,due to heat, with which

the carbon entered into chemical combination . In dy

ghine obviated an imperfect contact with the carbon74

N EW FORMS O F LAMPS . 75

co nductor by making the luminous section a reduced

portion of a large carbon . L odyguine, Konn, Kosloff,a nd B ouliguine, recognizing the destructibili ty of the

co n ductor, sought compensation in self-renewing de

v ice s ; but their lamps were imperfect in that they did

n o t preserve the carbon from contact with gases with

w h ich, at high temperatures, it enters into chemical

c ombination. A ll of the old lamps,excepting that of

S ta rr-King, were inadequate ly sealed . A ll were some

w here attended by conditions calculated to prevent the

To preserve incandescent carbon from chemical change,

i t must be hermetical ly sealed in vacuo, or in a globe

e ontaining a pure and perfectly dry cyanogen , nitrogen,l ydmgwen , or hydrocarbon atmosphere . If there is a trace

o f oxygen or other gas or vapor present, or any third

mon-gaseous body in condition to come in contact with

the carbon,chemical change is the result. Nor can the

incandescent carbon establish connection with any metal,

for the reason that the carbide of that metal is then form

ed I ts connections must be with carbon of greater mass,in order that the temperature of the metal contactsmaybe low and the contacts perfect ;and it must itself be

pure and also homogeneous, as imperfections in its strueture produce consequent points of resistance at which the

current concentrates and where disintegration occurs .

In the dioxide of ca rbon (carbonic acid gas), which insmutly extinguishes ordinary flame

,the incandescent

conductor is consumed, not quite so rapidly, but just assurely, as in air . In the monoxide of carbon consumption is cermin, though still less rapid. The explanation

73 msc'

nuc LIGHTI N G B Ymomsscss ca

of this is found in the fact that a current of the heated

atmosphere is constantly flowing past the conductor, andthe heat of the conductor is so great that the carbonic

oxide is decomposed before the two come in contact ;and the oxygen thus set free

,and having a higher em

nity for the carbon of the conductor than for the less

hea ted atom from which it has been dissociated , com

bines with the former, while the dissociated ca rbon atom

is deposiwd either upon the interior works of the lamp

or upon the inner surface of the enclosing globe or the

oxygen rises in a free state (the carbon being deposited

as described), and upon subsequently coming in co ntact

with the incandescent conductor thereupon combines with

it to form the monoxide . The monoxide, not the diox

ide, is always formed when there is a limited amount of

oxygen present . Thus it will be clear that, however

slight may be the trace of oxygen in the sealed globe

of an electric lamp, and however great in mas s the in s

candescent carbon may be, it is only a question of timcwhen this circular process of chemical dissociation and

recombination will entirely destroy the conductor and

deposit it upon the in terior works and the globe of the

lamp . What occurs with oxygen occurs with other sub

stances having an affinity for carbon at high temperatures ;and to procure a non -combining atmosphere suhi

ciently free from impurities involves a very delicate

laboratory process . The employment of hydrogen is dis

advantageous in these respects,that it necesd tates a

more powerful current to produce a given light than

when the conductor is in vacuo or surrounded by nitro

gen . and that, should any leak occur, air sufficient to

nnw FORMS or LAMPS . 77

tow a dangesous explosive mixture soonfinds accessto the globe . For the latter reason an hydrocarbon at

mosphere is impracticable, in addition to the fact thatthe decomposition of the hydrocarbon so blackens the

globe as to greatly obscure the light . The incandescent

carbon. therefore, can only be practica lly employed in

vacuo, or surrounded by an atmosphere of pure nitrogen,or in a partial or nearly perfect vacuum of hydrogen,nitrogen , cyanogen, or hydrocarbon gas, which last,however, speedily becomes a vacuum of hydrogen, for

the reason that the hydrocarbon is decomposed aid thehydrogen set free in the lamp.

T he idea of protecting carbon from chemical change

by enclosing it in a vacuum or a carbon-preservative

atmosphere is, as has been shown , by no means new .

Atmospheres of nitrogen, hydrogen, and the carbonic

oxides, and their vacuums, as well as the ordinary

vacuum. have been employed 1n the laboratory for many

yea rs, and are common property of which all experi

mentalists may avail themselves . *

Next to preserving the carbon from chemical change,the greatest difficulty is found in hermetically sealingthe globe of the lamp . The sealing of glass upon plati

nnmis familiarly shown in Geissler vacuo-tubes ; andwhile the degree of skill required for this method of

T he fdlowing data. abstracted fromthe report of Co lonel Bolton to theLondon S ociety of Telegraph E ngineers . March 26, 1879 . refer to expiredEnglish patents relating to incandcwent lighting

1841 . D : Mou n ts. Uses a coil of platinumwire at the base of

which is a M e of spongy platinumand into which fa lls a shower offinely-pulverized boxwood charcoa l orplu‘mbago . the whole being euclosed in an exhausted tube .

1845. Ki s s , Applica tion of continuous metallic and carbon con

78 ELECTRIC LIGHT I N G B Y IN C A N D E S O E N C E .

sea ling is rare,the Geissler method is undoubtedly as

perfect as any yet devised .

In the Edison lamp (Fig. 42) the Geissler method of

sealing is employed, the two conducto rs, A A, lead ing

to the carbon loop, D ,being sealed at B B in the glas s

of the compound globe, E . In order to obtain a per

fect connection With the carbonfil ament its ends are eularged and clamped in suitable blocks, 0 . Exhaustion

of the air by way of the neck, F, to the one millionth

of an atmosphere, leaving in the lamp a portion of oxy

gen represented bym yfollows . Thefilament ori .

gina lly used by Mr. Edison was prepared by cutting

same by placing the loops thus formed in layers within

an iron box,with intervening layers of tissue-paper.

closing the box to exclude oxygen, and raising the

whole to red heat in a furnace . Lack of homogeneity

in the structure of these carbons subsequently led Mr.

Edison to the adoption of carbonized bamboo-wood ,Which is worked down by successive cutting and scra

ping until the entire length of the loop between its en

larged ends, which length varies fromfive to seven inches

, is reduced to a uniform cross-section of from one

ducto rs, intensely heated by the passage of a suitably regulated cur

rent of electricity. Uses T oricellian vacuumwhen carbon is employed . [King was S tarr’s agent !

1848 . Bu rn , Uses an iridiumor an iridio-platinumwire.

1850. S HE PARD, In a. ground-glamglobe. exhausted . a vertical rod

ofcarbon is, bymeans of a weight, pushed down into a small carboncone constituting the terminal .

1852. Ronmn '

s , Complete apparatus for rendering a rod of graphite, coke, or charcoal incandescent in a non-oombnstible atmosphere.

Placing the carbon in a deoxygenated atmosphere (as hydrogen or

nitrogen), rarefied, was patented by S ts ite in 1846, N o.

N EW FORMS O F LAMPS . 79

sixty -fourth to thirty-second of an inch . The deli

ma mm m

cacy of manipulation of the

wood, in order to make thefilament uniform in size

throughout, renders its cost

excessive ;but this difficul ty,in a measure at least. Will

probably be overcome . The

resistance of the loop when

ca rbonized is from 100 to 300

ohms, and the amount of

light obtainable,With safety

to the conducto r,varies from

two to ten candl es . Fig. 43

is an ill ustration of an E di

son bamboofilament, fullsize

,before bending and car

In carrying out the Edison

method of manufacture a

glass bulb (Fig. of the

size desired for the enclosing

globe of the lamp,is formed

,

with a supporting neck, ex

tending in one direction, of a

diameter snficient to permitthe passage of the illuminating conductor through it.

Preferably a piece of tubing,

of the size of the neck, has

Upon a point on the bulb op

E LECTRIC L IGH TIN G B Y IN CAN D E S C E N C E .

posite the centre of the neck is formed a long

tube for attachment of the bulb to the air-ex

hausting apparatus . Upon the end of a smal l er

piece of tubing a small bulb is formed,and the

body of the tube, a little below the bulb, is eu

larged for a small space to about the size of the

supporting neck of thefirst bulb . This portion

constitutes the loop-supporting part,platinum

Wires,terminating in clamps for holding the

loop,being passed

'

tbrongh it and hermetically

sealed therein . After thefilament is in place, as

Fig. 44. Edison Outer G lobe. G lobe andWorks .

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32 ELECTRIC LIGHTI N G BYmcw nsscssca

complete, it is attached to the vacuum-

pnmphefore-mentioned, and when a proper degree

tion has been attained. the end of the tube is so ftened

and seal ed by heat, after Which the lamp is removed from

the pump . Finally, the tube is softened and sealed near

its point of juncture With the globe, when the portion

remaining above is broken off and the neck again soft o

ened'

and sealed immediately above the sealing before

made at the point of juncture . Fig . 47 shows the completed lamp.

The Maxim lamp (Fig . recently

York,differs from Mr. Edison’s in no

lar . The Geissler method of sealing

the carbonfilament, manufacturedmade in the form of a double loop,the letter M . Thus prepared

,the

substantially the same as that from

When thefilament is treated bybon by the process of depositing already

section is en larged and improved, and the

tainable is from 1 0 to 30 candles .

Before sealing his lamp,Mr. Maximfil ls

the vapor of gasoline,to the exclusionfinall y exhausts by means of

Run at a power of eight candles,

A n erroneous impression , in regard to the Maximlainp, due to theemployment ofgasoline in the process of exhaustion. is that it is a self-renewing devicH .c. , that whenever consumption or disintegu tiou 0 01mm,

thefilament is repaired by an ever present supply of hydrocarbon. T he

reverse is the case. When ready for use the globe contains a tmee of 33 30line vapor, and this is almost immediately decompbsed. setting the hydromfree, and leaving present a trace of hydrogenmerely .

N EW scams 0 ? LAMPS . 33

is from ten

hours .

T he W h om

system offighting was exhibited inFig. 49 is an illustration of thefirst

E LECTRI C LIGHTI N G B Y IN C AN D E S C EN O E .

device of these experimentalists to which publicity was

given .

In this lamp the enclosing globe was provided wi th a

flange constituting an integral part of the globe, and a

disk of glass perforated with two small holes was accu o

rately ground tofit the same . The ground surfaces werecoated withfir balsam

,and the globe and stopper

strongly clamped together by means of bolts passing

through an elastic flange below the stopper, and a metal

lic flange bearing upon the glass flange. Through the

holes in the stopper passed the diminished . ends of two

stop-cocks, whose joints were made perfect by drawing

their shoul ders powerfully downfirst thoroughl y impregnated withly, melted sealing-wax was poured

the base . B y this means very perfect joints were as .

cured,and to retain them so it wa s only necessary to pre

vent undue heating of the parts . Therefore, the con

dnctors leading from the outside stop-cock connections

to the ill uminating part of the lamp were given co nsider

able length and large rad iating surface . A n insulating

diaphragm supported the upper works .

length , and varying in

second to one-twelfth of an inch in

smal l carbon blocks let into larger blocks,one of which

wasfixed in the lower standard. and the other in a connecting arm, which, in order to allow for expansion and

contraction of the pencil Without friction, was supported

upon a knife-edge bearing. This connecting-arm was

held in place by a coiled spring . The spiral conductors

N EW FORMS O F LAMPS .

consis ted of tubes, one of which

was provided with openings

al ong its length, and ea ch con

necting With a stop-cock . A

lamp of metallic sodium or po .

tassiumas an absorbent of oxy

gen;and its oxide. when formed,as an absorben t of carbonic acid

gas , was placed in the lamp .

To charge the lamp, a stream of

nitrogen was caused to flow

through one of the tubes to the

upper part of the globe,escap

by way of the openings in

the other tube . Carbons of a

m. so. u lnpwith natoc C onductors . m. 51. M u ted (Amp;

86 E LEC TRIC LIGHT IN G BY IN CAN D E S CE N CE .

density before unattained were employed in this lamp ;and although, through imperfect contacts and a faul ty

atmosphere, many of the lamps fai led to last more than

a few hours,some of them were used daily for several

weeks without exhibiting marked change . In the con

struction of the lamp, it was found essential to round the

ends of the carbon pencil, and to make a tapering cavi ty

in the small co nnecting-blocks, which werefirmly set inthe larger blocks . Thefinal sealing of the lamp was

effected by soldering the stop-cocks . Fig. 50 represen ts

the lamp in another form , with radiators of copper rib

bon to prevent conduction of heat to the base ; and in

Fig. 51 is shown the perfected lamp, With small spiral

conductors, in which the soap-stone was replaced by a

The Sawyer-Man experiments were of an extensive

and diversified character, and among the earliest a t

tempts to obtain a practicable lamp was the i ncluding

of an arch or loop of carbon in the circuit of the radi

a tors (Fig.

This carbon loop was originally employed in March,

1878,a rod of retort-carbon being turned true in a lathe

and bored out to form a tube ; from this, thin flanges

were cut,and after being clamped between carbon was h

ers,the upper half was left standing and the lower part

broken out . It was not until the following winter that

the carbonizing of different substances in the form of a

loop,and especially twigs offine Willow, was attempted.

with varying results . A year later Mr. Edison grea tly

improved the manufacture of these loops by processes

much better calculated to attain the end desired tha n

N EW roams O F” LAMPS . 37

those employed by Sawyer 81 Man, whose success in this

Fig .m. T he Em ilee Lamp. Fig . 58. S elt-renewing Lamp.

The fact appearing tha t it is only a question of a brief

period of time when a carbon loop or pencil subjected

88 E LE C TRIC L iG HT I N G BY IN CAN D ES CE N CE.

to the aet'

ion of powerfnl cnrrents will snfier disinteg ation, it is clear that some means of renewing the incan

descent conductor of any lamp must be provided ; and

this renewal must be accomplished without destroying

the lamp. To replace a Sawyer-Man carbon

workman’s time from two to three hours,

charging of the lamp with absolutely

about seventy cents,without taking

the cost of the carbon . It was

ble lamp. To obviate frequent renewal the

feeding-lamp (Fig. 53) was devised .

In this lamp several short carbon pencils were held by

copper rods,as in the Konn lamp

,and as fast as one 4

was consumed or disintegrated,a cam , rotated by a

coiled spring,forced another carbon into contact wi th

the block above . Thus a very d

was obtained, but by no means a

for when the lamp is properly cl

chemical change in the carbon is no longer to be con

sidered, and the point of disintegration is generally the

upper point of contact . In this form of self-renewing

device we do not, therefore, obtain the full val ue of the

pencil,which ordinarily drO ps out when it is only par

tially or even very slightly disintegrated.

A long pencil , fed through an elastic contact, was

originally-held conception,and this was eventually

sorted to in the lamp (Fig. 54) designed early in the

year 1879 . In this lamp,by means of an electro-mag

netic switch , an electro-magnet, operating through the

glas s stopper of the globe, was caused to feed upward

between elastic contacts, as fast as disintegmtiea oe

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90 E LE CTRIC LIGHTIN G B Ymcw nsscascs .

(Fig. in which the pencil was fed upward from the

outside, when necessary, or drawn downward from its

connection with the upper contact-rollers when extin

guishment of the light was desired. With lamps of this

type thefirst private residence, it is believed, in theworld

,was practically illuminated by electricity in the

winter of 1879—80 and during the following month of

March .

* The halls,parlors

, and upper. chambers of a

New York dwelling-honse were supplied with electrici

ty,through a single conductor

,by a generator loca ted a

block and a half distant . Each light was turned on or

ofl’

,or graduated to any desired degree of intensity, in

dependentl y of other lights . The internal resistance of

each lamp was about . 25 ohm .+

N o . 220 West Fifty-fourth S treet, N ew York City.7S ince this was written our attention has been called to the fact that at

S alem, him, during themonth ofJuly, 1859 , Pro fessor Farmer lighted hisparlor by two incandescent platinumlamps . I n a letter to the S alem06

server of N ovember 2, 1878, Pro fessor Farmer adds : And this electric

light was subdivided, too ! This was nineteen years ago ,and it was nu

doubtedly thefirst dwelling-honse ever lighted by electricity. A galvanicbattery of some three dozen six-gal lon jars was placed in the cellar oi the

house,and it furnished the electric current

,which was conveyed by suitable

conducting-wires to the mantelpieee ot the parlor. E ither lamp could belighted at pleasure, or both at once, by simply turning a little button to theright for a light, to the left ( or a dark. ” I t is barely possible that ProfessorFarmer'smemorymay be in error in respect of dividing the current. Whether it would have beenmore natural for himto divide the battery into twoseparate parts of some one and a half dozen jars each

, and operate one la inpfromeach part, than to go to the trouble of arranging resistances and complicawd switches in order to operate so small a number of lamps as two

froma single battery in close proximity to them. is not considened;but it

would have beenmore satisfacto ry ii , inmaking the above claim,Professor

Farmer had stated in whatmanner a button was arranged so as to light

both lamps at once, or to light either one separately, by the one Operation 0 !

turning the button to the right.

CHAPTE R VII.

s aw roams or L AMPS (commvsn) .

WE may now be supposed to have arrived at an adequate conception of the principles underlying

the various forms of incandescent lamps . We have

seen that an incandescent carbon, however complete

ly isolated from gases with which at high tempera

tures it en ters into chemical combination, is a destructi

ble mass of matter. We have,perhaps, reached the

concl usion that means for its renewal must be provided.

and that this renewal must not be frequent, and that it

must be cheaply accomplished . The lamp, furthermore,must be cheaply and hermetica lly sealed, and readily recha rged with a carbon-preservative atmosphere, or ex

ha nsted of such atmosphere,or exhausted of atmos

The new Sawyer lamp, exhibited in New York, and at

the Franklin Institute in Philadelphia within the pas t

few weeks, is designed to meet the requirements men

tioned. The il lustration (Fig. 56 ) shows this lamp in its

pesfected form .

In Fig. 57 the lamp is shown with the interior works

and base apart from the enclosing globe . Upon a thin

metal lic base isfixed one of the upright meta llic conductors leading to the top of the lamp. The other

ducto r isfixed to an insulated bolt passing downward

through the centre of the base . These conducto rs are of01

92 E LECTRIC LIGHTIN G B Y IN CAN D ES CEN CE .

steel,in order to prevent rapid con ~

duction of heat to the base, and are

formed as shown in order that they

may be readily stamped from sheet

metal and pressed into the requir

ed shape . B y means of a copper

plunger attached to a wire running

over a winding-drnmat the bas e ofthe lamp

,in which drum an ordina

ry watcho spring, furnishing the mo

tive power,is coiled

,a long pencil

of carbon in the plunger—tnbe is an

tomatical ly fed upward through thelower elas tic carbon-contacts to a

connection with the upper perfora t

ed carbon-block . Thus the pencil

is constantly forced to a bearing

against the upper carbon-block un

til entirely disintegrated ;and when

entire disintegration has occurred the

pl unger closes the circuit of the lam

As heretofore explained,the point at

which disintegration mainly takes

place is the upper point of contact ;and as, when the pencil is protected

from combining matter,this disinte

gration amounts to between the one

hundredth and thefiftieth part of aninch for every hour the lamp is run,

and as the pencil is eight inches in

length, it follows that the useful

lifetime of the carbon is from 400E“56 SW ” :

N EW FO RMS O F LAMPS .

m07 . T heM yer Lamp.watt.

94 ELEC TRIC LIGHT IN G B Y I N CAN D E S CE N CE . .

to 800 hours,equivalent to four hours’ daily use for

from 100 to 200 days . In this calculation it is assumed

that the intensity of the light shall not exceed that of

two goodfive-foot gas -burners, or at most thirty candle

power. Run at a higher intensity the durability of the

pencil is diminished.

The glass globe of the lamp has no direct connection

with the base supporting the lamp mechanism. In a

thin , spnn-metal,open cup, amounting practically to a

short tube,the globe is sealed by heating the cup and

the glass, and pouring into the annular space between

the glass and cup a sealing compound which is elastic

at all ordinary‘

temperatures, adheres to both glass

and metal, and does not soften at temperatures at

tained in the lamp . The sealing space is two inches

deep and one quarter inch Wide, and the sealing oom

ponnd substantially as homogeneous as glas s hence the

element of leakage at this point may be disregarded .

In order to place the carbon pencil in the lamp, the

upper carbon-block is ca rried to one side by moving the

sustaining-arm on the standard connected wi th the insu

lated steel upright, and space is made for the pencil bymoving the plunger to the bottom of the tube and thus

unwinding the wire on the drum . The lower ca rbon

clamping-blocks, whose mutual pressure is sustained by

a spiral spring, placed lower down in the lamp so as to

prevent its undue heating, are then separated, and the

pencil of carbon is dropped into the tube . Finally, the

upper carbon-block is moved back into the position

shown,when the lower carbon-clamps and the winding

drum are released, and the pencil is brought to a bearing

N EW roams O F LAMPS . 95

in a central opening through the upper ca rbon-block .

The circuit is by way of an insulated wire enclosed in the

bracket to the central insulated bolt, one of the upright

steel conducto rs, and the upper carbon-block and down

ward, through the pencil , as far as the lower clamping

blocks, and the other upright steel conductor, to the base

of the lamp and the brasket. To connect a lamp in circuit it is there fore necessary tofix it to the ordinarynipple-thread of a gas -fixtnre, the two con tacts thusThe peculiar shaping and general design of the parts

of the lamp are such as to facilitate and cheapen their

manufa cture . The carbon-blocks are formed in moulds .

T o prevent oxidization from handling and exposure,all

of the parts are nickel-plated . All of the metallic parts

above the upright steel conductors, and the pencil-tnbe,are of pure copper. The leading wires of the winding

drum and the coiled clamping-spring are of steel . All

o f the parts at the base of the lamp,excepting the

s crews, are of brass . A stop-cock,or a single opening

,

through the base, closed by a short brass screw,is em

p loyed in the charging of the lamp.

When the carbon pencil ha s been introduced,the

g las s globe, sea led in the brass spun cup, is lowered

o ver the works andfits closely to the shoulder turnedon the base . The workman then passes a solderingtool around the junction of the cup With the base, and

this joint is hermetically sealed . To facilitate the sol

dering,as well as to economize ma terial and prevent

excessive heating of the sealing compound between the

globe and the cap, the base as well as the cup is made

96 E LECTRI C LIGHTI N G B Y IN CAN D E S CE N C E .

only thick enough to be substantial . To renew the

pencil , when en tirely destroyed, the junction of the cup

and base is rotated in the flame of a Bunsen burner,when the

'

so lder softens and the globe and cup are re

moved . To replace the pencil,and resolder the connec

tion of the cup and base,is the work of a few minutes .

The globe,once sealed in the cup

,is not again disturbed .

A t each renewal of the carbon it is of course necessary

to refill the globe withOnitrogen, the stop—cock or screw .

closing the charging opening, being alsofinally soldered ,

in order to ensure hermetical sealing of the lamp

throughout .

All insulations above the base are of mica, in order

that the heat of the upper works may not disengage

dust or vapors,whose action upon the incandescent pen

cil would be deleterious . The diameter of the globe is

2 inches and its length 10 inches . Lamps have been

constructed of all sizes down to one having a globe 4inch in diameter and 2} inches in length, but the dimen

sions adopted have been found to

be the best in practice . The shape

or design of the globe is inconse

quential , which may also be said

of the general structure of the

lamp, except in so far as questions

of economy are concerned.

The method of seal ing the insu

lated central bolt, and establish

ing the external connections of

the lamp,is shown in Fig . 58 , in which A is the arm of

any gas -fixture,and B the base of the lamp . The upright

Fig . 58 . B racket-O onnections .

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93 E LE CTRIC LIGHTIN G B Ymcas nnscss cn.

wire N , screwed into contact-nnt F . The coiled spring

E gives ela sticity to the lower point of contact, so tha t

narrow, annular space around the bolt I ,fil led with homogeneons cement adhering perfectly to the meta l, eusures the hermetical sealing of this last and most difficul t

joint to seal .

In Fig . 59 the arrangement of a chandelier system of

lamps is illustrated .

The luminous intensity of the new Sawyer lamp,whi ch

is the same, under like circumstances, as that of all the

Sawyer-Man,Konn

,Kosloif, B onlignine, and other Saw ,

yer lamps,is from two to three ordinaryfive-foot gas

bnrners . What is meant by this is the intensity of ligh t

produced at which it is considered safe to run the lamp

continuously, when it is desired that renewal of the car

bon pencil shall not be necessary more frequently tha n

once in from six °months to a year. Doing two hun

dred honrs’ actual work the lamp may be run at an in

tensity of from 100 to 200 candles . Doingfifty hours’work it may be run at an intensity of from 200 to 600

candles .

Numerons measurements of the power of the lighthave been made, but the most critical , conducted by

Mr. Edgerton, with a Sugg photometer, accord the small

power lamp a luminous intensity of candles .

*

T he following certificate byMr. E dgerton, referring to the perfectedS awyer-Man lamp, and which applies as wel l to all pencil lamps in which a

pencil of the same length and em otion is rendered incandescent, contains some valuable suggestions in view of the candle-powerclaimed by gascorporations and that shown at their laboratories

N EW scams or LAMPS . 99

luminous intensity is from 100 to 1 ,000 candl es, accord

ing to the length of pencil brought to incandescence

and the volume of current supplied . A t the Franklin

Institute, in Philadelphia, on November 9 , 1880, a

single la rge lamp served to illuminate the lecture-hall

with the bril liancy of mid-day . There is no difference

in construction between this lamp and the small lamp,excepting that in the large lamp the upright conduc

to rs are made of round steel rods,which is sometimes

true of the small lamps . In the large lamp the carbon

pencil is 12 inches in length and of an inch in diame

ta '

,with an exposed section of 1} inches ;while in the

small lamp it is 11, inch in diameter, with an exposed secN sw Y oax. N ovember8, 1878.

T he illnminating power of one of the S awyer-Man lamps, tested bymethis day, gave, in comparison with a standard sixteen-candle burner, a powerof burners, or standard spermcandles .

(S igned) H . H . E b es a'rox.

In order to compare the light with tha t afl'orded by ordinary ga s-bnrners .

thediflerent burners in ordinary use. with coal gas ,may be rated about as

fo llows, for a rate offive cubic feet per hour consumptionOrdinaryM il , S cotch tip, about 5 candles .

Young America , brassfish-tail , 8 candles .

Gleason, noiseless Argand , 1 1 candles .

Lava tip (excavated head), 12 to 13 candles .

A very large flame, burning at a rate 0 1 8 or 9 cubic feet, will give a prorata light of about 15 candles for 5 cubic feet.

T he above is based upon gasmade fromordinary Pittsburgh coal . Mix

tures of cannel or naphtha improve the quality according to the amountH . H . Ens u res .

London is supplied with ga s of 16 candle-powerper5-toot burner. T he

L iverpool street -lamrms give a light at the rate of 10 candles per 5 cubic feetwith4cubic feetconsumption .

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N EW FORMS O F LAMPS . 103

The uppermost carbon burns in the air at intense incan

desech es , while the lowermost carbon, immersed in oil

in a suitable containing vessel, becomes coated with de

posit carbon . As the uppermost carbon consumes and

decreases in size the intensity of the light does not in

crease,for the increase in the size of the lowermost car

bon balances the effect of the current above by increas

ing the supply below and decrea sing the supply above .

B y means of intermittently-operating clock-work,before

the uppermost carbon occurs, the next pair

brought into position ; and the operations

described continuing, there is presented the anomaly ofan incandescent open-air lamp of indefinite duration, inwhich

,by one operation

,light is produced and carbon

manufactumd, so long as the supply of oil is main

tained. The objection to this lamp is that one-hal f of

the current is always employed in renewing was ted

than light by the volta ic arc,when the volume of light

obtainable is the sole consideration . The same expendi

ture of power that will produce a light of candles

by the volta ic arc will not produce,on the average, more

than one-half or one-third as much light by incan

descence in a divided circuit . It should not,however.

be foxgotten that the power of any light decreases as the

square of the distance from it, and that one-fourth of the

reducing the power of each light to one

that of the voltaic arc,will give substan

amination as the voltaic arc .

104 ELECTRIC LIGHTIN G BY IN CAN DES CEN CE.

T he vo lta ic~arc light is necessarily a powerful one T he

objection to it, if used without a shade, is its grea t in

tensity and ghas tly effects, and in order to obv ia te these

defects glass shades of more or less opacity are em

ployed, which, according to practical tests , invol ve a

wastage in light of

With ground glass, 30 per cent.

With thin opal glass, 40 per cent.

With thick opal glass, 60 per cen t.

In some cases the wastage is nearly, if not quite, 75 pa

cent.

The loss of light involved in the “ toning down ”of

the arc is clearly set forth in confirmed tests of thepower of the Jablochkofl’ candle, now extensively us ed

in England and Fratwe. The actual power of this light

is 453 standard candl es, but owing to obscuration, ocea

sioned by the opalescent globes with which it is neces

sa ry to surround the light, it is found that only 43 per

cent . of its full power is availa ble . In incandescent

lighting no such loss occurs, and the cost of the carbon

consumed, which in voltaic-arc lamps amounts to from

four to six cents per hour per candles’ light,is re»

duced to an inconsequentialfigure.

In concluding this chapter. it is proper to remark tha t

the light of an incandescent carbon is very unlike thmof the vo ltaic arc . Its characteristics are the CM

istics of daylight ; and this is true to such an extent

that, 1mmits soft and agreeable nature and absence of

glaring effects, the degree of illumination afforded is not

always rea dily appreciated .

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ELECTRIC LIGHTIN G B Y IN C AN D ES CEN CE.

the manufacturers in Germany as used by Mr. Edison,it is prepared by himself by the combustion of phos

phora s in a large containing vessel, to which air is slowly

admitted . The resultant vapor is condensed upon the

sides of the vessel , which is fnnnel-shaped at the bot

tom,and collec ted in a glas s receiver below .

Protracted tests of many kinds of lamps show that in

a perfect vacuum as to oxygen, and in an absolutely pure

atmosphere of ni trogen, there is no consumption of the

carbon, which stands sharp and clear, except as to gra

dual decay of structure, so long as the volume of cur

rent supplied is not too great .

From disintegration, more or less rapid, the carbon

cannot be protected . It has been supposed tha t the eu

tire absence of any atmosphere is more conducive to lon

gevity of the incandescent conductor than themesenceof an atmosphere with which it cannot enter into chemi

cal combination,because in the latter cas e there exists

in the lamp a constant circulation of currents of the

gas,due to the heat evolved

,which may be supposed to

wash the carbon, and, by some process of reasoning,to waste it away . If carbon, heated to incandescence ,usually became a soft, unstable mas s, instead of the

hard,dense body it is, there might be some foundation

for this idea, which perhaps originated fromobservations of that form of disintegration in which extremely

thin,feathery flakes are disengaged and float away .

Their disengagement occurs equally in nitrogen and in

vacuo, with this difference : that in nitrogen thew7 are car

ried upward and around by the currents of heated gas .

and in vacuo they fall to the base of the lamp.

mass ava '

rios ormcw nsscsa'

rcaasos s . 107

The preparation of nitrogen sufficiently pure for thep urposes of incandescent lighting is ordinarily an ex

tremely del icate laboratory process . Prepared by the

burning of phosphorus in a clomair-chamber, it is a tterly inadequate ; for, however carefully its subsequent

manipulations may be conductedfthere are present atthe outset to o many elements of impurity, and a trace of

phosphorus always remains .

The best method of obtaining nitrogen that we have

employed is that of Prof. Stillman . Solutions of ammo

nic chloride and potassic nitrite are heated in a glass re

to rt . The vapor-gaseous product, consisting of ni trogen ,water, ammonia, and nitric oxide (although the reaction

given in the text books is KNO,

N H,C L KO L

N 2H,O ), is passed successively through the conden

ser; sulphuric acid (to remove excess of water), and so

lutions of iron, caustic potassa, and pyrogal lic acid

mixed with caustic potassa , in Wolff’ s bottles and then

through long tubesfilled with pumice-sto ne in pieces,moistened with sulphuric acid . Finally, the ga s is

passed through tubes containing phosphoric anhydride,and a combustion-tube containing melted sodium , to re

move the last trace of oxygen, oxidized particles of which

are prevented from coming over by means of Wo lfl’s

bottlesfilled with cotton . The gas is stored in ta nks, or

in strong iron reservoirs under pressure . Thus prepared

the cost of the nitrogen is about ten cen ts per ga llon .

Infilling a globe the simplest process is that ofwashing out, illustrated in Fig . 62, in which several

lamps areconnected in series, and a divided circuit . Thegas pas ses from a receiver through a purifier consisting

1m E LECTRIC LIGHTIN G B Y I N CAN D E S CE N CE.

of drying apparatus and a sodium tube,and thence

through the lamps F seriatim,thefirst flow of gas being

was ted, and the remainder collected in a second receiver,from which, whenfilled , it is passed back directly into

thefirst receiver by means of a connecting-tube ; andthen again pa sses through the purifier and the lamps .As every gas acts as a vacuum towards every other gas,

Fig. 62. Kim Process .

the lamps become ul timatelyfil led with pure nitrogen .

In order to expel occluded air, it is useful to succes

sively heat and cool the carbons while the nitrogen is

flowing. B y closing and subsequently soldering the

stop-cocks, the hermetical sealing of the lamps is ef

fected .

Exhaustion of air has been reduced, by means of the

Sprengel pump, to a degree heretofore thought nnat

tainable. In the manufacture of the Edison lamp, the

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1 10 ELE CTRIC LIGHTI N G B Y IN C AN D E S C E N O E .

anhydride, and 0 the lamp to be exhaa . The time

is from ten to twenty hours,for the operation of the

slow . The

Fig . 64. S awyer N itrogen E xhaustion.

the one-millionth of an atmosphere .

In order to improve and facili tate the process of iso~

lating the carbon, the apparatus shown in Fig. 64 is em

PRES ERVATION osmcas nsscs sr cs asos s. 1 1 1

the Sawyer lamp. A is a

r pressure B,the drying

0 , Sprengel Pump ; D .

ordinary air-pump ; and E ,the lamp or series of lamps

to be exhausted . The greater portion of the air isfirstby means of the machine pump D ,

stop-cock connecting it is closed, and that

connecting the Sprengel pump is opened . B y this ar

rangement the slowly-acting Sprengel pump ha s only a

fraction of the whole work to do . As soon as the de

exhaustion equals the one-hundred-thousandth

an atmosphere,which is but one~ tenth as high as

the Edison lamp and is quickly accomplished,the exhausting process is stopped, and the reservoir stopcock being opened

,the globe isfilled with nitrogen .

The reservoir is then shut oil”, and pumps D and O are

used as before, until the vacuum again reaches the one

hundred-thousandth part of an atmosphere . The stop.

cock of the lamp, shown in the lowerfigure, connectedby a rubber tube which is prevented from collapsing by

an melosed spiral spring, is then closed by driving inthe small ta pering pin while the tube is still connected,and subsequently soldering. The proportion of air re

main ing in the lamp is,therefore

,the one-hundred

thousandth part of the one hundred-thousandth part, or

the cha teh -Ml lionth part of an atmosphere, a degree of

perfection as readily obtained as an exhaustion of . 00001

by other means .

Fil ling and exhausting with hydrogen and hydrocar

bon gases operate to similarly reduce the quantity of

oxygen present in the lamp, but nitrogen is preferable

1 12 E LECTRI C LIGHTIN G B Y IN C A N D E S C E XC E .

on account of its greater freedom

When,however

,the hydrogen or the hydrocarbon gas

is absolutely pure,it may be used with equal advantage,

and in some cases is perhaps more readily obtainable in

In the plate (Fig. 65) the behavior of carbon under va

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1 14 ELEC TRIC LIGHTIN G B Y IN CAN D ES CEN CE .

its full size, due to the diflerence in temperature of dif

ferent parts of the pencil. Fig. 10 shows the pencil 00 n

snming and diminishing uniformly in section, as in air

or a full supply of oxygen,until, if there is any pres~

sure brought to bear, it softens and bends as shown

in Fig. 1 1 . Fig . 12 represen ts a perfect Sawyer-Man

loop,and Fig. 13 a loop fractured . In Fig. 14 the

loop,diminishing in section at points but otherwise

perfect,is well represented . Bending of the loop from

heat,as in Fig . 15, occurs only when at different

points the carbon is reduced to a merefilament and anarc is upon the point of forming . Long pencils held

with connectors,one in each hand, and subjected in the

air to extremely powerfu l currents, have frequently been

bent into peculiar shapes, one of which is ill ustrated in

Fig. 16 .

In Fig. 17 we have a striking example of the tu

tensity of the heat of an incandescent carbon . Owing

to dis integration of the upper point of contact, one of

the short Sawyer-Man pencil s, losing its support while

at limpid incandescence,was projected against the side

of the globe,through which it instantly passed as

though the glass,which was one-twelfth of an inch in

thickness,had been so much tissue-lnper, fusing its way

slightly downward,andfinally sefih g in the position

shown,seal ed in the glass as a

path ethys a s a platinumwire is sea led in a Geissler tube .

*

9 A section of the globe conta ining this pencil was, we believe, at one

ti ne in the hands of Mr. H opkins , of the S cientificAmerican.

CHAPTER IX .

D I VI S IO N O F C URRE N T A N D L IGHT .

MUCH has been written concerning the loss of light by

subdivision of the current, and this has been vari

a s thecube of the number of lights amon

g which the

conceive, for they have no foundation in practica l tact.

If to the conducting pipe of a gas system a given vol

tune of illuminating gas is supplied in a given time, and

all this gas is consumed in a single burner in order to

yield a given light, when we divide the volume of gas

thus supplied among two or more burners the total light

produced may, indeed, have greatly decreased . We do

not,however, supply gas in this manner, but the volume

of gas supplied is in dimct proportion to the number ofburners to be fed .

What is true of gas is equally true of electricity . If

afixed volume of curren t, sufficient for one light, is furhished to a single lamp the maximumeffect is produced,and if we divide thisfixed volume among two or morelamlmthe tota l effect is grea tly diminished ;but to suppose tha t such a division is contemplated is to suppose

a similar operation in the cas e of gas,and criticismof

statements bas ed upon such a supposition is, simply,115

1 16 ELE CTRIC L lG H T I N G B Y IN C A N D E S O E N O E .

was te of time and labor. When we increase the num

ber of lights in circuit, we increa se the volume of cur

rent in proportion ;and the power of the tota l light is

increased in proportion ; and the energy expended in

producing the light, and therefore its cost, is increas ed

Without at this time entering into any considerations

of the fact that the current from a single generator of

electricity has repea tedly been divided between from two

to two hundred incandescent burners,the operations of

the Brush system of voltaic-arc lighting set at rest the

question of economical subdivision .

Two machines of the Brush type are selected for com

parison— via , the six-light and the sixteen-light machines, both of which are in practical use throughout the

United States— the light of each of the twenty-two lampsbeing of the same intensity as that of each and every

other lamp .

With the six-light machine the total driving power

abso rbed per minute is foot pounds, or

foot pounds per lamp .

With the sixteen-light machine the total dri ving power

absorbed is foot-pounds,or foot-pounds

It is thus clearly shown that for each lamp added to

the circuit there is an expenditure of power in propor

tion to the additiona l work,the somewhat diminished

power per lamp expended in the sixteen-light machine

being mainly due to the element of friction, in which

the percentage of absorption of power is less in large

than in small generators .

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1 18 ELECTRIC LIG HTI N G B Y IN C AN DM E N C E .

the number of instruments and

cnit ;all the instruments, since

ately less current. become pwe increase the number of cell s,electro-motive force of the battery, in proportion to

the additional work required, which is that of overcoming the added res istance . If, on the other hand, we

divide the current from a single generator among two or

more lines,each including a number of instruments in

series, we require a current of greater quantity ; hence

we increase the size of the elements of the generator.

In electric lighting there arefive methods of dividingthe current from a single generator of electricity :

1 . The series system . Passing the current seria timthrough the lamps, as in the Brush system of lighting .

2 . The multiple system . Connecting the poles of the

generator with two parallel wires, and placing each lamp

in a branch running from wire to wire, as in the Edison

and Maxim systems .

3. The multiple-series system . Connecting the poles

of the generator with two parallel wires, and placing a

number of lamps in each branch running from wire to

wire,as in the S awyerMan system .

4. The series-mul tiple system .

the generator to a wire which,at

is needed, divides into a number of strands, each contain»

ing a lamp or lamps,and which strands again combine

together in a single wire,Which runs to thenext point of

division and so on indefinitely, returningfina lly to theother pole of the generator ; as in the

‘

Sawyer system.

5 . The secondary system . Passing the main current

D IVI S I O N O F CURRE N T A N D LIGHT. 1 19

primary wire o f an induction-coil, in the

the seconda ry coil of which the lamp is pla ced

Fig . 66 .

Al ternating or intermittent currents are employed, and,owing to the reactive earth inductions, this principle can

no t be appl ied over any considerable territory. Mmeover

,it involves loss of power in the heating of the iron

tion of power, and, in electric as in a ll other forces , di

rect applica tion is found to be the most economical .

’

How to practically divide the curren t from a single

source among a large number of inca ndescent lamps has

M eonsidered a debatable question . We shall content

ourselves with glancing at the results which must follow

an extension of the four systems which appear to be

As recently as 1877- 78 several claimants to this method of subdivisionhave appeu ed, but the systemwas patea ted in England by Harrison in 1857(Intteu -Patent under the title, Improvements in obta ining Light byE lectricity. ” and it is not quite clear that Harrison was the origina l ih

vellum T he Ha rrison patent expired in 1871. unless the Government tamm unpaid, in which case itmust have expired at an earlier date .

120 E LE CTRIC LIGHTIN G BY IN C A N D E S C E N O E .

sui table, as suming that in each case lamps andlamps are to be operated upon a a

’

ngle circuit

Where there is a limited number of lamps either the

series,the multiple, the multipla series

,or the series

multiple systems may be employed with about equal advan tage ; but where the number of lamps is increas ed to

hundreds or thousands , as must be the case in any gene

ral application of electric lighting,considerations novel

in character rapidly present themselves .

Taking first the series system (Fig . in which the

Fig . 67 . lamps in S eries .

interruption of the circui t of any lamp will not interrupt

the entire circuit,we have with lamps a resistance

,

not including the internal resistance of the generator or

the exte rnal resistance of the main conductor,of

ohms. W'

ith lamps the resistance becomes

ohms .

Can this resistance be overcome by any practicable

construction of generator?

The electro-motive force of curren t necessary to ope

rate an incandescent lamp of one ohm resistance is, as to

the lamp,such as will yield a voltaic are 3

1, of an inch

in length . The electro-motive force necessary to over

come the resistance of lamps is,therefore, that

which will yield an are 31} inches in length , or with

10,000 lamps an are 26 feet in length .

Assuming its existence, we need not describe the pm

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122 E LECTRIC LIGHTI N G B Y I N O A N DM N O E .

resistance. The total resista nce of the exteml circuit

becomes ohms, and1 66 . 66

of the

cd in the machine . Let the number of lamps be ten ;

to tal res istance of ohms . We thus obtain in the

external circuit only the current generated,or

about 23 per cent . Extending the cal culation to one

hundred lamps, thus making the external resistance two

ohms,we are able to utilize less than 3 per cent. of the

current generated. In order to be able to operate one

hundred lamps with a utilization of 50 per cent. of the

whole current,we must, therefore, reduce the interna l

resistance of the generator to two ohms wi th one thea

sand lamps, its resistance must be reduced to two-tenths

of one ohm ;and with ten thousand lamps, to two one

hundredths of an ohm . In order

li ttle loss in the main conductors

erator,they must be of large size, for the res istance of a

stantially four one-hundredths of

as there are two mains,the total resistance of the con

dnctors,costing

,as bare copper at 30 cents per pound,

$12, 672 , is eight one-hundredths of an ohm . With such

a conductor, the total resistance of the circu it of

lamps would be .48 of an ohm ,divided as follows : gen e

crator, . 2 ;ma ins, . 08 ; lamps, . 2 . There would thns be

was ted in the generator 41 4} per cent . of the current, and

in the mains 1 61 per cent ; utilized as light, 414} per

D IVI S iO N or cnaass r A N D monr. 193

mt. To bring the utilization up to between 49 and 50

per cen t ,the main s must weigh 32 pounds per foot, and

will therei'

are cost The respective resistances

will then be : generato r, . 2 ;mains, . 01 ; lamps, . 2 01 an

lamps must be increased, if we desire to approach

a rea lization in light of even 50 per cent. of the current

generated, and the internal resistance of the generator

must bemduced to two one-hundredths of an ohm . We

shall not pause to consider the character of a generator

of the required power and of so low an internal resist

ance, for we have no practical data upon which to base

an opinion. The production of a generator of the resist

ance given ,combined with the capacity indicated, is at

all events possible . Concerning the requirements of any

multiple-circuit generator, however, we are enabled to

see that it must be one of multiple induction, the coils of

which shall be automatica ll y joined together to form a

multiple internal circuit, which shall both increas e the

quantity of the curren t generated and reduce the inter

nal resistance of the generator in proportion as the num

ber of lamps in the external circuit is increased and the

externa l resistance reduced . In the mechanical construc

tion of such a generator there is a widefield for studyReferring now to the multiple-series system (Fig .

it is evident tha t, in operating lamps of 200 ohms

resistance each . there may be one hundred branches

across frommain to main, and in each branch ten lamps,which would make the external resistance of the circuit

,

124 ELECTRICmha '

rme BYmew nsscascs .

10X2m)um

With a resistance in the mains of one ohm, and in the

generator of hye ohms, making the total resistance twen

ty-six ohms

,there is util izable as light the ten-thirteen

'

th

part of the current generated, or about 77 per cent. A p

plied to lamps of low resistance, as one ohmeach, the

not including that of themains, 20 ohms

mx. 60. l l altiple-S amC ircuit.

arrangement woul d have to be materially changed for,unless changed, the external res istance of the lamp cir

10X 1cuit would be but one tenth of an ohm

and the total resistance of the system ohms whence

it follows that we would only be able to utilize in the

production of light per cent . of the curren t gene

rated .

Reversing this arrangement and providing 10 branches ,each containing 100 lamps ,we have a circuit resistance of

10 ohms (100 X 1 and with a generator resistance

of 2 . 5 ohms, and a resistance in the mains of 2 5 tmaking the total resistance 12 75 ohms

,we are enabled

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126 E LECTRIC LIGHTIN G B Ymes s nsscs s cs .

made 10 ohms1

and with a generator

resistance of 2 . 5.

ohms,and a resistance in the connecting

conductors of . 25 ohm,we uti lize as light 78 per cent . of

the whole current . With lamps there may be 500

points of divergence,each containing 20 lamps, by which

arrangement the resistance of the lamp circuit becomes

25 ohms 500

251 and with a generator resist

ance of 5 ohms,and a resista nce in the connecting con

ductors of 1 ohm,the proportion of current available for

light is 80 per cent . of the to ta l production.

We might continue these calculations indefinitely, bu t

to no further purpose . The flexibility of the systemisobviously such as to permit of any regular combination

of lamps whatever, and thus to obtain any external re

sistance whatever and it will be found to permit equal ly

well of all irregular combinations,so that in one division ,

where the volume of light required is great, there may he,say

,five lamps in multiple

,and in the next division

,where

the volume of light required is ordina ry, there may be

ten lamps in multiple, each of the latter receiving but

one-fourth as much current as each of the former,be

cause the joint resistance of the ten lamps is . 1 ohm ,

while the joint resistance of thefive lamps is . 2 ohm ;

and the ten lamps receive but half as much current as

thefive lamps, while the number of lamps is doubled .

The closing-up, short-circuiting, or reducing the resist

ance of any division acts simply to reduce the resistance

of the whole circuit, in the same manner as removing a

portion of the lamps in a simple-series system . The re

D IVI S ION O F CURRE N T A N D LIGHT. 127

lative advantages of the multiple-series and the series

multiple systems can only be determined by the numberof lamps operated from a single source and the practical

operation of both systems al though there are considera

tions of simplicity which would seem to favor the series

multiple arrangement of lamps,whose connection with a

line of dwellings is ill us trated in Fig. 71 .

128 E LECTRIC L lG fl T l N G B Y l N O A N DmO E N C E .

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E LECTRIC LIGHT IN G B Y IN O A N D E S C E N O E .

and as there was abundance of power,and as the speed

remained constant under almost any circumstances, i t

was deemed necessary, in order to obtain a satisfactory

resul t, that the resistance external to the machine should

be kept constant . Therefore the internal resistance of

the lamp to be experimented upon was measured,and it

was found to be as sta ted . A new form of curren t regu

lator,afterwards known as the Sawyer-Man switch (Fig .

was employed in the tests . The poles of the gen e

.

‘m M

Fig. 72 . T he éawyer-Man Switch.

rator connections at the and points,A being

a sliding-bar,and the cross-piece B being a spring con

tact-piece brought to a bearing upon the two rows of

studs 1 , 2, 3, 4, 5 , 6 , 7 , 8, accordingly as it is moved

backward or forward . Whatever position the cross

piece as sumes . it will be noted that the resistance of the

circuit from the to the point is the same . In the

position shown , all the current traverses the lamp. With

the contacte piece B bearing upon the studs 7 , 7 , two

RE G [I L A T ORS A N D SWITC HE S . 181

paths for the current are afiorded , one by way of a re

s istance of . 10 ohm and the lamp outward, making a

total resistance of . 70 ohm in that circuit, and the other

by way of resistances of . 70 , . 35, . 21 , . 14, . 10, and

. 60 ohms outward, the sumtotal of which series of resistances is 4. 2 ohms, thus sending through the lamp sixsevenths of the current, while maintaining the resistance

from the to the point the same.

It was found that when the vol ume of current supplied

to the laml) was three-sevenths of the whole current, thecontact piece B bearing upon the studs 4, 4. the carbon

was brought to a low red-heat . With four-sevenths of

the current supplied to the lamp, the carbon gave a

light of about one candle ;withfive-sevenths of the cur

rent, the light, measured by a Sugg photometer, was

three candles ;with six-sevenths of the current, nine

candles ;with the whole current, twenty -seven candles .

When the contact piece B was bearing upon the studs

1 , 1 , the whole current passed through the artificial re

sistence of . 60 ohm . The gradations of light by this

means being too sudden (from less than one candle-light

to three candle light, from three to nine, and from nine

to twenty-seven candle light), the resistances were subse

quen tly. changed so as to admit to the lampfirst one-hal fof the current, thenfive-eighths, three-quarters, seven

eighths,fii teen -sixteenths,thirty -one-thirty-seconds, and

finally the whole current . With this arrangement the

gradations were gradual and pleasing.

The disparity between the volume of current supplied

and the intensity of the light obta ined is very clearly in

dica tive of the requirements of an incandescent lamp .

132 E LECTRIC L lG B T IN G B Y IN CAN D ES CEN CE.

Sincefive-sevenths of the to tal current for a single lampproduces but three candle light, while the whole current

produces twenty-seven candl e light, or nine times as

much,it follows that in order to secure the maximum

economy the carbon must be raised to a high tempera

ture . For if we have a supply of current equal only to

the maximum requiremen ts offifty lamps, from whichwe may obtain a sumto ta l of candles, we cannot

divide this current among seven ty lamps without sus

ta ining enormous loss, as the sum total of light given

by the seventy lamps will be but 210 candl es, while

the expenditure of power Will be the same. There

is a compensating influence in the case of lamps in

series driven by a dynamo-generator, consisting in the

increased percentage of current exterior to the gen

crator when the resistance of the external circuit is in

To sustain the high temperatures necessary to the

economical operation of an incandescent-lighting system

the carbon must be hard, den se, and substan tial ; and in

the absence of these qualities is found the explanation

for the inefficiency offine,filamentary carbons, whichcan never be safely brought above the temperature of a

gas-flame. Carbon incandescence (that of white light),unlike the incandescence of an iron or platinum condue

tor,is of two grades and various intensities . In thefirst

the carbon is intensely white,and its form optically

broadened and lost in a surrounding haze of light . In

the second and more intense incandescen ce its form

stands out sharply defined, and it appears no longer

opaque but limpid, seemingly translucent, like the body

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1 34 E L E C TRlO L IGHT IN G B Y IN C A N D E S C E N G E .

a bras s contact bar, which is forced to

the brass segments by means of a steel

the head of the cap. Upon the end offinger~pieee isfina lly screwed . B y tu

piece in one direction or the other the light is turned on

or off, or regulated to intermediate points of intensity.

In Fig. 75 the switch, as attached to the

Fig . 75 . S witch attached to B racket.

delier or bracket , is illustrated, the circular

end of the arm being shown partly.in section .

lamp isfixed to the nipple abovinsulated conducting-wires pas s through the hollew amT he connections of the switch are shown in Fig . 76 .

When both ends of the cross-bar A are hearing upon

RE GULA T O RS A N D SWITC H E S . 135

segment 4, the whole current passes through the

1mm. When the cross bar bears upon segments 3 and

4, the current divides, a part passing through the lamp

and part through the artificia l resis tance of . 50 and . 25

ohm When the cross-bar hears upon segments 2 and 4,the current is divided between the lamp and the artificia l resistance of . 25 ohm . Bearing upon segments 1

and 4, the lamp is short-circuited and practically re

The artificial resistances are preferaFig . 76 . S witch-C onnectiona.

blymade of naked copper Wire exposed to the air or

embedded in plas ter-of-Paris and enclosed in the case(Fig.

By means of this switch it is clear that When a lampis extinguished its resistan ce is removed from the circuit

and the curren t is not wasted 1n heating an artificia l reM oe . B ut in order that the changes Which take

place in its circuit may not add to or lessen the volumeOff (surrent supplied to other lamps , it is necessary thatthe Changes Which occnr in its circ uit shall in somemannerreact upon the source of the current and this brings

E LE C TRIU LIGH TIN G B Y IN C AN D E S CE N CE.

current in proportion to the requirements of a system.

Before taking up this subject,however, a form 01

switch designed for use upon a circuit of lambs in series,

cuit, will be described .

In Fig. 77 the switch is shown as

Fig . 77. Emmac Switch.

the room, and

79 we have a diagram of the connections .

A is the magnet- lever B and C are 0 1 ? levers D is

a cam operating to raise and lower lever C ,which is

pressed downward by coiled spring H . Lever B is

pressed upward by insulated spring E . F and G ums top pins , and I is an artificial w a nes

In the position shown lever A is in . u with stop

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138 EL E CTRICmomma B Ymcmssos sca

downward to a contact with lever A . The lamp is thu s

sho rt-circuited, the current pass ing from the poin t

through levers A and C to the cam D and outward a t

the point . To give the lamp sufficient current toproduce oue-half its full light

,the cam D is moved fur

ther to the right,so as to pass from its contact wi th

lever ( J. Then lever C ,falling further, forces lever A to

make connection with lever B,and the current di vides , a

part hewing from the point through the coils of th e

magnet and the lamp outward, and the remainder ho w

ing, by way of levers A and B and resistance I , outwa r d

to the point. Wi th the cam turned to the intern e

diate point the lamp is extinguished . Turned as far 8 8

it will go to the right, one-half of the light is emitte d

Turned as far as it will go to the left, themaximum i n

tensity of light is produced . l a the event of an in t e l“

r uption of the lamp-circuit the lever A,which

,when t h e

circuit is complete, is attracted by the magnet, drops t o

contact with lever B,and the circuit is re established b y

way of res istance 1 . Lever A can only be drawn towa f ‘ l 8

the magnet when the pressure of spring H is remov e ‘1

by raising lever C from its contact with lever A .

A form of artificia l resistance useful in electricing is illustrated in Fig . 80 , in which a

RE GUL ATO RS A N D S WITC H E S . 139

held in brass connecting-clamps upon a soapstone base.

A thin piece of platinum, to establish perfect contact, isplaced between the end of the carbon and a plate of

brass upon which the upper set-screw presses . Copper

wire for artificia l resistances is preferable to iron wire ofequal diameter, owing to the greater surface exposed to

radiation and convection of heat by the bette r conduc

to either.

In the Edison and Maxim systems of lighting the ordi

nary make-and-break circuit switch is employed. In te

spect to simplicity it cannot be improved , but it affordsnomew s of graduating the light

, which must either be

kept at its full power or entirely extinguished . The

Ed ison switch , however, like the swi tches employed in

the S awyer system , does not interpose current~was tingresistances when no light is required

,the supply of elec

tricity being supposed to be regulated at the generator in

proportion to the requiremen ts of the circuit.Manya ttempts at automatic regulation of the supply

o f current have been made both in this country and

s ign electricians being the device of Dr . Siemens, who in

January, 1879 , proposed to place a number of carbon

disks in an insulating tube, pas s the current through

them , and by means of a platinum wire, also in the cir

cuit, to vary the conductivity of the carbon pile by vary

ing the pressure of the disks upon each other. For

several .reasons , unnecessary to state , this arrangement

could have no practical application in an electric-light

ing system.

140 E LE CTRIC u s sn sc BY moamsscmvoaThe conditions to bemet are not so easilymet asmightappear from a superficial examination . le t us suppose

that there are ten lamps, of one ohm resistance w ith.

armnged in multiple circuit, and tha t each lamp xeceivesone-tenth part of the whole current. Suppose

,new,

tha t we add a lamp ; then each lainpeleven th of the fo rmer current . We must, 1

increa se the supply that w eb of the eleven lamps

receive as much current as each of the ten lampsbefore . To aecomplieh this increase, tbere are two

1

similar forms O f regulators, thefirst O f WhifihWM i i

cd by Sawyer 8: Man , June 25 , 1878 , and the n at

which was recently devised by Mr. Maxim. The lattet‘

is illustrated in Fig. 81 . Its operation is as follows : In

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142 E LE CTRIC LIGHTI N G B Y I N O AN D E S C E N C E .

have operated to maintain the intensity of the light

constant. *

ren t, without regard to the speed of the generator or the

electro-motive force of the current (Fig. we havefirstFig .m. S yma negnhfion.

tofind the proper relation between the strength ofrent and the number of lamps to be operated . Let us

suppose that there are ten lamps arranged in series,

and that the full current is exactly sufficient to operatethese lamps at their maximum intensity . A t any point

in the circuit we place an electro-magnet,B ,having the

sensitiveness of a telegraphic re lay . The relation of this

In Letters-Patent of the United S tates, N o . of January 80,1880 , granted to Profemors Thomson and H ouston,members of the Franklin Institute of Philadelphia, the principles of this regulator are described.with the fo l lowing claim

A s amoto r for effecting the adjustment of the commutator collectingbrushes , an electro-magnet, M, traversed by the current, or a portion of the

current, of themachine, whose attraction upon its armature, N ,moves saidcommuta torcollecting brushes in one direction ,

motion in the other (timetion being obta ined by the action of a spring.

”

assumross A N D SWITCHES . 143

magnet towards the regulating apparatus is actually the

same as the relation of the telegraphic relay towards the

local telegraphic instrument. The armature-lever of this

magnet is set between two contact-points,between which

it plays without appreciable motion . Indeed, both

actual conta ct with the lever, so that

ot move at all ;but the local circuit

shal l be changed by the change in resistance due to the

mere difference in pressure of the relay-lever upon the

separate contact-poin ts . Thus arranged,variations in

the strength of the lighting current, sensible only to a

galvanometer, may be made to operate the circuit of a

local ba ttery,and thus to energize el ectro-magnetic regu

lamps in circuit,and A a rotating

represent a series of ten a rtificialthe sum -total of which is ohms . The sum

resistance of the ten lamps in circui t is also

When all the lamps are in operation, the cir

from the point to the stud No . 1 . and

relay B and the ten lamps C C to the

resistance of B is for convenience disre

s but a fraction of the to tal resistance .

that we extinguish half of the lamps by

The resistance of the lamp cirand the efiect of the current

U pon B is correspondingly increased Its lever at once

a ctuates the regulating mechanism,which moves lever A

“

t o contact With stud 6, thus bringing the resistance of

t he circuit to its normal point—viz.,ohms . The same

a ction ensues whenever a lamp is short-circuited,and

ELECTRIC LIGHTIN G BY IXC AN DW

into the circuit. In practice the resistances D D amgreater in number and each of a lese value than described,

bnt the sum-total of all remains the same. The

B in practice is in constant vibration between imconmt»

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148 ELECTRICmen'

rme BYmow nsscsscs .

C loselyfitting in cylinder B is the cylinder A ,open at

the bottom . Supported by a tube passing through the

base,and closelyfitted ih ’ cylinder A

,is the piston 0 .

Insulated upon one side of cylinder B is a stationary con

tact-plate,E,to which one pole of the generator is a t

teched . Insulated upon the opposite side of the cylinder

are the 18 grooved central plates F . Running in the

grooves of E and F are two contact-arms, G and H ,

whose pressure upon E and F is regulated by spring I .

The current,therefore

,passes by way of plate E to arms

H and G and a contact-plate F outwardl y, as s hown in

the regulator-connections, Fig. 82 . T he ends of the cores

of an electro-magnet, K. provided with an armature-lever,L pas s through the piston head , and serve to open and

close the valves N M . When the magnet K 1s not ener

gized, a coiled spring forces the armature away, and val ve

N 15 opened to the how of a stream of water,and valve M

is closed against its escape into the lower chamber and

outwardl y through the exit-tnbe 0 . Therefore the cylin

der A rises . When the magnet is energized, the val ve N

is closed and the ingres s of water stopped,while valve M

is opened and the water conta ined in the upper chamber

is allowed to escape . T he cylinder A then fal ls by its

own weight as rapidly as the escaping water permits .

B y a suitable arrangement the waste water is used to

cool the various artificial resistances . The local circuit

of the magnet K is established by the back contact of the

relay-lever. The movements of the cylinder A are

smooth and the changes rapid . The contacts of G and

H with F and E are of afirmand substantial character .With a pressure of 10 pounds of water and a pisto n

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CH APT ER XI .

G E N E RAL D IS TRI BU TIO N .

THE date of the original conception of the idea of a

general distribution system, supplying electricity

from a central station to an entire city, and the identity

of the personfirst conceiving this idea, will probablynever be satisfactorily determined . The one most de

serving of honor in this respect would appear to be

Starr. As conceived by Sawyer, thirty years later than

the time of Starr, it was patented in the Uni ted States

August 14,1877 , and it is believed that this was thefirs t

systematic reduction of the idea . The ill ustration (Fig .

86 ) is a facs imileof thefirst sheet of drawings aecompanying the specifica tion , printed by the United States

Patent O ffice : R being the central station, in which thegenerato rs a

,a'

,a

’

, a’ are located ; 6 , blocks of houses ;

0 , points of divergence of ma ins to lamps, e and d. hackg.

T he following sta tement occurs in the specification of these LettersPatent :

T he object ofmy invention is to supply the streets , blocks. or buildingsof a town orcity in a practicablemanner with any desired quantity of electricity for the purposes ofelectric illumination , electro plating, the runningof electm-magnetic engines, etc. I place the generator or generators of

electricity in any convenient portion of a locality, whence I carry the necessary conductors over or under ground to the streets . blocks , or buildings inwhich the current is to be utilized . I n place of electric conductors leadingfroma centra l sta tion, Imay substitute tubes or pipes. throughwhich water

GE N E RAL D I S TRIB UTION . 151

The considerations involved in a general dis tributing

s ystem are of a more complex character than has yet

b een indicated . In a system in which the lamps are

a rra nged in series the introduction in circuit of addi

tional lamps must operate to increa se the electro-motive

force of the current supplied to the circui t. O n the

o ther hand, in a system in which there is a multiple

a rrangement of lamps the introduction in circuit of ad

ditional lamps must operate to increase the quantity of

current supplied to the circuit . In a combination of

these two systems there must be a combination of the

It may be assumed at the outset that in any practical

distributing system,the power expended at the generat

ing station in producing current must be proportionate

to the current requirements of the system, for obviouslywe cannot economically expend as much power in ope

rating a few lamps as in operating a large number of

lamps . When we reduce the number of lamps it isnecessary that we correspondingly reduce the expendi

ture of power in current production as well as the sup

ply of current to the circuit of the lamps . To a certain

extent this must be done automatically and since power

is al ready provided with the practical adjuncts of con

or 0 0d air is carried to a building , there to drive magneto—electricapparatus, etc. , for loca l work. The advantages ofmy invention are that it

enables householders to obtain a supply of electricity for any purpose without the care and inconven ience attending the maintenance of local batteo

rice; that it greatly reduces the cost ofelectricity to consumers ; and that itrenders practicable the lighting of buildings by electricity . 1 do not limitmyself in any way as to the number of conduits for any locality, or the

pnrme for which the electricity is used in combination withmy centra l

E LE CTRIC LIGHTI N G B Y I N CAN D E S CE N CE .

we must look to the electric regulator for the inter

lary means of supplying curren t in proportion to the

and .

Fig . as. G eneral D istribution .

0 a limited extent, starting froma point of minimum

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GE N E RAL D IS TRIB UTION . 155

The contact-armN serves to vary the magnetic intensity of generators C D by changing its position of con

nection with the insulated contact-plates M . The pins

QQ, insulated from the piston -rod by co llars P, serve

to introduce and remove generator D from circuit by

changing the position upon blocks 8 S ' of the sliding

connections R R’

. When the connections RR'

are in

the position shown,the circuit of the distributing mains

is from connection R' to stud S '

, and generator D ;thence

through generator 0 , and relay-magnet G ,to the system

of lamps Z thence by way of stud S'

. to connector R’

.

The circuit of the exciting-machines is from connection

R to stud S . ; thence through exciting-machine F, the

coils of magn ets B and A and exciting-machine E to the

lower regulator-plate Mm;and thence by way of resistances O to another plate

,M, the connecting-arm N and

stud S , to the connection R. The amount of current

flowing through the coils of relay-magnet G is propor

tioned by an adjustable resistance Y . As lamps are

added to the circuit of the main the armN falls, and bythus removing resistan ce from the circuit of the exciting

machines the intensity of thefield of force of the generetors is increas ed, and more current is supplied to the

mains . When lamps are removed from the main byshort- circuiting them

,there being less resistance in the

main and correspondingly less current required, the armN rises

,and thefields of force are weakened and when

the requirements of the circuit are reduced to the caps»

city of a single generator, the pins QQ’ throw the conn ections RR’ upon the pieces 8 S

’

, N0 8 . 1 and 2 ;

g enerator D and exciting-machine F are removed from

156

the circnit, and power is no longer

them. The arm alls to a point

which the intensity of the

maintained at the proper

tery K actuates the valve

of indefinite variability, and itguid ing the one element of fri ction, the

in the production of current is almos

the val ue of the current produced.

The proper construction of the distribn

matter of great importance, and it is not

bes t construction will be found without the aid of prac

perfection of telegraphic conductors need not be expected

and should not be required . The

cities,should be laid under ground otherwise

lity of interruption is considerable. With an insulated

copper conductor enclosed in an iron tube,the

tion is efficien t, compact, and simple ; andmains to be done is to protect the iron from

and bury the whole well under the surface

A t

cd to one pol

pole of which

minus of theconductor are connected together. Thus the

the main is from the generating appara tus, by

copper conductor, to the distant end of the

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158 ELE CTRICmomma B Y [Ncas nascss ca

consists in pas sing the copper wire through

ing material in a viscous state,and thence

tnbe around the mouth of which a stream of

is caused to how (Fig . The insulating

contained in the cavity A ,and the molten

chamber B . The flow of lead through the annular space

opening in the chamber B and themouth efthe tube 0 is produced by the pressure of a steel

plunger,D

,operated by an hydraulic press . The result

is a compact and perfect covering of lead around thefitFig. 89 . AW O I PN L E aton.

suls ted conductor ;and it does not appear that there is

any immediate limit to the number of separate insulated

strands of copper that

tube, al though, in th

thus far only seven strands have been insulated.

The questions which arise regarding the limit of ex'

tension of any distribn

swered in a satisfactory

station ten,fifty, or one

s ss saax. D IS TRIBUTION . 159

be decided by considerations of cost and practicality .

If the lamps to be operated are distributed over a section such as would be included in a circle one mile in

diameter,with the generating station located at a centra l

point,there may be said to be no real difficulties in the

way ;but when we attempt to extend the lighting area

the questions of cost then arising are not easily met, and

in turning from them we are brought face to face with

ques tions of practicability . The resistance of a circuit

external to the lamps and generators is in the mains and

in order that current may be conveyed with a minimum

of loss,it is necessary that the resistance of the mains

shall be,if not nil, at leas t inconsequential . If we double

the radius of a distributing system,we must double the

length of each main ; and in order that the resistance of

the mains shall not be increas ed , we must double the

mass of metal composing them . Thus we quadruple the

cost . It is true, also, that we quadruple the number of

mains in order to cover the quad rupled area ;but this

should not properly be taken into consideration, for it is

assumed tha t only the same number of lamps is operated

upon each main in the enlarged as in the orig inal sec

tion, and that all the mains ra diate in sensibly straight

lines fromthe distributing station . Increas ing the ra»

dins of lighting area to two miles again quadruples the

cost of each main ; so that it appears tha t the cost of

mains alone, necessary to conduct the current for a given

number of lamps, is sixteen times greater when the dista nce from the distributing station to the most remote

lamp is two miles than when it is but half a mile . For

this reason it is extremely improbable tha t the transmis

130 ELE CTRIC LIGHTI N G B Ymcasnascsmcs .

sion of electricity to any great distance will ever be at

If it were possible to increase the delivering capacity

of a conductor indefinitely by increasing the elecmmotive force of the current, it might be practicable to con

vey the power of Niagara Fall s to the Atlantic seaboard ;and if it were possible to devise

using the current,it would

in the production of light in electric lamps and power in

electric engines . We have already had occas ion, in de

scribing the connection of electric lamps in series, to

speak of the difficulties of insulation . To convey the

current of a thousand horse-power a distance of one

mile through a copper conductor one-quarter of an

inch in diameter would involve a high degree of per

fection of insulation in the conductor,and the conse

quences in loss of life fromaccidental diverting of thecurrent through the person between the generator and

the mile terminus would be such as to prevent its em

ployment in any community . To extend the conductor

3. distance offive hundredmiles, involving an increas e inelectro-motive force of cu rrent offive hundred times, andan increase in the cost of the conductor offive hundredtimes

,would be to magnify the error

,the danger, and

the impracticabili ty hye hundred times . No generato r

or series of generators which would not short cimuit thecurrent within themselves could ever be devised,

The cost of a quarter-inch copper conductor laid and

insulated for ordinary currents is about

for a distance of 500 miles its cost would be

and the cost of maintenance would be per annum

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162 ELEC TRI C L IGHT IN G B Y IN C A N D ES C EN C E.

termine the quantity of curretit consumed in a lamp inany period of time

,all tha t is neeessary is to deduct the

weight of the cathode before its introduction into the

bath fromits weight after removal from the bath,and to

multiply the remainder by the number of times the resistance of the lampocircuit is contained in the resistance

of the circuit C D E , the electrolytic action of unit

rent being known . For theRof B being 1 ohm,and the

Rof C D E being ohms,the lamp receives H—H part

of the current,and the electrolytic bath n

in part . B y

arranging in a suitable receptacle a. sufficient number ofthe baths A

,each connected with a lamp, the val ue of

the current supplied to any number of lamps may be

The Fuller metre,designed for the measurement of

al ternating currents,is shown in Fig. 9 1 . The purpose

G E N ERA L D IS TRIB UT IO N . 163

of this metre is to automatical ly register the number of

hours during which a lamp is operated . Two electro

ma gnets,so wound and connected as to produce the

p ol arities indimted, are placed in the circuit of the lamp.

A polarized steel armature playing between the poles of

t he magnets is connected, by way of the armature-lever,w i th ratchet-and-pawl mechanism . Changingin polarityo f the electro—magnets, produced by the alternating curren ts supplied to the lamp, serves to keep the arma ture

in vibration, and thus to rotate a train of registering

wheels.

The Sawyer metre, Fig. 92 , is also a time metre . It

seryes to register the time during which a lamp is in use

and since the unit strength of current and the require

men ts of the lamp are known,it is easy to determine the

value of the current used . B y means of ratchet-and

pawl mechanism the motion of the armature of an elec

tro-magnet is communicated to a set of dial-hands which

are so arranged as to indica te the current consumption or the candle light res ulting from such con

sumption . A shaft, E , continuously rota ted by a biweekly or monthly chronometer

,carries two insulated

EL EC TRI C L IGHT IN G BY IN C A N D E S C E N O E .

springs, E ,which are in electrical connection with the

coils of the registering magnet, and al ternately establish

con tact with the opposite pairs of pins, A A , B B , C C ,

D D,thus diverting a small fraction of the current sup

plied to lamps A ’

B’

c'

D" through the coils of the mag

gizing the magnet and ca using the ratchet-wheel to move

one tooth. For every lamp added to the circuit there isan additional pair of o

pins . If only one lamp is in use,the springs F energize the magnet but twice in a revolu

tion of the shaft ; if two lamps four times ; if all the

lamps are in use,the ratchet-wheel is kept in constant

Fl; 98 . E dhon ‘o fld ety nevioe.

motion ; therefore the record of the dial -hands is as ex

act. when one or two are in use as when any other num

ber of lamps is in use, and to determine at any time the

consumption of curren t it is onl y necessary to note the

position of the dial-hands . A more complete metre, to

register the variations of current consumed in each lamp,

has been devised, andfinds special applicability in aseries ~multiple system : but enough has been written to

indicate the methods of measurement that are most like

ly to come into use .

To preserve the continuity of a circuit in case of acci

dent,and to obviate the dangers of short-circuiting,

there are several devices of about equally practical aoplica tion. In the Edison system of distribution obvia

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E LECTRIC LIGHTIN G B Y IN C AN D ES CEN CE .

an excessive flow of current through the branch, the ar

mature is attracted beyond the force of its retrachng

spring, and the lever through which we obtain the a’

r

cnit is released, and thus the circuit of the overloaded

branch is broken .

In the B rush and the Sawyer systems preservationof the continuity of the circuit, rather than its automa ticinterruption, is the end sought In the Brush systemthe circuit is through the lamp and

,by way of a shunt,

through the coils of an electro-magnet,whose armature»

lever operates to short-circuit the lamp when the circuit

Fig . 95. C ircuit-Pmerving Magnet.

of the lamp is interrupted. In the Sawyer system the

circuit is htat through the coils of an electro-magnet and

then through the lamp,and when the circuit is inter

rupted the armature-lever,being no longer attracted,

falls and establishes a short-circuit around the lamp

(Fig .

The Sawyer differential magnet device (Fig. 9 6) has

special application in a series -multiple system of distri

bution . The circu it from the point is a divided one,

one-half of the current flowing in one direction around

the core of magnet A , and the other half flowing in the

opposite direction around the core,the divided circuit

,

including the lamps I , uniting and terminating at the

GE N ERAL D lS TRIB UT I O N . 1 67

the magnetism in magnet A ,developed by the current

flowing in the circuit of one lamp, is neutralized by the

magnetic effects of the current flowing in the circuit of the

o ther lamp, and armature B , attached to lever C (which

is pivoted at D and ordinarily retracted by spring E to a

c o ntact with stop-pin F ). is unaffected . When, however,

Fig . 96. Automa tic D if ferentia l Magnet Switch.

an interruption of either circuit occurs, the neutralizing

magnetic influences of the current upon the magnet A

no longer exist,armature B is attracted by the magnet

A,and by way of contact face-plates G one-half of the

current is diverted to the artificial resistance H . In cas e

ofinterruption of the circuit of the other lamp, the en

tire current passes, by way of the core of magnet A and

contact-plates G ,through the resistance H .

CHAPTER XI I .

C O MME RC I A L AS PE C TS .

TH E light of an incandescent lamp has been

be suitable in every respect for domestic

characteristics are the characteris

stead iness it is comparable only to the ligh

N 0 other artificia l light, not excepting thatArgand burner, is as steady . This is

the Sawyer lamp,but of al l other lam

ba stion of the carbon is preven ted

raised to the temperature of limpid

is no difference between the ligh

proceeding from the sun,is

stratum of air it traverses . The heat

less than that of gas-light of equal power.

vapors proceeding from the combustion of

gas di sappear. N 0 chemical action

metica lly seal ed in its crysta l chamber,danger offire and explosion, a fragmenters and glows

,rises to the light of a

and broadens,andfinally illuminates wi

of day . This is what the incandes cent

and what it is under proper conditions .

There being no question as to the

new illuminant to all the purposes168

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170 E LECTRIC LIGHTI N G B Y IN CAN DES CE N CE .

pounds . Thefiveconserved in the

trio lamp a light of 120 candles . Burned in

it develops but 15 candlel ight Therefore

to convert coal into gas , and the gas into

and the steam -power into electricity,and the

into light, than it is to produce light by the direct con

sumption of gas .

In this it will be noted that the cost of lighting by the

voltaic arc is alone considered . We have now to com

pare with this cost the cost of lighting by incandes

cence .

The tests of the Konn and B ouliguine lamps, made by

M. Fontaine, ga ve a development of eighty Camel burners from the current

light of one hundred

with pencils hea ted

shown a development

eighty per cent . recovered b

that the lamp may be lasting,from the same current should not mocent . of the light of the arc . * Thus,cence is twice as costly as light by the

it may be stated that, taking the

the cost of incandescent lighting is about

cost of gas -lighting.

We have shown in Chapter I I I . a development bycandle-light fromthe current which, in

500 candles .

commacu n AS PECTS . 171

In the estimate of cost of the voltaic-arc light, we have

n ot included the consumption of carbon in the lamp, for

the reason that in incandescent lamps the carbon is pre

served from consumption ;and we have only introduced

the subject of vol taic-arc l ighting in order to exhibit

the verified results obtained by Professor Tyndall and

We have not yet considered the cost of plant or the

cost of attendance in either the gas system or the elec

tric system of lighting,and we have allowed but 50 cents

per thousand cubic feet as the cost of gas, whereas in

New York City the average cost of gas-production,all

items of expense included,is 70 cents per thousand, and

the leakage 8 per cent,while the cost to the consumer is

$2 25 per thousand .

The followingfigures relate to the business of N ew

Capital invesw¢ $20,

Gross sales per annum (cubic feet),

Cost of gas (70 cen ts per

Interest on capital,at 7 per cent ,

Taxes,

Was tage (8 per cent ),

Total,

Gross receipts,

Leaving a net profit, over 7 per cent upon the capital invests d, of or a to tal net profit of 151} percent

172 ELE CTRIC LIGHTIN G B Y IN CAN DES C EN CE.

fairly stated by the-gas interest on the one hand and

by the electric-light interest on the other. The state

ments of the former have been bas ed upon the work

them,always excessive, and the cost of attendance,

men t of light ; whereas with large steams ugines—eu

gines of 500 horsepower and upward— the cost per horsa

power is less than one cent per hour. Instead of taking

the cost of gas as the basis of calculation , the electric

light interest has cons idered only the cost to the con

sumer,which is no more to be considered the cost than

the retail price of any production is to be considered the

cost of that production . Furthermore,the gas interest

has invariably urged the cost of the conducting-wires as

an insurmountable obstacle to the general use of the

el ectric light, basing its conclusions upon the sizes of the

wire employed in special uses of voltaic-arc lamps where

the utmost utilization of the current developed has been

attempted .

In no case will the cost of electric mains equal the cost

of gas mains . In most cases it will fall belowfifty percent . of the cost of gasmains In no case will the cost

of branch electric conductors equal the cost of branch

gas conductors .

In cal culating the cost of el ectric conductors,the fol

lowing table will be found of use

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174 EL ECTRICms smo B Ymcw osscsscn.

metal , and whatever its size or cost, is all that is

needed .

We have shown in Chapter IX . that in a series -mul

tiple system of lamps, the resistance of the mainconductor may be as high as one ohm

,and yet permit

the utilization as light of eighty per cent . of the current

generated. We find by the table of resistances that this

conductor,leading a distance of one mile from the sup:

plying station and re turning thereto,making its total

length two miles . would be substantially of an

inch in diameter, or less than one-third of an inch . As

the resistan ce of feet of this conductor is . 097501

ohm , the resistance of two miles of it, or feet,would be exactly ohms . The cost of this condue

tor, as copper at thirty cents per pound, would be

10. The cost of a copper conductor, one mile in

length,and a return conducto r consisting of an iron

tube of equal resistance per foot length,would be about

$900 . Insulated as a round copper wire, one mile long,in an iron enclosing-tube

,the cost would be about

or twenty cents per foot .*

But here we are brought to the consideration of an

other question,and one of decided importance—via ,

the

heating of the conductor by the current traversing it ;for

it will receive and was te as heat ons twenty-fifth as

much current as is used in the lamps, or the hea t of 400

lamps, and the surface of the outer tube exposed to

earth-conduction is not sufficient to prevent a considerable rise in temperature

,with consequent waste of cur

rent,equivalent to leakage in a gas system . As much

A s the prices ofmeta ls change this estimatemust be changed .

COMME RCIAL AS PECTS . 175

heat would be developed in each section of the condue

tor thirteen feet long as would be developed in a single

lamp,which

,although small in itself, owing to the poor

heat-conductivity of the earth, would soon appreciably

increase the resistance of the conductor. In order to

obviate any difficul ty from this source, and to realize agreater economy of working, it is well to increase the

size of the copper conductor beyond the actual require

ments— in this case, say, to a diameter of . 65146 inch

and thus to quadruple its conductivity and cost, and to

increase the diameter of the enclosing-tube in propor

tion .

We thus reduce the resistance of the main to . 25 ohm,

and the waste of current to that of 100 lamps ;and not

only'

is the lateral cooling-surface doubled, but the

l ength of main through which the heat of a single

lamp is distributed is feet,comparable to feet

of the smaller main . The result is that the very slight

heat developed by the current is dissipated, and there

is no appreciable increase in the resistan ce of the main .

The cost of such a main, per mile, would be as follows

C opper, at 30 cents per pound ,at 3 cents per pound,

150

Total co st of electric main, per mile, $3,208

C ost of eight-inch gas main, at 3 cen ts per pound,

It will thus be seen how little foundation there is for

the absurd estimates from time to time published con

cerning the cost of electric conductors . B y reference to

176 ELECTRIC LIGHT IN G B Y IN CAN DES CEN CE .

mine the cost of the main necessary for any number of

lamps, and the percentage of was te in the same . In the

case of a system of lamps,the waste of current

in the mains is almost exactly one per cent , whil e the

leakage of a New York gas system is eight per cent.

B y far the greater portion of the plant of a gas system

is in poorly-paying,or comparatively poorly-paying

,dis

tricts . In the lighting of houses where very little gas is

used , and in large sections of border te rri tory, there is

but little and sometimes no profit. The profits of a gassystem are in the lighting of factories and large business

houses, stoves and hotels, halls and theatres, and the

wealthier parts of a city where the most bf the gas pro

duced is consumed . The area of NewYork City is about

sixteen square miles,but the most profita ble territo ry

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173 morale u s armo B Ymcw ossossc'

a

ised in light-production, which would allow an average

use of 5-foot burners four hours da ily . We are

to compare this consumption of gas in gas lighting with

steam-power consumption in electric lighting and as in

the new development of electric lighting we do not con

sume power except as light is needed,and as more or less

light is nwded throughout the twenty-four hours of each

day, we may employ almost any number of hours as the

basis of cal culation . Taking the high average of 12 can

dleJight per burner [see Edgerton’s certificate, Chapter

wefind that the total light obtainable fromburners is candles . These burners are not dis

tributed among different apartments, but there

are, say, apa rtments

,as stores

,dining-rooms , eta ,

averaging 30 burners each,

averaging 10 burners

each, averaging 4 burners each,

of 2 bumers each, and of 1 burner each , distributing the

light among apartments . It may be said that at

certain hours there are more than separate apart

ments lighted, and at other hours less . This is true, but

the electric-lighting system ,which consumes power in

proportion to the requirements of the system,is capable

of expanding and contracting the supply of electricity ,just as the gas system is capable of expanding and con

tracting the supply of gas, and just as economically . It

costs less to get 100 horse power out of an engine capable

of developing 200 horse-power than it costs to get 100

horse-power out of a 100 horse-power engine .

In another chapter we have explained the economy

of incandescent lamps of large foci as compared Withthose of small foci . Thus the current generated by the

commaacuu. AS PECTS . 179

in a single lamp a light of 275 candles the curren t gene

rated by one horse~ power produces in two lamps in series

a light of 120 candles perM p in three lamps, 60 candles

per lamp ; in four lamps, 30 candles per lamp ; infivelamps, from 10 to 15 candl es per lamp the increasing

external resistance and the greater percentage of current

utilized as light,together with the easier motion of the

generator,when the number of lamps is increased, ao

counting for the proportions given.

In order to supplant the 5 -foot burners of the

p a system , we must employ electric burners, dis

tributed and requiring power to operate as shown in the

following table (page which also shows the distribu

tion,power

,and consumption of gas -burners .

It will be noted that thesefigures are not founded upona rea limtion of

.

from 10 to 20 lights, of 16 candle-power

each, per horse-power of force expended in driving the

generator, but upon

2 lammof 120 candl e-power, or3 lamps of 60 candle-power, or

4 lamps of 30 candle-power, or

5 lamps of 10 to 15 candle-power.

In further division there is great loss . We have never

obtained more than 17 lights of 12 candle-power ea ch per

three horse-power,and this only in laboratory experi

ments under favorable conditions ; nor can very muchmore ever be obtained from magneto or dynamo-electricgenerators . Further economical division is to be looked

180 E LECTRIC LIGHTIN G B Y IN CAN DES CEN CE .

35

140

105

zinc sad io puadx

qa Jams;

~w 0q mom

s g g g4 .1c Joqmnx

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182 E LECTRIC LIGHTI N G BY IN CAN D E S CEN C E .

8 stokers, at $1 50, $12 00

1 electrician, 5 00

1 as sistant, 2 00

40 tons coal, at $4 35 in bunkers , 1 74 00

Oil, waste, etc , 10 00

Total per day, ml 50

Tota l for four stations, m00

These engines would consume two pounds of coal per

hour per horse-power,which for four hours’ run

,and a

development of horse-power per station , would

make the consumption in four hours 24 tons ;but, not

withstanding the fact that the consumption'

is in almost

direct proportion to the current requirements, we have

thought bes t, as more or less power will be used during

the entire twenty-four hours of the day, to increase the

estimate of coal consumption 66 } per cent . In prac

tice the consumption would fall considerably below 40

tons,but we have in all cases preferred to make the at

lowance excessive .

The mains are calcula ted, not from centrally-located

stations,but from stations located upon the outskirts of

the terri to ry to be supplied :

We have not yet taken into consideration the cost of

renewal of the electric burner,which varies according to

the system employed . In the Sawyer lamp, which is re

newed without destroying it, the cost per renewal is from

eight to ten cen ts . The average frequency of renewal

per lamp (combining in the consideration lamps of all

foci) is once in three to four months . There is claimed

for the Edison burner a life-time of six months.

counsaomn AS PECTS . 133

In recapitulating the cost of el ectric lighting per sta

tion per year,we obtain the following result

Interest on investment, at 7 per cent ,00

Depreciation of plant (real estate and ap

purtenances, and mains), at 5 per cent ,00

Depreciation of engines,boilers, and gene

rators, at 10 per cent ,

Taxes,

Cost of operating,at $221 50 per day,

4 renewal s of lamps,at 10 cents per

00

Total per station, 00

Total for the four stations,

00

a s against a total cost per annum by the gas system of

A t a rate of $1 124»per thousand for gas, the gross re

ceipts of electric lighting would be or a net

profit, over and above 7 per cent . upon the capital invested, of or a total net profit of 60 per cent .To be as cheap as electri c light, gas must bemanufactured, all items of cost and management included, at aslow a rate as twenty-three cents per thousand cubic

feet, without deduction for leakage . We have, however,perhaps overlooked the fact that whil e from the gas sys

temwe obtain a total light of candles, we

obta in from the electric system a total of 2,

In order that the matter of economy may be madestill clea rer, let it be assumed that we can accomplish

EL E C TRIC LIGHTI N G BY I N CAN DES CEN CE .

butfifty per cent. of what is shown and wha t has beendone with the electric light—that with an expendi ture

of one horse-power we can only obtain

1 light of 120 candl e-power, or

1 1} lights of 60 candle-power, or

2 lights of 30 candl e-power, or

2} lights of 10 to 15 candl e-power.

The cost of the engines and boilers would

bled ; that of the generators and remainder

plant would remain as before .

be increased from per

station, and the cost of operating (in coal-consumption,etc. ) would be increased from $221 50 to $415 50 per

day . The table of cost would then stand as follows :

Interest on investment, at 7 per cent ,

Depreciation of plant (real estate and ap

purtenances, and mains), at 5 per cen t ,

Depreciation of plant (engines, boilers, and

generators), at 10 per cent ,

Taxes,Cost of operating, at $415 50 per day,Renewal s of lamps

Total per station,

For the four stations,

as against a total cost per annum by the gas systemof

3

A t a rate of $1 12& per thousand for gas the gross re¢

ceipts would be or a net profit, over and

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I N D E X .

A rmatures , different forms of

B reguét, 53.

B rush, 32 .

D eMeritens, 20.

E dison ,41

, 43.

Frolich, 52.

Gramme, 28, 29 .

H ainer-A lteneck, 37, 39 , 48 .

H ochhausen, 41 .

L ontin, 20.

Maxim, 31 .

Pacinotti, 35 .

S awyer, 22, 41 , 45 , 46 , 48 .

S eeley, 24.

S iemens, 14, 15, 26 , 37, 39 , 48.

Thomson and H ouston , 41 .

Weston , 41 .

A rtificial resistances, 138.

B ouliguine lamp, 60.

B rushmachine, 18, 33.

CarbonsB ehavior of, under incandes

cence, 1 12.

C arbide forming with metallicconnections , 75 .

Carbon disintegrating, 75 .

Carbon decomposing in a trace

of combiningmatter, 75 .

Connections in lamps, 96 .

Carré, 65 .

C arbonsE dison, 72.

Jacquelin, 65 .

Mechanical division oi, 65 .

S awyer-Man , 68.

S awyer Treating A pparatus,S wan, 72.

D ivision of current and light, 115 .

D ynamo-electricmachinesB rush

, 18, 33.

E dison, 41 .

G ramme, 18, 27.

H afuer-A lteneck, 18, 37.

H ochhausen, 18, 41 .

Ladd, 1 1 .

Lontin, 20.

Maxim, 31 .

S awyer distributor, 22.

S awyer, 41 , 43.

S eeley, 24.

S iemens a lternating-curreut. 26 .

S iemens (N ew) , 37.

Thomson and H ouston, 41 .

Weston, 41.

E lectro-magnets, different formsoi

B rush. 33.

D e Meriteus, 19 .

E dison,41.

Gramme, 27.

188

E lectromagnetsl lnfner-A lteneck, 37, 39 .

Lontin , ao.

Maxim, 31 .

Pacinotti, 85.

S awyer, 22, 48 .

S eeley, 24.

S iemens. 26 , 37, 39 .

Wilde, 14, 15.Economy of the electric light, 10,

21, 35, 38, 46, Chap. Xl l .

E dison switch, 139 .

machine, 41 .lamp, 78.

Faraday (magneto-electriction), 13, 185 .

Failures of old lamps, 74.

due to combustion in a trace of

combiningmatter. 75.the carbide forming with metallic contacts, anddisintegration, 75 .

Farmer’s lamp, 62.

induo

G as and electric light compared ,

C hap. XI I .

Generators of electricityPrinciples of same in general,

10, 13, 17.

Br ushmachine, 32 .

Grammemachine, 28 .

N ew S iemensmachine, 37-53.

Accumulation by mutual ac.tion, 17.

Machines ofthemagneto-electrictypeClarke. 11, 13.

D eMeritens . 19 .

Faraday (magneto-induction),13.

H o lmes,1

L ontin , 20.

N ollet and Van Ma lderen, l l ,

13.

I N D EX.

Heating of generators. 30. 32 , 35.

41, 43, 45, 47, 48 .

Heating ofconductors, 173. 174.

Incandescent lampsBouliguine, 60.

D e Moleyns, 77.

Edison. 78.

Farmer, 62.Fontaine, oo.

Konn . 59 .

Koslofl, 60.

L odyguine, 58.

Maxim, 82.

Reynier. 56 .Roberts . 78.

Generators of electricityPacinotti, 35 .

Pixii, l l , 13.

S awyer, 22.Saxton, 13.

S iemens , old, 14.

S iemens alternating-curreut,

26 .

Wilde, 11 , 14.

Machines 0 ! the dyuamo-e lectrictype

Brush, 18, 33.

Edison, 41.

Gramme, 18 . 27.

Hainer-Alteneck, 18, 37.

Hw hhausen, 18, 41 .

Ladd . 11 .

Lontin, ao.

Maxim, 31 .

S awyer distributor, 2 ’

S awyer, 41 , 48 .

S eeley, 24.

S iemens a ltemating-current,26 .

S iemens (new). 37 .

Thomson and Houston. 41 .

Weston, 41 .

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