, 1879-01-30
n1IE ELECTRIC LIGHT.
Ills principles and Its His
~ tory.
c.,,v Attempts at Electric 1llumina-
''"' tion aud the Recent I'm.
prsvenlents.
r,.ht whose Great Fault Is That 1t
IA Too Brilliant.

u 1yeht Whose tireat fault ~ 'Da' "
Is Too Brilliant.
~. attention lately e!Fen to illumination b'
-'.n. of electricity makes cspee'a't5 interesting
p.s,rtful rcview Of tut suoleet printed !" tne
ts"s ,nmtwr Of tic 4finsfetnsh Century, with
-. iodorsemens nj Prof. Huxley, some extracts
s.nleh are herewith given. In inc hrst place
". N ,e remarked that when an electric cur
.., arch !. that from so'tnIc bastery, meets
9" ,s,,s,.pce to its passage, tue electricity Is
,.s ."..,1, converted Into heat. II thin wlsa bc
,'s.I IN the circuit the temperature OF the wire
p s,.,,, rt.e.: au,t II uas long been known That
'.e' .s.monnt Of hext thus generated Is directly
spDs.o,tions, ~ 10 the electric resistance OF tho
Wv. ~. Soa the Resistance depends, among
.h.. things, on the nature Of tha mctai; these
....1, vhict, Ate good conductors, stlch silver.
'xa.,ra much less reststancc than thoso which
ss.t,l conductors, such as platinum, which from
~ Ms iow electric coninct'yltS-or what
ssos'u',snce-s soulss peculiarly fttea for exhibiting
teAsnd'Errnct teA.ddr 1t sho,f1d b. unmarked
nsth n,s the resistance which platinum
o,her wire offers 10 the current IL raatcd not
Gas .s.ness Of liz wirc, Reduce the thickness aud
,bs 1t.ktance IS Immediately increased. Again,
he !e heatI1c eIee. IL elo4elr concerted With ils
wv .,.rnotb O! fhc currcnt. Hence powerful cur
,."t ,ent through thin platinum wire ltntnedl-
,t't ,rl5 rsulers 1t incaldescent. Many attempts
~. ~. hem male to u.iLx. the brilliant 1iEtt
.s .seh ID ih1s emitted. Az fur back a. 1876
r,,sut vas granted III hr. L. A. King, OF Lon
eaL iot method Of obtatntng electric tllnn,t-
sstsoo BY thr 1neantcscct,cc Of either platinum
- tsarboy, In one form Of bis lamp harrow
%So ot piatIou u.lc4f Is held vertically between
,nnabc conductors ana! rendered luminous BY
nsnnet|y.te1uated current, tie wholc arrange
n, ii telng protected by Elass 9loho winch
xrtsot the iucsr.desccnt metnt from currents Ut
m. Other pa!cutces have advocated the tsc Of
irttutn,-a metal OF extreme rarity which ia
rlotsly related to platinum. The metal which
H. Ellison ctnploys Is an alloy Of platinum and
Iridium. -.
.lfip * metal. bc sufficiently powerful. the
ltst rises to such MI iutunstty TINT the metal
heonts ftsca. Even substance IN refractory
asylstInunl InaY thns be readily melted. The
iu.:nn, u: course, breaks the continuity nj the
rtult mn, the current .is consequently inter-
1uoted. To avid til,s md other sources Of an.
nofanre Nj. Hing pra7osed. IN ''!s patent cited
aboye, 10 employ thin ruls Ut carbon.-n mnterl-
II Hhcl, NAV b. exposed to Intense heat with
out +tt',er ttston or vntaltxaton. When the
osid.set,, a,nt to aYoid this consumption Of the
spd II WIS suggested 10 iac!osc It IN 4 glass
riotv attached to long tube, from, which alt
sr had beeu expelled by first filling it with
nstcurr.
Kiuea fa,up, and most subsequent methods of
tlccllr lighting lad been based OH entirely dlf.
ferrut prlnclptey, until III 1873 attention Was
s:ata called to the production Of light by tho
txanjesernce Of curbnn. The subject was re-
Y!7si lr II. i.oiyguinc, Russian nhYefcist, " TO
,ue1uiticA to til. Academy Of Scienccs OK 81.
Petersburg lamp which wls considered to be
70 noyef in construction, ulll so promising m a
pactIsa! sourre of light, t!Iat the Academy
lxa.ded to hin tho I.omonossow prize. In
idyg,fne's latnp tbs 1pi Of cnri,on through
t!un OF tn lcnRth. Aut! u tlc electric resistance
Il thtEttUrv greater here than elsewhere, it IL
this PORTION alone that becomes tncalldekCent.
rnF ELRcrAic LIGHT rRorEa.
Tie various 1ncthotls Of abtaintng light by tho
'tnea13esrenee uf a resistsnE madtnnI--wilethrr
thu rod of cnrbon-Are cntrety different from
tbosc Whic!. are employed in producing that
bhiIaht surce vi illumination whtct. Is specially
dlstIngutsltl rs the electric light. This jIght
sM lint ublalnetl by Sir Humphrey Dsyy, In
lsl3, BY ,neans Ut lin fa,Huus battery at tile
Roya! Institution which cubaiatcl 0f no fcwpr
fhsn @,V0u Zine aud copper couples, exposing an
tgrfrgxle surface OF II, ,000 square iuches.
psfY found that When tie current from this
pic was passed hetweeu TWO pointed pieces OF
hVo0 th0lEOHlI AllAGHEtt 10 tuHAuE[ItlX ~lrcks
lIRht MS psodureu OF such dazzling brilltaucy
ns" bc comparable only with sunlight. More.
'feF, It was found tlIai i,c lDtcnsc light wns a4-
!0lnpanfrl by inteusc heat. II tilu electric light
bt caranily studied, II will he scen that glow
Ing particles Of CARBON ars constantly eprti,ztng
t''ls ttaoEterclMo OF solid matter tnkrs
paeo IN both directions, tho prevalent
9uFte Is from the positive to tho negative
tvett~le, ln fact, the poaitive carbon bcco1nes
1nuch moEe highly heated aitl wears AWAY much
mosr rapidly thni, docs the negative rarDon.
hcnee tue extremity ot tic positive carbon at
Iehgtl presents cup-llke coucayIly, while tin
tha o! tlle negative carbon rrtnalas uIore or
!ssa sharply pointed. This erosion Of the posi-
I'VE 'o1e takes place even In yaeuo, and lN,
Mcte1ore, tue tn the actunl emission Of solid
PARTICLES an1 not to The combustion Of The cur
noh. It Is, indeed, generally believed that tho
iieht Is produced by the !ncAntlcscencc Of par
te!ea u easb1N WHICH form u conducting chain
astR that this moiB Of Illumination Ia, after I'll,
guy lRodldcatlon Ut illumination by ihcan.
aeseeace. III order 10 produce The electric light
tne eatoon poles arc tnomcntafily brought Into
.uatacl' and then separated 10 slight dis
,nnse,- tho d!stancc actosa which the light can
i'M luminous portion OF the circuit, which
!e1lhs bridge between tho two solid poles. ID
generally known as thu yolta!c arc. The color
a.n aaape ot this luminous arc depend upon the
IA TIC Original experiments Of DAvy, rood.
taafsual was employed. As lohg US this suit
1aac continued to be used tl,e light afforded
notnllle but brilliant experiment for tin lcct-
a'e'3t!e. hat III 1914 ii. Leon Foucuuit pro-
loaed IN substitute for charcoal that cabOn2-
ttous matter which IL deposited In the interior
4 III sastelorts sha IL kn0wn ~ gas.Rraphite.
W. nasR tl''s tall anil dense caribou IL sswn Into
ssoa4, Or pencffs, II nsy 6e used with advantage
psoaaein1 tho electric light, since 1t u vastly
ao1s durable than tho softer tottnx Of carbon,
sasl u "oet!-etlaseoAl. Considerable objection
aa 'na} nevertheless be urged Agalust this use OF
HHsf!apa'te, 1t ts found. for instance, tint it,
H., alltt tsxtute sra not always uniform, and
~ ~ ixhs consequently duetuates III bsill,ancy.
a!ass s,l n!e carbon poles nre slowly consut1ed
aaanng lie production Of the electric light, II
sol1es nsas ntedful to move them together lu
%op4fi'on ~ they wear away. II tha light IL
~. pt continuous, The aistauce between
.s caribou must be kept constant; and
a,., Gs poslslvs carbon IL destroyed
asa. @aen more rapidly thau tie negative carbon,
wosla'otl must b. made for corresponding tn
~ sas 10 tts Velocity, This haa aiwAys been one
w, u!s sIe.t d!ulcalt!ea In attempting to carry
~. ~. electric illumination. Various automatic
..sulatost .sst have been devised to keep lhp {oles
otsatea by definite d..tancu, but nost Of ihrke
Mes mr,se involve the use Ut delicate 4nd complex
, rAs 1AuLocuRoYr CANDLE.
an.,Nu.s LILLE pFoersss. however, was made Ia the !n-