,transcrib]'s ,notes3 ,und]scores 80 be=e & aft] a ^w or phrase indicate italics 9 ! orig9al text4 ,equal signs 80 be=e & aft] a ^w or phrase indicate bold 9 ! orig9al text4 ,small capitals h be5 conv]t$ to ,,solid capitals4 ,illu/rations h be5 mov$ s !y d n break up p>agraphs4 ,typographical & punctuation errors h be5 sil5tly correct$4 ,,signall+ ,,across ,,space ,,)\t ,,wires4 ,,be+ ,a ,,description ,,( ,,! ,,"w ,,( ,,h]tz ,,8 ,,successors4 ,,by ,,pr(4 ,,oliv] ,j4 ,,lodge1 ,f4,r4,s4 ,,?ird ,,edition1 ,) ,additional ,rem>ks conc]n+ ! ,application to ,telegraphy1 & ,lat] ,developm5ts4 ,,london3 8,,! ,,electrician0 ,,pr9t+ ,,& ,,publi%+ ,,company1 ,,limit$1 ,,salisbury ,,c\rt1 ,,fleet ,,/reet4 ,copyright4 ,,works ,,by ,,dr4 ,o4 ,j4 ,,lodge4 ,lightn+ ,conductors & ,lightn+ ,gu>ds4 ,a ,complete ,treatise on ! subject ( ,electric ,dis*>ges 9 g5]al4 ,pione]s ( ,sci5ce4 ,a popul> ,illu/rat$ ,hi/ory ( ! ,e>ly ,a/ronom]s & _! ,"w up to ,rec5t ,times4 ,mod]n ,views ( ,electricity4 ,elem5t>y ,me*anics4 ,protection ( ,build+s f ,lightn+4 ,mann ,lectures to ! ,society ( ,arts1 #ahhh4 ,second>y ,batt]ies & ! ,electrical ,/orage ( ,en]gy4 ,cantor ,lectures to ! ,society ( ,arts1 #ahhc4 ,,table ,,( ,,cont5ts4 7,! l9es 9 italics :i* look l head+s ( p>agraphs are really /atem5ts ab\t exp]im5ts :i* 7 at t place %[n47 #a4 ,,royal ,,in/itution ,,lecture ,,on ,,! ,,"w ,,( ,,h]tz ,,& ,,"s ,,( ,,8 ,,successors3-- ,,pages ,biographical ,introduction #a ,elem5t>y ,explanation ab\t ,electrical ,radiation & ,absorption & ! ,effect ( ,syntony #c-h ,syntonic ,leyd5 ,j> ,exp]im5t #f1 #ba ,side ,obs]vations on ! ,effect ( ,light on ,electric ,dis*>ge #i-ab ,v>i\s ,detectors ( ,radiation #ac-bc ,physiological ,non-,effect ( ,suffici5tly ,rapid ,alt]nations #ag ,boltzmann ,gap ,detector--! ,precursor ( ! ,coh]] #ah ,branly's ,obs]vations 7see also ,app5dix1 page #ie7 #bj ,e>ly ,=m ( ,coh]] & ( ,branly ,fil+s ,tube #ba-bc ,e>ly ,signall+ ov] #dj or #fj y>ds #bd-be ,use ( ,telephone z ,receiv] #bf ,exp]im5ts %[+ ,syntony #bg-bh ,hypo!sis conc]n+ ! ,nature ( ,vision #bi-ca ,summ>y ( ,v>i\s ,detectors ( ,radiation #cj ,radiation ,detect$ f extremely ,weak ,sp>ks1 & by v compact ,receiv] ) ,collect+ ,wire #cb-cd ,vacuum ,fil+s ,tube #cd ,effect ( ,metallic ,enclosure #ce-ch ,exp]im5ts on ,reflection1 ,refraction1 & ,pol>isation ( ,radiation #ci-db ,note ab\t ,electric ,waves on ,wires #dc #b4 ,,application ,,( ,,h]tz ,,waves ,,& ,,coh]] ,,signall+ ,,to ,,telegraphy #de-dh ,coh]] ,behavi\r & ,tommas9a's ,exp]im5t #di ,s+le-,po9t ,coh]] #ee ,g5]al ,rem>ks ab\t ,pat5t ,law #ej ,attempts at ,syntonic ,telegraphy #eb-fj ,syntonic ,radiators & ,receiv]s #ea-ef #c4 ,,details ,,( ,,o!r ,,telegraphic ,,developm5ts3-- ,pop(f's #ahie ,demon/ration #fj-fb ,slaby's ,ov]l& ,exp]im5ts #fc-ff ,m>coni's ,rec5t ,demon/ration #ff-gb #d4 ,a ,,hi/ory ,,( ,,! ,,coh]] ,,pr9ciple #gc-hg ,pr(essor ,hughes' ,e>ly ,obs]vations be=e ,h]tz or ,branly #hh-id ,"w ( ,monsieur ,branly #ie-ajh #e4 ,,communications ,,) ,,respect ,,to ,,coh]] ,,ph5om5a ,,on ,a ,,l>ge ,,scale3-- ,pr(essor ,elihu ,?omson #aji ,dr4 ,morton #aaa #f4 ,,photo-,,electric ,,rese>*es ,,( ,,drs4 ,,el/] ,,& ,,geitel #aae-abf #g4 ,,photo-,,electric ,,rese>*es ,,( ,,pr(essor ,,righi #abg ,,signall+ ,,?r\gh ,,space ,,)\t ,,wires4 ,,! ,,"w ,,( ,,h]tz ,,& ,,"s ,,( ,,8 ,,successors4 ,! foll[+ pages 7up to page #db7 are ! ,notes ( a ,lecture deliv]$ by ,dr4 ,o4 ,j4 ,lodge be=e ! ,royal ,in/itution ( ,great ,brita9 on ,friday ev5+1 ,june #a1 #ahid4 ,^! notes h be5 revis$ by ,dr4 ,lodge1 & prep>$ = publication 9 ! =m "h pres5t$4 ,aft] page #db an acc\nt is giv5 ( ! lat] applications ( ,h]tzian wave exp]im5ts to wireless telegraphy1 & a s]ies ( ,app5dices are also giv54 ,introductory4--#ahid4 ,! untimely end ( a "y & brilliant c>e] _c fail to /rike a note ( sadness & awak5 a *ord ( sympa?y 9 ! he>ts ( 8 fri5ds & fell[-work]s4 ,( m5 ?us cut d[n 9 ! e>ly prime ( _! p[]s !re w occur to u "h ! names ( ,fresnel1 ( ,c>not1 ( ,clif=d1 & n[ ( ,h]tz4 ,8 0 a /r5u\s & fav\r$ y\?2 he 0 surr\nd$ f 8 bir? ) all ! influ5ces t g to make an accompli%$ man ( sci5ce--accompli%$ bo? on ! exp]im5tal & on ! ma!matical side4 ,! front rank ( sci5tific work]s is weak] by 8 dea?1 :i* occurr$ on ,janu>y #a1 #ahid1 ! ?irty-sev5? ye> ( 8 life4 ,yet did he n g till he _h effect$ an a*ievem5t :i* w h& 8 "n d[n to po/]ity z ! f\nd] ( an epo* 9 exp]im5tal physics4 ,9 ma!matical & speculative physics o!rs _h s[n ! se$4 ,x 0 s[n by ,f>aday1 x 0 s[n by ,?omson & by ,/okes1 by ,web] also d\btless1 & by ,helmholtz2 b 9 ?is p>ticul> dep>tm5t x 0 s[n by none m fruitfully & pl5tifully ?an by ,cl]k ,maxwell4 ,( ! se$ ?us s[n ,h]tz reap$ ! fruits4 ,?r\gh 8 exp]im5tal discov]y1 ,g]many awoke to ! tru? ( ,cl]k ,maxwell's !ory ( light1 ( light & electricity comb9$1 & ! able army ( work]s 9 t c\ntry 7n =gett+ "s 9 ,switz]l&1 ,france1 & ,irel&7 h done mo/ ( ! glean+ aft] ,h]tz4 ,?is is ! "w ( ,h]tz :i* is be/ kn[n1 ! "w :i* br\ght him imm$iate fame4 ,x is n always t public notice is s well ju/ifi$4 ,! popul> in/9ct is g5]\s & tru/ful1 & x is apt to be misl$4 ,! sci5tific em95ce accord$ to a few en]getic p]sons by popul> e/imate is m or less amus+ to ^? work+ on ! same l9es4 ,9 ! case ( ,h]tz no su* mi/ake has be5 made4 ,8 "n is n ov] well-kn[n1 & 8 "w is imm5sely great] 9 e way ?an t ( sev]al :o h made m noise4 ,8 be/ kn[n discov]y is by no means 8 only "o1 & no less ?an eighte5 ,pap]s 7 contribut$ to ,g]man p]iodicals by him1 9 addition to ! pap]s incorporat$ 9 8 n[ well-kn[n book on electric waves4 ,9 clos+ ^! introductory & p]sonal rem>ks1 ,i %\ld l to say t ! en?usia/ic admiration = ,h]tz's _s & "* felt & express$ by /ud5ts & work]s :o came into contact ) him is n easily to be exagg]at$4 ,nev] 0 a man m pa9fully anxi\s to avoid w\nd+ ! susceptibilities ( o!rs2 & he 0 accu/om$ to deprecate ! prom95ce giv5 to him by speak]s & writ]s 9 ?is c\ntry1 le/ x might seem to exalt him unduly above o!r & old] work]s among 8 own s5sitive c\ntrym54 ,speak+ ( ! o!r great work]s 9 physics 9 ,g]many1 x is n out ( place to record ! sorr[ ) :i* we h he>d ( ! rec5t dea? ( ,dr4 ,augu/ ,kundt1 ,pr(essor 9 ! ,univ]sity ( ,b]l91 successor to ,von ,helmholtz 9 t capacity4 ,:5 ,i cons5t$ to disc\rse on ! "w ( ,h]tz1 my int5tion 0 to repeat "s ( 8 actual exp]im5ts1 & especially to demon/rate 8 less-kn[n discov]ies & obs]vations4 ,b ! fasc9ation ex]t$ ^u me by electric oscillation exp]im5ts1 :5 ,i1 too1 0 indep5d5tly work+ at !m 9 ! spr+ ( #ahhh1a resum$ its hold1 & my lecture w accord+ly consi/ ( exp]im5tal demon/rations ( ! outcome ( ,h]tz's "w r ?an any precise repetition ( portions ( t "w itself4 #a ,phil4 ,mag41 ,,xxvi41 pp4 #bbi1 #bcj1 ,augu/1 #ahhh2 or 8,lightn+ ,conductors & ,lightn+ ,gu>ds10 pp4 #ajd1 #aje2 also ,proc4 ,roy4 ,soc41 ,vol4 #ej1 p4 #bg4 ,9 case a m9ority ( my audi5ce are 9 ! pr$icam5t ( n kn[+ any?+ ab\t ! subject1 a five m9utes' explanatory prelude may be p]mitt$2 & ! simple/ way w be = me ha/ily to summ>ise our k ( ! subject be=e ! era ( ,h]tz4 ,illu/ration3 ,,fig4 #a4--,oscillations ( ,dumb-bell ,h]tz ,vibrator 7aft] ,bj]knes74 ,j z a pebble ?r[n into a pond excites surface ripples1 :i* c heave up & d[n float+ /raws "u :i* !y pass1 s a /ruck bell or tun+ =k emits en]gy into ! air 9 ! =m ( :at are call$ s\nd waves1 & ?is radiant en]gy is able to set up vibrations 9 o!r suitable ela/ic bodies4 ,if ! body receiv+ !m has its natural or free vibrations viol5tly damp$1 s t :5 left to itself x spe$ily returns to re/ 7,fig4 #a71 !n x c respond fully to notes ( almo/ any pit*4 ,?is is ! case ) y\r e>s & ! tones ( my voice4 ,tones mu/ be exce$+ly %rill be=e !y cease to excite ! e> at all4 ,if1 on ! o!r h&1 ! receiv+ body has a p]si/5t p]iod ( vibration1 cont9u+ 9 motion long aft] x is left to itself 7,fig4 #b7 l ano!r tun+ =k or bell1 = in/ance1 !n f> m facility ( response exi/s1 b great accuracy ( tun+ is necess>y if x is to be fully call$ out2 = if ! receiv] is n ?us accurately syntonis$ ) ! s\rce1 x fails m or less completely to res\nd4 ,illu/ration3 ,,fig4 #b4--,oscillation ( ,r+-%ap$ ,h]tz ,resonator excit$ by ,syntonic ,vibrator 7aft] ,bj]knes74 ,illu/ration3 ,,fig4 #c4--,oscillation ( ,r+ ,resonator n q syntonic ) ,radiator4 7,= me?od ( obta9+ ^! curves see ,fig4 #ad47 ,conv]sely1 if ! s\rce is a p]si/5t vibrator1 correct tun+ is ess5tial1 or x w de/roy at "o mom5t 7,fig4 #c7 motion :i* x orig9at$ ! previ\s mom5t4 ,:]eas1 if x is a dead-beat or /rongly-damp$ excit]1 almo/ any?+ w respond equally well or equally ill to x4 ,:at ,i h said ( s\nd+ bodies is true ( all vibrators 9 a m$ium compet5t to transmit waves4 ,n[ a s5d+ telephone or a microphone1 :5 spok5 to1 emits waves into ! e!r1 & ?is radiant en]gy is likewise able to set up vibration 9 suitable bodies4 ,b we h no delicate means ( directly detect+ ^! electrical or e!rial waves2 & if !y are to produce a p]ceptible effect at a di/ance1 !y mu/ be conf9$1 z by a speak+-tube1 prev5t$ f spread+1 & conc5trat$ on ! di/ant receiv]4 ,?is is ! function ( ! telegraph wire2 x is to ! e!r :at a speak+-tube is to air4 ,a metal wire 9 air 79 function1 n 9 details ( analogy7 is l a long holl[ cavity surr\nd$ by ne>ly rigid b slightly ela/ic walls4 ,sph]e *>g$ f ,electrophorus4 ,fur!rmore1 any conductor electrically *>g$ or dis*>g$ ) suffici5t sudd5ness mu/ emit electrical waves into ! e!r1 because ! *>ge giv5 to x w n settle d[n in/antly1 b w surge to & fro sev]al times fir/2 & ^! surg+s or electric oscillations mu/1 accord+ to ,maxwell1 />t waves 9 ! e!r1 because at ! end ( ea* half-sw+ !y cause electro/atic1 & at ! middle ( ea* half-sw+ !y cause electromagnetic effects1 & ! rapid alt]nation f "o ( ^! modes ( en]gy to ! o!r con/itutes e!rial waves4#b ,if a wire is h&y !y w run along x1 & may be felt a long way (f4 ,if no wire exi/s !y w spread out l s\nd f a bell1 or light f a sp>k1 & _! int5sity w decrease accord+ to ! inv]se squ>e ( ! di/ance4 #b ,/rictly speak+1 9 ! waves !mselves !re is no lag or diff]5ce ( phase betwe5 ! electric & ! magnetic vibrations2 ! diff]5ce exi/s 9 emitt] or absorb]1 b n 9 ! transmitt+ m$ium4 ,true radiation ( en]gy does n beg9 till ab\t a qu>t] wave l5g? f ! s\rce1 & )9 t di/ance ! initial qu>t] p]iod diff]5ce ( phase is oblit]at$4 ,maxwell & 8 foll[]s well knew t !re w\ld be su* waves2 !y knew ! rate at :i* !y w\ld g1 !y knew t !y w\ld g sl[] 9 glass & wat] ?an 9 air1 !y knew t !y w\ld curl r\nd %>p edges1 t !y w\ld be p>tly absorb$ b ma9ly reflect$ by conductors1 t if turn$ back ^u !mselves !y w\ld produce ! ph5om5a ( /ation>y waves1 or int]f]5ce1 or nodes & loops2 x 0 kn[n h[ to calculate ! l5g? ( su* waves1 & ev5 h[ to produce !m ( any requir$ or pr$et]m9$ wave l5g? f #a1jjj miles to a foot4 ,o!r ?+s 7 kn[n ab\t !m :i* w\ld take too long to enum]ate2 any homog5e\s insulator w\ld transmit !m1 w\ld refract or conc5trate !m if x 7 ( suitable %ape1 w\ld reflect none ( a p>ticul> mode ( vibration at a c]ta9 angle1 & s on1 & s on4 ,all ?is 0 kn[n1 ,i say1 kn[n ) v>y+ degrees ( confid5ce2 b by "s kn[n ) z great confid5ce z1 p]haps ev5 m confid5ce ?an1 is legitimate be=e ! actuality ( exp]im5tal v]ification4 ,h]tz suppli$ ! v]ification4 ,he ins]t$ suitable conductors 9 ! pa? ( su* waves1 conductors adapt$ = ! occurr5ce 9 !m ( induc$ electric oscillations1 & to ! surprise ( ev]yone1 himself d\btless includ$1 he f\nd t ! second>y electric surg+s ?us excit$ 7 /rong en\gh to display !mselves by m9ute electric sp>ks4 ,illu/ration3 ,,fig4 #d4--;,exp]im5t ) ,syntonic ,leyd5 ,j>s 7cf4 page #ba74 ,syntonic ,leyd5 ,j>s4 ,i %all %[ ?is 9 a =m :i* requires great precision ( tun+ or syntony1 bo? emitt] & receiv] be+ p]si/5tly vibrat+ ?+s giv+ "s #cj or #dj sw+s be=e damp+ has a s]i\s effect4 ,i take two ,leyd5 j>s ) circuits ab\t a y>d 9 diamet]1 & situat$ ab\t two y>ds ap>t 7,fig4 #d74 ,i *>ge & dis*>ge "o j>1 & obs]ve t ! surg+s set up 9 ! o!r c cause x to ov]fl[ if x is syntonis$ ) ! fir/4#c #c ,see ,nature1 ,vol4 ,,xli41 p4 #cfh1 :]e ,i fir/ describ$ ?is exp]im5t2 or quotation 9 ,j4 ,j4 ,?omson's 8,rec5t ,rese>*es10 p4 #cie4 ,a clos$ circuit su* z ?is is a feeble radiator & a feeble absorb]1 s x is n adapt$ = action at a di/ance4 ,9 fact1 ,i d\bt :e!r x w visibly act at a range beyond ! at :i* true radiation ( brok5-(f en]gy occurs4 ,if ! coat+s ( ! j> are sep>at$ to a great] di/ance1 s t ! dielectric is m expos$1 x radiates bett]2 because 9 true radiation ! electro/atic & ! magnetic en]gies mu/ be equal1 :]eas 9 a r+ circuit ! magnetic en]gy pr$om9ates4 ,by sep>at+ ! coats ( ! j> z f> z possible we get a typical ,h]tz vibrator 7,fig4 #e71 ^: dielectric ext5ds out into ! room1 & ?us radiates v p[]fully4 ,illu/ration3 ,,fig4 #e4--,/&>d ,h]tz ,radiator4 ,ord9>y ,size ,h]tz ,vibrator4 ,9 consequ5ce ( its radiation ( en]gy1 its vibrations are rapidly damp$1 & x only gives "s ?ree or f\r good /rong sw+s 7,fig4 #a74 ,h5ce x foll[s t x has a wide range ( excitation2 i4e41 x c excite sp>ks 9 conductors b>ely at all 9 tune ) x4 ,! two conditions1 conspicu\s en]gy ( radiation & p]si/5t vibration electrically produc$1 are at pres5t incompatible4 ,:5ev] ^! two conditions coexi/1 consid]able p[] or activity w1 ( c\rse1 be necess>y 9 ! s\rce ( en]gy4 ,at pres5t !y only coexi/ 9 ! sun & o!r />s1 9 ! electric arc1 & 9 furnaces4 ,two ,circul> ,vibrators ,sp>k+ 9 sympa?y4 ,! receiv] ,h]tz us$ 0 *iefly a circul> resonator 7,fig4 #f71 n a good absorb] b a p]si/5t vibrator1 well adapt$ = pick+ up di/urbances ( precise & measurable wave l5g?4 ,its mode ( vibration :5 excit$ by emitt] 9 tune ) x is depict$ 9 ,fig4 #b4 ,i f9d t ! circul> resonators c act z s5d]s too2 "h is "o excit+ q long sp>ks 9 a second "o4 ,electric ,syntony4--,t 0 8 discov]y1 b he did n /op !re4 ,he at once proce$$ to apply 8 discov]y to ! v]ification ( :at _h already be5 pr$ict$ ab\t ! waves1 & by labori\s & difficult int]f]5ce exp]im5ts he asc]ta9$ t ! previ\sly calculat$ l5g? ( ! waves 0 ?or\ghly borne out by fact4 ,^! int]f]5ce exp]im5ts 9 free space are 8 greate/ a*ievem5t4 ,illu/ration3 ,,fig4 #f4--;,circul> ,resonator4 7,! knobs ought to ne>ly t\* ea* o!r47 ,illu/ration3 ,,fig4 #f;,a4--,any circul> ,resonator c be us$ z a s5d] by br++ its knobs ne> ! sp>k+ knobs ( a coil2 b a simple arrangem5t is to take two semi-circles1 z 9 above figure1 & make !m ! coil t]m9als4 ,! capacity ( ! cut ends c be v>i$1 & ! p]iod !reby l5g!n$1 by exp&+ !m into plates4 ,he work$ out e detail ( ! !ory spl5didly1 sep>ately analys+ ! electric & ! magnetic oscillation1 us+ language n always su* z we %\ld use n[1 b himself gr[+ 9 !oretic insight ?r\gh ! m$ium ( :at w\ld h be5 to mo/ physici/s a confus+ maze ( tr\blesome facts1 & dis5tangl+ all _! ma9 relations mo/ h>moni\sly4 ,holtz ,ma*9e1 ,a & ,b ,sp>ks2 ,glass & ,qu>tz ,panes 9 ,scre54 ,:ile ,h]tz 0 obs]v+ sp>ks su* z ^!1 ! prim>y or excit+ sp>k & ! second>y or excit$ "o1 he obs]v$ z a bye issue t ! second>y sp>k occurr$ m easily if ! light f ! prim>y fell ^u its knobs4 ,he exam9$ ?is new influ5ce ( light 9 _m ways1 & %[$ t al?\gh sp>k light & electric bru% light 7 peculi>ly effective1 any s\rce ( light t gave v ultra-violet rays produc$ ! same result4 ,illu/ration3 ,,fig4 #g4--;,exp]im5t arrang$ to %[ effect on "o sp>k ( light f ano!r4 ,! ,b sp>k occurs m easily :5 x c see ! ,a sp>k ?r\gh ! w9d[1 unless ! w9d[ is glaz$ ) glass4 ,a qu>tz pane transmits ! effect3 glass cuts x (f4 ,! above figure repres5ts my way ( %[+ ! exp]im5t4 ,x w be obs]v$ t ) ?is arrangem5t ! ,b knobs are at ! same pot5tial up to ! in/ant ( ! fla%1 & 9 t case ! ultra-violet portion ( ! light ( ! ,a sp>k assi/s ! occurr5ce ( ! ,b sp>k4 ,b x is int]e/+ to note :at ,el/] & ,geitel h f\nd 7see ,app5dix ,,iv41 ,fig4 #ei71 t if ! ,b knobs 7 subject$ to /eady /ra9 in/ead ( to impulsive ru%--e4g41 if !y 7 connect$ to ! inn] coats ( ! j>s in/ead ( ! out] coat+s--t !n ! effect ( ultra-violet light on ei!r sp>k gap w\ld ex]t a det]r5t influ5ce1 s t ! sp>k w\ld probably occur at ! o!r1 or non-illum9at$ gap4 ,) ! alt]$ connections x is1 ( c\rse1 n feasible to illum9ate "o sp>k by ! light ( ! o!r2 ! sp>ks are !n alt]native1 n successive4 ,wi$emann & ,eb]t1 & a numb] ( exp]im5t]s1 h repeat$ & ext5d$ ?is discov]y1 prov+ t x is ! ca?ode knob on :i* illum9ation takes effect2 & ,hallwa*s & ,righi made ! important obs]vation1 :i* ,el/] & ,geitel1 ,/olet[1 ,branly1 & o!rs h ext5d$1 t a fre%ly-poli%$ z9c or o!r oxidisable surface1 if *>g$ negatively1 is gradually dis*>g$ by ultra-violet light4 ,illu/ration3 ,,fig4 #h4--,z9c ,rod 9 ,arc ,light1 protect$ by ,glass ,scre54 ,! l5ses are ( qu>tz1 b !re is no ne$ = any l5ses 9 ?is exp]im5t2 leakage ( electricity beg9s directly ! glass plate is )drawn4 ,x is easy to fail 9 reproduc+ ?is exp]im5tal result if ! "r conditions are n satisfi$2 b if !y are x is absurdly easy1 & ! ?+ might h be5 obs]v$ ne>ly a c5tury ago4 ,z9c dis*>g+ ,negative ,electricity 9 ,light2 ,gold ,leaf ,electroscope2 ,glass & ,qu>tz ,panes2 ,qu>tz ,prism4 ,take a piece ( z9c1 clean x ) em]y pap]1 connect x to a gold leaf electroscope1 & expose x to an arc lamp4 7,fig4 #h74 ,if *>g$ positively no?+ appe>s to happ51 ! action is v sl[2 b a negative *>ge leaks away 9 a few seconds if ! light is bright4 ,any s\rce ( light ri* 9 ultra-violet rays w d2 ! light f a sp>k is p]haps mo/ p[]ful ( all4 ,a pane ( glass cuts (f all ! action2 s does atmosph]ic air 9 suffici5t ?ickness 7at any rate1 t[n air71 h5ce sunlight is n p[]ful4 ,a pane ( qu>tz transmits ! action almo/ undim9i%$1 b fluorsp> may be m transp>5t /ill4 ,cond5s+ ! arc rays ) a qu>tz l5s & analys+ !m ) a qu>tz prism or reflection grat+1 we f9d t ! mo/ effective "p ( ! light is high up 9 ! ultra-violet1 surpris+ly f> beyond ! limits ( ! visible spectrum#d 7,fig4 #i1 next page74 #d ,:ile prep>+ = ! lecture x occurr$ to me to try1 if possible dur+ ! lecture itself1 "s new exp]im5ts on ! effect ( light on negatively *>g$ bits ( rock & ice1 because if ! effect is n limit$ to metals x mu/ be important 9 connection ) atmosph]ic electricity4 ,:5 ,mr4 ,branly coat$ an alum9ium plate ) an insulat+ v>ni%1 he f\nd t its *>ge 0 able to soak 9 & out ( ! v>ni% dur+ illum9ation 7,comptes ,r5dus1 ,vol4 ,,cx41 p4 #hih1 #ahij74 ,n[ ! m\nta9 tops ( a negatively *>g$ e>? are expos$ to v ultra-violet rays1 & ! air is a dielectric 9 :i* quiet up-c>ry+ & sudd5 d[np\r ( electricity c\ld g on 9 a mann] n v unlike ! well-kn[n behavi\r ( wat] vap\r2 & ?is p]haps may be ! reason1 or "o ( ! reasons1 :y x is n unusual to exp]i5ce a ?und]/orm aft] a few f9e days4 ,i h n[ tri$ ^! exp]im5ts on su* geological fragm5ts z 7 h&y1 & f9d t _m ( !m dis*>ge negative electricity "u ! action ( a nak$ arc1 especially f ! side ( ! specim5s :i* 0 some:at du/y1 b t :5 wet !y dis*>ge mu* less rapidly1 & :5 positively *>g$ h>dly at all4 ,ice & g>d5 soil dis*>ge negative electrification1 too1 "u ultra-violet illum9ation1 b n s quickly z lime/one1 mica s*i/1 f]rug9\s qu>tz1 clay1 & "s o!r specim5s4 ,granite b>ely acts2 x seems to insulate too well4 ,! ice & soil 7 tri$ 9 _! usual moi/ condition1 b1 :5 ?or\ghly dry1 soil dis*>ges q rapidly4 ,no rock te/$ 0 f\nd to dis*>ge z quickly z does a surface ( p]fectly bright metal1 su* z iron1 b _m dis*>g$ mu* m quickly ?an ord9>y dull iron1 & r m quickly ?an :5 ! bright iron surface 0 ?9ly oil$ or wett$ ) wat]4 ,to-day 7,june #e1 #ahid7 ,i f9d t ! leaves ( ,g]anium dis*>ge positive electrification five times z quickly z negative1 "u ! action ( an arc light1 & t glass cuts ! effect (f :ile qu>tz transmits x4 7,= ,el/] & ,geitel's exp]im5ts1 & ^? ( ,righi1 see ,app5dices1 p4 #aae et seq47 ,?is is r a digression1 b ,i h tak5 "s pa9s to %[ x prop]ly because ( ! int]e/ betray$ by ,"l ,kelv9 on ?is matt]1 & ! caution :i* he felt ab\t accept+ ! results ( ! ,cont95tal exp]im5t]s too ha/ily4 ,x is probably a *emical ph5om5on1 & ,i am dispos$ to express x z a modification ( ! ,volta contact effect#e ) illum9ation4 #e ,see ,b4 ,a4 ,report1 #ahhd1 pp4 #ejb-eai2 or ,phil4 ,mag41 ,vol4 ,,xix41 pp4 #bfg-ceb4 ,illu/ration3 ,,fig4 #i4--,z9c ,rod dis*>g+ ,negative ,electricity 9 ! v ,ultra-violet ,light ( a ,spectrum =m$ by a ,qu>tz ,tra94 ,! be/ dis*>g+ light is f\nd f> beyond ! limits ( ! visible spectrum4 ,return n[ to ! ,h]tz vibrator1 or ,leyd5 j> ) its coat+s well sep>at$1 s t we c get into its electric z well z its magnetic field4 ,"h is a great "o giv+ waves #cj metres long1 radiat+ :ile x la/s ) an activity ( #ajj ,h4,p41 & mak+ t5 million complete electric vibrations p] second4 ,x is made ( f\r l>ge copp] %eets sold]$ toge!r two & two1 /rung up by ?9 rope to a gall]y1 & ea* pair connect$ ) ! o!r by sev]al y>ds ( ,no4 #j pure copp] rod1 int]rupt$ by a pair ( sp>k+ knobs 7,fig4 #aj74 ,l>ge ,h]tz ,vibrator 9 action2 ,abel's ,fuse ,detector2 ,vacuum ,tube ,detector2 ,/rik+ ( an ,arc4 ,its great radiat+ p[] damps x d[n v rapidly1 s t x does n make above two or ?ree sw+s2 b nev]!less1 ea* "t x is excit$1 sp>ks c be drawn f mo/ ( ! reasonably elongat$ conductors 9 ! !atre ( ?is ,in/itution1 & inde$ f wire f5c+ & iron ro(s outside ?is build+4 ,a suitably situat$ gas leak c be ignit$ by ^! induc$ sp>ks4 ,an ,abel's fuse connect+ ! wat] pipes ) ! gas pipes w bl[ (f2 vacuum tubes connect$ to no?+ w gl[ 7?is fact has be5 famili> to all :o h work$ ) ,h]tz waves s9ce #ahhi71 electric leads1 if any:]e ne> ea* o!r1 z !y are 9 "s inc&esc5t lamp-hold]s1 may sp>k across to ea* o!r1 ?us /rik+ an arc & bl[+ _! fuses4 ,?is bl[+ ( fuses by electric radiation frequ5tly happ5$ at ,liv]pool till ! susp5sions ( ! !atre lamps 7 alt]$4 ,!y _h at fir/ be5 held 9 position by wire guides1 :i* s]v$ z collectors ( ! ,h]tz waves or impulses4 ,illu/ration3 ,,fig4 #aj4--;,h]tz ,oscillator on r$uc$ scale1 ? in* to a foot4 ,! /rik+ ( an arc by ! little rev]b]at+ sp>ks betwe5 two lamp-c>bons connect$ ) ! #ajj-volt ma9s ,i incid5tally n[ demon/rate4 ,an arc is />t$ directly ! l>ge ,h]tz vibrator is excit$ at a di/ance4 ,!re are "s :o ?9k t lightn+ fla%es c d none ( ^! second>y ?+s4 ,!y are mi/ak54 ,specim5s ( ,emitt]s & ,receiv]s4 ,on ! table are specim5s ( v>i\s emitt]s & receiv]s su* z h be5 us$ by diff]5t p2 ! or?odox ,h]tz radiator 7,fig4 #e71 & ! or?odox ,h]tz receiv]s3--,a circul> r+ 7,fig4 #f7 = int]f]5ce exp]im5ts1 because x is b little damp$1 & a /raight wire = receiv+ at a di/ance1 because x is a mu* bett] absorb]4 ,beside ^! are ! sph]es & ellipsoids 7or elliptical plates71 :i* ,i h myself introduc$ & ma9ly us$ 7,fig4 #ai71 because !y are p[]ful radiators & absorb]s1 & because _! !ory has be5 work$ out by ,horace ,lamb & ,j4 ,j4 ,?omson4 ,also dumb-bells 7,fig4 #aa7 )\t air gap1 :i* mu/ be excit$ by a positive sp>k at "o end & a negative sp>k at ! o!r1 & _m o!r %apes1 ! mo/ rec5t ( m9e be+ ! inside ( a holl[ cyl9d] ) sp>ks at ends ( a diamet] 7,fig4 #ab72 ?is be+ a feeble radiator1 b a v p]si/5t vibrator1#f &1 !re=e1 well adapt$ = int]f]5ce & diffraction exp]im5ts4 ,b1 inde$1 sph]es c be made to vibrate long] ?an usual by putt+ !m into copp] hats or enclosures1 9 :i* an ap]ture ( v>y+ size c be made to let ! waves out 7,figs4 #bj & #ba74 #f ,j4 ,j4 ,?omson1 8,rec5t ,rese>*es10 #cdd4 ,illu/ration3 ,,fig4 #aa4--;,a ,small ,dumb-bell ,=m ( ,radiator = ,impulsive ,ru%4 ,illu/ration3 ,,fig4 #ab4--;,dr4 ,lodge's ,holl[ ,cyl9drical ,radiator1 arrang$ horizontally aga9/ ! outside ( a ,metal-l9$ ,box conta9+ ! ,sp>k-produc+ ,app>atus4 ,half natural size4 ,emitt+ #c 94 waves4 ,_m ( ^! s5d]s w d = receiv]s too1 giv+ (f sp>ks to o!r insulat$ bodies or to e>?2 b besides ! ,h]tz type ( receiv]1 _m o!r detectors ( radiation h be5 employ$4 ,vacuum tubes c be us$1 ei!r directly or on ! trigg] pr9ciple1 z by ,zehnd] 7,fig4 #ac71g ! resonator sp>k precipitat+ a dis*>ge f "s auxili>y batt]y or s\rce ( en]gy1 & s mak+ a feeble di/urbance v visible4 ,explosives may be us$ = ! same purpose1 ei!r 9 ! =m ( mix$ wat]-gases or 9 ! =m ( an ,abel's fuse4 ,fitz,gerald f\nd t a trem5d\sly s5sitive galvanomet] c\ld indicate t a feeble sp>k _h pass$1 by reason ( ! consequ5t di/urbance ( electrical equilibrium :i* settl$ d[n aga9 ?r\gh ! galvanomet]4#h ,?is 0 ! me?od he us$ 9 ?is !atre f\r ye>s ago4 ,bly? us$ a "o sid$ electromet]1 & ,v4 ,bj]knes has greatly develop$ ?is me?od 7,fig4 #ad71 aboli%+ ! ne$ = a sp>k1 & mak+ ! electromet] metrical1 integrat+ & satisfactory4#i ,) ?is detector _m measurem5ts h be5 made at ,bonn by ,bj]knes1 ,yule1 ,b>ton & o!rs on waves conc5trat$ & kept f space dissipation by guid+ wires4 #g ,wi$4 ,ann41 ,,xlvii41 p4 #gg4 #h ,fitz,gerald1 ,nature1 ,vol4 ,,xli41 p4 #bie1 & ,vol4 ,,xlii41 p4 #agb4 #i ,wi$4 ,ann41 #dd1 p4 #gd4 ,illu/ration3 ,,fig4 #ac4--,zehnd]'s ,trigg] ,tube4 ,half ,natural ,size4 ,! two "r-h& t]m9als1 close toge!r1 are atta*$ to ! ,h]tz receiv]2 ano!r pair ( t]m9als are connect$ to "s s\rce j n able to make ! tube gl[ until ! sc9tilla occurs & makes ! gas m conduct+--z obs]v$ by ,s*u/] & o!rs4 ,mr4 ,boys has exp]im5t$ on ! me*anical =ce ex]t$ by electrical surg+s1 & ,h]tz also made obs]vations ( ! same k9d4 ,v>i\s ,detectors4 ,go+ back to old] me?ods ( detect+ electrical radiation1 we h1 mo/ important ( all1 a discov]y made long be=e man exi/$1 by a creature t develop$ a s5sitive cavity on its sk92 a creature :i* nev] s mu* z _h a "n to be rememb]$ by 7?\gh p]haps we n[ call x trilobite74 ,!n1 9 rec5t times we recall ! photographic plate & ! !rmopile1 ) its modification1 ! radiomicromet]2 also ! s-call$ bolomet]1 or o!rwise-kn[n ,siem5s' pyromet]1 appli$ to a/ronomy by ,langley1 & appli$ to ! detection ( electric waves 9 wires by ,rub5s & ,ritt] & ,paalz[ & ,arons4 ,! !rmal junction 0 appli$ to ! same purpose by ,kolacek1 ,d4 ,e4 ,jones & o!rs4 ,&1 be=e all ^!1 ! late ,mr4 ,gregory1 ( ,coop]'s ,hill1 made 8 s+ul>ly s5sitive expansion met]1 :]eby waves 9 free space c\ld be detect$ by ! m9ute rise ( temp]ature !y caus$ 9 a plat9um wire1 a k9d ( e>ly & s5sitive =m ( ,c>dew voltmet]4 ,illu/ration3 ,,fig4 #ad4--;,bj]knes' ,app>atus1 %[+ 7#a7 a ,h]tz vibrator connect$ to an induction coil2 7#b7 a ne>ly clos$ circuit receiv] prop]ly tun$ ) ! vibrator2 & 7#c7 a "o sid$ electromet] = ins]t+ 9 ! air gap ( #b4 ,! receiv] is n provid$ ) knobs1 z %[n1 b its op5 circuit is t]m9at$ by ! quadrants ( ! electromet]1 :i* is %[n on an enl>g$ scale alongside4 ,! ne$le is at z]o pot5tial & is attract$ by bo? quadrants4 ,by calculation f ! indications ( ?is electromet] ,bj]knes plott$ ! curves #a1 #b & #c on pages #d & #e4 ,fig4 #a repres5ts ! oscillations ( ! prim>y vibrator1 rapidly damp$ by radiation ( en]gy4 ,fig4 #b repres5ts ! vibrations !reby set up 9 ! resonat+ circuit :5 ! two are accurately 9 tune2 & :i* p]si/ = _m sw+s4 ,fig4 #c %[s ! vibrations excit$ 9 ! same circuit :5 slightly out ( tune ) ! excit]4 ,a receiv] ( ?is k9d makes _m sw+s be=e x is s]i\sly damp$1 ?\gh ! op5 plate radiator does n4 ,go+ back to ! physiological me?od ( detect+ surg+s1 ,h]tz tri$ ! frog's leg n]ve-muscle prep>ation1 :i* to ! /eadi] types ( electrical /imulus is s surpass+ly s5sitive1 & to :i* we owe ! discov]y ( curr5t electricity4 ,b he fail$ to get any result4 ,ritt] has succe$$2 b1 9 my exp]i5ce1 failure is ! normal & prop] result4 ,work+ ) my colleague1 ,pr(4 ,got*1 at ,liv]pool1 ,i too h tri$ ! n]ve & muscle prep>ation ( ! frog 7,fig4 #ae71 & we f9d t an excessively viol5t /imulus ( a rapidly alt]nat+ "*1 if pure & unaccompani$ by second>y actions1 produces no effect--no /imulat+ effect1 t is--ev5 ?\gh ! voltage is s high t sp>ks are ready to jump betwe5 ! ne$les 9 direct contact ) ! n]ve4 ,all t su* oscillations d1 if cont9u$1 is to produce a tempor>y p>alysis or fatigue ( ! n]ve1 s t x is unable to transmit ! n]ve impulses evok$ by o!r /imuli1 f :i* p>alysis x recov]s readily en\gh 9 c\rse ( "t4 ,illu/ration3 ,,fig4 #ae4--;,exp]im5t ( ,got* & ,lodge on ! physiological effect ( rapid pure electric alt]nations4 ,n]ve-muscle prep>ation1 ) f\r ne$les1 or else non-pol>isable electrodes appli$ to ! n]ve4 ,c & ,d are ! t]m9als ( a rapidly-alt]nat+ electric curr5t f a conductor at z]o pot5tial 7namely1 ! t]m9als ( a d]iv$ circuit f a wire connect+ ! out] coats ( a pair ( dis*>g+ ,leyd5 j>s71 :ile ,a & ,b are ! t]m9als ( an ord9>y v weak galvanic or induction coil /imulus only j suffici5t to make ! muscle twit*4 ,! ,c ,d t]m9als d n /imulate ! n]ve1 ?\gh at v high alt]native pot5tials1 b !y gradually & tempor>ily p>alyse x1 s t ! te/ t]m9als ,a ,b produce no effect = a "t4 ,?is has be5 expect$ f exp]im5ts on human be+s1 su* exp]im5ts z ,tesla's & ^? ( d',arsonval4 ,b an entire animal is n at all a satisfactory in/rum5t :]e) to attack ! "q2 its n]ves are s emb$d$ 9 conduct+ tissues t x may easily be d\bt$ :e!r ! alt]nat+ type ( /imulus ev] rea*es !m at all4 ,by dissect+ out a n]ve & muscle f a deceas$ frog aft] ! hi/oric mann] ( physiologi/s1 & apply+ ! /imulus direct to ! n]ve1 at ! same "t z "s o!r well kn[n _/? a volt /imulus is appli$ to ano!r "p ( ! same n]ve fur!r f ! muscle1 x c be %[n t rapid electric alt]nations1 if entirely unaccompani$ by /atic *>ge or by resultant algebraic electric transmission1 evoke no excitatory response until !y are s viol5t z to give rise to second>y effects su* z heat or me*anical %ock4 ,yet1 not)/&+ ?is inaction1 !y gradually & sl[ly ex]t a p>alys+ or ob/ructive action on ! portion ( ! n]ve to :i* !y are appli$1 s t ! n]ve impulse excit$ by ! feeble j p]ceptible _/?-volts /imulus above is gradually ?rottl$ on its way d[n to ! muscle1 & rema9s s ?rottl$ = a "t v>y+ f a few m9utes to an h\r aft] ! cessation ( ! viol5ce4 ,i did n %[ ?is exp]im5t at ! lecture4 ,air ,gap & ,electroscope *>g$ by ,glass ,rod & dis*>g$ by ! ,wave ,impulse f a mod]ately di/ant ,sph]e excit$ by ,coil4 ,illu/ration3 ,,fig4 #af4--;,air gap = ,electroscope4 ,natural size4 ,! bottom plate is connect$ to1 & repres5ts1 ! cap ( an electroscope2 ! 8knob0 above x1 m5tion$ 9 text1 is ! poli%$ end ( ! screw1 ^: t]m9al is connect$ ) ! case ( ! in/rum5t or 8e>?40 ,! electroscope be+ *>g$ to ! v]ge ( ov]fl[1 ! impact ( weak electric waves collect$ by a bit ( wire /ick+ up f ! left-h& b9d+ screw precipitates ! collapse ( ! leaves4 ,among trigg] me?ods ( detect+ electric radiation1 ,i h spok5 ( ! ,zehnd] vacuum tubes2 ano!r me?od is "o us$ by ,boltzmann4#aj ,a pile ( sev]al hundr$ volts is on ! v]ge ( *>g+ an electroscope ?r\gh an air gap j too wide to break d[n4 ,v slight electric surg+s precipitate ! dis*>ge across ! gap1 & ! leaves div]ge4 ,i %[ ?is 9 a modifi$ & simple =m4 ,on ! cap ( an electroscope is plac$ a highly poli%$ knob or r\nd$ end connect$ to ! sole1 & j n t\*+ ! cap1 or1 r1 j n t\*+ a plate connect$ ) ! cap 7,fig4 #af71 ! di/ance betwe5 knob & plate be+ almo/ inf9itesimal1 su* a di/ance z is appreciat$ 9 sph]ometry4 ,su* an electroscope ov]fl[s sudd5ly & completely ) any g5tle rise ( pot5tial4 ,br+ excit$ glass ne> x1 ! leaves div]ge gradually & !n sudd5ly collapse1 because ! air space snaps3 remove ! glass1 & !y r$iv]ge ) negative electricity2 ! knob above ! cap be+ !n *>g$ positively1 & to ! v]ge ( sp>k+4 ,9 ?is condition any electrical waves1 collect$ if weak by a foot or s ( wire project+ f ! cap1 w dis*>ge ! electroscope by excit+ surg+s 9 ! wire1 & s break+ d[n ! air gap4 ,! *ief int]e/ ab\t ?is exp]im5t seems to me ! extremely def9ite dielectric /r5g? ( s inf9itesimal an air space4 ,moreov]1 x is a detector = ,h]tz waves t might h be5 us$ la/ c5tury2 x might h be5 us$ by ,b5jam9 ,frankl94 #aj ,weid4 ,ann41 #dj1 p4 #cii4 ,= to excite !m no coil or any?+ complicat$ is necess>y2 x is suffici5t to flick a metal sph]e or cyl9d] ) a silk h&k]*ief & !n dis*>ge x ) a well-poli%$ knob4 ,if x is n well poli%$ ! dis*>ge is comp>atively gradual1 & ! vibrations are weak2 ! m poli%$ are ! sides ( an air gap1 ! m sudd5 is ! collapse & ! m vigor\s ! consequ5t radiation1 especially ! radiation ( high frequ5cy1 ! high] h>monics ( ! di/urbance4 ,= delicate exp]im5ts x is sometimes well to repoli% ! knobs e h\r or s4 ,= metrical exp]im5ts x is (t5 bett] to let ! knobs get into a less effici5t b m p]man5t /ate4 ,?is is true ( all s5d]s or radiators4 ,= ! g5]ation ( !1 s to speak1 8infra-r$0 long-p]iod ,h]tz waves any knobs w d1 b to g5]ate ! 8ultra-violet0 %ort-p]iod waves high poli% is ess5tial4 ,microphonic ,detectors4 ,receiv]s or detectors1 :i* = ! pres5t ,i tempor>ily call microphonic1 are liable to respond be/ to ! m rapid vibrations4 ,_! s5sitiv5ess is to me surpris+1 ?\gh ( c\rse x does n approa* ! s5sitiv5ess ( ! eye2 at ! same "t ,i am by no means sure t ! eye diff]s f !m 9 k9d4 ,x is ^! detectors t ,i wi% specially to br+ to y\r notice4 ,pr(4 ,m9*91 ^: long & pati5t "w 9 connection ) photo-electricity is n[ becom+ kn[n1 & :o has devis$ an in/rum5t m s5sitive to radiation ?an ev5 ,boys' radiomicromet]1 9 t x responds to ! radiation ( a /> :ile ! radiomicromet] does n1 f\nd "s ye>s ago t "s ( 8 light-excitable cells lo/ _! s5sitiv5ess caprici\sly on tapp+1 & lat] he f\nd t !y frequ5tly rega9$ x aga9 :ile ,mr4 ,gregory's ,h]tz-wave exp]im5ts 7 go+ on 9 ! same room4 ,^! 8impulsion cells10 z he t]ms !m1 are tr\blesome ?+s = ord9>y p]sons to make & "w )--at lea/ ,i h nev] presum$ to try--b 9 ,mr4 ,m9*9's h&s !y are surpris+ly s5sitive to electric waves4#aa ,! s5sitiv5ess ( sel5ium to light is kn[n to ev]yone1 & ,mr4 ,%el=d ,bidwell has made exp]im5ts on ! v>iations ( conductivity exhibit$ by a mixture ( sulphur & c>bon4 ,ne>ly f\r ye>s ago ,m4 ,ed\>d ,branly f\nd t a burni%$ coat ( porphyris$ copp] spread on glass or ebonite1 dim9i%$ its resi/ance enorm\sly1 f "s millions to "s hundr$s ( ohms1 :5 x 0 expos$ to ! neighb\rhood1 ev5 ! di/ant neighb\rhood1 ( ,leyd5 j> or coil sp>ks4 ,he likewise f\nd t a tube ( metallic fil+s behav$ simil>ly1 & t bo? recov]$ _! orig9al resi/ance on %ak+ or tapp+4 ,mr4 ,cr(t exhibit$ ?is fact rec5tly at ! ,physical ,society4 ,m4 ,branly also made pa/es & solid rods ( fil+s1 9 ,canada balsam & 9 sulphur1 & f\nd !m likewise s5sitive4#ab #aa ,phil4 ,mag41 ,vol4 ,,xxxi41 p4 #bbc4 #ab ,e4 ,branly1 ,comptes ,r5dus1 ,vol4 ,,cxi41 p4 #ghe2 & ,vol4 ,,cxii41 p4 #ij4 ,) me ! matt] arose some:at diff]5tly1 z an outcome ( ! air gap detector employ$ ) an electroscope by ,boltzmann 7,fig4 #af74 ,= ,i _h obs]v$ 9 #ahhi t two knobs suffici5tly close toge!r1 f> too close to /& any voltage su* z an electroscope c %[1 c\ld1 :5 a sp>k pass$ betwe5 !m1 actually coh]e2 conduct+ an ord9>y bell-r++ curr5t if a s+le voltaic cell 0 9 circuit2 &1 if !re 7 no su* cell1 exhibit+ an electromotive =ce ( _! own suffici5t to di/urb a l[ resi/ance galvanomet] vigor\sly1 & sometimes requir+ a fa9tly p]ceptible am\nt ( =ce to deta* !m4 ,! exp]im5t 0 describ$ to ! ,in/itution ( ,electrical ,eng9e]s 9 #ahij1ac & ,pr(4 ,hughes said he _h obs]v$ ! same ?+4 #ac ,j\rnal ,in/itution ( ,electrical ,eng9e]s1 #ahij1 ,vol4 ,,xix41 pp4 #ceb-d2 or 8,lightn+ ,conductors & ,lightn+ ,gu>ds10 pp4 #chb-d4 ,illu/ration3 ,,fig4 #af;,a4--,receiv] 9 ,syntonic ,j> ,exp]im5t1 ) ,knob ,coh]] & ,tapp]-back 7cf4 ,fig4 #d74 ,! exp]im5t ( ! syntonic ,leyd5 j>s c be conv5i5tly %[n ) ! d\ble-knob or #ahhi coh]]4 ,! pair ( knobs are arrang$ to connect ! coat+s ( ! receiv+ j> 7a l>ge cond5s] be+ int]pos$ to prev5t _! complet+ a purely metallic circuit71 & 9 circuit ) !m is a batt]y & a bell4 ,e "t ! receiv+ j> responds syntonically to ! electric vibration ( ! o!r j>1 ! knobs coh]e 7if prop]ly adju/$7 & ! bell r+s4 ,if ! bell is free 9 air x cont9ues r++ until ! knobs are g5tly tapp$ asund]2 b if ! bell /&s on ! same table z ! knobs1 especially if x re/s "o foot on ! actual /&1 !n its fir/ /roke taps !m back in/antly & automatically1 & s e dis*>ge ( ! s5d+ j> is signall$ by a s+le /roke ( ! bell4 ,"h we h 9 ess5ce a sy/em ( v di/9ctly syntonic telegraphy1 = ! j>s & _! circuits mu/ be accurately tun$ toge!r1 if !re is to be any response4 ,a v little error 9 tun+1 easily made by alt]+ ! position ( ! slid] 7,fig4 #d71 w make !m q unresponsive1 unless ! di/ance betwe5 !m is r$uc$4 ,illu/ration3 ,,fig4 #ag4--;,e>ly ,=m ( ,coh]]1 consi/+ ( a spiral ( ?9 iron wire m\nt$ on an adju/able sp9dle & an alum9ium plate4 ,:5 ! lev] is mov$ clockwise ! tip ( ! iron wire presses g5tly aga9/ ! alum9ium plate1 ^: end is b5t at "r angles & pass$ ?r\gh into ! holl[ circul> wood5 box1 ( :i* ! upp] figure %[s ! top & g5]al appe>ance1 & ! l[] figure %[s ! inside4 ,at ! maximum di/ance ( response ! tun+ requir$ is excessively %>p4 ,b1 c]ta9ly1 = ^! clos$ & durably-vibrat+ circuits1 ! di/ance ( response is small1 z has be5 said be=e4 ,fig4 #af;,a %[s ! syntonic ,leyd5 j> exp]im5t arrang$ ) ! d\ble knob coh]]1 in/ead ( ) ! sp>k gap ( ,fig4 #d4 ,coh]] 9 op51 respond+ to ,feeble ,/imuli3--,small ,sph]e1 ,gas-light]1 ,di/ant ,sph]e1 ,electrophorus4 ,well1 ?is arrangem5t1 :i* ,i call a coh]]1 is ! mo/ a/oni%+ly s5sitive detector ( ,h]tz waves4 ,x diff]s f an actual air gap 9 t ! insulat+ film is n really insulat+2 ! film breaks d[n n only mu* m easily1 b also 9 a less discont9u\s & m p]man5t mann]1 ?an an air gap4 ,branly's tube ( fil+s1 a s]ies ( bad contacts1 cle>ly works on ! same plan2 & ?\gh a tube ( fil+s is by no means s s5sitive1 yet x is 9 _m respects easi] to "w )1 & except = v feeble /imuli1 is m metrical4 ,if ! fil+s us$ are co>se1 say turn+s or bor+s1 ! tube approximates to a s+le coh]]2 if !y are f9e1 x has a l>g] range ( s5sibility4 ,9 e case :at ^! receiv]s feel are sudd5 j]ks ( curr5t2 smoo? s9u\s vibrations are ineffective4 ,!y seem to me to respond be/ to waves a few in*es long1 b d\btless t is det]m9$ *iefly by ! dim5sions ( "s conductor ) :i* !y happ5 to be associat$4 7,figs4 #ag & #ah47 ,illu/ration3 ,,fig4 #ah4--;,e>ly ,=m ( ,iron ,bor+s ,tube4 ,"o-half natural size1 ) solid brass cyl9d] t]m9als 9 ea* end ( ! tube1 mak+ contact ) ! bor+s4 ,exp]im5t %[+ ,fil+s ,tube respond+ to ,sph]e1 to ,electrophorus1 & to a ,quasi-8,sp>k0 f ! ,dis*>ge ( an ord9>y ,gold-leaf ,electroscope4 ,i picture ! action z foll[s3 ,suppose two fairly clean pieces ( metal 9 light contact--say two pieces ( brass or ( iron--connect$ to a s+le voltaic cell2 a film ( :at may be call$ oxide int]v5es betwe5 ! surfaces s t only an insignificant curr5t is all[$ to pass1 because a volt or two is insuffici5t to break d[n ! insulat+ film1 except p]haps at "o or two atoms4#ad ,if ! film is n p]mitt$ to conduct at all1 x is n v s5sitive2 ! mo/ s5sitive condition is atta9$ :5 an inf9itesimal curr5t passes1 /rong en\gh j to %[ on a mod]ate galvanomet]4 #ad ,see ,phil4 ,mag41 ,jan41 #ahid1 p4 #id1 :]e ?is explanation 7:e!r true or n7 0 fir/ giv51 & :]e ! au?or fir/ publi%$ 8 full] exp]i5ce ( coh]] behavi\r4 ,n[ let ! slighte/ surg+ occur1 say by reason ( a sph]e be+ *>g$ & dis*>g$ at a di/ance ( =ty y>ds2 ! film at once breaks d[n1 p]haps n completely--t is a "q ( int5sity--b p]man5tly4 ,z ,i imag9e1 m molecules get )9 ea* o!r's range1 incipi5t cohesion sets 9 & ! mom5t>y electric quiv] acts some:at l a flux4 ,x is a s+ul> v>iety ( electric weld+4 ,a /rong] /imulus enables m molecules to hold on1 ! process is surpris+ly metrical2 & z f> z ,i r\ghly "k at pres5t1 ! *ange ( resi/ance is proportional to ! en]gy ( ! electric radiation1 f a s\rce ( giv5 frequ5cy4 ,x is to be specially not$ t a batt]y curr5t is n ne$$ to effect ! cohesion1 only to demon/rate x4 ,! batt]y c be appli$ aft] ! sp>k has occurr$1 & ! resi/ance w be f\nd *ang$ z mu* z if ! batt]y _h be5 on all ! "t4 ,! incipi5t cohesion electrically caus$ c be me*anically de/roy$4 ,s\nd vibrations1 or any o!r feeble me*anical di/urbances1 su* z scrat*es or taps1 are well adapt$ to re/ore ! contact to its orig9al high resi/ance s5sitive condition4 ,! m feeble ! electrical di/urbance ! slight] is ! correspond+ me*anical /imulus ne$$ = re/oration4 ,:5 work+ ) ! radiat+ sph]e 7,fig4 #ai7 at a di/ance ( =ty y>ds out ( w9d[1 ,i c\ld n = ?is reason %\t to my assi/ant to cause him to press ! key ( ! coil & make a sp>k1 b ,i %[$ him a du/] in/ead1 ?is be+ a sil5t signal :i* _h no di/urb+ effect on ! coh]] or tube ( fil+s4 ,i m5tion #dj y>ds1 because t 0 "o ( ! fir/ outdoor exp]im5ts2 b ,i %\ld ?9k t some?+ m l half-a-mile 0 ne>] ! limit ( s5sitiv5ess = ?is p>ticul> app>atus z !n arrang$4 ,h[ev]1 ?is is a ra% /atem5t n at pres5t v]ifi$4#ae ,at #dj or #fj y>ds ! excit+ sp>k c\ld be di/9ctly he>d1 & x 0 int]e/+ to wat* ! spot ( light beg9 its long excursion & actually travel a di/ance ( #b 94 or #c 94 be=e ! s\nd arriv$4 ,?is exp]im5t prov$ def9itely en\gh t ! effici5t cause travell$ quick] ?an s\nd1 & dispos$ completely ( any sceptical d\bts z to s\nd waves be+1 p]haps1 ! real cause ( ! ph5om5on4 ,signals 7 obta9$ across ! full wid? ( ! college quadrangle1 & lat]1 ) l>g] app>atus1 betwe5 ! college t[] & ano!r high build+ half-a-mile away4 #ae ,?is /atem5t has be5 absurdly misund]/ood1 z if x 0 a pr$iction ( :at w\ld always be ! limit ( s5sitiv5ess = any app>atus & any siz$ s5d]4 ,no?+ ( ! k9d 0 9 my m9d4 ,su* pr$ictions are always prepo/]\s1 & ,i am n oblig$ to ^? :o imag9$ t ,i _h be5 guilty ( "o ( !m4--,o4 ,j4 ,l41 #ahii4 ,illu/ration3 ,,fig4 #ai4--,radiator us$ 9 ! libr>y ( ! ,royal ,in/itution1 excit+ ! ,coh]] 7,fig4 #ag7 on ! lecture table 9 ! ,!atre4 ,i also us$ a radiator ) two or ) ?ree l>ge sph]es betwe5 two knobs1 & describ$ x 9 ,nature1 ,vol4 #da1 p4 #dfb1 #ahij4 ,?is is ! radiator :i* ,pr(4 ,righi has improv$ & made 9 a compact =m ) oil betwe5 ! two middle sph]es4 ,inv>iably1 :5 ! receiv] is 9 good condition1 s\nd or o!r me*anical di/urbance acts "o way1 viz41 9 ! direction ( increas+ resi/ance1 :ile electrical radiation or j]ks act ! o!r way1 decreas+ x4 ,:ile gett+ ! receiv] into condition1 or :5 x is gett+ out ( ord]1 vibrations & sometimes electric dis*>ges act irregul>ly2 & an occasional good %ak+ does ! fil+s good4 ,i h tak5 r\gh measurem5ts ( ! resi/ance by ! simple process ( re/or+ ! orig9al galvanomet] deflection by add+ or remov+ resi/ance coils4 ,a half-in* tube1 #h 94 long1 ( select$ iron turn+s 7,fig4 #ah7 _h a resi/ance ( #b1ejj ohms 9 ! s5sitive /ate4 ,a feeble /imulus1 caus$ by a di/ant electrophorus sp>k1 br\ght x d[n #djj ohms4 ,a r /rong] "o r$uc$ x by #ejj & #fjj1 :ile a trace ( sp>k giv5 to a po9t ( ! circuit itself ran x d[n #a1djj ohms4 ,?is is only to give an idea ( ! quantities4 ,i h n yet done any s]i\sly metrical exp]im5ts4 ,add$ lat]4--,my assi/ant1 ,mr4 ,e4 ,e4 ,rob9son1 e>ly notic$ t :5 a telephone 0 us$ z receiv]1 say ) a s+le-po9t coh]] 7see illu/ration on opposite page71 :i* is a v s5sitive arrangem5t1 e di/urbance ( ! coh]] due to receiv$ waves is accompani$ by a crackle or tick 9 ! telephone1 )\t any tapp+ back be+ necess>y4 ,?is is1 inde$1 ! easie/ mode ( receiv+ signals1 & we (t5 practis$ x4 ,if a suitable1 well-damp$ galvanomet]1 su* z a ,?omson m>9e speak+-galvanomet]1 is includ$ also 9 ! circuit 7a m s5sitive "o is sometimes necess>y--& we frequ5tly us$ a ,d',arsonval--b x mu/ be well damp$71 ! mean+ ( ^! ticks is recognis$2 ea* repres5ts a m9ute *ange 9 ! resi/ance ( ! coh]]--n at all ! full *ange usually employ$1 b little subsidi>y *anges1 sometimes up & sometimes d[n1 b>ely suffici5t to affect a galvanomet]1 b q adequate 7be+ s sudd57 to di/urb a telephone4 ,?is me?od ( receiv+1 :i* at fir/ is v s5sitive1 aft] a "t becomes less s2 ! po9t %[s signs ( fatigue1 probably due to too p]fect cohesion hav+ be5 gradually e/abli%$1 & a me*anical tap back is desirable to re/ore x to its orig9al condition4 ,if all ! signals receiv$ 7 precisely ( ! same /r5g?1 ,i d\bt if ^! sup]pos$ crimples ( resi/ance w\ld occur2 b signals dep5d+ on quality ( s5d+ sp>k nev] are ( ! same /r5g?1 & accord+ly ! sudd5 slight v>iations ( resi/ance d occur4 ,usually an ord9>y high resi/ance telephone 0 employ$1 & x 0 jo9$ to ! coh]] circuit ?r\gh "o ( ! usual small trans=m]s--a plan :i* has _m obvi\s advantages4 ,illu/ration3 ,simple/ ,receiv+ ,arrangem5t3 a ,telephone 9 ,circuit ) ,s+le-po9t ,coh]] )\t ,tapp]-back4 ,b a ne$le re/+ aga9/ a wat*-spr+ ,a adju/$ by screw ,c4 ,illu/ration3 ,syntonic ,s5d] & ,receiv] us$ 9 ! exp]im5ts plott$ on page #bh4 ,! swit* enables ! coh]] ,k to be connect$ ei!r to ! tun$ resonator ,m ,l ,n or to ! detect+ circuit ,e ,f4 ,weak impulses are felt :5 ! swit* is ,c ,e1 ,d ,f2 /rong impulses :5 ! swit* is ,c ,a1 ,d ,b2 provid$ ! coil ,l is simil> to ! coil ( ! radiator above4 ,! impulses are plott$ 9 ! diagram ,fig4 #ai;,a4 ,illu/ration3 ,octob] #bg1 #ahig4 ,,fig4 #ai;,a4--,curr5t ?r\gh ,coh]] aft] successive ,electrical ,/imuli1 )\t any me*anical tapp+ back4 ,! sudd5 rises are obta9$ :5 ! circuits are syntonis$4 ,weak] /imuli cause ! desc5ts4 ,! fluctuations ( resi/ance ( a coh]] dep5d5t on v>i\s /r5g?s ( /imulus are in/ructively %[n 9 "s metrical exp]im5ts made by ,mr4 ,rob9son1 & a plott+ ( :i* ,i %[$ to ! ,physical ,society ( ,london 9 #ahig4 ,?is plott+ is "h reproduc$1 & x %[s ! s+ul> fact t1 :]eas a /rong] electrical /imulus usually decreases ! resi/ance1 z is natural1 a weak] subsequ5t /imulus usually increases x aga93 s t alt]nately /rong & weak /imuli s5d ! curve zigzagg+ up & d[n1 until x gets into a condition dem&+ rejuv5ation by a me*anical tap back4 ,sometimes a decid$ly /rong electrical /imulus knocks d[n ! conductivity ( ! coh]] z if x _h be5 tapp$ back4 ,?is is almo/ c]ta9ly due to a burn+ ( ! delicate contacts--a bl[+ ( a fuse z x 71--& ! effect ( ?is electrical burn back is q diff]5t f ! effect ( a me*anical tap back1 inasmu* z x leaves ! coh]] ins5sitive4 ,a %ak+ up is necess>y to re/ore x4 ,i n[ call y\r att5tion to ! ,table on next page ( v>i\s k9ds ( detector = electric radiation di/ribut$ 9 gr\ps4 ,sel5ium is ins]t$ 9 ?is table 9 ! microphone column1 because x is a sub/ance :i* 9 c]ta9 /ates is well kn[n to behave to visible light z ^! o!r microphonic detectors behave to ,h]tz waves4 ,x is ins]t$ ) a qu]y1 to indicate t its position 9 ! table is n c]ta9ly kn[n4 ,x may possibly belong to "s o!r column4 ,electrical ,!ory ( ,vision4 ,& ,i want to sugge/ t q possibly ! s5sitiv5ess ( ! eye is ( ! coh]] k9d4 ,z ,i am n a physiologi/1 ,i _c be s]i\sly blam$ = mak+ wild & haz>d\s speculations 9 t region4 ,i !re=e wi% to guess t "s "p ( ! ret9a is an electrical organ1 say l t ( "s fi%es1 ma9ta9+ an electromotive =ce :i* is prev5t$ f /imulat+ ! n]ves solely by an int]v5+ lay] ( badly conduct+ mat]ial1 or ( conduct+ p[d] ) gaps 9 x2 b t :5 light falls ^u ! ret9a ^! gaps become m or less conduct+1 & ! n]ves are /imulat$4 ,i d n feel cle> :i* "p is tak5 by ! rods & cones1 & :i* "p by ! pigm5t cells2 ,i mu/ n try to make ! hypo!sis too def9ite at pres5t1 ?\gh ,i hope x is obvi\s :at ,i int5d to sugge/4 ,if ,i _h to make a demon/ration model ( ! eye on ^! l9es1 ,i %\ld arrange a little batt]y to excite a frog's n]ve-muscle prep>ation ?r\gh a circuit complet$ all except a lay] ( fil+s or a s+le bad contact4 ,su* an arrangem5t w\ld respond to ,h]tz waves4 ,or1 if ,i want$ actual light to act1 in/ead ( gross] waves1 ,i w\ld use a lay] ( sel5ium4 ,b ! bad contact & ! ,h]tz waves are ! mo/ in/ructive1 because we d n at pres5t really "k :at ! sel5ium is do+1 any m ?an :at ! ret9a is do+4 ,& obs]ve t 7to my surprise1 ,i confess7 ! r\gh outl9e ( a !ory ( vision ?us sugge/$ is 9 accordance ) "s ( ! pr9cipal views ( ! physiologi/ ,h]+4 ,! s5sation ( light is due to ! electrical /imulus2 ! s5sation ( black is due to ! me*anical or tapp+ back /imulus4 ,d>kness is physiologically n ! m]e cessation ( light4 ,bo? are positive s5sations1 & bo? /imuli are necess>y2 = until ! fil+s are tapp$ back vision is p]si/5t4 ,9 ! eye model ! p]iod ( me*anical tremor %\ld be1 say1 ? second1 s z to give ! "r am\nt ( p]si/5ce ( impression4 ---------------------------------------- ------------------------------ ,,detectors ,,( ,,radiation4 ---------------------------------------- ------------------------- ,physio- ,*emical4 ,!rmal4 ,electrical4 ,me*anical4,microphonic4 logical4 ---------------------------------------- ------------------------- ,sel5ium4787 ,eye4 ,photo- ,!rmopile4 ,sp>k4 ,electro- ,impulsion graphic 7,h]tz47 met]4 ,cell4 ,plate4 7,bly? & 7,m9*947 ,bj]knes47 ,frog's ,explosive ,bolomet]4 ,telephone2 ,susp5d$ ,fil+s4 ,leg ,gases4 7,rub5s & ,air-gap ,wires4 7,branly47 7,h]tz ,ritt]47 & ,arc4 7,h]tz & & 7,lodge47 ,boys47 ,ritt]47 ,photo- ,exp&+ ,vacuum ,tube4 ,coh]]4 electric ,wire4 7,drag\mis47 ,hughes & ,cell4 7,gregory47 ,galvanomet]4 ,lodge4 ,!rmal 7,fitzg]ald47 ,junction4 ,air-gap & 7,klem5cic47,electroscope4 7,boltzmann47 ,trigg] ,tube4 7,w>burg & ,zehnd]47 ---------------------------------------- ------------------------- ,! cross aga9/ ! frog's leg indicates t x does n appe> really to respond to radiation1 unless /imulat$ 9 "s second>y mann]4 ,! names aga9/ ! o!r ?+s are unimportant1 b sugge/ ! p]sons :o appli$ ! detector to electric radiation4 ,! int]rogation m>k aga9/ ,sel5ium indicates t its position 9 ! microphonic column may be d\btful4 ,no d\bt 9 ! eye ! tapp+ back is done automatically by ! tissues1 s t x is always ready = a new impression1 until fatigu$4 ,& by m\nt+ an electric bell or o!r vibrator on ! same bo>d z a tube ( fil+s1 x is possible to arrange s t a feeble electric /imulus %all produce a feeble /eady effect1 a /rong] /imulus a /rong] effect1 & s on2 ! tremor ass]t+ its pr$om9ance1 & br++ ! spot back1 :5ev] ! electric /imulus ceases4 ,an electric bell ?us close to ! tube is1 inde$1 n ! be/ vibrator2 clockwork might d bett]1 because ! bell conta9s 9 itself a j]ky curr5t1 :i* produces "o effect1 & a me*anical vibration1 :i* produces an opposite effect1 h5ce ! spot ( light c h>dly keep /ill4 ,by less5+ ! vibration--say1 by deta*+ ! bell f actual contact ) ! bo>d1 ! electric j]ks ( ! int]mitt5t curr5t drive ! spot viol5tly up ! scale2 me*anical tremor br+s x d[n aga94 ,x mu/ be cle>ly und]/ood t electric j]ks1 due to ! make-&-break ( an ord9>y curr5t1 are q adequate to electrically /imulate a coh]] 9 _! neighb\rhood4 ,x is con/antly to be notic$ t a coh]] responds be/ to excessively %ort sp>ks ( a c]ta9 %>p quality4 ,y obs]ve t ! eye on ?is hypo!sis is1 9 electromet] language1 het]o/atic4 ,! en]gy ( vision is suppli$ by ! organism2 ! light only pulls a trigg]4 ,:]eas ! organ ( he>+ is idio/atic4 ,i might draw fur!r analogies betwe5 ?is arrangem5t & ! eye1 e4g41 ab\t ! effect ( bl[s or disord] caus+ irregul> conduction & /imulation1 ( ! galvanomet] 9 ! "o in/rum5t1 ( ! bra9 cells 9 ! o!r4 ,a h&y portable excit] ( electric waves is "o ( ! ord9>y h& electric gas-light]s1 conta9+ a small revolv+ d\bl]--i4e41 an inductive or repl5i%+ ma*9e4 ,a coh]] c feel a gas-light] across a lecture !atre4 ,m9*9 (t5 us$ !m = /imulat+ 8 impulsion cells4 ,i f9d t :5 held ne> !y act a little ev5 :5 no ord9>y sp>k occurs1 pla9ly because ( ! little incipi5t sp>ks at ! bru%es or t9foil contacts inside4 ,a ,voss ma*9e acts simil>ly1 giv+ a small deflection :ile work+ up be=e x sp>ks3 inde$1 ^! small sp>ks are (t5 m effective ?an bigg] ones4 ,demon/ration ( ,ord9>y ,holtz ,ma*9e ,sp>ks n excit+ ,tube3 except by help ( a poli%$ knob4 ,& notice "h t our model eye has a well-def9$ range ( vision4 ,x _c see waves too long = x4 ,! p[]ful di/urbance caus$ by ! viol5t fla%es ( a ,holtz or ,wim%ur/ or ,voss ma*9e x is bl9d to4 ,! l\d sp>ks h no effect on x4 ,!y are l infra-r$ radiation to ! eye4 ,if ! knobs ( ! ma*9e are well poli%$ ! coh]] beg9s to respond aga91 evid5tly by reason ( "s high h>monics1 due to vibrations 9 ! t]m9al rods2 & ^! are ! vibrations to :i* x responds :5 excit$ simply by an induction coil4 ,! coil %\ld h knobs in/ead ( po9ts4 ,sp>ks f po9ts or dirty knobs h>dly excite ! coh]] at all4 ,b hold a well-poli%$ sph]e or ?ird knob betwe5 ev5 ! dirty knobs ( a ,voss ma*9e1 & ! coh]] responds at once to ! surg+s got up 9 t clean sph]e4 ,feeble %ort sp>ks aga9 are (t5 m p[]ful excit]s ?an are /rong long ones4 ,i suppose because !y are m sudd54 ,?is is in/ructively %[n ) an electrophor\s lid4 ,sp>k x to a knuckle1 & x does v little4 ,sp>k x to a clean knob held 9 ! h& & x works well4 ,b n[ sp>k x to an insulat$ sph]e1 !re is "s effect4 ,dis*>ge ! sph]e1 & take a second sp>k1 )\t re*>g+ ! lid2 d ?is sev]al times2 & at la/1 :5 ! sp>k is inaudible1 invisible1 & o!rwise imp]ceptible1 ! coh]] "s y>ds away responds m viol5tly ?an ev]1 & ! spot ( light ru%es f ! scale4 ,if a coh]] be atta*$ by a side wire to ! gas pipes1 & an electrophor\s sp>k be giv5 to ei!r ! gas pipes or ! wat] pipes or ev5 to ! hot-wat] sy/em 9 any o!r room ( ! build+1 ! coh]] responds4 ,x is surpris+ h[ f> ^! impulses c be felt along an ord9>y un9sulat$ wire or o!r conductor4 ,9 fact1 :5 ?us connect$ to gas pipes "o day :5 ,i tri$ x1 ! spot ( light c\ld h>dly keep /ill five seconds4 ,:e!r !re 0 a di/ant ?und]/orm1 or :e!r x 0 only pick+ up telegraphic j]ks1 ,i d n "k4 ,! j]k ( turn+ on or (f an extra ,swan lamp c affect x :5 s5sitive4 ,i hope to try = long-wave radiation f ! sun1 filt]+ out ! ord9>y well-kn[n waves by a blackbo>d or o!r suffici5tly opaque sub/ance4 ,i did n succe$ 9 ?is1 = a s5sitive coh]] 9 an outside %$ unprotect$ by ! ?ick walls ( a sub/antial build+ _c be kept quiet = long4 ,i f\nd its spot ( light liable to frequ5t weak & occasionally viol5t excursions1 & ,i c\ld n trace any ( ^! to ! influ5ce ( ! sun4 ,!re 7 evid5tly too _m t]re/rial s\rces ( di/urbance 9 a city l ,liv]pool to make ! exp]im5t feasible4 ,i don't "k t x might n possibly be successful 9 "s isolat$ c\ntry place2 b cle>ly ! arrangem5t mu/ be highly s5sitive 9 ord] to succe$4 ,we c easily see ! detector respond to a di/ant s\rce ( radiation n[1 viz41 to a #e 94 sph]e plac$ 9 ! libr>y betwe5 second>y coil knobs2 sep>at$ f ! receiv]1 !re=e1 by sev]al walls & "s heavily gild$ pap]1 z well z by #bj or #cj y>ds ( space 7,fig4 #ai47 ,illu/ration3 ,,fig4 #ai;,b4--,a ,portable ,detector1 ,b ! ,collect+ ,wire4 ,also ,i exhibit 7,fig4 #ai;,b7 a small complete detector made by my assi/ant1 ,mr4 ,davies1 :i* is q portable & easily set up4 ,! ess5tials 7batt]y1 galvanomet]1 & coh]]7 are all 9 a copp] cyl9d]1 ,a1 ?ree in*es by two4 ,a bit ( wire1 ,b1 a few in*es long1 pegg$ into x1 helps x to collect waves4 ,x is j conceivable t at "s di/ant date1 say by d9t ( ins]t+ gold wires or p[d] 9 ! ret9a1 we may be enabl$ to see waves :i* at pres5t we are bl9d to4 ,obs]ve h[ simple ! production & detection ( ,h]tz waves are n[4 ,an electrophorus or a frictional ma*9e s]ves to excite !m2 a voltaic cell1 a r\gh galvanomet]1 & a bad contact s]ves to detect !m4 ,inde$1 !y might h be5 obs]v$ at ! beg9n+ ( ! c5tury1 be=e galvanomet]s 7 kn[n3 a frog's leg or an iodide ( />* pap] w\ld d almo/ z well4 ,a bad contact 0 at "o "t reg>d$ z a simple nuisance1 because ( ! s+ul>ly unc]ta9 & caprici\s "* ( ! curr5t transmitt$ by x4 ,hughes obs]v$ its s5sitiv5ess to s\nd waves1 & x became ! microphone4 ,n[ x turns out to be s5sitive to electric waves1 if x be made ( any oxidisable m$al 7n ( c>bon71#af & we h an in/rum5t :i* might be call$ a micro-some?+1 b :i*1 z x appe>s to act by cohesion1 ,i at pres5t call a coh]]4 ,p]haps "s ( ! caprici\sness ( an ana!matis$ bad contact 0 sometimes due to ! fact t x 0 respond+ to /ray electric radiation4 7,see ,app5dix ,,iii41 pp4 #aji & #aaa47 #af ,fitz,gerald tells me t he has succe$$ ) c>bon also4 ,my exp]i5ce is t ! less oxidisable ! metal1 ! m s5sitive & also ! m tr\blesome is ! detector4 ,mr4 ,rob9son has n[ made me a hydrog5 vacuum tube ( brass fil+s1 :i* beats ! coh]] = s5sitiv5ess4 ,july1 #ahid4 ,! break+ d[n ( cohesion by me*anical tremor is an anci5t process1 obs]v$ on a l>ge scale by eng9e]s 9 railway axles & gird]s2 inde$1 ! cutt+ ( small gird]s by p]si/5t bl[s ( hamm] & *isel rem9d$ me ! o!r day ( ! tapp+ back ( our coh]+ surfaces aft] !y h be5 expos$ to ! unit+ effect ( an electric j]k4 ,receiv] 9 ,metallic ,enclosure4 ,if a coh]] is %ut up 9 a complete metallic enclosure1 waves _c get at x1 b if wires are l$ f x to an outside ord9>y galvanomet]1 x rema9s ne>ly z s5sitive z x 0 be=e 7ne>ly1 n q71 = ! circuit picks up ! waves & !y run along ! insulat$ wires into ! clos$ box4 ,to scre5 x effectively1 x is necess>y to enclose batt]y & galvanomet] & e bit ( wire connection2 ! only ?+ t may be left outside is ! ne$le ( ! galvanomet]4 ,accord+ly1 "h we h a compact arrangem5t ( batt]y & galvanomet] coil & coh]]1 all %ut up 9 a copp] box 7,fig4 #ai;,c74 ,! galvanomet] coil is fix$ aga9/ ! side ( ! box at su* height t x c act conv5i5tly on an outside susp5d$ compass ne$le4 ,! sl[ magnetic action ( ! curr5t 9 ! coil has no difficulty 9 gett+ ?r\gh copp]1 z ev]yone kn[s3 only a p]fect conductor c\ld scre5 (f t2 b ! ,h]tz waves are effectively kept out by ! %eet copp]4 ,illu/ration3 ,,fig4 #ai;,c4--,protect$ ,detector4 ,a is an occasional wire pass+ ?r\gh %utt]$ ap]ture4 ,e is a lead tube enclos+ lead+ wires1 z 9 ,fig4 #ba4 ,x mu/ be said1 h[ev]1 t ! box mu/ be exce$+ly well clos$ = ! scre5+ to be p]fect4 ,! v n>r[e/ *9k p]mits _! entrance1 & at "o "t ,i ?\ght ,i %\ld h to sold] a lid on be=e !y c\ld be kept entirely out4 ,clamp+ a copp] lid on to a flange 9 six places 0 n en\gh4 ,b by ! use ( pads ( t9foil & tight clamp+1 *9ks c be avoid$1 & ! inside ( ! box becomes !n electrically d>k4 ,if ev5 an in* ( ! circuit protrudes1 x at once becomes slightly s5sitive aga92 & if a m]e s+le wire protrudes ?r\gh ! box1 n connect$ to any?+ at ei!r end1 provid$ x is insulat$ :]e x passes ?r\gh1 ! waves w utilise x z a speak+-tube1 & run bli!ly 94 ,& ?is happ5s :e!r ! wire be connect$ to any?+ inside or n1 ?\gh x acts m /rongly :5 connect$4 ,9 c>eful exp]im5ts1 :]e ! galvanomet] is protect$ 9 "o copp] box & ! coh]] 9 ano!r1 ! wires connect+ ! two mu/ be encas$ 9 a metal tube 7,figs4 #ai;,c & #ba71 & ?is tube mu/ be well connect$ ) ! metal ( bo? enclosures1 if no?+ is to get 9 b :at is want$4 ,illu/ration3 ,,fig4 #bj4--,sph]ical ,radiator = emitt+ a ,horizontal ,beam1 arrang$ inside a ,copp] ,hat1 fix$ aga9/ ! outside ( a metal-l9$ ,box1 :i* conta9s induction coil & batt]y & key4 ,"o-eigh? natural size4 ,! wires pass into ! box ?r\gh glass tubes n %[n4 ,simil>ly :5 def9ite radiation is desir$1 x is well to put ! radiator 9 a copp] hat op5 9 only "o direction 7,fig4 #bj71 & 9 ord] to gu>d aga9/ reflect$ & collat]al surg+s runn+ along ! wires :i* pass outside to ! excit+ coil & batt]y1 z !y are liable to d1 ,i am accu/om$ to put all ! s5d+ app>atus 9 a pack+ case l9$ ) t9foil1 to ! outside ( :i* ! s5d+ hat 7,fig4 #bj7 is fix$1 & to pull ! key ( ! prim>y excit+ circuit by a /r+ f outside1 s t n ev5 key connections %all protrude1 else exact optical exp]im5ts are impossible4 ,illu/ration3 ,,fig4 #ba4--;,g5]al arrangem5t ( exp]im5ts ) ! ,copp] 8,hat10 %[+ ,metal ,box on a ,/ool1 /&+ outside ! ,!atre4 ,! ,box is n exactly repres5t$1 b inside x ! ,radiators 7 fix$ ) a graduat$ s]ies ( ap]tures2 ! ,copp] ,hat conta9+ ! ,coh]] is se5 on ! ,table ) ! ,metal ,box on ! left ( ! ,table conta9+ ,batt]y & ,galvanomet] ,coil connect$ to x by a compo pipe convey+ ! wires1 z 9 ,fig4 #ai;,c2 ! ,lamp & ,scale b>ely indicat$ at "o side ( ! ,table2 a ,p>aff9 ,prism2 & a ,pol>is+ ,grid ( copp] wires /ret*$ on a frame4 7,?is figure is f a ?umbnail sket* by ,mr4 ,a4 ,p4 ,trott]1 tak5 at ! ,lecture 9 #ahid47 ,ev5 !n1 ) ! lid ( ! hat well clamp$ on1 some?+ gets out1 b x is n en\gh to cause s]i\s di/urbance ( qualitative results4 ,! s5d] mu/ evid5tly be ?\ght ( z emitt+ a mom5t>y blaze ( light :i* escapes ?r\gh e *9k4 ,or1 inde$1 s9ce ! waves are "s in*es long1 ! difficulty ( keep+ !m out ( an enclosure may be lik5$ to ! difficulty ( exclud+ s\nd2 ?\gh ! difficulty is n q s great z t1 s9ce a reasonable ?ickness ( metal is really opaque4 ,i fanci$ once or twice ,i detect$ a trace ( transp>5cy 9 su* metal %eets z ord9>y t9plate1 b unnotic$ *9ks else:]e may h deceiv$ me4 ,x is a ?+ easy to make sure ( z soon z ,i h m "t4 7,t9plate is q opaque4 ,lead pap] lets a little ?r\gh47 ,"o ?+ 9 ?is connection is noticeable1 & t is h[ little radiation gets ei!r 9 or out ( a small r\nd hole4 ,a n>r[ long *9k 9 ! receiv] box lets 9 a lot2 a r\nd hole ! size ( a %ill+ lets 9 h>dly any1 unless inde$ a bit ( insulat$ wire protrudes ?r\gh x l a collect+ e> trumpet1 z at ,a1 ,fig4 #ai;,c4 ,x may be ask$ h[ ! waves get out ( ! metal tube ( an electric gas-light]4 ,b !y d n2 !y get out ?r\gh ! h&le1 :i* be+ ( ebonite is transp>5t4 ,wrap up ! h&le 9 t9foil1 & a gas-light] is p[]less4 ,,optical ,,exp]im5ts4 ,& n[1 9 conclusion1 ,i w %[ "s ( ! ord9>y optical exp]im5ts ) ,h]tz waves1 us+ z s\rce ei!r "o ( two devices3 ei!r a #e 94 sph]e ) sp>ks to ends ( a diamet] 7,fig4 #ai71 an arrangem5t :i* emits #g 94 waves b ( s dead-beat a "* t x is wise to enclose x 9 a copp] hat to prolong !m & s5d !m out 9 ! desir$ direction1 or else a #b 94 holl[ cyl9d] ) sp>k knobs at ends ( an int]nal diamet] 7,fig4 #ab74 ,?is la/ emits #c 94 waves ( a v fairly p]si/5t "*1 b ) no?+ l ! int5sity ( "o ( ! outside radiators4 ,z receiv] !re is no ne$ to use any?+ s5sitive1 s ,i employ a glass tube full ( co>se iron fil+s1 put at ! back ( a copp] hat ) its m\? turn$ well askew to ! s\rce1 :i* is put outside ! door at a di/ance ( "s y>ds1 s t only a little direct radiation c rea* ! tube4 ,sometimes ! tube is put l5g?ways 9 ! hat in/ead ( crossways1 :i* makes x less s5sitive1 & has also ! advantage ( do+ away ) ! pol>is+1 or r analys+1 p[] ( a crossway tube4 ,! radiation f ! sph]e is /ill too /rong1 b x c be /opp$ d[n by a diaphragm plate ) holes 9 x ( v>y+ size clamp$ on ! s5d+ box 7"r-h& side ( ,fig4 #ba74 ,reflection4 ,hav+ ?us r$uc$ ! excursion ( ! spot ( light to a foot or s1 a metal plate is held z reflector1 & at once ! spot travels a c\ple ( y>ds4 ,a wet clo? reflects some?+1 b a ?9 glass plate1 if dry1 reflects next to no?+1 be+1 z is well kn[n1 too ?9 to give any?+ b 8! black spot40 ,i h fanci$ t x reflects some?+ ( ! #c 94 waves4 ,) ref]5ce to ! reflect+ p[] ( diff]5t sub/ances1 x may be int]e/+ to give ! foll[+ numb]s %[+ ! motion ( ! spot ( light :5 #h 94 waves 7 reflect$ into ! copp] hat1 ! angle ( incid5ce be+ ab\t #de deg41 by ! foll[+ mirrors3-- ,%eet ( w9d[ glass #j or at mo/ #a division4 ,human body #g divisions4 ,draw+ bo>d #ab 0 ,t[el soak$ ) tap-wat] #ab 0 ,tea-pap] 7lead87 #dj 0 ,dut* metal pap] #gj 0 ,t9foil #hj 0 ,%eet copp] #ajj & up aga9/ /ops4 ,refract+ ,prism & ,l5s4 ,a block ( p>aff9 ab\t a cubic foot 9 volume is ca/ into ! %ape ( a prism ) angles #ge deg41 #fj deg41 & #de deg4 ,us+ ! l>ge angle1 ! rays are refract$ into ! receiv+ hat 7,fig4 #ba71 & produce an effect mu* l>g] ?an :5 ! prism is remov$4 ,an ord9>y #i 94 glass l5s is next plac$ ne> ! s\rce1 & by means ( ! light ( a tap] x is focuss$ betwe5 s\rce & receiv]4 ,! l5s is se5 to increase ! effect by conc5trat+ ! electric radiation4 ,arago ,disc2 ,grat+2 & ,zone-plate4 ,! l5s helps u to set correctly an #ah 94 circul> copp] disc 9 position = %[+ ! bright diffraction spot4 ,remov+ ! disc1 ! effect is mu* ! same z :5 x 0 pres5t1 9 accordance ) ! !ory ( ,poisson4 ,add ! l5s & ! effect is great]4 ,) a diffraction grat+ ( copp] /rips #b 94 broad & #b 94 ap>t1 ,i h n yet succe$$ 9 gett+ good results4 ,x is difficult to get %>p nodes & int]f]5ce effects ) ^! s5sitive detectors 9 a room4 ,i expect to d bett] :5 ,i c try out ( doors1 away f s _m reflect+ surfaces2 indoors x is l try+ delicate optical exp]im5ts 9 a small :itewa%$ *amb] well suppli$ ) look+-glasses2 nor h ,i ev] succe$$ 9 gett+ cle> conc5tration ) ?is zone-plate hav+ ,newton's r+s fix$ to x 9 t9foil4 ,! coh]]1 at any rate 9 a room1 does n seem well adapt$ to int]f]5ce exp]im5ts2 x is probably too s5sitive1 & responds ev5 at ! nodes1 unless !y are made m p]fect ?an is easily practicable4 ,b really !re is no?+ ( mu* int]e/ n[ 9 diffraction effects1 except ! demon/ration ( ! waves & ! measure ( _! l5g?4 ,!re 0 imm5se int]e/ 9 ,h]tz's "t1 because !n ! wave "* ( ! radiation _h to be prov$2 b e possible k9d ( wave mu/ give int]f]5ce & diffraction effects1 & _! !ory is1 s to say1 work$ out4 ,m int]e/ atta*es to pol>isation1 d\ble refraction1 & disp]sion exp]im5ts4 ,illu/ration3 ,,fig4 #bb4--,zone-plate ( ,t9foil on ,glass4 ,e circul> /rip is ( area equal to c5tral space4 ,pol>is+ & ,analys+ ,grids4 ,pol>isation exp]im5ts are easy en\gh4 ,radiation f a sph]e1 or cyl9d]1 or dumb-bell is already /rongly pol>is$1 & ! tube acts z a p>tial analys]1 respond+ mu* m vigor\sly :5 its l5g? is p>allel to ! l9e ( sp>ks ?an :5 !y are cross$2 b a conv5i5t extra pol>is] is a grid ( wires some?+ l :at 0 us$ by ,h]tz1 only on a mu* small] scale2 say an #ah 94 octagonal frame ( copp] /rip ) a h>p ( p>allel copp] wires 7see ,fig4 #ba1 on floor74 ,! sp>k-l9e ( ! radiator 7,fig4 #bj7 be+ set at #de deg41 a v]tical grid plac$ ov] ! receiv] r$uces ! reflection to ab\t "o-half1 & a cross$ grid ov] ! s\rce r$uces x to ne>ly no?+4 ,rotat+ ei!r grid a little rapidly increases ! effect1 :i* becomes a maximum :5 !y are p>allel4 ,! int]position ( a ?ird grid1 ) its wires at #de deg41 betwe5 two cross$ grids1 re/ores "s ( ! oblit]at$ effect4 ,radiation reflect$ f a grid is /rongly pol>is$1 ( c\rse1 9 a plane normal to t ( ! radiation :i* gets ?r\gh x4 ,!y are ?us analog\s 9 _! effect to ,nicols1 or to a pile ( plates4 ,! electric vibrations :i* get ?r\gh ^! grids are at "r angles to ! wires4 ,vibrations p>allel to ! wires are reflect$ or absorb$4 ,reflect+ ,p>aff9 ,surface2 ,direction ( ,vibrations 9 ,pol>is$ ,light4 ,to demon/rate t ! s-call$ plane ( pol>isation ( ! radiation transmitt$ by a grid is at "r angles to ! electric vibration1#ag i4e41 t :5 light is reflect$ f ! b\nd>y ( a transp>5t sub/ance at ! pol>is+ angle ! electric vibrations ( ! reflect$ beam are p]p5dicul> to ! plane ( reflection1 ,i use ! same p>aff9 prism z be=e2 b ?is "t ,i use its l>ge/ face z a reflector1 & set x at some?+ ne> ! pol>is+ angle4 ,:5 ! l9e ( wires ( ! grid ov] ! m\? ( ! emitt] is p>allel to ! plane ( incid5ce1 9 :i* case ! electric vibrations are p]p5dicul> to ! plane ( incid5ce1 pl5ty ( radiation is reflect$ by ! p>aff9 face4 ,turn+ ! grid s t ! electric vibrations are 9 ! plane ( incid5ce1 we f9d t ! p>aff9 surface set at ! prop] angle is able to reflect h>dly any?+4 ,9 o!r words1 ! vibrations contemplat$ by ,fresnel are ! electric vibrations2 ^? dealt ) by ,mc,cullagh are ! magnetic ones4 ,?us are "s ( ! surmises ( g5ius v]ifi$ & made obvi\s to ! wayf>+ man4 ,,end ,,( ,,lecture4 #ag ,cf4 ,tr\ton1 9 ,nature1 ,vol4 #ci1 p4 #cic2 & _m optical exp]im5ts by ,mr4 ,tr\ton1 ,vol4 #dj1 p4 #cih4 ,s9ce !n ! above describ$ & depict$ app>atus = electro-optic exp]im5ts has be5 imitat$ 9 a neat1 compact =m by ,pr(4 ,j4 ,*und] ,bose1 ( ,calcutta1 & ) x he has obta9$ _m admirable & int]e/+ optical results4 ,see ,proc4 ,roy4 ,soc4 ,,note ,,) ,,ref]5ce ,,to ,,electric ,,waves ,,on ,,wires4 ,x may be well to expla9 t 9 my ,royal ,in/itution lecture ,i made no ref]5ce to ! transmission ( waves along wires4 ,i reg>d ! transmission ( waves 9 free space z ! special discov]y ( ,h]tz2 ?\gh und\bt$ly he got !m on wires too4 ,_! transmission along wires is1 h[ev]1 a mu* old] ?+4 ,von ,bezold saw !m 9 #ahgj1 & ,i myself got quantitative evid5ce ( nodes & loops 9 wires :5 work+ ) ,mr4 ,*attock 9 ! session #ahhg-h 7see1 = in/ance1 contempor>y reports ( ! ,ba? ,meet+ ( ! ,briti% ,association1 #ahhh1 9 ,! ,electrician71 & ,i exhibit$ !m "s "t aft]w>ds to ! ,physical ,society1 ! wires !mselves becom+ mom5t>ily lum9\s at e dis*>ge except at ! nodes1 ?us enabl+ ! waves to be actually se51 hav+ be5 made /ation>y by reflexion z 9 ! correspond+ ac\/ic exp]im5t ( ,melde4 ,?is exp]im5t does n appe> to h be5 prop]ly kn[n 7p4 #gh74 ,illu/ration3 ,,fig4 #bc4 ,x may be wor? m5tion+ t ! arrangem5t frequ5tly ref]r$ to 9 ,g]many by ! "n ( ,le*] 7viz41 t %[n 9 ,fig4 #bc71 & on :i* a great numb] ( exp]im5ts h be5 made1 is no?+ b a pair ( ,leyd5 j>s ) long wires lead+ f _! out] coats1 su* z ,i con/antly employ$ 9 ^! exp]im5ts4 ,! wires f ! out] coat 9 my exp]im5t 7 v long1 sometimes go+ five or six times r\nd a l>ge hall1 l telegraph wires4 ,& _m measurem5ts ( wave l5g? 7 ?us made by me at ! same p]iod z t 9 :i* ,h]tz 0 work+ at ,c>lsruhe4 ,! use ( air dielectric in/ead ( glass p]mits ! capacity to be adju/$1 & also readily enables ! capacity to be small1 & ! frequ5cy1 !re=e1 high2 b o!rwise ! arrangem5t is ! same 9 pr9ciple z _h frequ5tly be5 us$ by myself 9 ! s]ies ( exp]im5ts call$ 8! recoil kick0 7,proc4 ,roy4 ,soc41 ,june #ahia1 ,vol4 #ej1 pp4 #bc-ci74 ,= ^! & o!r reasons no ref]5ce has be5 made 9 my lecture to ! "w done on wires by ,s>as9 & ,de la ,rive2 nor to o!r excell5t "w done by ,le*]1 ,rub5s1 ,arons1 ,paalz[1 ,ritt]1 ,blondlot1 ,curie1 ,d4 ,e4 ,jones1 ,yule1 ,b>ton1 & o!r exp]im5t]s4 ,,application ,,( ,,?is ,,me?od ,,( ,,signall+ ,,at ,a ,,di/ance ,,to ,,actual ,,telegraphy4 ,al?\gh ! me?od ( signall+ to a mod]ate di/ance ?r\gh walls or o!r non-conduct+ ob/ructions by means ( ,h]tz waves emitt$ f "o /ation & detect$ by ,branly fil+ tubes at ano!r /ation 0 practis$ by ! au?or & by sev]al o!r p]sons 9 ?is c\ntry1 x 0 n appli$ by !m to actual telegraphy4 ,! idea ( replac+ a galvanomet]1 :i* 0 pref]ably a well-damp$ or speak+ galvanomet]1 by a relay work+ an ord9>y s\nd] or ,morse 0 an obvi\s "o1 b s f> z ! pres5t au?or 0 conc]n$ he did n realise t !re w\ld be any p>ticul> practical advantage 9 ?us ) difficulty telegraph+ across space in/ead ( ) ease by ! highly develop$ & simple telegraphic & telephonic me?ods r5d]$ possible by ! use ( a connect+ wire4 ,9 ?is non-p]ception ( ! practical uses ( wireless telegraphy he und\bt$ly err$4 ,b o!rs 7 n s bl9d1 ?\gh equally busy2 & notably ,dr4 ,alex&] ,muirhead =esaw ! telegraphic importance ( ?is me?od ( signall+ imm$iately aft] he>+ ! au?or's lecture on ,june #a/1 #ahid1 & arrang$ a siphon record] = ! purpose4 ,capta9 ,jackson also1 at ,devonport1 made exp]im5ts = ! ,admiralty1 & succe$$ 9 telegraph+ betwe5 %ips 9 #ahie 7or #ahif74 ,pr(4 ,pop(f's telegraphic application 9 #ahie is m5tion$ on page #fb4 ,by "s *ance a k ( ! coh]] me?od ( detect+ electric waves did n spread fa/ 9 ,g]many1 ! _m ,g]man work]s 9 ,h]tz waves cont9u+1 = "s "t aft] #ahid1 ! old] & less effici5t1 ?\gh = metrical purposes (t5 m conv5i5t1 mode ( detect+ !m4 ,b1 9 ,italy1 ! "w describ$ 9 ! prec$+ lecture became well kn[n1 & ! subject 0 develop$ l>gely1 especially by ,pr(4 ,righi1 ( ,bologna1 9 ! optical direction4 ,x 0 also develop$ 9 ! same direction ) _m mo/ int]e/+ results by ,pr(4 ,bose1 ( ,calcutta1 z m5tion$ 9 ! text4 ,pr(4 ,righi made a l>ge numb] ( exp]im5ts1 :i* he has s9ce describ$ 9 an ,italian treatise1 8,optic ,elettrica10 & x appe>s t x 0 f him t ,signor ,m>coni le>n$ ab\t ! subject1 & imm$iately conceiv$ ! idea ( apply+ x to comm]cial telegraphy4 ,he appe>s to h work$ at ! subject = a %ort "t 9 ,italy1 aim+ at gett+ ! receiv] to be m satisfactory & dep5dable1 & improv+ ! e>ly =m ( ,branly fil+s tube depict$ on page #bc by greatly dim9i%+ its size1 br++ ! t]m9als clos] toge!r1 & replac+ ! co>se bor+s by f9e fil+s4 ,he also seal$ !m up 9 a vacuum1 j z ! au?or did1 z relat$ on page #cd4 ,! only diff]5ces1 inde$1 betwe5 8 proc$ure & ! au?or's dur+ ?is "t 7 t ,signor ,m>coni pref]r$ nickel fil+s ) a little m]cury & a l[ vacuum1 :]eas ! au?or adh]$ *iefly to iron & brass fil+s & to high vacua4 ,at la/ he br\ght x ov] to ,dubl91 :]e he 0 advis$ to take x to ! ,*ief ( ! ,gov]nm5t ,telegraphs1 ,mr4 ,preece1 & accord+ly he took 81 at t "t1 crude app>atus to ! ,po/ ,(fice 9 a seal$ box4 ,!re 0 no po9t ( novelty 9 x at ?is /age4 ,) ! p[]ful aid ( ! ,po/ ,(fice ,signor ,m>coni proce$$ to develop 8 sy/em ( telegraphy on a l>ge scale2 &1 sometimes fail+1 sometimes succe$+1 gradually increas$ ! di/ance ov] :i* signall+ 0 possible1 & especially began to develop f unpromis+ beg9n+s 8 special me?od = long-di/ance1 viz41 ! employm5t ( a s5d+ & receiv+ conduct+ plate or o!r small surface1 at ! top ( a l(ty pole1 connect$ ?r\gh :at 0 at t "t suppos$ app>5tly to be ! real radiator1 ) ! e>?4 ,?is elevat$ plate1 connect$ z x n[ is ?r\gh a simple sp>k gap ) ! e>?1 is an obvi\s modification ( a ,h]tz vibrator2 = x may be reg>d$ simply z a ,h]tz vibrator ) its axis v]tical1 z ,h]tz (t5 us$ x1 & ) its l[] plate replac$ by ! e>?1 s z to d\ble ! available capacity2 b ! action ( a pair ( su* elevat$ plates1 connect$ ?r\gh ! e>? conductively & ?r\gh ! air inductively1 z n[ us$ by ,m>coni = s5d] & receiv] respectively1 is n q l t ( a ,h]tz vibrator & a ,h]tz receiv] act+ on "o ano!r by emitt$ radiation 9 ! ord9>y way4 ,if x 7 n ! same e>? to :i* ! plates 7 connect$1 !y w\ld h to act ord9>ily by radiation1 b s9ce x is ! same e>?1 & t e>? conduct+ 7possibly1 inde$1 ) a subm]g$ cable %ea? connect+ fav\rably-*os5 /ations71 !n ! two elevat$ plates are p>tially l ! greatly sep>at$ t]m9als ( a s+le ,h]tz vibrator4 ,only "o ( ! plates is *>g$ dur+ a s5d+ op]ation1 ! o!r is at z]o pot5tial1 b "s trace ( ! electro/atic l9es f "o plate may ext5d 9 curv$ l9es to ! o!r1 j z !y ext5d to e elevat$ conductor )9 hail ( ! s5d] 9 any direction4 ,!n comes ! snap ( ! sp>k gap & ! sudd5 dis*>ge1 equival5t to ! ru% ( an opposite *>ge ( electricity sudd5ly into ! s5d+ plate1 di/urb+ ! electric equilibrium at a di/ance--at any di/ance to :i* any trace ( electro/atic field _h be5 able to rea*--& giv+ a k9d ( :at is call$ 9 lightn+ a 8return /roke40 ,! effect ( ?is on ! di/ant plate & conductor mu/ be almo/ inf9itesimal2 nev]!less1 sep>at+ x f ! e>? is ! mo/ s5sitive detector to a m9ute sudd5 ru% or j]k ( electricity t c be imag9$1 or t has hi!rto be5 inv5t$1--! coh]]4 ,accord+ly1 absurdly m9ute ?\gh ! di/urbance is1 ! coh]] feels x1 in/antly increases 9 conductivity1 works ! relay1 & gives ! signal4 ,e sp>k at ! di/ant sp>k gap causes a simil> ru% 9 or out ( ! di/ant elevat$ plate1 & ! receiv+ plate collects su* a fraction ( ?is di/urbance z to /imulate ! coh]] & give a signal e "t4 ,n t x is to be suppos$ nev] to miss fire4 ,at ! pres5t "t a coh]] is n a r\gh in/rum5t t c be left free f exp]t att5tion ) safety = a long "t4 ,!re are times :5 x goes on work+ = days or ev5 weeks1 b !re are o!r times :5 x gives tr\ble & ne$s "s =m ( att5tion4 ,let u hope t ^! latt] times w become less frequ5t1 & t ! :ole ?+ w become q dep5dable be=e long4 ,! p]t9aci\s way 9 :i* ,mr4 ,m>coni & 8 able co-op]ators h1 at great exp5se1 gradually work$ ! me?od up f its e>ly difficult & caprici\s /age to its pres5t great di/ances & comp>ative dep5dabl5ess is wor?y ( all praise4 ,telegraphy by means ( ,h]tz waves1 ?\gh p]haps *iefly develop$ 9 ?is c\ntry1 has also be5 pursu$ successfully by ,pr(4 ,slaby 9 ,g]many1 :o has atta9$ consid]able di/ance ov] l&1 ) its num]\s ob/acles1 & has publi%$ an acc\nt ( 8 rese>*es 9 a book call$ 8,funk5telegraphie02 :ile l success ov] l& has be5 atta9$ by ,m4 ,e4 ,ducretet1 ,m4 ,blondel & o!rs 9 ,france4 ,m4 ,ducretet has1 inde$1 put on ! m>ket a compact app>atus :]eby beg9n]s c readily try _! h&s at ?is mode ( signall+2 z well z a l>ge-scale app>atus l t employ$ by ,lieut5ant ,tissot = ligh?\se signall+ on ! coa/ ( ,brittany4 ,! fil+s tube n[ *iefly employ$ by ! au?or is ( ! foll[+ =m3--,x is a seal$ glass tube conta9+ c>efully select$ iron fil+s1 & exhau/$ to ! highe/ vacuum4 ,close toge!r are two little silv] globes melt$ ea* on its own plat9um wire t]m9al1 :i* are connect$ ) conv5i5t screws on an ebonite /&4 ,! fil+s are adju/$ s z j to cov] ! two silv] globes1 & no m2 a pocket1 or res]voir1 h[ev]1 is sometimes provid$ :]eby m or few] fil+s c be easily introduc$ into ! work+ comp>tm5t = exp]im5tal purposes4 ,?is pocket s]ves to fix ! :ole tube to its ebonite body1 :i* is provid$ ) a clamp to atta* x to ! /iff spr+1 or movable lev]1 or o!r =m ( support1 ?r\gh :i* x is to receive ! me*anical %ocks necess>y to re/ore or decoh]e x aft] an electrical /imulus4 ,! usual plan is to employ an electrical hamm] to rap /rongly on a /iff brass spr+ to :i* ! ebonite is clamp$1 b ano!r plan is to atta* ! coh]] to a lev] tilt$ /rongly by an electromagnet aft] ! fa%ion ( a s\nd]4 ,a rapid succession ( g5tle taps is (t5 bett] ?an "o viol5t "o1 b exp]i5ce is ! be/ te/ ( ! k9d ( re/oration want$1 = x dep5ds a good deal on ! /r5g? ( ! electrical /imulus4 ,!re are me?ods ( disp5s+ ) ?is decoh]+ op]ation altoge!r4 ,aft] a fairly /rong electric /imulus all ! fil+s are /uck toge!r into a sort ( mat1 & no?+ b a ?or\gh %ak+ up w pull !m asund] aga94 ,a /ill m viol5t electric %ock may inde$ h a decoh]+ effect1 b x is n a plan to be recomm5d$1 = x seems to be a heat effect1 ak9 to ! bl[+ ( a fuse4 ,= protect+ a coh]] f undesir$ /imuli1 e4g41 f ! radiator at its own /ation1 ! g5]al me?od is describ$ on page #ce1 c41 & ! details ( x1 ) ! necess>y swit* = *ang+ ov] f s5d+ to receiv+1 are m5tion$ fur!r on 7page #fj74 ,b by ref]r+ to page #ajf x w be se5 t ,m4 ,branly _h already employ$ su* a protect+ case1 & _h work$ details out admirably4 ,rec5tly ,signor ,tommas9a has %[n t1 if "o end ( a %ort rod or wire be dipp$ into fil+s :ile sp>ks are occurr+ 9 ! neighb\rhood1 ! fil+s adh]e to x & to ea* o!r1 & ) c>e a long /r+ ( !m c be pick$ up4 ,! au?or has exam9$ ! behavi\r ( fil+s "u electrical influ5ce on a glass plate 9 a microscope1 & _! movem5ts t[>ds ! =mation ( a complete conduct+ bridge betwe5 ! t9foil t]m9als toge!r ) _! disjunctive behavi\r :5 ! electrical /imulus is too /rong1 ! ?or\gh cohesion set up by a succession ( electrical /imuli1 & ! p>tial or complete disruption by an appropriate me*anical /imulus is in/ructive4 ,an e>li] & mo/ important telegraphic application1 bas$ ^u in=mation giv5 9 ! prec$+ lecture1 0 made 9 #ahie by ,pr(4 ,pop(f1 ( ,russia1 & w be m5tion$ %ortly 7see page #fb74 ,i n[ proce$ to developm5ts ( syntonic or attun$ telegraphy on ! true ,h]tz-wave pr9ciple1 ! prelim9>y exp]im5ts on :i* are m5tion$ above 9 connection ) ! figures on page #bg4 ,,fur!r ,,developm5ts ,,9 ,,! ,,telegraphic ,,direction4 ,,syntonic ,,telegraphy4 ,9 ! pres5t /ate ( ! law 9 ?is c\ntry x appe>s to be necess>y = a sci5tific man ^: inve/igations may h any practical be>+ to refra9 f communicat+ 8 "w to any sci5tific society1 or publi%+ x 9 any j\rnal until he has regi/]$ x & paid a fee to ! ,gov]nm5t "u ! s-call$ ,pat5t ,law4 ,?is un=tunate sy/em is well calculat$ to prev5t sci5tific m5 9 g5]al f giv+ any att5tion to practical applications1 & to det] !m f an attempt to make _! rese>*es useful to ! community4 ,if a sci5tific work] publi%es 9 ! natural way1 no "o has any rights 9 ! ?+ publi%$2 x is giv5 away & lies useless1 = no "o w c>e to exp5d capital ^u a ?+ ov] :i* he has no effective control4 ,9 ?is case practical developm5ts g5]ally wait until "s outsid] /eps 9 & ei!r pat5ts "s slight addition or modification1 or else1 z sometimes happ5s1 pat5ts ! :ole ?+1 ) "s slight addition4 ,if a sci5tific work] refra9s f publi%+ & himself takes out a pat5t1 !re are innum]able tr\bles & possible litigation ahead ( him1 at lea/ if ! ?+ turns out at all remun]ative2 b ! probability is t1 9 8 o!rwise occupi$ h&s1 x w n s turn out until ! p]iod ( 8 pat5t "r has expir$4 ,p5d+ a mu*-to-be-desir$ em5dation ( ! law1 :]eby ! c\rts c take cognisance ( discov]ies or fundam5tal /eps 9 an inv5tion communicat$ to & (ficially dat$ by a responsible sci5tific society1 & c !reaft] aw>d to ! discov]] su* due & mod]ate recomp5se z %all seem appropriate :5 a great indu/ry has ris5 on ! basis ( t same discov]y or fundam5tal inv5tion--p5d+ ?is mu*-to-be-desir$ modification ( ! law1 x appe>s to be necess>y to g ?r\gh ! inappropriate & repulsive =m ( regi/]+ a claim to an attempt at a monopoly4 ,! in/9ct ( ! sci5tific work] is to publi% ev]y?+1 to hope t any useful aspect ( x may be z quickly z possible utilis$1 & to tru/ to ! in/9ct = fair play t he %all n be ! los] :5 ! ?+ becomes comm]cially pr(itable4 ,to grant him a monopoly is to grant him a m ?an d\btful boon2 to grant him ! privilege ( fight+ = 8 monopoly is to grant him a p]nici\s privilege1 :i* w sap 8 en]gy1 wa/e 8 "t1 & de/roy 8 p[] ( future production4 ,illu/ration3 ,,fig4 #bd 7,fig4 #e ( ,specification #aa1ege_/ig74--,syntonic ,radiator1 adapt$ = s5d+ & = receiv+4 ,h[ev]1 ! au?or1 9 consultation ) fri5ds1 decid$ t regi/ration 01 "u pres5t conditions1 necess>y1 &1 accord+ly1 = 8 attempt at syntony & o!r improvem5ts 9 ! ,h]tz wave me?od ( signall+1 he c ref] "h to c]ta9 pat5ts tak5 out1 9 conjunction *iefly ) ,dr4 ,alex&] ,muirhead1 8 co-work]1 :i* are numb]$ respectively z foll[s3-- ,illu/ration3 ,,fig4 #be 7,fig4 #ac ( ,specification #aa1ege_/ig74--;,diagram ( connections = ,syntonic ,receiv]2 e be+ coh]] & w a non-inductive conduct+ or capacity %unt1 to elim9ate ! self-induction ( ! receiv+ in/rum5t4 7#a7 #aa1ege ( #ahig1 :]e9 is describ$ ! g5]al syntonic pr9ciple & ! mode ( prolong+ ! duration ( ! vibrations emitt$ by a radiator or by a receiv]4 ,?is is done by add+ to x electromagnetic in]tia 7t is1 a self-induction coil7 9 su* a way z to less5 its radiat+ p[]1 conv]t+ its type ( emission f some?+ l a :ip-crack into some?+ m l t ( a /ruck /r+4 7,n pu%+ x s f> z to make x l a =k1 ?\gh t c\ld be done if desir$3 see ,j\rnal ,in/4,e4,e41 ,decemb]1 #ahih47 ,b too prolong$ a duration ( vibration is n desirable1 = x c only be obta9$ at ! exp5se ( radiat+ p[]4 ,= ! mo/ di/ant signall+ ! s+le pulse or :ip-crack is ! be/1 & ?is is :at 9 practice has hi!rto always be5 employ$2 b1 ) x1 tun+ is ( c\rse impossible4 ,a radiator ) sev]al sw+s is less viol5t at its fir/ impulse ?an is a mom5t>y emitt]2 b !n ! less5$ emitt+ p[] ( a radiator is to be comp5sat$ by a correspond+ly prolong$ duration ( vibration on ! "p ( ! receiv] or absorb]1 ?us r5d]+ ! radiator susceptible ( tun+ to a special simil>ly-tun$ receiv] or resonator4 ,! tun$ resonator is !n to respond1 n to ! fir/ impulse ( ! radiator1 b to a rapidly work$ up succession ( prop]ly tim$ impulses2 s t at l5g?1 aft] an accumulation ( two or ?ree1 or p]haps f\r1 sw+s1 ! electro/atic *>ges 9 its t]m9al plates become suffici5t to ov]fl[ & spit (f into ! coh]]1 !reby effect+ its /imulation & giv+ ! signal4 ,a resonator n prop]ly tun$--i4e41 "o tun$ to "s diff]5t frequ5cy ( vibration--w\ld n be able to accumulate impulses1 & h5ce w\ld n respond1 unless ( c\rse x 7 s mu* too ne> ! radiator t ! v fir/ sw+ /imulat$ x suffici5tly to di/urb ! coh]]2 9 :i* case1 aga91 !re is no room = tun+4 ,! two po9ts to att5d to = syntonic discrim9ation are3 7a7 t ! receiv] %all n be s ne> ! emitt] z to feel its impulses too easily1 i4e41 )\t accumulation2 7b7 t ! prop]ly tun$ receiv] %all be s arrang$ t x c "w up & accumulate ! impulses ( ! radiator1 & be=e atta9+ its maximum sw+ c ov]fl[ into ! coh]] associat$ ) x & ?us give ! signal4 ,illu/ration3 ,,fig4 #bf 7,fig4 #aj ( ,specification #aa1ege_/ig74--;,int]*angeable ,self-,induction ,coils = signall+ to diff]5t /ations4 ,illu/ration3 ,,fig4 #bg 7,fig4 #c ( ,specification #aa1ege_/ig74--;,diagrammatic repres5tation ( ,syntonic ,radiator & ,receiv]4 ,! middle sp>k gap h h is unnecess>y1 ?\gh sometimes helpful4 ,! ma9 *>g+ is done by impulsive ru% at ! outside knobs4 ,illu/ration3 ,,fig4 #bh 7,fig4 #g ( ,specification #aa1ege_/ig74--,syntonic ,radiator ) e>? connection arrang$ = s5d+4 ,! g5]al appe>ance ( a pair ( signall+ /ations on ?is plan is %[n 9 ,fig4 #bd1 :]e ! huts conta9 ! s5d+ & receiv+ in/rum5ts4 ,! self-induction coil jo9+ ! two capacity-areas is bett] depict$ 9 ,fig4 #be1 :i* also %[s "o mode ( jo9+ up ! coh]] to a syntonic receiv]4 7,! galvanomet] & %unt are1 ( c\rse1 m]ely typical ( any k9d ( telegraphic in/rum5t :atev]47 ,fig4 #bf indicates "o =m ( s5d] ) ?ree alt]native syntonis+ coils = speak+ to ?ree di/ant attun$ /ations4 ,fig4 #bg %[s a radiator arrang$ = receiv+1 b illu/rates ano!r me?od ( *>g+1 & "o frequ5tly employ$ by ! au?or1 viz41 ! me?od by impulsive ru% 7comp>e ,figs4 #aa1 #ab & #ai1 on pp4 #ad & #be ( ?is book74 ,! t]m9als ( ! ,ruhmkorff coil are "h connect$1 n to ! capacity-areas direct1 b to a pair ( knobs ne> ! c5tre ( gravity ( ea* area1 s t :5 ! dis*>ge occurs ea* area is sudd5ly *>g$ oppositely1 & ! two opposite *>ges are left to surge into "o ano!r & set up ! oscillations4 ,?is impulsive me?od ( *>g+ is ess5tially t adopt$ 9 ! sph]ical :ip-crack emitt] depict$ 9 ,fig4 #ai 7p4 #be1 ante71 ! two poles ( ! sph]e hav+ b small capacity & be+ jo9$ by z ?ick a conductor z ! equator ( ! sph]e4 ,b = su* a radiator z is indicat$ 9 ,fig4 #bd or ,fig4 #bg ! au?or commonly f\nd t a ?ird %ort sp>k gap 9 ! middle 0 an improvem5t1 & s1 z is well kn[n1 did ,pr(4 ,righi f9d x1 & embodi$ x 9 8 well-kn[n d\ble-sph]e d\ble-knob emitt]4 ,illu/ration3 ,,fig4 #bi 7,fig4 #ab ( ,specification #aa1ege_/ig74--,s+le-po9t ,coh]]1 ) clockwork ,tapp]-back op]at+ on ! project+ end ( ! spr+ clamp$ at ,p & lightly t\*+ a ne$le po9t n4 ,! specification also conta9s figures ( e>?-connect$ =ms ( radiators1 ) or )\t self-induction coils1 ( :i* ,fig4 #bh may be "h reproduc$2 & likewise a modification ( ! po9t coh]] depict$ 9 ,fig4 #ag1 on page #bb 7see ,fig4 #bi1 & also fig4 on page #bg71 :]e ! spiral wire spr+ is replac$ by a piece ( /raight wat*-spr+1 clamp$ at "o end1 adju/$ by a screw at ! o!r1 & lightly t\*$ by a ne$le po9t at its middle2 a v g5tle tapp+ back /imulus be+ provid$ 9 ! =m ( a clockwork or o!r me*anically-driv5 motor graz+ lightly aga9/ "o end ( ! spr+ protrud+ beyond ! clamp = ! purpose4 ,illu/ration3 ,,fig4 #cj 7,fig4 #ad ( ,specification #aa1ege_/ig74--;,ano!r diagram ( connections = ,syntonic ,receiv]1 ) ,coh]] 9 a second>y or trans=m] circuit2 a conduct+ or a capacity %unt = ! telegraphic in/rum5t be+ applicable z be=e4 ,illu/ration3 ,,figs4 #ca & #cb 7,figs4 #e & #f ( ,specification #ah1fdd_/ig74--,modes ( connect+ a ,coh]] to "o or to a pair ( ,syntonic ,radiators s t x may feel _! electro/atic di/urbance4 ,illu/ration3 ,,fig4 #cc 7,fig4 #aa ( ,specification #ah1fdd_/ig74--;,actual connections = a ,s5d+ & ,receiv+ ,/ation on ! plan %[n 9 ,fig4 #cg4 ,left-h& side %[s sp>k s5d+1 "r-h& side %[s ,coh]] receiv+4 ,fig4 #cj %[s a coh]] ins]t$ 9 a second>y or trans=m] circuit1 & op]at$ inductively by ! oscillations ( ! receiv]1 :i* are ?us trans=m$ up & rais$ 9 pot5tial4 7#b7 ,no4 #af1dje1 #ahig1 :]e9 are describ$ *iefly v>i\s practical me?ods ( decoh]+1 by means ( cams & o!rwise1 :i* are appropriate :5 work+ rapidly ) automatic transmitt] & siphon record]4 7#c7 ,no4 #ah1fdd1 #ahig1 repres5ts diff]5t ways ( connect+ up a coh]] to a syntonic resonator1 s z to get ! b5efit ( its ov]fl[ )\t int]f]+ ) ! work+ up ( ! electric oscillations1 e4g41 ,figs4 #ca1 #cb & #cc4 ,x also %[s a plan = con/antly decoh]+ by a rapidly revolv+ cam a numb] ( coh]]s 9 p>allel1 s t "o at lea/ is always ready to receive an impulse 7,fig4 #cd74 ,fur!r1 x arranges to utilise ! e>? or a cable %ea?1 or o!r un9sulat$ conductor1 = ! purpose ( convey+ electric impulses to a di/ance 7,figs4 #ce1 #cf1 #cg & #ch74 ,& next x is arrang$ to assi/ ! coh]] to feel ! full effect ( any electric j]k by %unt+ out ! batt]y & galvanomet]1 :i* are necess>ily 9 s]ies ) x1 by means ( a cond5s] ( mod]ate capacity 7,fig4 #ce71 :i* also %[s a self-induction mode ( s5d+ a /imulus along an un9sulat$ l9e4 ,?is cond5s] ob/ructs all /eady curr5ts1 su* z give ! signal1 b x transmits freely any mom5t>y electric impulses1 su* z /imulate a coh]]4 ,illu/ration3 ,,fig4 #cd 7,fig4 #a ( ,specification #ah1fdd_/ig74--,s+le-po9t ,coh]]s 9 p>allel1 ) successive decoh]5ce4 ,illu/ration3 ,,fig4 #ce 7,fig4 #c ( ,specification #ah1fdd_/ig74--;,a self-induction me?od ( s5d+ j]ks into a badly insulat$ l9e1 & arrangem5t = detect+ su* j]ks by a s+le-po9t ,coh]]4 ,illu/ration3 ,,fig4 #cf 7,fig4 #d ( ,specification #ah1fdd_/ig74--;,ano!r arrangem5t = s5d+ j]ks into a b>e or badly insulat$ l9e1 & connections = ,coh]] detection4 ,illu/ration3 ,,fig4 #cg 7,fig4 #aj ( ,specification #ah1fdd_/ig74--;,ano!r mode ( s5d+ a j]k f a sp>k gap at j into a badly insulat$ cable or o!r conductor1 :i* is connect$ at ! o!r end to a ,coh]]1 ! circuit be+ complet$ inductively ?r\gh ! air by means ( ! areas p1 p4 ,! dott$ l9es s repres5t ! swit* connection ( ,fig4 #cc4 ,illu/ration3 ,,fig4 #ch 7,fig4 #ac ( ,specification #ah1fdd_/ig74--;,ano!r me?od ( signall+ ?r\gh a pair ( imp]fect conductors1 su* z gas & wat] pipes i1 )\t ! above elevat$ inductive connection4 ,illu/ration3 ,,fig4 #ci 7,fig4 #c ( ,specification #bi1jfi_/ig74--;,diagram ( ,coh]] connection to ,syntonic ,collector1 ) capacity %unt = telegraphic in/rum5t4 7#d7 ,no4 #bi1jfi1 #ahig4 ,9 ?is pat5t v>i\s me?ods ( connect+ up ! %unt+ cond5s]1 ^: object x is to transmit all j]ks undilut$ to ! coh]]1 are %[n1 all adapt$ to "w ) a syntonic resonator 7,fig4 #ci74 ,!re is also %[n a complete swit* 7,fig4 #dj7 = effect+ ! transition f 8s5d+0 to 8receiv+10 expos+ ! coh]] to ! full effect ( ! di/ant radiator1 & completely protect+ & isolat+ x f its home radiator2 ! swit* be+ s arrang$ t signall+ is impossible unless ! home coh]] is protect$4 ,a rotat+ commutator is also %[n1 ^: object is to expose ! coh]] to ! full influ5ce ( a receiv]1 especially ( a non-syntonic receiv] or simple collector1 )\t its be+ %unt$ or o!rwise int]f]$ ) by ! telegraphic app>atus2 to :i*1 h[ev]1 imm$iately aft]w>ds ! rotat+ commutator connects x1 & !n effects ! tapp+ back4 ,connections are %[n 7,fig4 #da7 = a complete s5d+ & receiv+ /ation on ?is plan ) a syntonic radiator & resonator indicat$ 7?\gh n to scale74 ,b ) syntonic resonators ! revolv+ commutator me?od is n f\nd to be necess>y2 ! s5d+ & receiv+ swit*1 toge!r ) ! clos$ box = protect+ ! coh]] 9 an in/antly accessible mann] is !re=e ! *ief feature ( ?is diagram4 ,illu/ration3 ,,fig4 #dj 7,fig4 #f ( ,specification #bi1jfi_/ig74--,swit* at a ,s5d+ & ,receiv+ ,/ation1 to *ange all ! connections ) a protect$ ,coh]] f receiv+ to s5d+ by depress+ ! knob l4 ,illu/ration3 ,,fig4 #da 7,fig4 #g ( ,specification #bi1jfi_/ig74--;,diagram ( connections at a protect$ ,coh]] ,/ation ) ,syntonic ,radiator & ,collector4 ,,e>li] ,,telegraphic ,,advances4 ,9 ,april1 #ahie1 a communication 0 made to ! ,russian ,physical ,society by ,pr(4 ,a4 ,pop(f1 ( ! ,torp$o ,s*ool1 ,cron/adt1 ,russia1 & appe>s 9 ! ,j\rnal ( t ,society = ,janu>y1 #ahif4 ,9 ?is communication ! use ( an elevat$ wire & ( a tapp]-back work$ ?r\gh a relay by ! coh]] curr5t are cle>ly describ$1 & signall+ 0 effect$ = a di/ance ( #e kilometres 7#c miles74 ,an extract f ?is communication is giv5 9 ,! ,electrician = ,decemb]1 #ahig1 ,vol4 ,,xl41 page #bce1 & f x we reproduce ,fig4 #db1 illu/rat+ ! tapp+ back arrangem5t4 ,! foll[+ extracts f ?is pap] may also be quot$3-- 8,on us+ a s5sitive relay 9 ! circuit ) ! coh]] tube1 & an ord9>y electric bell 9 ! o!r circuit ( ! relay1 = s\nd signals & z an automatic tapp] = ! coh]]1 ,i obta9 an app>atus :i* exactly answ]s e electric wave by a %ort r+1 & by rhy?mical /rokes if electric vibrations be excit$ cont9u\sly40 8,on connect+ an electromagnetic record] 9 p>allel ) ! bell1 trac+ a /raight l9e along ! pap] b& :i* is mov$ by a #ab-;h\r clockwork cyl9d]1 ,i obta9 an in/rum5t regi/]+ by a cross l9e on ! mov+ b& e electric wave t rea*es ! coh]] f across ! atmosph]e4 ,su* an app>atus 0 plac$ at ! ,meteorological ,obs]vatory at ,/4 ,pet]sburg 9 ,july1 #ahie1 "o ( ! electrodes ( ! coh]] be+ connect$ by an insulat$ wire ) an ord9>y lightn+ conductor1 ! o!r electrode ( ! tube-coh]] be+ connect$ ) ! gr\nd40 ,illu/ration3 ,,fig4 #db 7,fig4 #b on p4 #bce ( ,! ,electrician1 ,vol4 ,,xl474--,me?od ( automatic tapp+ back by relay curr5t employ$ = telegraphy by ,pr(4 ,pop(f 9 #ahie4 ,pr(4 ,pop(f !n goes on to say t 8 app>atus works well z a lightn+ record]1 & t he hopes x c be us$ = signall+ to great di/ances4 ,he says3-- 8,i c detect waves at ! di/ance ( "o kilometre if ,i employ z s5d] a ,h]tz vibrator ) #cj c5timetre sph]es1 & if ,i use ! ord9>y ,siem5s relay2 b ) a ,bj]knes vibrator #ij c5timetres diamet]1 & a m s5sitive relay1 ,i rea* five kilometres ( good work+40 ,?us x is pla9 t ,pr(4 ,pop(f employ$ ! elevat$ wire z receiv] 9 #ahie1 b did n employ x z s5d]4 ,9 #ahig ,pr(4 ,slaby1 ( ,b]l91 publi%$ 79 ,g]man7 a book call$ 8,sp>k ,telegraphy10 9 :i* he describ$ 8 success 9 signall+ f #c to #ac miles across l&4 ,f ?is book we take ! foll[+ illu/rations ( ! coh]] & its connections3-- ,fig4 #dc %[s ! coh]] ti$ on to a glass tube1 by :i* x is support$4 ,illu/ration3 ,,fig4 #dc 7,fig4 #g ( ,slaby's book74 ,fig4 #dd %[s ! simple/ =m ( its connection to a "o-cell batt]y ,a & a pol>is$ relay ,b1 :i* swit*es on ano!r batt]y ( sev]al cells a op]at+ ! ,morse in/rum5t or electric bell or s\nd] b & also ! tapp]-back c1 ! hamm] ( :i* raps g5tly on ! coh]] tube at e signal4 ,illu/ration3 ,,fig4 #dd 7,fig4 #h ( ,slaby's book74--,slaby's arrangem5t ( ,coh]] & ( tapp]-back & relay connections4 ,! actual app>atus is depict$ 9 two views1 ,figs4 #de & #df1 :]e w be recognis$ on ! left-h& side ! coh]] & tapp]-back2 9 ! middle ! batt]ies1 bo? = relay & = coh]] circuits2 & on ! "r-h& side a relay & ! signall+ or call+ in/rum5t1 9 ?is case %[n z an ord9>y electric bell4 ,illu/ration3 ,,fig4 #de 7,fig4 #af ( ,slaby's book74--,view ( ,slaby's ,receiv+ ,app>atus1 ) call-bell rung by relay1 or ) ,morse in/rum5t jo9$ on to t]m9als ,m1 & swit* to *ange f ,call+ to ,signall+4 ,k ,k are ! t]m9als ( elevat$ wire & e>?1 & ! ,coh]] & ,tapp]-back are close to !m4 ,illu/ration3 ,,fig4 #df 7,fig4 #ag ( ,pr(4 ,slaby's book74--,an elevation view ( ,pr(4 ,slaby's same ,app>atus1 %[+ ! electromagnet & hamm] ( ! tapp]-back work$ by relay curr5t f local batt]y1 z 9 ,pop(f's plan ( #ahie4 ,a ,morse in/rum5t is to be connect$ to ! t]m9als ,m1 & ei!r x or ! bell c be swit*$ into ! circuit at pleasure4 ,! =m ( relay depict$ is special to ,slaby1 b ! re/ ( ! arrangem5ts are practically id5tical ) ^? %[n by ,m>coni at ,dov]4 ,fig4 #dg gives a diagram ( ! actual connections4 ,fig4 #dh is a picture ( "o ( ,slaby's signall+ /ations1 %[+ ! way ! elevat$ wire ent]s ! build+4 ,illu/ration3 ,,fig4 #dg 7,fig4 #ai ( 8,sp>k ,telegraphy074--,diagram ( ,slaby's connections 9 ! above app>atus4 ,f is ! coh]] & ,k ! tapp]-back4 ,dur+ ,septemb]1 #ahii1 ! ,m>coni me?od ( signall+ to long di/ances 0 demon/rat$ be=e ! ,briti% ,association at ,dov]4 ,! *ief feature ( ! in/allation 0 ! elevat$ wire support$ by a ma/1 & t]m9at+ at ! top 9 a small conductor1 :i* is usually made ( wire nett+1 & is susp5d$ f an insulat+ rod4 ,! l[] end ( ?is elevat$ wire pass$ into ! build+ ?r\gh an ap]ture1 & 0 connect$ to "o t]m9al ( ! usual ,ruhmkorff coil1 ! o!r t]m9al ( :i* 0 e>!d4 ,! signall+ key 0 ( ! simple/ description1 be+ no?+ m ?an a well-insulat$ ,morse key work$ by h& & caus+ a make-&-break 9 ! prim>y circuit ( ! coil4 ,! ord9>y trembl+ break ( ! induction coil 0 at "w 9 ! usual way1 s t :ile ! signall+ key 0 depress$ cont9u\sly !re 0 a torr5t ( sp>ks betwe5 ! knobs ( ! second>y4 ,?is me?od ( signall+ 0 id5tical ) t employ$ by ev]yone s9ce ! "t ( ,h]tz1 except t1 in/ead ( connect+ ! second>y t]m9als to two insulat$ plates1 "o 0 n[ connect$ to e>? & ! o!r to a small insulat$ conductor at consid]able elevation4 ,illu/ration3 ,,fig4 #dh 7,fig4 #aa ( ,pr(4 ,slaby's book on 8,sp>k ,telegraphy074 ,illu/ration3 ,,fig4 #di 7p4 #gfb1 ,! ,electrician1 ,vol4 ,,xliii474--,m>coni ,signall+ ,ma/ at ,dov] ,t[n ,hall4 ,illu/ration3 ,,fig4 #ej 7,fig4 #a1 p4 #g1 ,! ,electrician1 ,vol4 ,,xliii474--,ma/ at ,s\? ,=el&2 f :i* ,signals w5t to a simil> ,ma/ at ,wim]eux1 ne> ,b\logne4 ,f ?is ma/ 9 ! t[n ( ,dov] 7,fig4 #di7 signals c\ld be s5t to ano!r l(ti] ma/ at ! ,s\? ,=el& 7,fig4 #ej71 :]e x is itself elevat$ by *alk cliffs f> above ! sea4 ,f ?is ,s\? ,=el& /ation1 :i* 0 simil> 9 all ess5tial respects to ! ,dov] /ation1 except t its elevation 0 great]1 messages c\ld be s5t & receiv$ to & f a /ation ne> ,b\logne1 on ! coa/ ( ,france1 & to & f ! ,ea/ ,goodw9s light%ip4 ,! signall+ 0 sl[1 b appe>$ dep5dable1 & ! simplicity ( all ! arrangem5ts 0 rem>kable 7,fig4 #ea74 ,conc]n+ ! receiv+ app>atus !re is little to be said1 s9ce x is 9 ess5ce ! same z t :i* has already be5 describ$4 ,x consi/s ( a coh]] ( ! plug tube patt]n1 some?+ l t depict$ on page #bc1 b excessively r$uc$ 9 size1 ! glass tube be+ ! size ( a quill1 ! two silv] plugs close toge!r sep>at$ only by a v few nickel fil+s4 ,?is tube is m\nt$ s t x c be /ruck aft] ea* signal by a light electric hamm] work$ by a curr5t f a local batt]y swit*$ on by a ,siem5s' pol>is$ relay1 :i* is itself actuat$ by ! coh]] curr5t4 ,:5ev] ! coh]] receives a signal ! same curr5t t works ! tapp] works also ! ,morse in/rum5t /&+ on ! table alongside1 & records a %ort or a long signal on ! tape4 ,! coh]] ) its tapp]1 ! pol>is$ relay1 & ! batt]y 7a few dry cells7 are all enclos$ 9 "o oblong iron box1 ?r\gh an ap]ture 9 :i* ! l[] end ( ! elevat$ wire c be ins]t$ & br\ght into direct connection ) ! coh]]4 ,to *ange f transmitt+ to receiv+ no?+ is ne$$ b ! deta*m5t ( ?is wire f ! ,ruhmkorff coil t]m9al & its ins]tion ?r\gh ! ap]ture ( ! enclos+ box s z to t\* ! coh]] circuit4 ,! object ( ! box is1 ( c\rse1 ! protection ( ! coh]] f undesir$ di/urbances1 exactly z describ$ on page #cd1 & ! collect+ wire has ! function !re describ$ likewise4 ,! electric tapp]-back is also m5tion$ on page #ca1 b n z be+ op]at$ ?r\gh a relay by ! coh]] circuit's own curr5t4 ,?is la/ improvem5t seems to h be5 devis$ & employ$ by ,pr(4 ,pop(f at ,cron/adt 9 #ahie 7see ,fig4 #db74 ,no d\bt x 0 arriv$ at indep5d5tly aga9 by ,mr4 ,m>coni & ! telegraph (ficials :o assi/$ him 9 8 e>ly exp]im5ts 9 ?is c\ntry4 ,! o!r box %[n 9 ,fig4 #ea is probably a /&-by 9 case ( accid5t4 ,x is difficult to imag9e a simpl] contrivance1 & x appe>$ to "w at ,dov] dep5dably1 ! messages com+ out sl[ly 9 ord9>y dots & da%es1 ! torr5t ( sp>ks be+ suffici5tly rapid n to necessitate ! break+ up ( ! da% into a s]ies ( dots4 ,! sluggi%ness ( ! ,morse in/rum5t or ! relay1 or ! circuit z a :ole1 enabl$ ?is excell5t result to be atta9$ ) app>5t ease4 ,illu/ration3 ,,fig4 #ea 7p4 #gfa1 ,! ,electrician1 ,vol4 ,,xliii474--,app>atus = ,s5d+ & ,receiv+1 %[n by ,pr(4 ,flem+ to ! ,briti% ,association at ,dov]4 ,a diagram ( ,m>coni's connection ( s5sitive tube to ! relay & tapp]-back & ,morse in/rum5t1 :]e ,w repres5ts ! elevat$ wire1 is giv5 9 ,fig4 #eb4 ,illu/ration3 ,,fig4 #eb 7,fig4 #b1 ( p4 #fia1 ,! ,electrician1 ,vol4 ,,xlii474--,diagram ( ! connection ( ,relay & ,tapp]-back & ,morse ,in/rum5t1 z giv5 9 ,mr4 ,m>coni's ,pap] 9 ! ,j\rnal ( ! ,in/4 ,elec4 ,eng9e]s = ,april1 #ahii2 ! relay be+ an ord9>y ,siem5s pol>is$ relay4 ,! ma/ at ! ,s\? ,=el& 0 /at$ to be #aej ft4 high1 b ! cliff on :i* x /&s mu/ be at a /ill great] elevation above ! sea4 ,x 0 f ?is /ation t ! real di/ant signall+ 0 p]=m$1 & probably n f ! l[] ma/ at ,dov]4 ,,! ,,hi/ory ,,( ,,! ,,coh]] ,,pr9ciple4 ,! foll[+1 writt5 by ,dr4 ,oliv] ,lodge1 appe>$ 9 8,,! ,,electrician0 = ,novemb] #ab?1 #ahig3-- ,probably ! e>lie/ discov]y ( cohesion "u electric influ5ce 0 conta9$ 9 t old1 =gott5 obs]vation ( ,guit>d 9 #ahej1 t :5 du/y air 0 electrifi$ f a po9t ! du/ p>ticles t5d$ to coh]e into /r+s or flakes4 ,! same ?+ no d\bt occurs 9 ! =mation ( sn[flakes "u ! influ5ce ( atmosph]ic electrification2 & ! cohesion ( small drops into l>ge ones 9 ! proximity ( a *>g$ cl\d is exce$+ly famili>1 s9ce x results 9 ! ord9>y ?und]-%[]4 ,great light 0 ?r[n on ^! meteorological ph5om5a by ! discov]y ( ,"l ,rayleigh 9 #ahgi ( ! curi\s behavi\r ( a small f\nta9 or v]tical wat]-jet :5 expos$ to ! neighb\rhood ( a /ick ( excit$ seal+-wax4 ,a smoo? orifice be+ arrang$ to ?r[ a jet ( wat] ab\t ?ree or f\r feet ne>ly v]tically1 ! jet breaks into drops1 & ! drops scatt] 9 all directions1 reb\nd+ f "o ano!r & giv+ a %[] ( f9e spray2 b if a /ick ( seal+-wax be rubb$ on ! sleeve ( a coat & br\ght )9 "o or two y>ds ( ! place :]e ! jet breaks into drops1 x w be f\nd t ! scatt]+ ceases1 ! f9e spray is no long] =m$1 & ! brok5 jet rises & desc5ds 9 great blobs ( wat]4 ,! ra9-%[] has1 9 fact1 be5 conv]t$ into a ?und]-%[]4 ,fur!r exp]im5ts1 conduct$ *iefly ) two jets1 elucidat$ ! ph5om5on4#ah ,arrang+ two ne>ly p>allel jets f neighb\r+ orifices s z to imp+e aga9/ ea* o!r1 !y 7 f\nd ord9>ily to reb\nd aft] collid+1 a sort ( film or sup]ficial lay] appe>+ to prev5t amalgamation ( ! jets into "o2 b if a slight diff]5ce ( electric pot5tial 7 ma9ta9$ betwe5 ! two jets1 say by connect+ !m to ! t]m9als ( a ,leclan* cell1 !n ! b\nd>y lay] broke d[n1--! two collid+ jets no long] sep>at$ ) a reb\nd1 b amalgamat$ & became "o4 #ah ,proc4 ,roy4 ,soc41 #ahgi & #ahhb4 ,"l ,rayleigh develop$ a simil> explanation = ! s+le jet4 ,! scatt]+ ( ! jet 9 its ord9>y /ate 0 due to ! reb\nd ( collid+ drops1 z c\ld be se5 by exam9+ x ) a suffici5tly in/antane\s or int]mitt5t mode ( illum9ation2 b if an electric *>ge 7 9 ! neighb\rhood x mu/ be suppos$ t a trace ( pot5tial diff]5ce exi/$ betwe5 ! drops1 :i* caus$ !m to amalgamate into "o :5ev] !y collid$1 & ?us spe$ily to become unit$ into a comp>atively few l>ge drops1 :i* !n cont9u$ on _! p>abolic way4 ,at fir/ sight x w\ld seem z if ! neighb\rhood ( a negative *>ge %\ld *>ge all ! drops positively at ! place :5ce !y break (f f ! e>?-connect$ p>5t jet1 & %\ld ?us cause !m all to repel ea* o!r4 ,& if ! electrifi$ seal+-wax is held too close1 ?is is exactly :at happ5s4 ,all ! drops are !n simil>ly electrifi$1 & scatt] m viol5tly ?an ev]1 nev] 9 t case com+ into any reb\nd+ or o!r contact ) ea* o!r4 ,b "u a g5tl] electric influ5ce ! simil> *>g+ has a less m>k$ result1 & a pol>isation diff]5ce ( pot5tial ( "o or two volts may )\t difficulty be suppos$ to exi/ 9 ! air betwe5 drops1 p>tly because !y are n all equally *>g$ & p>tly because ea* is a conductor act$ on inductively by a neighb\r+ electrifi$ body4 ,9 ?is connection x mu/ be rememb]$ t rubb$ seal+ wax is at a pot5tial ( sev]al ?\s& volts1 & !re=e c readily cause a pot5tial gradi5t ( two or ?ree volts p] millimetre ?r\gh\t a y>d or two ( space4 ,! next /age 0 ! re-discov]y1 9 #ahhc1 ( ,guit>d's old du/ ph5om5on by ! pres5t writ] & ! late ,j4 ,w4 ,cl>k 7,nature1 ,july1 #ahhc2 ,phil4 ,mag41 ,m>*1 #ahhd71 :5 !y 7 work+ toge!r at ! du/-free region se5 ov] hot bodies :5 /rongly illum9at$ 9 du/y air4 ,! fact ( su* du/-free spaces 0 discov]$ by ,tyndall1 & !y c readily be se5 by plac+ a light$ _s lamp or a hot pok] 9 ! beam ( an electric lamp4 ,tyndall ?\ght ! du/ 0 calc9$ or burnt up1 & t ?us ! air 0 fre$ f x2 b ?is is an utt]ly errone\s explanation1 & ! true explanation is ( a m recondite "*1 be+ connect$ ) ! bomb>d+ effect ( gas molecules z illu/rat$ 9 ! ,crookes radiomet]4 ,! du/ p>ticles are beat5 away f ! hot body by a molecul> bomb>dm5t1 :i* manife/s itself ev5 at ord9>y pressures on bodies ( suffici5tly small size1 z inde$ 0 also o!rwise %[n by ,tait & ,dew> & ,osborne ,reynolds 9 ! c\rse ( rem>kable !oretical & practical inve/igations4#ai ,be=e arriv+ at ?is explanation1 h[ev]1 we exp]im5t$ to see if ! ph5om5on 0 caus$ by ! air hav+ become slightly electrifi$1 p]haps by reason ( its hav+ /ream$ z an upw>d convection curr5t ov] ! surface ( ! w>m solid1 at :i* we 7 look+1 9 a ?ick smoky atmosph]e1 9 ! conc5trat$ light ( an electric arc4 ,we !re=e purposely electrifi$ ! rod1 to see :at t w\ld d1 & we f\nd to our surprise1 directly ! electric ma*9e 0 turn$1 t ! smoky atmosph]e almo/ in/antane\sly disappe>$1 & ! box became q cle>4 ,?is exp]im5t1 aft] developm5t1 ?\gh describ$ 9 ,july1 #ahhc1 0 %[n 9 public = ! fir/ "t at ! ,dubl9 ,royal ,society 7,nature1 ,april #bd1 #ahhd71 & subsequ5tly at ! ,briti% ,association meet+ 9 ,montreal#bj 9 #ahhd1 & 0 appli$ to ! exp]im5tal cle>+ ( rooms f d5se smoke or fume4 ,x has (t5 be5 %[n s9ce1 by ,mr4 ,swan & o!rs1 & has become fairly well kn[n4#ba #ai 8,dim5sional ,prop]ties ( ,matt]10 ,phil4 ,trans41 #ahgi4 #bj ,ev5+ ,lecture on 8,du/10 by ! writ]1 see ,nature1 ,vol4 #ca1 p4 #bfe2 also ,j\rnal ( ! ,royal ,in/itution1 ,may1 #ahhf4 #ba ,app>atus = ! purpose is n[ 9 ! catalogue ( ,messrs4 ,ducretet1 ( ,p>is1 b !y supply a pair ( combs ( po9ts4 ,x makes a m int]e/+ exp]im5t if only "o po9t is us$1 9 a mod]ate space1 & ! electric supply regulat$ s z n to hurry ! disappe>ance ( ! smoke too quickly1 b to exhibit ! /ages ( aggregation :i* prec$e ! f9al disappe>ance by deposition4 ,any k9d ( smoke s]ves1 b a bit ( magnesium ribbon burnt "u a bell j> is cleanly & effective4 ,x %\ld be look$ at 9 a w9d[ or o!r good light1 ( c\rse4 ,! next obs]vation ( cohesion "u electrical influ5ce 0 made by ! writ] 9 #ahhi1 :ile work+ at ! protection ( telegraphic in/rum5ts & cables f lightn+1--a rese>* :i* result$ 9 ! use ( *oke coils z supplem5t>y to ! air gaps ( ! ord9>y lightn+ gu>d1 & ?us to ! =ms ( in/rum5t con/ruct$ by ,dr4 ,alex4 ,muirhead = telegraphic "w 9 ?is c\ntry1 & to ! supplem5t>y additions adopt$ by ! ,we/+h\se ,company = _! non-arc+ gu>ds adapt$ to electric light & p[] in/allations 9 ,am]ica4 ,! obs]vation ( cohesion 0 a bye-issue1 notic$ :5 ! knobs ( ! lightn+ gu>d 7 br\ght too close toge!r4#bb #bb ,j\rnal ( ! ,in/itution ( ,electrical ,eng9e]s = #ahij1 pp4 #ceb-d4 ,:5 lightn+ itself /rikes a gu>d1 x has inde$ (t5 be5 f\nd t ! opposite sides ( ! protective air gap are fus$ toge!r4 ,?is1 no d\bt1 may be p>tly due to a /raight=w>d melt+ or weld+ by heat1 b x is probably n solely t4 ,molt5 metals )\t a flux d n s readily weld4 ,x is almo/ c]ta9ly due to a cohesive action also1 ! diff]5ce ( pot5tial betwe5 ! molt5 t]m9als result+ 9 adhesion & amalgamation1 a ph5om5on also obs]v$ 9 ! frequ5t lock+ ( an electric arc =m$ betwe5 two metallic electrodes4 ,h[ev] ?is may be1 c]ta9ly ! ph5om5on occurs on a small scale1 = if ! pair ( knobs or po9ts plac$ z a %unt to protect a galvanomet] or o!r telegraphic in/rum5t f lightn+ 7or :at is easi] exp]im5tally & ess5tially ! same ?+1 f a ,leyd5 j> dis*>ge7 be set too close toge!r1 ! galvanomet] w be f\nd to be %ort-circuit$ aft] a sp>k1 & ! knobs w be f\nd1 bo? by me*anical & electrical te/s1 to be feebly unit$ at a s+le po9t4#bc ,n only1 h[ev]1 is ! galvanomet] %ort-circuit$ by ! metallic junction s =m$1 b at ! in/ant ( ! =mation ( ! jo9t x exp]i5ces a v p]ceptible kick1 indicat+ a mom5t>y curr5t1 co9cid5t no d\bt ) ! electric dis*>ge1 b "o f :i* x w\ld h be5 protect$ _h n ! junction occurr$4 ,! galvanomet] kick is cle>ly an effect due to ! unit+ metals1 b x has n yet be5 fully elucidat$2 x seems to h be5 fir/ obs]v$ by ,mr4 ,/roh 9 8 excell5t rese>*es on microphonic action1 relat$ 9 ! ,j\rnal ( ! ,society ( ,telegraph ,eng9e]s1 #ahhc & #ahhg1 & x may possibly be !rmo-electric1 z ,pr(4 ,hughes1 :o also obs]v$ x1 ?9ks likely2 b x may be electro-*emical1 or x may be connect$ ) an effect obs]v$ lat] by ,fitz,gerald 9 8 galvanomet] mode ( detect+ ,h]tzian waves1 :i* he publi%$ at ! ,royal ,in/itution 9 #ahij4 ,! po9t ( pres5t int]e/ is ! cohesion :i* sets 9 betwe5 ! knobs :5 ! sp>k occurs3 an extremely feeble sp>k 0 f\nd suffici5t to produce ! effect1 provid$ ! surfaces 7 already almo/ inf9itely close toge!r1 i4e41 provid$ !y 7 already 9 :at w\ld be call$ contact1 ) ! m]e/ imp]ceptible film ( 7probably7 oxide sep>at+ !m1 j ! k9d ( film :i* a *emical flux is useful 9 remov+4 ,! electrical /imulus appe>s to act z su* a flux1 & ! adhesion ( ! two surfaces 0 demon/rat$ by an electric bell & s+le cell 9 circuit4 ,e "t ! sp>k occurr$ ! bell rang1 & cont9u$ r++1 until ! table1 or "s "p ( ! support ( ! knobs1 0 tapp$ s z to %ake or j> !m asund] aga94#bd ,! arrangem5t con/itutes a conv5i5t detector 9 ! syntonic ,leyd5 j> exp]im5t1 depict$ 9 ,fig4 #d1 p4 #f 7see also p4 #ba74 #bc 8,mod]n ,views10 second edition1 p4 #cei4 #bd ,j\rnal ( ! ,in/itution ( ,electrical ,eng9e]s1 #ahij1 p4 #ceb4 ,see also rem>ks by ,mr4 ,/roh 9 two microphone discussions1 ,j\rnal ( ! ,in/itution ( ,electrical ,eng9e]s1 #ahhc & #ahhg4 ,if ! electric bell /&s on ! same table z ! support ( ! sp>k+ knobs1 or1 /ill bett]1 if x be put into me*anical contact ) !m1 its tremor is q suffici5t to break ! contact asund] aga92 unless ! sp>k1 & !re=e ! adhesion1 has be5 too /rong4 ,rais+ ! bell into ! air1 x ceases to int]rupt ! sp>k-induc$ cont9uity1 & 9 t case cont9ues to r+2 b directly x is replac$ s t its vibration c rea* ! coh]$ surfaces ?r\gh _! solid supports x usually happ5s t a few /rokes--(t51 inde$1 ! fir/ /roke--( ! bell1 sometimes ev5 ! incipi5t movem5t ( ! hamm] prep>atory to a /roke1 is suffici5t to break ! circuit & susp5d in/antly ! action1 re/or+ ! gap to its orig9al condition & leav+ ! circuit ready to be complet$ aga9 by ano!r sp>k4 ,! sp>k 9 ^! e>ly exp]im5ts 0 usually suppli$ f ! out] coats ( a pair ( oppositely-*>g$ small ,leyd5 j>s1 ^: knobs sp>k$ into ea* o!r2 ! idea be+ to asc]ta9 all ! conditions p]ta9+ to ! feeble residue ( a light+ dis*>ge :i* is liable to be conduct$ by telegraph wires to a di/ance1 & !re cause "s damage to s5sitive in/rum5ts n suitably protect$ f sudd5 electric j]ks1 ^: laws ( fl[ are q diff]5t f ^? prop] to /eady curr5ts4 ,mean:ile1 9 #ahhg & #ahhh1 _h be5 p]=m$ ! great exp]im5ts ( ,h]tz on electric waves 9 free space4 ,! writ]1 assi/$ by ,pr(4 ,*attock1 _h also made "s exp]im5ts conc]n+ ! production & detection ( waves on a sy/em ( long p>allel wires /ret*$ on insulators across & ar\nd a l>ge room1 & excit$ by ! dis*>ge ( a pair ( cond5s]s1 an arrangem5t v simil> to t n[ kn[n "u ! "n ( ,le*]2 & cle> exp]im5tal evid5ce ( ! exi/5ce ( nodes & loops on su* wires1 z well z a me?od ( approximately measur+ ! wave l5g?1 0 giv54#be ,! bru% lum9osity ( ! wires1 aft]w>ds obs]v$ m /rik+ly by ,tesla1 0 also se5 & %[n to ! ,physical ,society4 ,! int]e/ ( ^! exp]im5ts 01 h[ev]1 altoge!r eclips$ by ! brilliant & ma/]ly inve/igation at ,c>lsruhe by ,h]tz1 :o1 z ev]yone except ! ,briti% public is aw>e1 put into practice ,fitz,gerald's #ahhc sugge/ion t ,leyd5 j> dis*>ges %\ld emit ,maxwellian radiation1 & conclusively demon/rat$ ! exi/5ce & "s ( ! prop]ties ( su* waves by ?is v means2 us+1 h[ev]1 ,leyd5s ( small capacity1 & ) ! coat+s well sep>at$1 s t ! electro/atic en]gy ( ! *>ge %\ld h an int5sity comp>able ) ! magnetic en]gy ( ! dis*>ge1 ev5 at "s di/ance f ! circuit4 #be ,v]bally to ,section ,a at ,ba?1 #ahhh4 ,see also ,phil4 ,mag41 ,augu/1 #ahhh1 p4 #bbi2 & ,! ,electrician1 ,vol4 #ba1 pp4 #fjg-h4 ,! :ole subject ( electric waves 0 ?us laid op5 to physici/s1 & _m h be5 ! work]s 9 ! field4 ,tr\ton1 ( ,dubl91 work$ long & successfully at _! optical analogies1 ) ! v inadequate means ( detection !n kn[n2#bf & s9ce bett] means h be5 kn[n p]haps ! mo/ complete set ( exp]im5ts publi%$1 aft] ,h]tz himself1 is t conta9$ 9 ! book 8,optice ,elettrica10 by ,pr(4 ,righi1 ( ,bologna2 b "s acc\nt ( sev]al previ\s rese>*es is conta9$ 9 ! second edition ( 8,mod]n ,views ( ,electricity10 9 ! *apt] call$ 8,rec5t ,progress10 ( date #ahib4 ,! means us$ by ,h]tz & 8 imm$iate foll[]s to detect ! waves 0 simply ! little sp>k :i* !y excit$ 9 conductors ^u :i* !y fell2 electric curr5ts be+ set up 9 su* conductors by ! act ( reflection4 ,! effect 0 (t5 at t "t attribut$ to electric resonance or syntony1 b !re 0 v little true resonance 9 ^! exp]im5ts2 ! fir/ sw+ 0 usually mu* m p[]ful ?an any ( ! succe$+ ones1 & 0 compet5t to cause ! little sp>k2 if x fail$ ! rema9d] ( ! sw+s _h b a poor *ance ( success4 ,consequ5tly precision ( tun+ 0 n really important1 ?\gh no d\bt x w\ld help a little4 #bf ,nature1 ,vols4 #ci & #dj4 ,x is int]e/+ to note t a magnetic ne$le detector n unlike ,ru!r=d's _h be5 us$ long ago by ,joseph ,h5ry at ,wa%+ton1 & t m9ute induc$ sp>ks1 id5tical 9 all respects ) ^? discov]$ by ,h]tz1 _h be5 se5 9 rec5t times bo? by ,edison & by ,silvanus ,?ompson1 be+ /yl$ 8e!ric =ce0 by ! =m]2 b _! !oretic significance _h n be5 p]ceiv$1 & !y 7 some:at sceptically reg>d$4 ,yet ,h5ry1 ev5 9 ^? pre-,maxwellian days1 0 l$ to an intuition conc]n+ ! spread ( electrical di/urbance surpris+ly ne> ! tru?4 ,! tru? inde$ x 0 9 "s sort1 b x 0 n work$ out or grasp$ 9 detail1 & s _c be consid]$ z m ?an a brilliant guess2 b ! fact t an obs]vation ( ! widespread surg+s induc$ 9 ! neighb\rhood ( a prim>y dis*>ge _h be5 made by ,h5ry1 & _h be5 se5 by o!rs to be capable ( giv+ actual sp>ks1 be=e ! "t ( ,h]tz1 al?\gh x has no real be>+ on ,h]tz's fre% discov]y1 & did n lead ^? :o1 l ! writ]1 _h long be5 try+ to ?9k ( a detector = ,maxwellian waves to discov] "o1 nev]!less is in/ructive z %[+ h[ frequ5tly x happ5s t a fact is ly+ ready to h& b is n tak5 up & appreciat$ until "s special or extra /imulus has be5 suppli$4 ,aft] ,h]tz's results _h become well-kn[n1 ! writ] devis$ a plan :]eby real electric resonance c\ld be demon/rat$ ) a pair ( actual glass ,leyd5 j>s ( ord9>y patt]n1 by connect+ ea* to a dis*>ge circuit1 ! "o complete1 ! o!r ) an air gap1 & provid+ ! fir/ or receiv+ j> ) an ov]fl[ pa? or bye-circuit provid$ ) an air gap across :i* a visible sp>k c\ld occur :5ev] ! induc$ oscillations or surg+s accumulat$ 9 its ma9 circuit 7 suffici5tly int5se to make ! j> ov]fl[4#bg ,! air gap 0 mo/ easily provid$ by a /rip ( t9foil pa/$ ov] ! lip ( ! j>1 b x s]v$ equally well if wires l$ f ! two coat+s to a pair ( adju/able knobs ne> toge!r1 l a lightn+ gu>d1 betwe5 :i* ! ov]fl[ sp>k c\ld pass4 ,! same knobs inde$ 7 us$ z _h already s]v$ = ! lightn+ exp]im5ts2 &1 z 9 t case1 if ! knobs are arrang$ v close toge!r & are put 9 circuit ) a batt]y & a bell1 cohesion sets 9 & ! bell r+s :5ev] ! ov]fl[ occurs4 ,! bell cont9ues to r+ until ! /& is tapp$1 b if ! bell itself t\*es ! /& or ! table1 x rapidly breaks contact by its vibration1 exactly z describ$1 p4 #gg 7see also ,fig4 #af;,a1 p4 #ba74 ,clos$ ,leyd5 j> circuits are n /rong radiators1 nor 0 ?is resonance !n obs]v$ excit$ by true waves4 ,no attempt 0 at ?is "t made to apply ! cohesion pr9ciple to ! detection ( true ,h]tz waves su* z c\ld be felt at a consid]able di/ance f a /rongly radiat+ s\rce4 ,be=e ?is "t1 ,fitz,gerald & ,tr\ton _h hit ^u _! galvanomet] me?od ( demon/rat+ to an audi5ce ! occurr5ce ( ! m9ute sc>cely-visible sp>k 9 ! gap ( a ,h]tz receiv]4#bh #bg ,nature1 ,vol4 #da1 p4 #cfh2 or1 8,mod]n ,views ( ,electricity10 second edition1 p4 #cch4 ,see also ,fig4 #d1 p4 #f4 #bh ,nature1 ,vol4 #da1 p4 #bie2 & ,vol4 #db1 p4 #agb4 ,pr(4 ,m9*9 also1 work+ at ,coop]'s ,hill ) 8 s5sitive photo-electric cells1 especially ) "s :i* he call$ 8impulsion cells10 t behav$ abnormally :5 subject$ to taps or o!r me*anical vibrations1 f\nd t :5 ,mr4 ,gregory 0 work+ a ,h]tz radiator 9 ano!r "p ( ! same laboratory ! electromet] connect$ to 8 cells respond$4#bi ,_m o!r detectors h be5 devis$ & us$1 b ?is ( ,m9*9's almo/ c]ta9ly dep5ds on ! cohesion pr9ciple1 ?\gh its action seem$ p>adoxical !n4 ,moreov] he 0 able1 by its aid1 to signal )\t wires ov] a consid]able numb] ( y>ds1 at t e>ly date 7#ahij & #ahia74 ,ab\t ! same "t1 ,pr(4 ,boltzmann us$ a *>g$ gold-leaf electroscope = ! same purpose1 hav+ x s arrang$ t ! electroscope 0 on ! po9t ( dis*>g+ across a m9ute air gap1 s t its leaves 7 dilat$ by a def9ite am\nt4 ,! slighte/ excess ( *>ge w\ld make x dis*>ge & ! leaves in/antly collapse4 ,9 ?is *>g$ condition x 0 s5sitive to v m9ute electric surg+s1 & if ,h]tz waves 7 excit$ 9 ano!r "p ( ! room1 ! wave di/urbances caus$ ! gap to break d[n & ! electroscope leaves to collapse4#cj ,?is me?od is n a cohesion me?od1 b x l$ ! writ]1 :5 subsequ5tly repeat+ ,boltzmann's results ) modifications1 to realise t1 if ! gap 7 almo/ clos$1 cohesion c\ld be made to set 9 by ! surg+s induc$ by regul> ,h]tz waves 7,fig4 #af1 p4 #ah74 #bi ,phil4 ,mag41 ,m>*1 #ahia2 also ,janu>y1 #ahid4 #cj ,wi$4 ,ann41 ,vol4 #dj4 ,! ,boltzmann gap me?od 0 accord+ly modifi$ 9 sev]al ways2 "o way 0 to make x ( c>bon & to connect x1 ) its wave collector1 to ! t]m9als ( #aaj-volt electric light leads1 s t :5ev] a ,h]tz vibrator 0 dis*>g$ & induc$ a m9ute sp>k across ! gap1 t same sp>k might close ! circuit & e/abli% an arc4 ,?is plan =c$ itself on my att5tion by ! behavi\r ( sundry ,swan lamps susp5d$ ) %ades s z to illum9ate my lecture table1 :i* became %ort-circuit$ :5ev] a l>ge ,h]tz vibrator 0 at "w2 = ! lamps 7 at t "t kept f rotation1 & !reby f gl>+ into ! eyes ( ! audi5ce in/ead ( be+ scre5$ f !m1 by a c\ple ( copp] wires /ret*$ across ! !atre4 ,s long z ^? wires 7 !re1 ! fuses us$ to bl[ :5ev] a ,h]tz oscillator 0 />t$2 an exp]im5t :i* 0 int]e/+ en\gh1 & 0 %[n to sev]al p1 includ+1 ,i ?9k1 ,pr(4 ,fitz,gerald1 b :i* 0 suffici5tly a nuisance to necessitate ! wires1 :i* 7 act+ z collect+ wires1 be+ tak5 d[n & replac$ by /ret*$ silk ?reads1 :i* are !re to ?is day4 ,ano!r modification 0 to connect ! gap to an ,abel's fuse or to a gas leak1 :i* explod$ or ignit$ "u ! influ5ce ( a feeble sp>k4 ,yet ano!r 0 to connect x to a s+le cell & electric bell or galvanomet]1 z already expla9$4 ,mean:ile1 h[ev]1 & well be=e ^! lat] exp]im5ts on ! detection ( ,h]tz waves 7 9 progress1 c]ta9 discov]ies _h be5 made by ,m4 ,branly1 ,pr(essor ( ,physics 9 ! ,ca?olic ,in/itute ( ,p>is1 :i* 7 ( ! greate/ int]e/ & importance4 ,pr(4 ,branly _h f\nd t a coat or v>ni% ( f9e copp] du/1 porphyris$ copp] or o!r su* sub/ance1 ?\gh x c\ld only conduct a curr5t v feebly1 & mu* z a blacklead p5cil trace conducts1 "u ord9>y conditions1 yet fell 9 resi/ance enorm\sly :5ev] an electric sp>k occurr$ 9 its neighb\rhood2 some:at 9 ! fa%ion t ! resi/ance ( sel5ium falls on exposure to light4 ,x is n cle> t ,m4 ,branly recognis$ t he 0 deal+ ) ,h]tz waves or true electrical radiation1 b 8 obs]vations 7 mo/ satisfactory & conclusive1 & he measur$ ! r$uction ( resi/ance caus$ 9 a numb] ( diff]5t sub/ances1 includ+ an assemblage ( metallic fil+s1 & conglom]ates or pa/e ( fil+s 9 v>i\s visc\s liquids & 9 dry p[d]s4 ,moreov]1 he f\nd t ! sp>k 0 /ill op]ative 9 r$uc+ resi/ance ev5 :5 x 0 sev]al y>ds di/ant4 ,! acc\nt ( ,pr(4 ,branly's exp]im5ts is to be f\nd 9 a c\ple ( %ort communications to ! ,fr5* ,academy ( ,sci5ce 7,comptes ,r5dus1 ,vols4 #aaa & #aab71 & ! writ] _h int5d$ to reproduce 9 ab/ract ! gi/ ( ^! memoirs2 b to read]s ( ,! ,electrician ?is is unnecess>y1 z a descriptive article f ,la ,lumire ,electrique has already be5 translat$ 9 full1 9 ,july & ,augu/1 #ahia 7see ,! ,electrician1 ,vol4 ,,xxvii41 pp4 #bba & #ddh1 n[ reproduc$ z ,app5dix74 ,un=tunately ! writ]1 9 common p]haps ) o!rs1 mu/ confess to hav+ ov]look$ ^! articles at ! "t1 probably by reason ( _! co9cid5ce ) ! holiday season4 ,9 8 second edition ( 8,mod]n ,views ( ,electricity10 publi%$ 9 #ahib1 ?\gh he ref]s on page #cei to ! cohesion pr9ciple 9 ?is connection1 ! writ] is cle>ly ignorant ( ,branly's exp]im5ts4 ,! matt] seems to h be5 ignor$ 9 ?is c\ntry till #ahib1 :5 ,dr4 ,dawson ,turn] describ$ ! exp]im5ts to ! ,briti% ,association 9 ,ed9burgh1 & ev5 till #ahic1 :5 ,mr4 ,cr(t br\ght !m to ! notice ( ! ,london ,physical ,society4 ,pr(4 ,m9*9 at once realis$ t "h 0 a ph5om5on analog\s to :at he _h be5 obs]v+ ) 8 impulsion cells1 & aft] a few trials wrote a ,pap] to ! ,physical ,society rec\nt+ 8 repetitions & modifications ( ,branly's exp]im5ts4#ca ,?is ,pap]1 be=e x 0 read1 0 circulat$ by ! ,society to its c\ntry memb]s1 & s came to ! eye ( ! writ]1 :o at once wrote a %ort note summ>is+ "s ( 8 "w 9 ! same direction1 & po9t+ out t ?is discov]y ( ,branly's1 ?us made kn[n to him1 0 ano!r case ( ! electrical cohesion ph5om5on already obs]v$ by sev]al exp]im5t]s4 ,?is is publi%$ along ) ,pr(4 ,m9*9's ,pap] 9 ! ,phil4 ,mag4 = ,janu>y1 #ahid1 & to x ! fri5dly read] is ref]r$4 ,! writ] at once proce$$ to try ! ,branly tube ( fil+s1 & f\nd x f> sup]ior 9 manageability to ei!r ! ,boltzmann gap or 8 own delicately adju/$ coh]+ knobs2 ?\gh imm$iately aft]w>ds he & ,fitz,gerald toge!r arrang$ a s+le-po9t coh]]1 ( iron & alum9ium 7po9t ( sew+ ne$le re/+ on alum9ium foil71 ( :at 0 at t "t extraord9>y s5sitiv5ess & ( reasonable manageability4 ,a :ole s]ies ( quasi-optical exp]im5ts 7 !n und]tak5 ) ! new detector1 & 7 %[n to /ud5ts & to ! ,liv]pool ,physical ,society2 moreov]1 be=e long1 v>i\s improv$ me?ods ( arrang+ ! fil+s 7 gradually adopt$1 especially by seal+ !m up 9 vacuum or 9 an atmosph]e ( hydrog5 7see page #cd7 s z to protect !m f cont9u$ oxidation by ! air1 & to prev5t ! film :i* hypo!tically sep>ates ! surfaces f gr[+ too ?ick4 ,inde$1 brass fil+s 9 hydrog5 spe$ily got too clean1 & became s s5sitive t x 0 almo/ impossible to re/ore ! orig9al high resi/ance by tapp+4 ,consequ5tly1 a p]fect or ,spr5gel vacuum 0 pref]r$ to hydrog54 ,almo/ any fil+s tube c\ld detect signals f a di/ance ( #fj y>ds1 ) a m]e six-in* sph]e z emitt] & )\t ! slighte/ tr\ble1 b ! s+le-po9t coh]] 0 usually mu* m s5sitive ?an any fil+s tube4 ,mr4 ,%el=d ,bidwell has also work$ ) v>ieties ( p[d]4 #ca ,phil4 ,mag41 ,janu>y1 #ahid4 ,! tapp+ back 0 at fir/ p]=m$ by h&1 & = optical exp]im5ts ?is is /ill1 p]haps1 ! mo/ conv5i5t plan2 b automatic tapp]s 7 v soon arrang$1 j z ) ! old knobs2 an electric bell m\nt$ on ! base ( a fil+s tube 7see page #ca7 0 n f\nd v satisfactory1 h[ev]1 because ( ! di/urbances caus$ by ! little sp>ks at its contact-break]1 to :i* ! previ\s co>s] knob-arrangem5ts _h fail$ to respond2 s a clockwork tapp]1 consi/+ ( a rotat+ spoke :eel driv5 by ! clockwork ( a ,morse in/rum5t1 & giv+ to ! fil+s tube or to a coh]] a s]ies ( j]ks occurr+ at regul> int]vals1 to imitate :at ! writ] suppos$ mu/ occur 9 ! eye1 viz41 a re/oration to s5sitiv5ess aft] an int]val correspond+ to ! p]si/5ce ( impression1 0 also employ$4 ,_m ( ^! ?+s 7 %[n at a ,friday ev5+ lecture at ! ,royal ,in/itution on ,june #a1 #ahid1 :ile o!rs 7 %[n ! same autumn at ! ,b4,a4 meet+ at ,ox=d4 ,9 bo? cases signall+ 0 easily c>ri$ on f a di/ance ?r\gh walls & o!r ob/acles1 an emitt] be+ outside & a galvanomet] detector inside ! room4 ,di/ance )\t ob/acle 0 no difficulty 9 ^! exp]im5ts1 only free di/ance is n v easy to get 9 a t[n1 & /upidly en\gh no attempt 0 made to apply any b ! feeble/ p[] s z to te/ h[ f> ! di/urbance c\ld really be detect$4 ,mr4 ,ru!r=d1 h[ev]1 ) a magnetic detector ( 8 own inv5tion1 con/ruct$ on a totally diff]5t pr9ciple1 & probably mu* less s5sitive ?an a coh]]1 did make ! attempt & succe$$ 9 signall+ across half-a-mile1 full ( int]v5+ /reets & h\ses at ,cambridge4#cb #cb ,phil4 ,trans41 #ahig1 ,a41 communicat$ to ! ,royal ,soc41 ,june1 #ahif4 ,numb]s ( p h work$ at ! detection ( ,h]tz waves ) fil+ tube receiv]s1 & e "o ( !m mu/ h kn[n t ! transmission ( telegraphic messages 9 ?is way ov] mod]ate di/ances 0 b a matt] ( dem& & supply2 ,sir ,w4 ,crookes1 inde$1 _h already cle>ly /at$ ?is telegraphic application ( ,h]tz waves 9 ! ,=tnightly ,review = ,febru>y1 #ahib1 & ref]s to c]ta9 exp]im5ts already conduct$ 9 t direction1#cc ! details ( :i* are unkn[n to ! writ] 7b see ,app5dix ,i474 ,!re rema9$ no d\bt a numb] ( po9ts ( detail1 & consid]able improvem5ts 9 con/ruction1 if ! me?od 0 ev] to become practically useful2 b ^! details c\ld safely be left to ^? :o _h *>ge ( ! ,gov]nm5t monopoly ( telegraphs1 especially z _! em95t ,head 0 kn[n to be int]e/$ 9 ?is k9d ( subject4 #cc ,quot$ 9 ,! ,electrician 8,notes10 ,octob] #a1 #ahig4 ,mean:ile ! optical developm5ts ( ! matt] excit$ mo/ int]e/ among physici/s1 bo? "h & on ! cont95t2 ! writ] p]=m$ "s exp]im5ts ( ! k9d1 ,pr(4 ,righi at ,bologna p]=m$ _m m1 & ,pr(4 ,*und] ,bose1 ( ,calcutta1 repeat$ sev]al ( !m ) additions & improvem5ts1 us+ z detector a sort ( half-way h\se betwe5 a po9t coh]] & a fil+s tube by squeez+ a few rolls or spirals ( wire betwe5 a po9t & a micromet] screw4 ,re/oration to s5sitiv5ess 0 9 ?is case a*iev$ by relax+ ! pressure ( ! screw1 & ! writ] has n f\nd ,bose's =m ( coh]] specially conv5i5t2 b ,pr(4 ,bose's :ole app>atus1 con/ruct$ z x 0 precisely on l9es publi%$ by ! writ]1 0 well design$ 9 detail & exce$+ly compact1 be+ on ! scale ( an ord9>y goniomet]2 & ) x _m exp]im5ts famili> 9 ord9>y optics c\ld readily be %[n ) electric radiation4 ,9 all ! optical exp]im5ts made by any ( ^! obs]v]s x 0 cu/om>y to place ! axis ( ! emitt] ei!r horizontally1 or v]tically1 or incl9$1 9 o!r words to emit radiation pol>is$ 9 any azimu? 7or r altitude71 & to arrange ! collect+ "p ( ! receiv] to correspond or o!rwise1 accord+ z response or no response 0 desir$4 ,9 fact1 obs]vations on pol>isation 7 ! easie/ & ! mo/ in/ructive t c\ld be made ) ! def9ite k9d ( radiation n[ = ! fir/ "t at comm&4 ,! rotation ( ! plane ( pol>isation1 ! conv]sion ( plane into elliptical pol>isation1 ! am\nt ( radiation reflect$ by sub/ances at diff]5t angles & diff]5t aspects ) reg>d to ! direction ( vibration1 7 readily obs]v$4 ,fur!rmore1 ev] s9ce ,h]tz's fir/ discov]y1 :5ev] waves _h to travel ?r\gh a metal grid or alongside a plane conductor1 x 0 natural to arrange ! electric oscillations s z to be normal to ! conduct+ l9es or plane1 = if !y 7 tang5tial !y excit$ electric curr5ts !re91 & _! en]gy became wa/$ 9 ! production ( heat4 ,s1 9 s f> z e>? & wat] are conductors1 x is desirable to use radiation pol>is$ 9 a horizontal plane1 i4e41 ) ! electric oscillations v]tical1 if consid]able di/ances are to be trav]s$ by x4 ,) respect to an explanation :y metallic cohesion is caus$ "u electrical influ5ce1 ! foll[+ consid]ations are (f]$3-- ,mr4 ,rollo ,appley>d made a liquid coh]] ( two globules or pools ( m]cury1 side by side & t\*+1 b kept ap>t by a ?9 film ( grease1 su* z is easily giv5 by a coat ( p>aff9 oil4 ,connect+ up a batt]y cell to ^! m]cury pools ?r\gh a key1 he f\nd t e "t ! key is depress$ ! pools move toge!r & become "o2 he po9ts out moreov] t m]cury globules %oot out a t5tacle t[>ds ! positive t]m9al 7on ! pr9ciple ( ! capill>y electromet]1 ( c\rse71 & ?is mu/ be tak5 into acc\nt 9 any coh]] !ory4#cd ,"l ,rayleigh also devis$ & exhibit$ a liquid =m ( coh]]4 ,x is int]e/+ to obs]ve1 z he po9ts out1 t 9 a m]cury =m ( coh]] an appreciable "t int]val occurs betwe5 ! depression ( ! key & ! amalgamation ( ! m]cury1 ! lag look+ z if a film _h to be me*anically squeez$ out betwe5 ! oppositely-*>g$ m]cury surfaces1 & z if ?is took a p]ceptible fraction ( a second to accompli%4 ,?is exp]im5t conveys ! useful sugge/ion t cohesion may 9 all cases be ! result ( electro/atic attraction1 & t ! molecul> films sep>at+ solids 9 contact may ?us also h to be squeez$ out1 ?\gh z !y only t\* at s+le po9ts su* extrusion is almo/ in/antane\sly a*iev$4 ,?is may v likely be ! *ief cause1 = al?\gh a true electro-*emical ext5sion ( ! range ( cohesion betwe5 pol>is$ molecules _h seem$ to ! writ] to be a possible explanation also1 he n[ p]ceives t ! electro/atic =ce alone may be suffici5t4 ,= x is easy to calculate ! =ce ( attraction betwe5 two surfaces diff]+ 9 pot5tial by a volt1 & sep>at$ f "o ano!r by ! smalle/ kn[n ?ickness ( ?9 film 7:i* is #aj c5timetre1 or #a millimicron1 call$ by microscopi/s72 su* =ce p] unit area w\ld be giv5 by ! squ>e ( ! pot5tial gradi5t divid$ by #h1 t is1 x w\ld am\nt to #b #a #aj -------- dynes p] squ>e c5timetre1 #be #cjj :i* equals #dd atmosph]es1 & is a v consid]able pressure4 ,a hundr$ times ?is attractive pressure w\ld exi/ if ! surfaces 7 )9 really molecul> di/ance ( ea* o!r2 9 addition to ! =ce ( true cohesion :i* w\ld !n1 /ill m p[]fully1 op]ate2 b ! film ?ickness assum$ above is su* z w\ld j prev5t ! =ce ( cohesion f effectively act+ across ! gap1 & w\ld leave ! electrical attraction due to ! "o volt alone4 ,?ree & a half volts c\ld !re=e squeeze metals toge!r ) a =ce equal to a ton load p] squ>e in*1 & might ?us be suffici5t to cause !m to weld or unite1 especially if ! electric /imulus simultane\sly act$ 9 any way z a flux1 by r$uc+ ! inf9itesimal t>ni% ( oxide or o!r comp\nd :i* mu/ be suppos$ normally to cov] !m4 #cd ,phil4 ,mag41 ,may & ,july1 #ahig4 ,he also %[s electrical cohesion by an emulsion ( oil & wat]1 ! two liquids1 ?or\ghly %ak5 up1 at once sep>at+ :5 expos$ to /rong electrical influ5ce4 ,9 s f> z ! approximate contact is n betwe5 surfaces1 b betwe5 po9ts consi/+ ( relatively few molecules1 ! attractive pressure is great] r ?an less4 ,?us to take an extreme case1 ! attraction betwe5 two oppositely-*>g$ molecules diff]+ only by a volt f ea* o!r1 & sep>at$ by a ?9 film l ! black spot ( a soap-film ^: ?ickness 0 s admirably measur$ by ,pr(s4 ,re9old & ,rck]1 is ov] #a1jjj atmosph]es 9 int5sity4 ,^! diff]5ces ( pot5tial across ?9 films _c cont9ue = any "t1 unless a batt]y is us$1 = ! films d n really insulate2 !y are able h[ev] to act z dielectrics = an in/ant1 & to be bur/ ) :at we mu/ be all[$ to call a sp>k1 ?\gh an inf9itesimally small "o1 if ! mom5t>y /ra9 caus$ by ! impulsive ru% ( electricity is too great4 ,,app5dix ,i4 ,,pr(4 ,,hughes',s ,,obs]vations4 ,an acc\nt ( ! hi/ory ( ! coh]] pr9ciple w\ld n be complete )\t a ref]5ce to an int]e/+ rem9isc5ce ( e>ly obs]vations rec5tly put on record by ! discov]] ( ! microphone4 ,at ea* /age ( 8 obs]vations ( electrical cohesion betwe5 metals ! au?or 0 confront$ by a ref]5ce to "s e>li] obs]vations ( ,pr(4 ,hughes1 & he felt sure t dur+ ! "w on ! microphone _m or all ( ! ph5om5a he 0 !n obs]v+ mu/ h be5 previ\sly enc\nt]$ by ,pr(4 ,hughes4 ,no full acc\nt 0 at t "t available1 h[ev]1 b n[ x is cle> t ! obs]vations 7 made 7l "s ( ,edison's on :at he call$ e!ric =ce1 & l ! v rem>kable /ill e>li] ones ( ,joseph ,h5ry7 be=e ! "t ( ,h]tz1 :5 ! exi/5ce ( electric waves able to excite sp>ks or p]=m o!r en]getic acts 0 unlook$ = & n cle>ly und]/ood4 ,nev]!less1 at ?is e>ly p]iod x is cle> t ,pr(4 ,hughes obs]v$1 ?\gh he did n foll[ up ! obs]vation1 n only ! occurr5ce ( electric waves or impulses 9 space1 b also ! coh]] me?od ( detect+ !m2 9 fact1 t he unwitt+ly made ! e>lie/ exp]im5ts on wireless telegraphy by ?is plan4 ,! simple/ way is to quote ,pr(4 ,hughes's lett] to ,mr4 ,j4 ,j4 ,fahie f ,! ,electrician1 ,may #e1 #ahii1 p4 #dj1 beg9n+ ) ,mr4 ,fahie's lett] z an introduction3-- ,extract f rec5t lett] f ,mr4 ,j4 ,j4 ,fahie to ,pr(4 ,hughes4 8,,de> ,,pr(4 ,,hughes3 ,i h n[ 9 ! press a hi/ory ( ,wireless ,telegraphy f #ahch to #ahii1 & 9 writ+ to ,sir ,william ,crookes = in=mation he tells me t _m ye>s ago he saw "s exp]im5ts ( y\rs ) ! microphone1 9 :i* y signall$ f "o "p ( a h\se to ano!r )\t connect+ wires1 & he desires me to ref] to y = p>ticul>s4 ,i ?9k1 ) ,sir ,william1 t x is a pity y h n hi!rto publi%$ y\r results1 & ,i s9c]ely hope y w n[ d s4 ,if also y w\ld k9dly fav\r me ) a %ort acc\nt1 ,i c\ld f9d room = x 9 my book1 :i* is n[ 9 ! pr9t]'s h&s4--,s9c]ely y\rs1 ,j4 ,j4 ,,fahie4 ,cl>emont ,hill1 ,/4 ,heli]'s1 ,j]sey1 ,april #bf1 #ahii40 ,reply f ,pr(4 ,d4 ,e4 ,hughes3-- #dj1 ,langham-/reet1 ,w41 ,april #bi1 #ahii4 ,,de> ,,sir3 ,9 reply to y\rs ( ! #bf? in/41 9 :i* y say t ,sir ,william ,crookes has told y 8t he saw "s exp]im5ts ( m9e on arial telegraphy1 9 ab\t ,decemb]1 #ahgi1 ( :i* he ?9ks ,i ought to h publi%$ an acc\nt10 & ( :i* y ask = "s in=mation1 ,i beg to reply ) a few lead+ exp]im5ts t ,i made on ?is subject f #ahgi up to #ahhf3-- 8,9 #ahgi1 be+ engag$ ^u exp]im5ts ) my microphone1 toge!r ) my induction balance1 ,i rem>k$ t at "s "t ,i c\ld n get a p]fect balance 9 ! induction balance1 ?r\gh app>5t want ( insulation 9 ! coils1 b inve/igation %[$ me t ! real cause 0 "s loose contact or microphonic jo9t excit$ 9 "s portion ( ! circuit4 ,i !n appli$ ! microphone 9 ! circuit1 & f\nd t x gave a curr5t or s\nd 9 ! telephone receiv]1 no matt] if ! microphone 0 plac$ direct 9 ! circuit1 or plac$ indep5d5tly at sev]al feet di/ance f ! coils1 ?r\gh :i* an int]mitt5t curr5t 0 pass+4 ,aft] num]\s exp]im5ts1 ,i f\nd t ! effect 0 entirely caus$ by ! extra curr5t produc$ 9 ! prim>y coil ( ! induction balance4 8,fur!r rese>*es prov$ t an int]rupt$ curr5t1 9 any coil1 ?r\gh :i* an electric curr5t 0 s5t1 gave out at ea* int]ruption ( ! prim>y curr5t1 su* int5se extra curr5ts1 t ! :ole atmosph]e 9 ! room 7or 9 sev]al rooms di/ant7 w\ld h a mom5t>y invisible *>ge1 :i* became evid5t if a microphonic jo9t 0 us$ z a receiv] to a telephone4 ,?is l$ me to exp]im5t ^u ! be/ =m ( a receiv] = ^! invisible electric waves1 :i* evid5tly p]meat$ great di/ances1 & ?r\gh all app>5t ob/acles1 su* z walls1 c4 ,i f\nd t all microphonic contacts or jo9ts 7 extremely s5sitive4 ,^? =m$ ( a h>d c>bon su* z coke1 or a comb9ation ( a piece ( coke re/+ ^u a bright /eel contact1 7 v s5sitive & self-re/or+2 :il/ a loose contact betwe5 metals 0 equally s5sitive1 b w\ld coh]e1 or rema9 9 full contact1 aft] ! passage ( an electric wave4 8,! s5sitiv5ess ( ^! microphonic contacts 9 metals has s9ce be5 r$iscov]$ by ,mons4 ,ed4 ,branly1 ( ,p>is1 & by ,pr(4 ,oliv] ,lodge1 9 ,engl&1 by :om ! "n ( #8coh]]' has be5 giv5 to ?is organ ( reception2 b1 z we wi% ?is organ to make a mom5t>y contact & n coh]e p]man5tly1 ! "n seems to me ill-suit$ = ! in/rum5t4 ,! mo/ s5sitive & p]fect receiv] t ,i h yet made does n coh]e p]man5tly1 b recov]s its orig9al /ate in/antly1 &1 !re=e1 requires no tapp+ or me*anical aid to ! sep>ation ( ! contacts aft] mom5t>ily be+ br\ght into close union4 8,i soon f\nd t1 :il/ an invisible sp>k w\ld produce a !rmo-electric curr5t 9 ! microphonic contacts 7suffici5t to be he>d 9 ! telephone 9 its circuit71 x 0 f> bett] & m p[]ful to use a feeble voltaic cell 9 ! receiv+ circuit1 ! microphonic jo9t !n act+ z a relay1 by increas+ & dim9i%+ ! resi/ance at ! contact1 by ! influ5ce ( ! electric wave receiv$ ?r\gh ! atmosph]e4 8,i w n describe ! num]\s =ms ( ! transmitt]1 & receiv]1 t ,i made 9 #ahgi1 all ( :i* ,i wrote d[n 9 sev]al volumes ( manuscripts 9 #ahgi 7b ^! h nev] be5 publi%$71 mo/ ( :i* c be se5 "h at my resid5ce at any "t2 b ,i w conf9e myself n[ to a few sali5t po9ts4 ,i f\nd t v sudd5 electric impulses1 :e!r giv5 out to ! atmosph]e ?r\gh ! extra curr5t f a coil1 or f a frictional electric ma*9e1 equally affect$ ! microphonic jo9t1 ! effect dep5d+ m on ! sudd5 high pot5tial effect ?an any prolong$ action4 ,?us1 a sp>k obta9$ by rubb+ a piece ( seal+-wax 0 equally z effective z a dis*>ge f a ,leyd5 j> batt]y ( ! same pot5tial4 ,! rubb$ seal+-wax1 or *>g$ ,leyd5 j>1 _h no effect1 until !y 7 dis*>g$ by a sp>k1--& x 0 evid5t t ?is sp>k1 h[ev] feeble1 act$ ^u ! :ole surr\nd+ atmosph]e 9 ! =m ( waves1 or invisible rays1 ( :i* ,i c\ld n at ! "t det]m9e4 ,h]tz1 h[ev]1 by a s]ies ( orig9al & ma/]ly exp]im5ts1 prov$ 9 #ahhg-i1 t !y 7 real waves simil> to light1 b ( a l[] frequ5cy1 ?\gh ( ! same velocity4 ,9 #ahgi1 :il/ mak+ ^! exp]im5ts on arial transmission1 ,i _h two diff]5t problems to solve3 #a/1 ,:at 0 ! true nature ( ^! electric arial waves1 :i* seem$1 :il/ n visible1 to spurn all idea ( insulation1 & to p]meate all space to a di/ance undet]m9$4 #bnd1 ,to discov] ! be/ receiv] t c\ld act ^u a telephone or telegraph in/rum5t1 s z to be able to utilise 7:5 requir$7 ^! waves = ! transmission ( messages4 ,! second problem came easy to me1 :5 ,i f\nd t ! microphone1 :i* ,i _h previ\sly discov]$ 9 #ahgg-h1 _h alone ! p[] ( r5d]+ ^! invisible waves evid5t1 ei!r 9 a telephone or galvanomet]1 & up to ! pres5t "t ,i d n "k ( any?+ approa*+ ! s5sitiv5ess ( a microphonic jo9t z a receiv]4 ,branly's tube1 n[ us$ by ,m>coni1 0 describ$ 9 my fir/ ,pap] to ! ,royal ,society 7,may #h1 #ahgh71 z ! microphone tube1 fill$ ) loose fil+s ( z9c & silv]1 & ,pr(4 ,lodge's coh]] is an ord9>y /eel microphone1 us$ = a diff]5t purpose f t 9 :i* ,i fir/ describ$ x4 8,dur+ ! long-cont9u$ exp]im5ts on ?is subject1 betwe5 #ahgi & #ahhf1 _m curi\s ph5om5a came out :i* w\ld be too long to describe4 ,i f\nd t ! effect ( ! extra curr5t 9 a coil 0 n increas$ by hav+ an iron core z an electromagnet--! extra curr5t 0 less rapid &1 !re=e1 less effective4 ,a simil> effect ( a delay 0 produc$ by ,leyd5 j> dis*>ges4 ,! mat]ial ( ! contact-break] ( ! prim>y curr5t _h also a great effect4 ,?us1 if ! curr5t 0 brok5 betwe5 two1 or "o1 piece ( c>bon1 no effect c\ld be p]ceiv$ ( arial waves1 ev5 at %ort di/ances ( a few feet4 ,! extra curr5t f a small coil1 )\t iron1 0 z p[]ful z an int5se sp>k f a second>y coil1 & at t "t my exp]im5ts seem$ to be conf9$ to ! use ( a s+le coil ( my induction balance1 *>g$ by six ,daniell cells4 ,) high] batt]y p[]1 ! extra curr5t inv>iably de/roy$ ! insulation ( ! coils4 8,9 ,decemb]1 #ahgi1 ,i invit$ sev]al p]sons to see ! results !n obta9$4 ,among/ o!rs :o call$ on me & saw my results 73-- 8,decemb]1 #ahgi4--,mr4 ,w4 ,h4 ,preece1 ,f4,r4,s42 ,sir ,william ,crookes1 ,f4,r4,s42 ,sir ,w4 ,rob]t ,au/51 ,f4,r4,s42 ,pr(4 ,w4 ,gryll ,adams1 ,f4,r4,s42 ,mr4 ,w4 ,groves4 8,febru>y #bj1 #ahhj4--,mr4 ,spottiswoode1 ,pres4,r4,s42 ,pr(4 ,huxley1 ,f4,r4,s42 ,sir ,george ,gabriel ,/okes1 ,f4,r4,s4 8,novemb] #g1 #ahhh4--,pr(4 ,dew>1 ,f4,r4,s42 ,mr4 ,l5nox1 ,royal ,in/itution4 8,!y all saw exp]im5ts ^u arial transmission1 z already describ$1 by means ( ! extra curr5t produc$ f a small coil & receiv$ ^u a semi-metallic microphone1 ! results be+ he>d ^u a telephone 9 connection ) ! receiv+ microphone4 ,! transmitt] & receiv] 7 9 diff]5t rooms1 ab\t #fj ft4 ap>t4 ,aft] try+ successfully all di/ances all[$ 9 my resid5ce 9 ,portl&-/reet1 my usual me?od 0 to put ! transmitt] 9 op]ation & walk up & d[n ,great ,portl&-/reet ) ! receiv] 9 my h&1 ) ! telephone to ! e>4 8,! s\nds seem$ to slightly increase = a di/ance ( #fj y>ds1 !n gradually dim9i%1 until at #ejj y>ds ,i c\ld no long] ) c]ta9ty he> ! transmitt$ signals4 ,:at /ruck me z rem>kable 0 t1 opposite c]ta9 h\ses1 ,i c\ld he> bett]1 :il/ at o!rs ! signals c\ld h>dly be p]ceiv$4 ,h]tz's discov]y ( nodal po9ts 9 reflect$ waves 79 #ahhg-i7 has expla9$ to me :at 0 !n consid]$ a my/]y4 8,at ,mr4 ,a4 ,/roh's telegraph in/rum5t manufactory1 ,mr4 ,/roh & myself c\ld he> p]fectly ! curr5ts transmitt$ f ! ?ird /ory to ! basem5t1 b ,i c\ld n detect cle> signals at my resid5ce ab\t a mile di/ant4 ,! innum]able gas & wat] pipes int]v5+ seem$ to absorb or weak5 too mu* ! feeble transmitt$ extra curr5ts f a small coil4 8,! ,presid5t ( ! ,royal ,society1 ,mr4 ,spottiswoode1 toge!r ) ! two hon4 secret>ies1 ,pr(4 ,huxley & ,pr(4 ,g4 ,/okes1 call$ ^u me on ,febru>y #bj1 #ahhj1 to see my exp]im5ts ^u arial transmission ( signals4 ,! exp]im5ts %[n 7 mo/ successful1 & at fir/ !y seem$ a/oni%$ at ! results1 b t[>ds ! close ( ?ree h\rs' exp]im5ts ,pr(4 ,/okes said1 #8t all ! results c\ld be expla9$ by kn[n electromagnetic induction effects1 & !re=e he c\ld n accept my view ( actual arial electric waves unkn[n up to t "t1 b ?\ght ,i _h q en\gh orig9al matt] to =m a ,pap] on ! subject to be read at ! ,royal ,society4' 8,i 0 s disc\rag$ at be+ unable to conv9ce !m ( ! tru? ( ^! arial electric waves1 t ,i actually refus$ to write a ,pap] on ! subject1 until ,i 0 bett] prep>$ to demon/rate ! exi/5ce ( ^! waves2 & ,i cont9u$ my exp]im5ts = "s ye>s1 9 hopes ( arriv+ at a p]fect sci5tific demon/ration ( ! exi/5ce ( arial electric waves1 produc$ by a sp>k f ! extra curr5ts 9 coils1 or f frictional electricity or second>y coils4 ,! triumphant demon/ration ( ^! waves 0 res]v$ to ,pr(4 ,h]tz1 :o by 8 ma/]ly rese>*es ^u ! subject 9 #ahhg-i completely demon/rat+ n only _! exi/5ce b _! id5tity ) ord9>y light1 9 hav+ ! p[] ( be+ reflect$ & refract$1 c41 ) nodal po9ts1 by means ( :i* ! l5g? ( ! waves c\ld be measur$1 ,h]tz's exp]im5ts 7 f> m conclusive ?an m9e1 al?\gh he us$ a mu* less effective receiv] ?an ! microphone or coh]]4 8,i !n felt x 0 n[ too late to br+ =w>d my previ\s exp]im5ts1 & ?r\gh n publi%+ my results1 & means employ$1 ,i h be5 =c$ to see o!rs remake ! discov]ies ,i _h previ\sly made z to ! s5sitiv5ess ( ! microphonic contact1 & its useful employm5t z a receiv] = electric arial waves4 ,among/ ! e>lie/ work]s 9 ! field ( arial transmission ,i w\ld draw att5tion to ! exp]im5ts ( ,pr(4 ,h5ry1 :o describes 9 8 "w1 publi%$ by ! ,smi?sonian ,in/itute1 ,wa%+ton1 ,d4,c41 ,u4,s4,a41 ,vol4 ,i41 p4 #bjc 7date unkn[n1 probably ab\t #ahej71 t he magnetis$ a ne$le 9 a coil at #cj ft4 di/ance1 & magnetis$ a ne$le by a dis*>ge ( lightn+ at eight miles di/ance4 8,m>coni has lately demon/rat$ t by ! use ( ! ,h]tzian waves & ,branly's coh]] he has be5 enabl$ to transmit & receive arial electric waves to a great] di/ance ?an previ\sly ev] dream$ ( by ! num]\s discov]]s & inv5tors :o h work$ sil5tly 9 ?is field4 ,8 ef=ts at demon/ration m]it ! success he has receiv$2 & if 7z ,i h lately read7 he has discov]$ ! means ( conc5trat+ ^! waves on a s+le po9t desir$ )\t dim9i%+ its p[]1 !n ! _w w be "r 9 plac+ 8 "n on ! highe/ p9nacle 9 relation to arial electric telegraphy4--,y\rs1 c41 ,d4 ,e4 ,,hughes40 ,,app5dix ,,ii4 ,,v>iations ,,( ,,conductivity ,,"u ,,electrical ,,influ5ce4 ,! foll[+ is ab/ract$ f an article by ,m4 ,e4 ,branly 9 ,la ,lumire ,electrique ( ,may #af1 #ahia1 & is tak5 f ,! ,electrician ( ,june #bf1 #ahia3-- ,! object ( ?is article is to describe ! fir/ results obta9$ 9 an inve/igation ( ! v>iation ( resi/ance ( a l>ge numb] ( conductors "u v>i\s electrical influ5ces4 ,! sub/ances :i* up to ! pres5t h pres5t$ ! greate/ v>iations 9 conductivity are ! p[d]s or fil+s ( metals4 ,! enorm\s resi/ance (f]$ by metal 9 a /ate ( p[d] is well kn[n2 inde$1 if we take a some:at long column ( v f9e metallic p[d] ! passage ( ! curr5t is completely /opp$4 ,! increase 9 ! electrical conductivity by pressure ( p[d]$ conduct+ sub/ances is well kn[n1 & has _h v>i\s practical applications4 ,! v>iations ( conductivity1 h[ev]1 :i* occur on subject+ conduct+ bodies to v>i\s electrical influ5ces h n be5 previ\sly inve/igat$4 ,! ,effect ( ,electric ,sp>ks4--,let u take a circuit compris+ a s+le cell1 a galvanomet]1 & "s p[d]$ metal enclos$ 9 an ebonite tube ( #a squ>e c5timetre cross-section & a few c5timetres long4 ,close ! extremities ( ! tube ) two cyl9drical copp] tubes press+ aga9/ ! p[d]$ metal & connect$ to ! re/ ( ! circuit4 ,if ! p[d] is suffici5tly f9e1 ev5 a v s5sitive galvanomet] does n %[ any evid5ce ( a curr5t pass+4 ,! resi/ance is ( ! ord] ( millions ( ohms1 al?\gh ! same metal melt$ or "u pressure w\ld only (f] 7! dim5sions be+ ! same7 a resi/ance equal to a fraction ( an ohm4 ,!re be+1 !re=e1 no curr5t 9 ! circuit1 a ,leyd5 j> is dis*>g$ at "s little di/ance (f1 & ! abrupt & p]man5t deflection ( ! galvanomet] ne$le %[s t an imm$iate & a p]man5t r$uction ( ! resi/ance has be5 caus$4 ,! resi/ance ( ! metal is no long] to be measur$ 9 millions ( ohms1 b 9 hundr$s4 ,its conductivity increases ) ! numb] & int5sity ( ! sp>ks4 ,"s #bj or #cj c5timetres f a circuit compris+ "s metallic fil+s conta9$ 9 an ebonite cup1 let u place a holl[ brass sph]e1 #ae to #bj c5timetres 9 diamet]1 insulat$ by a v]tical glass support4 ,! fil+s (f] an enorm\s resi/ance & ! galvanomet] ne$le rema9s at z]o4 ,b if we br+ an electrifi$ /ick ( res9 ne> ! sph]e1 a little sp>k w pass betwe5 ! /ick & ! sph]e1 & imm$iately ! ne$le ( ! galvanomet] is viol5tly j]k$ & !n rema9s p]man5tly deflect$4 ,on "s fre% fil+s be+ plac$ 9 ! ebonite cup1 ! resi/ance ( ! circuit w aga9 keep ! ne$le at z]o4 ,if n[ ! *>g$ brass sph]e is t\*$ ) ! f+]1 !re is a m9ute dis*>ge & ! galvanomet] ne$le is aga9 deflect$4 ,) a few accumulators ! exp]im5t c easily be made )\t a galvanomet]4 ,! circuit consi/s ( ! batt]y1 "s metallic p[d]1 a plat9um wire1 & a m]cury cup4 ,! resi/ance ( ! p[d] is s high t ! int]ruption ( ! circuit takes place )\t any sp>k+ at ! m]cury cup4 ,if n[ a ,leyd5 j> is dis*>g$ 9 ! neighb\rhood ( ! circuit ! p[d] is r5d]$ conduct+1 ! plat9um wire imm$iately becomes r$ hot1 & a viol5t sp>k occurs on break+ ! circuit4 ,! influ5ce ( ! sp>k decreases z ! di/ance increases1 b its influ5ce is obs]vable sev]al metres away f ! p[d]1 ev5 ) a small ,wim%ur/ ma*9e4 ,repeat+ ! sp>k increases ! conductivity2 9 fact1 ) c]ta9 sub/ances successive sp>ks produce successive j]ks1 & a gradually increas+ & p]si/5t deflection ( ! galvanomet]4 ,influ5ce ( a ,conductor trav]s$ by ,cond5s] ,dis*>ges4--,:ile us+ a ,wim%ur/ ma*9e x 0 notic$ t ! r$uction 9 ! resi/ance ( ! fil+s frequ5tly took place be=e dis*>ge4 ,?is l$ me to ! foll[+ exp]im5t3 ,take a long brass tube1 "o end ( :i* is close to ! circuit conta9+ ! metallic p[d]2 its o!r end1 sev]al metres di/ant f ! circuit1 is fairly close to a *>g$ ,leyd5 j>4 ,a sp>k takes place & ! conductor is *>g$4 ,at ! same in/ant1 ! conductivity ( ! metallic p[d] is greatly increas$4 ,! foll[+ arrangem5t1 ow+ to its efficacy1 conv5i5ce1 & regul>ity ( action 0 us$ by me 9 mo/ ( my rese>*es1 & ,i %all briefly call x ! ,a arrangem5t 7see ,fig4 #ec74 ,illu/ration3 ,,fig4 #ec4 ,illu/ration3 ,,fig4 #ed4 ,! s\rce ( electricity is a two-plate ,holtz ma*9e driv5 at f #ajj to #djj revolutions4 ,a s5sitive sub/ance is introduc$ into "o ( ! arms ( a ,:eat/one bridge1 or into ! circuit ( a s+le ,daniell cell at a di/ance ( "s #aj metres 7#cd;ft47 f ! ,holtz ma*9e4 ,betwe5 ! dis*>ge knobs ( ! ma*9e & ! ,:eat/one bridge1 & connect$ to ! =m]1 !re are two insulat$ brass tubes1 ,a ,a1 runn+ p>allel to "o ano!r #dj c5timetres ap>t4 ,! ,leyd5 j>s usually atta*$ to a ,holtz ma*9e may be disp5s$ )1 ! capacity ( ! long brass tubes be+ 9 "s measure equival5t to !m4 ,! knobs ,s 7 #a mm41 #e mm41 or #a mm4 ap>t4 ,:5 ! plates 7 rotat$ sp>ks rapidly succe$$ ea* o!r4 ,exp]im5ts %[$ t ^! sp>ks _h no direct effect at a di/ance ( #aj metres4 ,! two tubes ,a ,a are n absolutely necess>y1 ! dim9ution ( resi/ance is easily produc$ if only "o is employ$1 & 9 "s cases1 inde$1 a s+le conductor is m efficaci\s4 ,an increase 9 ! spe$ ( ! ma*9e increases its action to a m>k$ ext5t4 ,! sp>ks at ,s may be suppress$ by draw+ ! knobs ap>t1 b ! conductor ,a w /ill cont9ue to ex]t its influ5ce1 especially if !re is a sp>k gap any:]e ab\t4 ,effects ( ,induc$ ,curr5ts4--,! passage ( induc$ curr5ts ?r\gh a s5sitive sub/ance produces simil> effects to ^? describ$ above4 ,9 "o in/ance an induction coil 0 tak51 hav+ two simil> wires4 ,! circuit ( ! second>y wire 0 clos$ ?r\gh a tube conta9+ fil+s1 ! galvanomet] be+ also 9 circuit4 ,c>e 0 tak5 to asc]ta9 be=e introduc+ ! fil+s into ! circuit t ! curr5ts on make-&-break gave equal & opposite deflections4 ,fil+s 7 !n introduc$ into ! circuit1 ! prim>y be+ made & brok5 at regul> int]vals4 ,! foll[+ table gives ! results obta9$ 9 ! case ( z9c fil+s3-- ,,z9c ,,fil+s4 ,galvanomet] ?r[s4 ,galvanomet] ?r[s4 #a/ clos+ #a #a/ op5+ #ah #bnd 0 #fd #bnd 0 #ajj #crd 0 #adf #crd 0 #adj ,effects ( ,pass+ ,cont9u\s ,curr5ts ( ,high ,e4,m4,f4--,if a cont9u\s curr5t ( high ,e4,m4,f4 is employ$1 x r5d]s a s5sitive sub/ance conduct+4 ,! ph5om5on may be %[n 9 ! foll[+ mann]4 ,a circuit is made up consi/+ ( a batt]y1 a s5sitive sub/ance1 & a galvanomet]4 ,! ,e4,m4,f4 ( ! batt]y is fir/ "o volt1 !n #ajj volts1 !n "o volt4 ,bel[ ,i give ! galvanomet] deflections obta9$ ) an ,e4,m4,f4 ( "o volt = ?ree diff]5t sub/ances be=e & aft] ! application ( ! ,e4,m4,f4 ( #ajj volts3-- ,be=e application ( curr5t4 ,aft] application ( curr5t4 #af #ajj #j #ae #a #ejj ,9 ! case ( "s measurem5ts tak5 on a ,:eat/one bridge a prism ( alum9ium fil+s int]pos$ betwe5 two copp] electrodes (f]$ a resi/ance ( sev]al million ohms be=e a high ,e4,m4,f4 0 appli$1 b only (f]$ a resi/ance ( #cej ohms aft] ! application ( ?is pressure = "o m9ute4 ,! "t dur+ :i* ! p[d] %\ld be int]pos$ 9 ! batt]y circuit %\ld n be too %ort4 ,?us1 9 "o in/ance1 ! application = #aj sec4 ( #ge m]cury sulphate cells produc$ no effect1 b _! application = #fj sec4 result$ 9 ! resi/ance be+ r$uc$ f sev]al megohms to #b1ejj ohms4 ,x %\ld be obs]v$ t ! ph5om5on ( sudd5ly increas$ conductivity occurs1 ev5 if ! s5sitive sub/ance is n 9 circuit ) a batt]y at ! "t x is influ5c$4 ,?us1 ! metallic fil+s1 aft] hav+ be5 plac$ 9 circuit ) a ,daniell cell1 & its high resi/ance obs]v$1 may !n be completely insulat$ & submitt$ 9 ?is condition to ! action ( a di/ant sp>k1 or ( a *>g$ rod1 or ( induc$ curr5ts4 ,if1 aft] ?is1 ! fil+s are replac$ 9 _! orig9al circuit1 ! enorm\s increase 9 _! conductivity is imm$iately app>5t4 ,! conductivity produc$ by ^! v>i\s me?ods takes place ?r\gh\t ! :ole mass ( ! metallic fil+s1 & 9 e direction1 z ! foll[+ exp]im5t w %[4 ,a v]tical ebonite cup conta9+ alum9ium p[d] 7see ,fig4 #ed7 is plac$ betwe5 two metal plates1 ,a1 ,b2 lat]ally ! p[d] is 9 contact ) two %ort rods1 ,c1 ,d1 :i* pass ?r\gh ! sides ( ! ebonite cyl9d]4 ,a & ,b c be connect$ to two t]m9als ( "o ( ! arms ( ! ,:eat/one bridge1 ,c & ,d be+ free1 & vice v]s4 ,:atev] arrangem5t is adopt$1 if a batt]y ( #ajj cells is jo9$ up = a few seconds ) "o or ! o!r ( ! pairs ( t]m9als1 ! increase 9 ! conductivity is imm$iately visible 9 t direction1 & is f\nd to exi/ also 9 ! direction at "r angles4 ,sub/ances 9 :i* ,dim9ution ( ,resi/ance has be5 ,obs]v$4--,! sub/ances 9 :i* ! ph5om5on ( ! sudd5 increase ( conductivity is mo/ easily obs]v$ are fil+s ( iron1 alum9ium1 copp]1 brass1 antimony1 tellurium1 cadmium1 z9c1 bismu?1 c4 ,! size ( ! gra9s & _! nature are n ! only elem5ts to be consid]$1 = gra9s ( lead ( ! same size1 b com+ f diff]5t qu>t]s1 (f] at ! same temp]ature great diff]5ces 9 resi/ance 7#bj1jjj to #ejj1jjj ohms74 ,extremely f9e metallic p[d]1 z a rule1 (f]s almo/ p]fect resi/ance to ! passage ( a curr5t4 ,b if we take a suffici5tly %ort column & ex]t a suffici5tly great pressure a po9t is soon rea*$ :5 ! electrical influ5ce w effect a sudd5 increase 9 ! conductivity4 ,?us1 a lay] ( copp] r$uc$ by hydrog51 :i* does n become conduct+ "u ! influ5ce ( ! electric sp>k or o!rwise1 w become s on be+ submitt$ to a pressure ( #ejj grammes to ! squ>e c5timetre 7#g lb4 p] squ>e in*74 ,in/ead ( us+ pressure1 ,i employ$ z a conductor 9 "s exp]im5ts a v f9e coat+ ( p[d]$ copp] spread on a %eet ( unpoli%$ glass or ebonite ,e 7,fig4 #ee71 sev5 c5timetres long & two c5timetres broad4 ,a lay] ( ?is k9d1 poli%$ ) a burni%]1 has a v v>iable resi/ance4 ,) a little c>e "o c prep>e %eets :i* are m or less s5sitive to electrical action4 ,illu/ration3 ,,fig4 #ee4 ,metal p[d] or metal fil+s are n ! only s5sitive sub/ances1 z p[d]$ gal5a1 :i* is slightly conduct+ "u pressure1 conducts mu* bett] aft] hav+ be5 submitt$ to electrical influ5ce4 ,p[d]$ b9oxide ( maganese is n v s5sitive unless mix$ ) p[d]$ antimony & compress$4 ,mak+ use ( ! ,a arrangem5t1 ) v %ort sp>ks at ,s 7,fig4 #ce71 ! ph5om5on ( increas$ conductivity c be obs]v$ ) plat9is$ & silv]$ glass1 also ) glass cov]$ ) gold1 silv] & alum9ium foil4 ,"s ( ! mixtures employ$ _h ! consi/5cy ( pa/e4 ,^! 7 mixtures ( colza oil & iron1 or antimony fil+s1 & ( e!r or petroleum & alum9ium1 & plumbago1 c4 ,o!r mixtures 7 solid4 ,if we make a mixture ( iron fil+s & ,canada balsam1 melt$ 9 a wat] ba?1 & p\r ! pa/e into a little ebonite cup1 ! ends ( :i* are clos$ by metallic rods1 a sub/ance is obta9$ :i* solidifies on cool+4 ,! resi/ance ( su* a mixture is l[]$ f sev]al megohms to a few hundr$ ohms by an electric sp>k4 ,simil> results are obta9$ ) a solid rod compos$ ( fus$ fl[]s ( sulphur & iron or alum9ium fil+s1 also by a mixture ( melt$ res9 & alum9ium fil+s4 ,9 ! prep>ation ( ^! solid s5sitive mixtures c>e mu/ be tak5 t ! insulat+ sub/ance %\ld only =m a small p]c5tage ( ! :ole4 ,"s int]e/+ results are also obta9$ ) mixtures ( sulphur & alum9ium1 & ) res9 & alum9ium1 :5 9 a /ate ( p[d]4 ,:5 cold1 ^! mixtures z a rule d n conduct ei!r directly or aft] !y h be5 expos$ to electrical influ5ces1 b !y become conduct+ on comb9+ pressure ) electrical influ5ces4 ,?us1 a mixture ( fl[]s ( sulphur & alum9ium fil+s 9 equal volumes 0 plac$ 9 a glass tube #bd mm4 9 diamet]4 ,! weight ( ! mixture 0 #bj grammes1 & ! height ( ! column #bb mm42 ) a pressure ( #ahf grammes p] squ>e c5timetre 7#b lb4 p] squ>e in*74 ,! mixture is n conduct+1 b aft] exposure to electrical influ5ce1 obta9$ by ! ,a arrangem5t1 ! resi/ance falls to #ij ohms4 ,9 a simil> mann] a mixture ( sel5ium & alum9ium1 plac$ 9 a tube #ii mm4 long1 0 n conduct+ until aft] x 0 expos$ to ! comb9$ influ5ce ( pressure & electricity4 ,! foll[+ is "o ( ! gr\p ( num]\s exp]im5ts ( a slightly diff]5t "*4 ,a mixture ( fl[]s ( sulphur & f9e alum9ium fil+s1 conta9+ two ( sulphur to "o ( alum9ium1 is plac$ 9 a cyl9drical glass tube #ce mm4 long4 ,by means ( a pi/on1 a pressure ( #bj kilogrammes p] squ>e c5timetre 7#bhd lb4 p] squ>e in*7 0 appli$4 ,x 0 only necess>y to connect ! column = #aj sec4 to ! poles ( a #be cell batt]y1 = ! resi/ance orig9ally inf9ite to be r$uc$ to #d1jjj ohms4 ,! arrangem5t %[n 9 ,fig4 #ef illu/rates ano!r ord] ( exp]im5t4 ,two rods ( copp] 7 oxidis$ 9 ! flame ( a ,buns5 burn]1 & 7 !n arrang$ to lie across ea* o!r1 z %[n1 & 7 connect$ to ! t]m9als ( ! arm ( a ,:eat/one bridge1 ! high resi/ance ( ! circuit be+ due to ! lay]s ( oxide4 ,among/ ! _m measurem5ts made1 ,i f\nd1 9 "o case1 a resi/ance ( #hj1jjj ohms1 :i*1 aft] exposure to ! influ5ce ( ! electric sp>k1 0 r$uc$ to #g ohms4 ,analog\s effects are obta9$ ) oxidis$ /eel rods4 ,ano!r pretty exp]im5t is to place a cyl9d] ( copp]1 ) an oxidis$ hemisph]ical head1 on a %eet ( oxidis$ copp]4 ,be=e exposure to ! influ5ce ( ! electric sp>k1 ! oxide (f]s consid]able resi/ance4 ,! exp]im5t c be repeat$ sev]al times by m]ely mov+ ! cyl9d] f "o place to ano!r on ! oxidis$ %eet ( copp]1 ?us %[+ t ! ph5om5on only takes place at ! po9t ( contact ( ! two lay]s ( oxide4 ,illu/ration3 ,,fig4 #ef4 ,9 conclusion1 x may be wor? not+ t1 = mo/ ( ! sub/ances enum]at$1 an elevation ( temp]ature dim9i%es ! resi/ance1 b ! effect ( a rise ( temp]ature is transi5t1 & is incomp>ably less ?an ! effect due to curr5ts ( high pot5tial4 ,= a few sub/ances ! two effects are oppos$4 99 99 99 99 99 ,a second article by ,mr4 ,branly 9 ,la ,lumire ,electrique 0 ab/ract$ 9 ,! ,electrician = ,augu/ #ba1 #ahia1 z foll[s3-- ,9 a prec$+ article ,i %[$ t c]ta9 sub/ances und]go an increase 9 conductivity "u v>i\s electrical influ5ces1 & t ^! sub/ances are num]\s4 ,! increase 9 conductivity v>ies ) ! en]gy ( ! excit+ s\rce4 ,if ! electric influ5ce is due to ! passage ( a cont9u\s curr5t1 ! increase 9 conductivity is great] ! great] ! electromotive =ce ( ! batt]y employ$4 ,!re is1 h[ev]1 no proportionality1 ! increas$ conductivity gr[+ m rapidly ?an ! numb] ( cells1 & t5d+ quickly to a maximum4 ,if ! electric action consi/s 9 ! passage ( dis*>ge curr5ts 9 metallic rods1 z 9 arrangem5t ,a 7,fig4 #ec1 p4 #ig71 ! conductivity increases ) ! l5g? ( sp>k at ,s1 & x also increases :5 ! rods are br\ght ne>] ! s5sitive sub/ance4 ,successive sp>ks are additive 9 _! effects1 al?\gh1 if ! action ( ! fir/ "o has be5 v p[]ful1 ! resi/ance is sometimes almo/ imm$iately r$uc$ to a m9imum4 ,re/oration ( ,orig9al ,resi/ance4--,! conductivity causes by ! v>i\s electrical influ5ces la/s sometimes = a long p]iod 7#bd h\rs or m71 b x is always possible to make x rapidly disappe>1 p>ticul>ly by a %ock4 ,! majority ( sub/ances te/$ %[$ an increase ( resi/ance on be+ %ak5 previ\s to be+ submitt$ to any special electrical influ5ce1 b aft] hav+ be5 influ5c$ ! effect ( %ock is mu* m m>k$4 ,! ph5om5on is be/ se5 ) ! metallic fil+s1 b x c also be obs]v$ ) metalis$ ebonite %eets ) mixtures ( liquid insulators & metallic p[d]s1 mixtures ( metallic fil+s & insulat+ sub/ances 7compress$ or n compress$71 & f9ally ) solid bodies4 ,i obs]v$ ! return to orig9al resi/ance 9 ! foll[+ mann]3--,! s5sitive sub/ance 0 plac$ at ,k 7,fig4 #ec71 & =m$ "p ( a circuit :i* includ$ a ,daniell cell & galvanomet]4 ,at fir/ no curr5t passes4 ,sp>ks are !n caus$ at ,s1 & ! ne$le ( ! galvanomet] is p]man5tly deflect$4 ,on sm>tly tapp+ ! table support+ ! ebonite cap 9 :i* ! s5sitive sub/ance is conta9$1 ! orig9al condition is completely re/or$4 ,:5 ! electric action has be5 ( a p[]ful "*1 viol5t bl[s are necess>y4 ,i employ$ = ! purpose ( ^! %ocks a hamm] fix$ on ! table1 ! bl[s ( :i* c\ld be regulat$4 ,) "s sub/ances1 :5 feebly electrifi$1 ! return seem$ to be spontane\s1 al?\gh x 0 sl[] ?an ! return ( ! galvanomet] ne$le to equilibrium4 ,?is re/oration ( ! orig9al resi/ance is attributable to surr\nd+ trepidations1 z x 0 only necess>y to walk ab\t ! room at a di/ance ( a few metres1 or to %ake a di/ant wall4 ,?is spontane\s return to orig9al resi/ance aft] weak electrical action 0 visible ) a mixture ( equal p>ts ( f9e sel5ium & tellurium p[d]s4 ,! re/oration ( resi/ance by %ock 0 n obs]vable s long z ! electrical influ5ce 0 at "w4 ,aft] hav+ be5 submitt$ to p[]ful electric action1 %ock does n seem to entirely re/ore sub/ances to _! orig9al /ate1 9 fact1 ! sub/ances g5]ally %[ great] s5sitiv5ess to electric action4 ,?us1 a mixture ( colza oil & antimony p[d] be+ expos$ to ! influ5ce ( arrangem5t ,a1 a sp>k ( #e mm4 0 at fir/ necess>y to break d[n ! resi/ance1 b aft] ! conductivity _h be5 made to disappe> by means ( bl[s1 a sp>k ( only #a mm4 0 suffici5t to aga9 r5d] ! sub/ance conduct+4 ,f9ely p[d]$ alum9ium has an extremely high resi/ance4 ,a v]tical column ( p[d]$ alum9ium #e mm4 long ( #d sq4 cms4 cross-section1 submitt$ to consid]able pressure1 completely /opp$ ! curr5t f a ,daniell cell4 ,! influ5ce ( arrangem5t ,a produc$ no effect1 b1 by direct contact ) a ,leyd5 j>1 ! resi/ance 0 r$uc$ to #ej ohms4 ,! effect ( %ock 0 !n tri$1 & aft] ?is ! sp>ks produc$ by arrangem5t ,a 7 able to r$uce ! resi/ance4 ,! foll[+ exp]im5t is also ( ! same k9d4 ,alum9ium fil+s plac$ 9 a p>allelipidic tr\gh completely /opp$ ! curr5t f a ,daniell cell1 & ! resi/ance (f]$ to a s+le cell rema9$ inf9ite aft] ! tr\gh _h be5 plac$ 9 ! circuit ( #be sulphate ( m]cury cells = #ajsec4 ,! alum9ium 0 next plac$ 9 circuit ) a batt]y ( #ge cells2 a s+le ,daniell cell 0 !n able to s5d a curr5t ?r\gh ! sub/ance4 ,! orig9al resi/ance 0 re/or$ by %ock1 b n ! orig9al condition ( ?+s1 s9ce a s+le cell 0 able to s5d a curr5t aft] ! alum9ium _h be5 circuit$ = #aj sec4 ) a batt]y ( only #be cells4 ,i may add t if ! re/oration ( resi/ance 0 br\ght ab\t by a viol5t %ock1 x 0 necess>y to place ! alum9ium 9 circuit ) #ge cells = "o m9ute be=e ! resi/ance 0 aga9 brok5 d[n4 ,x mu/ be obs]v$ t electrical influ5ce is n always necess>y to re/ore conductivity aft] an app>5t return to ! orig9al resi/ance1 repeat$ feeble bl[s be+ sometimes successful 9 br++ ?is ab\t4 ,bo? 9 ! case ( sl[ return by "t & sudd5 return by %ock1 ! orig9al value ( ! resi/ance is (t5 increas$4 ,rods ( ,c>r c>bon1 #a metre long & #a mm4 9 diamet]1 7 p>ticul>ly noticeable = ?is ph5om5on4 ,return to ,orig9al ,resi/ance by ,temp]ature ,elevation4--,a plate ( copp]$ ebonite r5d]$ conduct+ by electricity1 & plac$ close to a gas jet1 quickly rega9$ its orig9al resi/ance4 ,a solid rod ( res9 & alum9ium1 or ( sulphur & alum9ium1 r5d]$ conduct+ by connection to ! poles ( a small batt]y w rega9 its orig9al resi/ance by %ock2 b if ! conduct+ /ate has be5 caus$ by p[]ful means1 su*1 = in/ance1 z direct contact ) a ,leyd5 j>1 %ock no long] has any effect1 at lea/ su* a %ock z ! fragile nature ( ! mat]ial c /&4 ,a slight rise ( temp]ature1 h[ev]1 has ! desir$ result4 ,by suitably regulat+ ! electric action x is possible to get a sub/ance into su* a condition t ! w>m? ( ! f+]s suffices to annul conductivity4 ,influ5ce ( ,surr\nd+s4--,electric action gives rise to no alt]ation ( resi/ance :5 ! sub/ance is entirely )9 a clos$ metal box4 ,! s5sitive sub/ance1 9 circuit ) a ,daniell cell & a galvanomet]1 is plac$ inside a brass box 7,fig4 #ed1 p4 #ig74 ,! abs5ce ( curr5t is asc]ta9$1 ! circuit brok51 & ! box clos$4 ,a ,wim%ur/ ma*9e is !n work$ a little way (f1 & w be f\nd to h _h no effect4 ,! same result w be obta9$ if ! circuit is kept clos$ dur+ ! "t ! ,wim%ur/ ma*9e is 9 op]ation4 ,if a wire connect$ at "s po9t to ! circuit is pass$ out ?r\gh a hole 9 ! box to a di/ance ( #bj cm4 to #ej cm41 ! influ5ce ( ! ,wim%ur/ ma*9e makes itself felt4 ,on tapp+ ! lid to re/ore resi/ance ! galvanomet] ne$le rema9s deflect$ s long z ! sp>ks cont9ue to pass4 ,if1 h[ev]1 ! wires are pu%$ 9 s t !y only project a few millimetres1 ! sp>ks /ill pass+1 a few taps suffice to br+ back ! ne$le to z]o4 ,on t\*+ ! end ( ! wire ) ! f+]s or a piece ( metal conductivity is imm$iately re/or$4 ,! movem5ts ( ! galvanomet] ne$le 7 r5d]$ visible 9 ^! exp]im5ts by look+ ?r\gh a piece ( wide me% wire-gauze ) a telescope4 ,! respective position ( ! ?+s 0 also rev]s$2 t is to say1 a ,ruhmkorff coil & a p]iodically dis*>g$ ,leyd5 j> 7 plac$ inside1 & ! s5sitive sub/ance outside1 ! box1 ) ! same results4 ,9 "s lat] exp]im5ts ) a l>g] metallic case 7,fig4 #eg71 & ) ! ,daniel cell1 s5sitive sub/ance1 delicate galvanomet]1 & ,:eat/one ,bridge plac$ inside1 ,i f\nd t a d\ble cas+ 0 necess>y 9 ord] to absolutely suppress all effects4 ,a glass cov]+ af=d$ no protection4 ,illu/ration3 ,,fig4 #eg4 ,consid]ations on ! ,me*anism ( ! ,effects ,produc$4--,:at conclusions are we to draw f ! exp]im5ts describ$8 ,! sub/ances employ$ 9 ^! inve/igations 7 n conductors1 s9ce ! metallic p>ticles compos+ !m 7 sep>at$ f ea* o!r 9 ! mid/ ( an insulat+ m$ium4 ,x 0 n surpris+ t curr5ts ( high pot5tial1 & especially curr5ts induc$ by dis*>ges1 %\ld sp>k across ! insulat+ int]vals4 ,b z ! conductivity p]si/$ aft]w>ds1 ev5 = ! weake/ !rmo-electric curr5ts1 !re is "s gr\nd = suppos+ t ! insulat+ m$ium is trans=m$ by ! passage ( ! curr5t1 & t c]ta9 actions1 su* z %ock & rise ( temp]ature1 br+ ab\t a modification ( ?is new /ate ( ! insulat+ body4 ,actual movem5t ( ! metallic p>ticles _c be imag9$ 9 exp]im5ts :]e ! p>ticles1 9 a lay] a few millimetres ?ick1 7 fix$ 9 an inv>iable relative position by extreme pressures1 rea*+ at times to m ?an #ajj kilogrammes p] sq4 cm4 7#a1dbj lb4 to ! squ>e in*74 ,moreov]1 9 ! case ( solid mixtures1 9 :i* ! same v>iations ( resi/ance 7 produc$1 displacem5t seems out ( ! "q4 ,to expla9 ! p]si/5ce ( ! conductivity aft] ! cessation ( ! electrical influ5ce1 are we to suppose 9 ! case ( metallic fil+s a p>tial volatilisation ( ! p>ticles creat+ a conduct+ m$ium betwe5 ! gra9s ( metal8 ,9 ! case ( mixtures ( metallic p[d]s1 & insulat+ sub/ances agglom]at$ by fusion1 are we to suppose t ! ?9 insulat+ lay]s are pi]c$ by ! passage ( v small sp>ks1 & t ! holes left beh9d are coat$ ) conduct+ mat]ial8 ,if ?is explication is admissible = induc$ curr5ts1 x mu/ hold good = cont9u\s curr5ts4 ,if s1 we mu/ conclude t ^! me*anical actions may be produc$ by batt]ies ( only #aj to #bj volts electromotive =ce1 & :i* only cause an insignificant curr5t to pass4 ,! foll[+ exp]im5t is wor? quot+ 9 ?is connection3-- ,a circuit 0 =m$ by a ,daniell cell1 a s5sitive galvanomet]1 & "s alum9ium fil+s 9 an ebonite cup4 ,! galvanomet] ne$le rema9$ at z]o4 ,! fil+s 7 cut out ( ?is circuit1 & swit*$ = "o m9ute into circuit ) a batt]y ( #dc sulphate ( m]cury cells4 ,on be+ replac$ 9 ! fir/ circuit1 ! fil+s exhibit$ high conductivity4 ,! result 0 ! same :5 #aj or #bj cells 7 employ$1 or :5 ! curr5t 0 dim9i%$ by int]pos+ 9 ! circuit a column ( di/ill$ wat]1 #dj cm4 long & #bj mm4 9 diamet]4 ,! cells us$ 7plat9um1 sulphate ( m]cury1 sulphate ( z9c1 z9c7 _h a high int]nal resi/ance4 ,?us1 #dc cells 7#fj volts71 :5 %ort-circuit$1 only gave a curr5t ( #e milliamp]es4 ,! same batt]y1 ) ! column ( di/ill$ wat] 9 circuit only1 caus$ a deflection ( #ajj mm4 on a scale "o metre (f1 ) an a/atic galvanomet] w\nd ) #ej1jjj turns4 ,we c1 !re=e1 see h[ inf9itesimally small ! initial curr5t mu/ h be5 :5 ! fil+s 7 add$ to ! circuit4 ,! batt]y act$1 !re=e1 ess5tially by virtue ( its electromotive =ce4 ,if me*anical displacem5t ( p>ticles or transportation ( conduct+ bodies seem inadmissible1 x is probable t !re is a modification ( ! insulator itself1 ! modification p]si/+ = "s "t by virtue ( a sort ( 8co]cive =ce40 ,an electric curr5t ( high pot5tial1 :i* w\ld be completely /opp$ by a ?ick insulat+ %eet1 may be suppos$ to gradually trav]se ! v ?9 dielectric lay]s betwe5 ! conduct+ p>ticles1 ! passage be+ effect$ v rapidly if ! electric pressure is great1 & m sl[ly if ! pressure is less4 ,increase ( ,resi/ance4--,an increase ( resi/ance 0 obs]v$ 9 ^! inve/igations less (t5 ?an a dim9ution2 nev]!less1 a numb] ( frequ5tly repeat$ exp]im5ts enable me to say t increase ( resi/ance is n exceptional1 & t ! conditions "u :i* x takes place are well def9$4 ,%ort columns ( antimony or alum9ium p[d] :5 subject$ to a pressure ( ab\t #a kilogramme p] squ>e c5timetre 7#adb lb4 p] squ>e in*71 & (f]+ b a l[ resi/ance1 exhibit$ an increase ( resi/ance "u ! influ5ce ( a p[]ful electrification4 ,p]oxide ( lead1 a fairly good conductor1 always exhibit$ an increase2 s also did "s k9ds ( plat9is$ glass1 :ile o!rs %[$ alt]nate effects4 ,= in/ance1 a %eet ( plat9is$ glass1 :i* (f]$ a resi/ance ( #gjj ohms1 became highly conduct+ aft] #aej sulphate ( m]cury cells _h be5 appli$ to x = #ajsec4 ,?is condition ( conductivity 0 annull$ by contact ) a *>g$ ,leyd5 j>1 & reappe>$ aft] aga9 apply+ #aej cells = #ajsec41 & s on4 ,simil> effects 7 obta9$ ) a ?9 lay] ( a mixture ( sel5ium & tellurium p\r$1 :5 fus$1 into a groove 9 a %eet ( mica plac$ betwe5 two copp] plates4 ,^! alt]nations 7 always obs]v$ sev]al times 9 succession1 & at int]vals ( sev]al days4 ,^! augm5tations & alt]nations are 9 no way incompatible ) ! hypo!sis ( a physical modification ( ! insulator by electrical influ5ce4 ,,app5dix ,,iii4 ,9 connection ) ! bran* ( ! subject dealt ) on page #cd1 ! foll[+ communications f ,pr(4 ,elihu ,?omson & ,dr4 ,william ,j4 ,morton1 ,m4,d41 :i* appe>$ respectively 9 ! ,electrical ,eng9e]1 ( ,new ,york1 ,july #d & ,octob] #bd1 #ahid1 w be read ) int]e/4 ,pr(4 ,?omson writes3-- ,,curi\s ,,effects ,,( ,,h]tzian ,,waves4 ,9 ! issue ( ! ,london ,electrician ( ,june #h1 #ahid1 "u ! head+1 8,h]tzian ,waves at ! ,royal ,in/itution10 ! foll[+ rem>k occurs3 8,x is :olly probable1 z ,dr4 ,lodge sugge/s1 t ,h]tzian waves may (t5 h manife/$ !mselves 9 physical laboratories to ! annoyance ( ! work]s1 c40 ,i may m5tion 9 ?is connection t 9 #ahgg1 if ,i rememb] ! ye> correctly1 :ile work+ a ,ruhmkorff induction coil1 "o t]m9al ( :i* 0 gr\nd$ & ! o!r t]m9al ( :i* 0 atta*$ to an insulat$ metallic body1 ,pr(4 ,h\/on & ,i notic$ t :5 ! sp>ks 7 pass+ betwe5 ! t]m9als ( ! coil1 x 0 possible n only to obta9 m9ute sp>ks f all metallic bodies 9 ! imm$iate neighb\rhood1 t is1 9 ! same room1 b t delicate sp>ks c\ld be tak5 by hold+ 9 ! h& a small piece ( metal ne> metallic objects 9 _m o!r rooms & on diff]5t floors 9 ! build+1 al?\gh ! pieces 7 n connect$ to gr\nd4 ,^! c\ld only h be5 ,h]tzian effects1 b !re 0 no recognition ( _! true "* at ! "t1 ?\gh ! effects 7 se5 to be connect$ ) ! v quick *>g+ & dis*>g+ ( ! insulat$ body4 ,an acc\nt ( ^! exp]im5ts 01 ,i ?9k1 publi%$ 9 ! ,j\rnal ( ! ,frankl9 ,in/itute at ! "t4 ,i desire also to m5tion1 z com+ "u my notice )9 ! pa/ ye>1 a curi\s & r amus+ illu/ration ( ! pr9ciple ^u :i* ! beautiful in/rum5t = detect+ ! pres5ce ( electric oscillations1 devis$ by ,dr4 ,lodge & call$ by him ! 8coh]]10 is bas$4 ,x 0 report$ to me :5 9 ,philadelphia t a c]ta9 electro-plat] _h f\nd t he c\ld n pursue 8 silv] plat+ op]ations dur+ ?und]/orms1 & t if he left 8 plat+ ov] night & a ?und]/orm came up ! "w 0 inv>iably ru9$4 ,i 0 dispos$ to be ?or\ghly sceptical1 & express$ my disbelief 9 any su* effect4 ,be+ urg$1 h[ev]1 ,i w5t to ! silv]-plat]'s %op1 :i* 0 a small "o1 & que/ion$ ! silv]-plat] himself conc]n+ ! circum/ance :i* _h be5 report$4 ,:ile x 0 evid5t t he 0 n a man :o _h in=m$ himself electrically1 ,i c\ld n d\bt t1 aft] conv]s+ ) him1 he _h inde$ be5 /at+ :at 0 p]fectly true1 namely1 t :5 8 op]ations ( plat+ 7 go+ on & a ?und]/orm arose1 8 batt]ies1 :i* 7 ,smee cells1 act$ z ?\gh !y 7 %ort-circuit$1 & ! deposit ( metal 0 made at too rapid a rate4 ,! secret came out on an inspection ( 8 connections4 ,! connections ( 8 batt]ies to 8 ba?s 7 made ?r\gh a numb] ( bad contacts :i* c\ld n fail to be ( high resi/ance "u ord9>y conditions4 ,i c\ld readily see t virtually he 0 work+ ?r\gh a consid]able resi/ance & t he _h an excess ( batt]y p[] = ! "w4 ,"u ^! circum/ances a fla% ( lightn+ w\ld cause coh]5ce ( 8 badly contact+ surfaces1 & w\ld improve ! conductivity s z to cause an excessive fl[ ( curr5t1 give a too rapid deposit1 &--z he put x--8make ! batt]ies boil40 ,! incid5t sugge/s ! use ( ,dr4 ,lodge's +5i\s in/rum5t 9 ! /udy ( ! waves :i* are propagat$ dur+ ?und]/orms1 ( :i* waves we h practically little or no in=mation4 ,dr4 ,morton's communication is z foll[s3-- ,,h]tzian ,,waves1 ,,c>bon ,,microphones ,,& 8,,coh]]s40 ,ab\t #ah mon?s ago ,i put into use 9 my (fice ! ,vett] me?od ( controll+ ! /r5g? ( ! curr5t d]iv$ f ! ,edison #aaj volt sy/em ( electrical di/ribution4 ,! controll+ devices 7 a #af c4p4 lamp & a pulv]is$ c>bon rheo/at4 ,by ^! means a milliamp]e1 or fraction !re(1 up to #ajj or m1 if desirable1 c be adm9i/]$ to a pati5t 7see diagram1 ,fig4 #eh1 on next page74 ,on sev]al occasions :5 ! electrodes ( ! sy/em above describ$ 7 p]man5tly atta*$ to "s "p ( a pati5t's p]son & a sp>k 0 be+ adm9i/]$ to ano!r pati5t seat$ ^u a plat=m *>g$ by an influ5ce ma*9e1 "s #ae ft4 di/ant 9 ! same room1 ! fir/ pati5t w\ld exclaim & prote/ aga9/ receiv+ a consid]able %ock4 ,on "o occasion1 :5 ! cont9u\s curr5t electrode 0 9 ! neighb\rhood ( a pati5t's temple1 ! pati5t exp]i5c$ ! s5sation ( a fla% ( light2 on o!r occasions muscul> contractions 7 produc$1 always simultane\sly ) ! sp>k4 ,also ^u ! occurr5ce ( ! sp>k & %ock ! ne$le ( ! milliamp]emet]1 a v]tical "o & calibrat$ to a wide range ( movem5t ov] #e milliamp]es1 flew across ! scale f1 = in/ance1 #b to #e milliamp]es & rema9$ at ! high] read+4 ,t a sp>k occurr+ #ae ft4 away %\ld cause a %ock to a p]son 9 an indep5d5t circuit excit$ my wond]2 x 0 inexplicable & yet s c]ta9 to occur t ,i 0 oblig$ to ab&on ! use ( ! two pieces ( app>atus at ! same "t4 ,at la/1 :5 "t p]mitt$1 ,i set out to inve/igate4 ,i s\ght = an ord9>y induction circuit ( p>allel wir+ & f\nd none4 ,i !n suspect$ ! microphonic rheo/at ( pulv]is$ c>bon & hav+ cut x out ( circuit ,i sub/itut$ = x a wat] rheo/at4 ,! ph5om5a n[ fail$ to occur4 ,replac+ ! c>bon rheo/at & putt+ a telephone 9 circuit ,i adju/$ ! milliammet] to read #b milliamp]es1 caus+ an assi/ant to evoke ! di/ant sp>k4 ,all 0 n[ cle>4 ,at ea* sp>k ! ne$le jump$ =w>d & a di/9ct telephone click 0 he>d f ! telephone receiv]4 ,i obs]v$ t ! fir/ jump ( ! ne$le 0 ! longe/ z well z ! fir/ click 9 ! receiv] ! l\de/1 bo? ne$le jump & click1 dy+ away gradually at ea* successive sp>k until !y ceas$ at f ! tw5tie? to ?irtie?4 ,to turn ! rheo/at (f & !n on aga9 r5d]$ ! exp]im5t repeatable4 ,! read+ ( ! met]1 be/ adapt$ to success1 0 ab\t #e milliamp]es ?\gh #bj to #ej yield$ good results4 ,illu/ration3 ,,fig4 #eh4 ,unable to furni% any reason :y ! electric radiation ( a di/ant sp>k %\ld r$uce ! resi/ance ( pulv]is$ c>bon ,i refra9$ f publi%+ ! b>e obs]vation 9 ! hopes ( f9d+ an explanation by fur!r exp]im5tation1 m]ely not+ to fri5ds ! delicacy ( ! pulv]is$ c>bon rheo/at z a detector ( ,h]tzian waves & mak+ "s fur!r exp]im5ts ) x & a telephone receiv] 9 circuit 9 ?is direction4 ,! rec5t publication ( ! brilliant rese>*es ( ,dr4 ,oliv] ,j4 ,lodge n[ makes ! entire matt] cle>4 ,dr4 ,lodge describes a new =m ( microphonic detector ( ,h]tzian waves1 consi/+ ( two or m pieces ( fairly clean metal 9 light contact & connect$ to a voltaic cell1 a film ( oxide ( ! metal int]v5+ betwe5 ! surfaces1 8s t only an insignificant curr5t is all[$ to pass40 ,he writes3 8,n[ let ! slighte/ surg+ occur1 say1 by reason ( a sph]e be+ *>g$ & dis*>g$ at a di/ance ( #dj y>ds2 ! film at once breaks d[n--p]haps n completely1 t is a "q ( int5sity--b p]man5tly40 ,?is detector1 ,dr4 ,lodge t]ms a 8coh]]0 because ( ! p>tial metallic cohesion above describ$4 ,^u ?is po9t he says3 8,a bad contact 0 at "o "t reg>d$ z a simple nuisance40 444 8,hughes obs]v$ its s5sitiv5ess to s\nd waves1 & x became ! microphone4 ,n[ x turns out to be s5sitive to electric waves1 if x be made ( any oxidisable metal 7n ( c>bon7 & we h an in/rum5t :i* might be call$ a micro-some?+ b :i*1 z x appe>s to act by cohesion1 ,i call at pres5t a coh]]40 ,! cohesive result betwe5 ! metallic surfaces is also ref]r$ to z a 8weld+ effect ( an electric j]k40 ,9 ! volume j publi%$1 entitl$ 8,! ,"w ( ,h]tz & ,"s ( ,8 ,successors10 repr9t$ f ,! ,electrician1 ,london1 ?is foot note is add$ on p4 #cj3 8,fitz,gerald tells me t he has succe$$ ) c>bon also40 ,my exp]im5ts w\ld seem to fully demon/rate t c>bon z well z metals may act z coh]]s4 ,at "s rec5t trials ! editors ( ! ,electrical ,eng9e] 7 pres5t & 7 fully satisfi$ z to ! sw++ up ( ! ne$le ( ! milliamp]emet] & ! click 9 ! telephone receiv]1 by repeat$ te/s4 ,! exp]im5tal side ( ! subject has be5 s exhau/ively & admirably pres5t$ by ,dr4 ,lodge 7detail$ 9 ! publications ref]r$ to7 t :at is "h said has no m ?an a second>y int]e/4 ,b x may n prove amiss to ga!r toge!r all ! evid5ce :i* t5ds to demon/rate ! influ5ce ( disruptive dis*>ges ^u neighb\r+ bad contacts convey+ curr5ts4 ,z ,lodge po9ts out1 fuses may easily be 8bl[n out0 9 ?is mann]4 ,?is has occurr$ to me on a numb] ( occasions ) #aj amp]e fuses4 ,"u prop] conditions ( sp>k+ surfaces & circuit a %ort sp>k might suffice4 ,may x n also be ! fact t ! fuses melt$ dur+ ?und]/orms 9 _! neighb\rhood are melt$ by reason ( ! effect ( ! electric radiations or surg+s ( ! lightn+ /roke ?r[+ a ru% ( ! curr5t already 9 ! circuit ?r\gh ! fuse r ?an by ! addition ( any new curr5t to ! circuit by ! atmosph]ic electricity itself4 ,9 ?is connection ,lodge writes3 8,!re are "s :o ?9k t lightn+ fla%es c d none ( ^! second>y ?+s4 ,!y are mi/ak540 ,9 ?is z 9 o!r directions ! new facts h a practical be>+ & a pursuit ( fur!r exp]im5ts may lead1 z (t5 happ5s1 to unexpect$ developm5ts4 ,s f> z c>bon contacts are conc]n$ & ! fact t ,h]tzian waves1 l me*anical motion1 r$uce _! resi/ance1 a curi\s problem is sugge/$ z conc]ns ! pr9ciple ^u :i* "s c>bon transmitt]s act4 ,an exclusive monopoly ( all c>bon transmitt]s is bas$ ^u ! claim t ! v>iations 9 resi/ance are produc$ by v>iations 9 pressure due to a me*anical =ce1 viz41 s\nd waves4 ,if my exp]im5ts1 above detail$1 are exact1 two facts appe>3 #a4 ,t ano!r =m ( motion1 e!r vibration1 causes a v>iation ( resi/ance ( c>bon contacts4 #b4 ,t x rema9s to be prov$ t v>iation ( pressure is ! only means ( v>y+ ! curr5t /r5g?1 = v>iation ( molecul> contact occurs 9 ! pres5t in/ance )\t any evid5ce t x is due to v>iation ( pressure4 ,,app5dix ,,iv4 ,,on ,,! ,,diselectrification ,,( ,,metals ,,& ,,o!r ,,bodies ,,by ,,light4 ,ref]r+ to a footnote to my ,royal ,in/itution lecture1 on page #aa1 ,messrs4 ,el/] & ,geitel h be5 good en\gh to call my att5tion to a great deal ( "w done by !m 9 ! same direction4 ,to make am5ds = my ignorance ( ?is "w at ! "t ( my ,royal ,in/itution lecture1 & to make x bett] kn[n 9 ?is c\ntry1 ,i make ab/ract ( _! ,pap]s z foll[s3-- ,wi$emann's ,annal51 #ch1 p4 #dj4--8,on ! ,dissipation ( ,negative ,electricity by ,sun- & ,daylight40 ,) a view to ,arrh5ius' !ory conc]n+ atmosph]ic electricity1 we arrang$ exp]im5ts on ! photo-electric p[] ( sunlight & diffuse daylight at ,wolf5bttel f ! middle ( ,may to ! middle ( ,june1 #ahhi4 ,hoor alone _h obs]v$ ! effect ( sunlight2 o!r exp]im5t]s _h fail$ to f9d x1 b we f9d a dis*>g+ effect ev5 9 diffuse daylight4 ,we take an insulat$ z9c di%1 #bj cm4 diamet]1 connect x to a quadrant electromet] or an ,exn]'s electroscope1 & expose x 9 ! op5 s t x c be d>k5$ or illum9at$ at pleasure4 ,sunlight makes x lose a negative *>ge ( #cjj volts 9 ab\t #fj seconds4 ,a positive *>ge ( #cjj volts is reta9$4 ,! dissipation ( negative electricity ceases 9 ! d>k1 & is mu* weak5$ by ! int]position ( glass4 ,b light f ! blue sky has a di/9ct effect4 ,fill ! di% ) wat]1 or /ret* a damp clo? ov] x1 & ! action /ops4 ,a fre%ly-scrubb$ plate acquires a positive *>ge ( #b volts1 :i* c be increas$ by bl[+4 ,) fre%ly-cleans$ wires ( z9c1 alum9ium1 or magnesium atta*$ to ! knob ( ! electroscope1 a p]man5t negative *>ge is impossible 9 op5 sunlight4 ,inde$1 magnesium %[s a dissipat+ action 9 diffuse ev5+ light4 ,su* wires act l gl[+ bodies4 ,expos+ an electroscope s provid$ 9 an op5 space x acquires a positive *>ge f ! atmosph]e4 ,no abnormal dissipation ( positive electricity has be5 obs]v$4 ,wi$4 ,ann41 #ch1 p4 #dig4--;,cont9uation ( ,same ,subject4 ,our success la/ "t 0 l>gely due to ! great cle>ness ( ! sky 9 ,june1 & we wi%$ to see if we c\ld get ! same effect at ! beg9n+ ( ! w9t]4 ,! foll[+ is our summ>y ( results3 ,bright fre% surfaces ( ! metals z9c1 alum9ium1 magnesium 7 dis*>g$ by bo? sun- & daylight :5 !y 7 negatively *>g$2 & !y spontane\sly acquir$ a positive *>ge1 ^: am\nt c\ld be increas$ by bl[+4#ce ,a /ill m notable s5sitiv5ess to light is %[n by ! amalgams ( c]ta9 metals1 viz41 9 ! ord] ( _! s5sitiv5ess1 ,k1 ,na1 ,zn1 ,sn4 ,s9ce pure m]cury %[s no effect1 ! hypo!sis is p]missible t ! active ag5t is ! metal dissolv$ 9 ! m]cury4 ,if s1 ! foll[+ are ! mo/ active metals3-- #ce ,a fact notic$ by ,bi*at & ,blondlot4 ,k1 ,na 7,mg1 ,al71 ,zn1 ,sn4 ,all o!r metals tri$1 su* z ,sn1 ,cd1 ,pb1 ,cu1 ,fe1 ,hg1 ,pt1 & gas c>bon1 %[ no action4 ,! same is true ( ne>ly all non-metallic bodies2 b "o ( !m--namely1 ! p[d] ( ,balma9's lum9\s pa9t--act$ rem>kably well 9 sunlight4 ,( liquids1 hot & cold wat]1 & hot & cold salt solution 7 completely inactive2 consequ5tly wett+ ! surface ( metals de/roys _! s5sibility to light4 ,! illum9ation exp]im5ts c be arrang$ 9 ei!r ( two ways4 ,= exp]im5ts 9 free space we use z9c1 alum9ium1 or magnesium wires1 or small amalgamat$ sph]es ( z9c provid$ ) an iron rod4 ,) ^! x c be easily %[n t ! illum9at$ surface ( c]ta9 metals act 9 ! same way z a flame collector4 ,= demon/ration exp]im5ts ! app>atus describ$#cf is bett]1 & ) ?is we %[ ! foll[+3-- ,amalgamat$ z9c1 negatively *>g$1 dis*>ges almo/ in/antly 9 sunlight2 & if ne> a positively-electrifi$ body *>ges itself positively4 ,! same ?+ happ5s1 ?\gh m sl[ly1 9 diffuse daylight4 ,r$ glass /ops ! action1 b ! foll[+ let "s ?r\gh3--,sel5ite1 mica1 w9d[ glass1 blue 7cobalt7 glass4 #cf ,9 ?is app>atus ! m]cury amalgams ( ,k & ,na are run ?r\gh a f9e funnel1 s t ! fre%ly-=m$ surface ( ! drops may be illum9at$4 ,"u ^! circum/ances1 :ile pure m]cury fell f -#ahe to -#age volts 9 #cjsec41 amalgam ( z9c fell f -#aie to -#aaf 9 #aesec41 amalgam ( sodium fell f -#aie to #j 9 #ajsec41 & an amalgam ( potassium fell f -#aie to #j 9 #esec4 ,illu/ration3 ,,fig4 #ei4 ,explanation ( ,fig4 #ei4--;,b is a brightly poli%$ amalgamat$ z9c plate atta*$ to ! negative pole ( a ,holtz ma*9e1 ) ! positive knob f #f to #aj c5timetres di/ant4 ,! s\rce ( a light is a /rip ( burn+ magnesium ribbon #cj to #ej c5timetres away4 ,:5ev] ! sp>k is able j to *oose ! pa? ,b ,b1 light %9+ on ! z9c plate *ecks x & transf]s ! sp>k to ,a ,a4 ,wi$4 ,ann41 #ci1 p4 #ccb4--,on a ,*eck+ ,action ( ,illum9ation on ,electric ,sp>k & ,bru% ,dis*>ge4 ,if sp>ks are j able to occur betwe5 a brass knob & a clean amalgamat$ z9c ca?ode1 illum9ation ( ! latt] by ultra-violet light t5ds to *eck !m4 7,?is is a curi\s inv]sion ( ,h]tz's fundam5tal exp]im5t on ! subject4 ,x is an effect ,i h n yet obs]v$2 b ,el/] & ,geitel's arrangem5t diff]s f m9e#cg 9 t ! surfaces are at a /eady high pot5tial be=e ! sp>k1 s t light c ex]t its dis*>g+ influ5ce1 :]eas 9 m9e ! surfaces 7 at z]o pot5tial until ! sp>k-ru% occurr$4 ,h]tz's arrangem5t 0 m l m9e1 inasmu* z he illum9at$ ! knobs ( an induction coil on ! v]ge ( sp>k+4 ,x appe>s1 !n1 t :]eas ! action ( light 9 dis*>g+ negative electricity f clean oxidisable metallic surfaces is def9ite en\gh1 its influ5ce on a sp>k dis*>ge diff]s accord+ to ! conditions ( t dis*>ge--9 cases ( 8/eady /ra90 x t5ds to h9d] ! sp>k2 9 cases ( 8sudd5 ru%0 x t5ds to assi/ x4--,o4 ,j4 ,l47 #cg ,see ,fig4 #g1 page #i4 ,wi$4 ,ann41 #da1 p4 #afa4--,on ! use ( ,sodium-,amalgam 9 ,photo-electric ,exp]im5ts4 ,el/] & ,geitel h repeat$ "s ( ,righi's exp]im5ts on ! dis*>ge ( negative electricity f metals 9 r>efi$ air1 & f9d1 9 agreem5t ) him1 t a r$uction ( pressure to ab\t "o millimetre increases ! dis*>ge velocity ab\t six or sev5 times4 ,!y proce$ to try sodium-amalgam expos$ to daylight 9 exhau/$ tubes1 & describe app>atus = ! purpose4 ,su* an arrangem5t simply _c hold a negative *>ge 9 bright daylight1 ev5 al?\gh x be unprovid$ ) qu>tz w9d[s4 ,ev5 p>aff9 lamps & sodium flames ex]t "s action4 ,!y obs]ve t "u ! action ( light ! b\nd>y surface ( ! metal & glass *anges1 & ! metal beg9s to cl+ to ! glass4 ,!y suppose t ,w>burg's vacuum tubes ( pure sodium may behave simil>ly1 & %[ photo-electric s5sibility4 ,! ,same1 p4 #aff4--,on a ,*eck+ ,action ( ,magnetism on ,photo-,electric ,dis*>ge 9 ,r>efi$ ,gases4 ,! au?ors po9t out analogies betwe5 ! above effects & ^? !y _h obs]v$ 9 ! action ( gl[+ bodies 9 air1 & !y m5tion ,l5>d & ,wolf's exp]im5ts 7,wi$4 ,ann4 ,,xxxvii41 p4 #ddc71 t5d+ to %[ t ! effect is due to a dis9tegrat+ or evaporative effect ( light on surfaces4 ,el/] & ,geitel _h obs]v$ t ! dis*>g+ p[] ( gl[+ bodies 0 dim9i%$ by application ( a magnetic field1 ! effect be+ ! same z if ! temp]ature 0 l[]$2 & !y proce$ to try if ! dis*>ge ( negative electricity f illum9at$ surfaces 9 highly-r>efi$ gas c\ld also be *eck$ or h9d]$ by a magnetic field4 ,!y f9d t x c4 ,illu/ration3 ,,fig4 #fj4 ,explanation ( ,fig4 #fj4--,! sodium & m]cury are introduc$ ?r\gh ! tube ,s into ! globe ,k4 ,! tube ,s is !n clos$1 a pump appli$ to ,x1 & exhau/ion c>ri$ on = "s days4 ,t is an op5 funnel seal$ into ! tube 7z is done 9 "s vacuum tubes made by ,holtz7 to %[ a curi\s unilat]al conductivity ( r>efi$ gas4 ,! object ( ?is funnel is to p]mit metal f ! int]ior1 free f scum1 to be introduc$ f ,k to ,d :5 ! :ole is tilt$4 ,?us a bright surface is expos$ to ! e>? r+ ,r4 ,x c be *>g$ negatively1 & its leak "u illum9ation be measur$1 ?r\gh ! t]m9al ,d4 ,sometimes ! tube is inv]t$1 s t ! active surface may be at ,d1 fur!r f ! e>? wire4 ,us+ ! light f sp>ks admitt$ ?r\gh a qu>tz w9d[ into ! vacuum tube :5 a negatively *>g$ amalgamat$ z9c surface 0 expos$ ne> an e>?-connect$ plat9um r+1 & betwe5 ! poles ( a small electromagnet1 !y f\nd t :5 ! tube 0 full ( air at #aj mm4 pressure ! magnet _h b little effect1 b t at #jae mm41 :]eas )\t ! magnet ! *>ge ( -#bgj volts disappe>$ completely 9 five seconds1 :5 ! magnet 0 excit$ x only fell ab\t half t am\nt 9 ! same "t4 ,) hydrog5 at #jbd mm4 ! result 0 mu* ! same1 & at ei!r great] or less pressure 9 bo? cases ! magnet _h less effect4 ,9 oxyg5 ! loss ( *>ge 0 n q s rapid2 &1 aga91 at a pressure ( ,o#amm41 ! magnet m ?an halv$ ! rate4 ,b 9 ,,co ! rapidity ( loss 0 extreme4#ch ,ei!r at #aa mm4 or at #jjje mm4 ! *>ge ( #bgj volts leak$ away completely 9 two seconds :5 ! magnet 0 n excit$2 b 9 ! latt] case 7l[ pressure7 excit+ ! magnet r$uc$ ! spe$ by ab\t "o-half4 ,at ! pressure ( #aa mm4 ! magnet did n seem to produce an effect4 ,) daylight ! results are simil>4 #ch ,correspond+ to ! activity ( ?is gas z f\nd by ,wi$emann & ,eb]t 7,wi$4 ,ann41 ,,xxxiii41 p4 #beh71 9 _! rese>*es on ! influ5ce ( light on ease ( sp>k+4 ,illu/ration3 ,,fig4 #fa4 ,explanation ( ,fig4 #fa4--,p is ! plate ( amalgamat$ z9c1 & ,r is ! e>? r+1 z be=e4 ,ultra-violet light is introduc$ ?r\gh a qu>tz w9d[ ,q f a sp>k gap r4 ,! vessel has a jo9t at ! middle1 s t ! s5sitive plate c be got at & *ang$4 ,magnet poles are appli$ outside ?is vessel 9 v>i\s positions4 ,! au?ors !n discuss ! mean+ ( ! result1 & its be>+ on ! opposition hypo!ses ( ,l5>d & ,wolf & ( ,righi4 ,l5>d & ,wolf's view is t ! loss ( negative electricity is due to du/ dis9tegrat$ f ! surface by ! action ( light1 b ^: exi/5ce !y consid] is e/abli%$ by an obs]v$ effect on /eam jets4 ,righi1 on ! o!r h&1 believes t gas molecules !mselves act ! "p ( electric c>ri]s4 ,el/] & ,geitel consid] t ! magnetic effect obs]v$ by !m supports ?is latt] view1 x be+ kn[n t a magnet acts on curr5ts ?r\gh gases2 & !y surmise t ! impact ( light vibrations may directly assi/ electric int]*ange betwe5 a gas molecule & ! surface1 by sett+ up 9 !m syntonic /ation>y vibrations1 some?+ l resonant ,leyd5 j>s4 ,x is to be rememb]$ t phosphoresc5t sub/ances1 su* z ,balma9's pa9t p[d]1 exhibit m>k$ photo-electric effect 9 daylight4 ,illu/ration3 ,,fig4 #fb4 ,explanation ( ,fig4 #fb4--;,a simpl] arrangem5t1 l ! "o above 7,fig4 #fa71 :]eby clean liquid alkali metals c be introduc$ into ! exp]im5tal *amb] ,b1 f ! prelim9>y *amb] ,a1 ?r\gh a cleans+ funnel1 ,f1 :i* dips its beak into ! int]ior4 ,! unilat]al "* ( ! electric motion1 & ! *>g+ ( neutral surfaces by light1 require special hypo!ses1 conc]n+ an ,e4,m4,f4 at ! b\nd>y ( gases & conductors1 su* z ,s*u/] & ,lehmann h made4 ,weid4 ,ann4 #db1 p4 #efd4--,note on a ,new ,=m ( ,app>atus = ,demon/rat+ ! ,photo-electric ,dis*>g+ ,action ( ,daylight4 ,a vacuum tube suitable = exp]im5ts ) sodium-amalgam or pure sodium1 or ! liquid sodium-potassium alloy1 is describ$1 ) ! aid ( :i* a curr5t 7%[n by ! *>ge ( an electroscope7 c be ma9ta9$ by a dry pile ?r\gh ! r>efi$ gas above ! metal :5 x is illum9at$ f ord9>y w9d[s4 ,wi$4 ,ann4 #dc1 p4 #bbe4--,on ! ,dep5d5ce ( ! ,dis*>g+ ,action ( ,light on ! ,nature ( ! ,illum9at$ ,surface4 ,exp]im5ts also on diff]5tly-col\r$ lights4 ,summ>y ( results4 ,! photo-electrically active metals arrange !mselves 9 ! foll[+ ord]--,pure ,k1 alloys ( ,k & ,na1 pure ,na4 ,amalgams ( ,rb1 ,k1 ,na1 ,li1 ,mg 7,tl1 ,zn72 ! same z _! voltaic ord]4 ,) ! mo/ s5sitive t]m ( ! s]ies a c&le six metres (f c be detect$1 & ! region ( spectral r$ is n inactive4 ,! lat] t]ms ( ! s]ies dem& small] waves1 & ev5 = potassium blue light gives a mu* great] effect ?an r$4 ,no dis*>ge ( positive electricity is obs]vable ) ^! sub/ances4 ,wi$4 ,ann4 #dd1 p4 #gbb4--,on ! ,dissipation ( ,electric ,*>ge f ,m9]al ,surfaces by ,sunlight4 ,hi!rto only ,balma9's pa9t p[d] has be5 obs]v$ to be active among non-metallic sub/ances4 ,n[ !y try o!r phosphoresc5t bodies1 & arrive at ! foll[+ results3-- ,fluorsp> is conspicu\sly photo-electric1 bo? 9 sunlight & daylight1 especially ! v>iety ( fluorite call$ /9kfluss4 ,fre%ly-brok5 surfaces dis*>ge mu* m rapidly ?an old surfaces4 ,blue waves1 & n alone ! ultra-violet1 h a p]ceptible effect on fluorsp>4 ,9 a vacuum ! m9]al loses its photo-electric s5sibility & its conductivity too4 ,contact ) damp air re/ores its s5sibility4 ,moi/5+ ) wat] weak5s b does n de/roy ! s5sitiv5ess4 ,on ! o!r h&1 ignit+ ! m9]al de/roys bo? its photo-electric p[] & its exceptional phosphoresc5t prop]ty4 ,di/9ct traces ( photo-electric p[] are %[n by ! foll[+ m9]als also3 ,cryolite1 heavy sp>1 cele/9e1 arragonite1 /rontianite1 calcsp>1 felsp> & granite4 ,! hypo!sis t ! p[] ( phosphoresc+ :5 illum9at$ is approximately a measure ( ! dis*>g+ p[] ( light has be5 v]ifi$ 9 _m cases2 ! exceptions c probably be expla9$ by ! influ5ce :i* ! electrical conductivity ( ! illum9at$ sub/ance ex]ts on ! rate ( dis*>ge ( electricity f its surface4 ,?is agreem5t confirms ! view express$ by u on ! occasion ( exp]im5ts ) ,balma9's pa9t1 t1 dur+ electrical dis*>ge by light1 actions take place :i* are analog\s to ^? ( resonance4 ,messrs4 ,wi$emann & ,eb]t _h previ\sly be5 l$ by o!r consid]ations to ! same conclusion4 ,we are compell$ by ! results ( ! pres5t exp]im5ts to conclude t a m rapid dis*>ge ( electricity into ! atmosph]e takes place 9 sunlight ?an 9 d>kness f ! surfaces ( ! e>?1 :i* is compos$ ( m9]al p>ticles *>g$1 z ! positive sign ( ! slope ( atmosph]ic pot5tial indicates1 ) negative electricity4 ,illu/ration3 ,,fig4 #fc4 ,explanation ( ,fig4 #fc4--;,arrangem5t us$ by ,el/] & ,geitel = expos+ v>i\s phosphoresc5t m9]als to daylight1 :ile "u inductive *>ge4 ,!y 7 put 9 p[d] 9 ! tray ,p1 & ! transp>5t wire-gauze ,n above !m 0 *>g$ positively f a batt]y4 ,! metal cov] ,m ,m c\ld be remov$ & replac$ at pleasure1 & ! effect on a delicate quadrant electromet] connect$ to ,p obs]v$4 ,by ?is me?od consid]able t5sion c be got up on ! m9]al surface1 not)/&+ t x is close ^u z]o pot5tial4 ,! light effect dep5ds on t5sion1 n pot5tial4 ,x seems to u evid5t t !re exi/s a direct electric action ( sunlight ^u ! e>?1 & t we h giv5 exp]im5tal evid5ce 9 fav\r ( ! !ory put =w>d by von ,bezold & ,arrh5ius1 accord+ to :i* ! sun acts on ! e>?1 n by electro/atic or electro-dynamic action-at-a-di/ance1 :i* w\ld involve difficulties ( a !oretical "*1 b ?r\gh ! m$ium ( ! electrical =ces ( light waves4 ,we hope soon to e/abli% ! consequ5ces ( ?is !ory 9 meteorology 9 ano!r ,pap]1 giv+ ! results ( two ye>s' obs]vations on ! int5sity ( ! mo/ refrangible rays ( sunlight & ( ! slope ( atmosph]ic pot5tial4 ,wi$4 ,ann41 #dh1 p4 #cch4--;,exp]im5ts on ! ,gradi5t ( ,atmosph]ic ,pot5tial & on ,ultra-,violet ,sol> ,radiation4 ,el/] & ,geitel describe ! obs]vations !y h made = two ye>s on sol> radiation1 at obs]v+ /ations ( l[ & high altitude1 z te/$ by its electrical dis*>g+ p[]2 & !y plot curves ( su* effective radiation = days & mon?s along ) ! curves ( atmosph]ic pot5tial obs]v$ at ! same places4 ,^! curves are ( mu* int]e/1 & ne$ /udy4 ,incid5tally !y f9d t1 ( ! :ole effective sol> radiation1 #fj p] c5t4 0 absorb$ at altitudes above #c1ajj metres2 #bc p] c5t4 ( ! rema9d] 0 absorb$ 9 ! lay] betwe5 ?is & a /ation at #a1fjj metres2 & #dg p] c5t4 0 absorb$ betwe5 ?is & #hj metres above sea level4 ,or1 9 o!r words1 ( #bcf p>ts :i* ent] ! atmosph]e #id rea* ! highe/ obs]v+ /ation 7,sonnblickgipfel71 #gb ! middle "o 7,kolm-,saigurn71 & #ch ! l[e/ 7,wolf5bttel74 ,!y discuss ! "q z to h[ f> ! daily v>iation ( t]re/rial magnetism is due to electrical curr5ts 9 ! atmosph]e excit$ by sun%9e & o!r meteorological matt]s4 7,! ,pap] & plates are wor?y ( reproduction 9 full 9 ! ,philosophical ,magaz9e47 ,weid4 ,ann41 #df1 p4 #bha4--,on ! ,behavi\r ( ,alkali ,metal ,ca?odes 9 ,geissl] ,tubes2 ,on ,photo-,electric ,dis*>ge 9 a ,magnetic ,field2 & ,on ! ,measure ( ,photo-,electric ,curr5ts 9 ,potassium ,cells by means ( a ,galvanomet]4 ,results3--,! resi/ance ( a ,geissl] tube provid$ ) a ca?ode surface ( pure alkali metal is dim9i%$ by ! light f ! sp>ks ( an induction coil2 especially :5 ! pressure is #a to #ja mm4 ( m]cury4 ,! resi/ance :i* r>efi$ gas opposes to an electric curr5t 9 a magnetic field is greate/ 9 ! direction normal to ! magnetic l9es4 ,! *anges ( resi/ance effect$ by any k9d ( light 9 a vacuum tube ) alkali metal ca?ode c be measur$ galvanometrically4 7,a ,daniell cell gives #ajj divisions on a ,ros5?al galvanomet] :5 c\pl$ up ?r\gh su* an illum9at$ tube1 ea* division mean+ ab\t #aj amp]e47 ,illu/ration3 ,,fig4 #fd4 ,explanation ( ,fig4 #fd4--;,a vacuum tube ( r>efi$ hydrog5 conta9+ alkali metal z ca?ode1 say ! liquid ,k-,na alloy1 or solid ,k or ,na4 ,a sp>k gap at ,s s]ves z alt]native pa?1 & a /ream ( sp>ks c occur to ! plate ,p 9 ! d>k4 ,b :5 light falls on ! surface ,a ?is /ream ( sp>ks c cease1 %[+ t ! resi/ance ( ! vacuum tube is dim9i%$4 ,illu/ration3 ,,fig4 #fe4 ,explanation ( ,fig4 #fe4--,%[+ position ( magnetic poles ) respect to ! vacuum tube dis*>ge4 ,) ! poles across ! l9e ( dis*>ge1 z 9 ,fig4 on left1 excitation ( ! magnet opposes ! leak f ! surface4 ,) ! poles z 9 ,fig4 on "r1 ! dis*>ge is n mu* affect$1 x is ev5 sometimes slightly increas$4 ,illu/ration3 ,,fig4 #ff4 ,explanation ( ,fig4 #ff4--,potassium vacuum bulbs conta9+ millimetre ( hydrog5 m\nt$ & connect$ to batt]y & galvanomet]1 & arrang$ z a photo-electric photomet]4 ,wi$4 ,ann41 #dh1 p4 #fbe4 ,on ! ,photo-,electric ,comp>ison ( ,s\rces ( ,light4 ,attempts to make su* a potassium cell into a photomet]4 ,wi$4 ,ann4 #eb1 p4 #dcc4 ,fur!r ,photo-,electric ,exp]im5ts4 ,plates ( plat9um1 silv]1 copp] ne$ exce$+ly ultra-violet light be=e !y %[ any photo-electric p[]2 z9c1 alum9ium1 magnesium %[ x = visible violet & blue light2 ! alkali metals1 9 an atmosph]e ( r>efi$ hydrog51 advance _! range ( s5sibility into ! spectral r$2 :ile "u ! mo/ fav\rable conditions !y %[ a s5sibility only inf]ior to t ( ! eye itself4 ,! au?ors n[ use galvanometric me?ods ( measur+ ! effect1 in/ead ( only electromet]s1 & !y arrive at ! foll[+ results3-- 7#a7 ,! ?ree alkali metals ,na1 ,k1 ,rb1 h diff]5t s5sibility = diff]5tly-col\r$ lights4 ,= long waves _! ord] ( s5sibility is ,rb1 ,na1 ,k2 ?\gh rhubidium is f> exce$$ by ! o!r two metals 9 :ite light4 7#b7 ,illum9ation ( a plane alkali metal ca?ode surface ) pol>is$ light causes greate/ dis*>ge if ! plane ( pol>isation is normal to plane ( incid5ce2 & lea/1 if ! two co9cide4 7,?is is a mo/ rem>kable obs]vation4 ,its probable mean+ is t ! electric oscillations ( light are photo-electrically effective 9 s f> z !y are normal to ! surface on :i* !y act2 :ile electric oscillations tang5tial to ! surface are sc>cely op]ative4 ,diff]5t angles ( incid5ce mu/ be tri$ be=e ! pro( is complete4--,o4 ,j4 ,l47 7#c7 ,electric oscillations ( v %ort p]iod1 su* z are giv5 by a ,h]tz oscillator1 are commutat$ by illum9ation 9 ! pres5ce ( alkali metals 9 r>efi$ gas1 s z to be able to set up a con/ant electric t5sion 9 ! gas4 7,a ,zehnd] tube#ci 0 us$1 & ! mom5t>y phases ( ! oscillation dur+ :i* ! metal is negatively *>g$ are app>5tly tak5 advantage ( by ! illum9ation47 7#d7 ,! photo-electric dissipation %[$ by p[d]$ fluorsp> is dep5d5t on ! col\r ( ! m9]al1 9 su* a way t ! deepe/ blue1 violet or gre5 specim5s are ! mo/ s5sitive4 #ci ,see ,fig4 #ac1 p4 #ae4 ,,app5dix ,v4 ,,photo-,,electric ,,rese>*es ,,( ,m4 ,,augu/e ,,righi4#dj ,m4 ,righi has obs]v$ ! foll[+ facts3 7#a7 ,t ultra-violet rays r$uce to s5sibly ! same pot5tial two metals plac$ ne> ea* o!r 7plate & gauze p>allel & close72 7#b7 ,t sev]al photo-electric c\ples ( ?is k9d c =m a batt]y2 7#c7 ,t a simple metallic plate *>ges itself positively "u ! influ5ce ( radiation2 7#d7 ,t a voltaic arc =m$ ) a z9c rod gives ! /ronge/ effect1 :ile ! sun gives none4 #dj ,comptes ,r5dus1 vol4 #ajg1 p4 #eei4 ,besides ^! facts he f9ds3--7a7 ,t c]ta9 gases & vap\rs1 su* z coal-gas & ,,cs1 absorb ! active rays /rongly4 7b7 ,t if ! dis*>g+ body is easily movable x rec$es l an electric w9dmill4 7c7 ,a film ( gypsum int]pos$ betwe5 gauze & plate *>ges itself negatively on ! side fac+ ! negatively *>g$ plate4 7d7 ,radiation produces its dis*>g+ effect ev5 on non-conductors 7ebonite & sulphur74 ,) glass1 res9 & v>ni%es ! action is feeble1 or ne>ly no?+4 7e7 ,if ! exp]im5t is made ) a copp] gauze & a z9c plate1 ! ph5om5on ne>ly disappe>s on v>ni%+ ! gauze4 ,8 hypo!sis is t radiation produces convection ( negative electricity1 ! c>ri]s be+ molecules ( air4 7f7 ,! c>ry+ molecules move along ! l9es ( =ce1 & ?r[ electric %ad[s4 ,to %[ ?is he v>ni%es a z9c cyl9d]1 all except a g5]at+ l9e1 *>ges x negatively to #a1jjj volts ) a dry pile1 & places x p>allel to a l>ge e>?-connect$ plane1 :i* has a n>r[ rectangul> portion insulat$ f ! re/ & communicat+ ) an electromet]4 ,light only acts on ! uncov]$ l9e ( ! cyl9d]1 & on turn+ ! cyl9d] r\nd ! electromet] is only deflect$ :5 x is expos$ to "s ( ! 7circul>7 l9es ( =ce emanat+ f ! active l9e ( ! cyl9d]4 7g7 ,radiation *>ges positively an insulat$ metal1 ev5 :5 x is an enclosure ) walls ( ! same metal2 ! metal be+ c]ta9ly un*>g$ at ! beg9n+ ( ! exp]im5t4 ,! same occurs ) sulphur & ebonite4 ,if !re is a feeble initial plus *>ge1 radiation increases x4 7h7 ,:ile ! dis*>g+ p[] ( radiation = negative electricity is /ronge/ ) z9c & alum9ium1 & sl[] ) copp] & gold1 foll[+ ! ,volta s]ies2 ! ,e4,m4,f4 set up by radiation1 :5 x *>ges ?+s positively1 is greate/ ) gold & c>bon1 & less ) z9c & alum9ium2 aga9 foll[+ ! ,volta s]ies1 b inv]sely4 7i7 ,if radiation falls on an insulat$ metal plate connect$ ) an electromet]1 9 an enclosure ( ! same metal1 ! positive electrification %[n by ! deflection ( ! electromet] is great] z ! plate is fur!r f ! walls ( ! enclosure4 ,! action /ops :5 ! metal has atta9$ a c]ta9 electric d5sity1 con/ant = a giv5 metal2 s ! pot5tial ( a plate is naturally high] z its capacity is less4 ,x is ?us e/abli%$ t radiation acts on ! p>ticles ( gas 9 contact ) a conductor2 !y g away ) a negative *>ge1 leav+ plus on ! conductor1 until an electric d5sity suffici5t to balance ?is action is atta9$4 7j7 ,x is probable t if ! sol> rays d n produce an effect x is because ( ! absorb+ action ( ! atmosph]e4 ,9 fact1 if "o places a tube ^: ends are glaz$ ) sel5ite betwe5 ! s\rce ( light & ! metals be+ exp]im5t$ on1 ! effects become s5sibly /rong] :5 ! tube is exhau/$4 ,,app5dix ,,vi4 ,,elliptically ,,pol>is$ ,,electric ,,radiation4 ,s9ce ! deliv]y ( my lecture to ! ,royal ,in/itution1 on ,june #a/1 ,h]r ,zehnd] has publi%$#da a mode ( gett+ elliptically & circul>ly pol>is$ electric radiation4 ,he takes a c\ple ( plane pol>is+ grids1 su* z are depict$ 9 ,fig4 #ba1 page #cg1 & places !m p>allel to ea* o!r at a little di/ance ap>t ) _! wires cross$4 ,if ! two grids are close toge!r !y w act l wire-gauze1 reflect+ any k9d ( pol>is$ radiation equally2 b if ! w>p & wo( are an eigh?-wave l5g? ap>t1 & ! plane ( ! incid5t radiation is at #de to ! wires1 ! reflect$ radiation w be circul>ly pol>is$4 ,a *ange 9 ! circum/ances w1 ( c\rse1 make x elliptical4 ,su* a pair ( grids acts1 9 fact1 l a ,bab9et's ,comp5sator4 #da ,b]i*te d] ,natur=s*5d5 ,gesells*aft zu ,freiburg i4 ,b41 ,bd4 ,,ix4 ,heft #b1 ,june #ba1 #ahid4 ,,app5dix ,,vii4 ,,on ,,magnetisation ,,produc$ ,,by ,,h]tzian ,,curr5ts2 ,a ,,magnetic ,,dielectric3#db ,,by ,m4 ,,birkel&4 8,two ye>s ago#dc x 0 prov$ by conclusive exp]im5ts t ,h]tzian waves travell+ along an iron wire magnetise transv]sely ! v ?9 lay] into :i* ! alt]nat+ curr5t p5etrates1 & ^: ?ickness does n exce$ "s ?\s&?s ( a millimetre4 ,once prov$ t alt]nate magnetisation c be produc$ ) su* rapidity1 o!r que/ions pres5t !mselves4 ,"o asks1 = in/ance1 if x is n possible to demon/rate 9 magnetic cyl9d]s /ation>y magnetic waves analog\s to ! electric /ation>y waves along metallic wires40 #db ,ab/ract$ f ,comptes ,r5dus1 ,june #aa1 #ahid1 & communicat$ by ,dr4 ,oliv] ,lodge4 #dc ,:y two ye>s ago8 ,x 0 practically prov$ by ,sav>t e>ly 9 ! c5tury1 & has be5 obs]v$ ov] & ov] aga9 s9ce4 ,h[ev]1 x is true t exp]im5ts h be5 m num]\s & conclusive ( late1 & h be5 pu%$ to v high frequ5cies4--,o4 ,j4 ,l4 ,! au?or f9ds t ! conductivity ( massive iron makes x an unsuitable sub/ance1 & uses in/ead a mixture ( iron fil+s1 or ( *emically-obta9$ iron p[d]1 ) p>aff91 to :i* he sometimes adds p[d]$ qu>tz4 ,?is he m\lds into cyl9d]s1 & ins]ts z ! core ( a spiral 9 an o!rwise ord9>y ,h]tz resonator4 ,fig4 #fg %[s emitt] & receiv] drawn to scale2 ! magnetic cores are introduc$ into ! spiral ,a1 & _! effect on ! l5g? ( ! resonator sp>k is obs]v$4 ,) ?is arrangem5t ( excit] ! electric effect ( ! spiral is negligible1 s9ce x is well remov$ f electro/atic di/urbance1 & subject only to magnetic4 ,! spiral is ( #ab well-insulat$ turns1 ! sp>k gap is a micromet] ) po9t & knob1 & a pair ( adju/able plates to v>y ! capacity = purposes ( tun+4 ,he employ$ #ab diff]5t types ( cyl9d]1 all ab\t #bj c5timetres long1 & #d c5timetres diamet]4 #a4 ,a massive cyl9d] ( s(t iron4 #b4 ,a bundle ( f9e iron wires emb$d$ 9 p>aff94 #c-i4 ,six cyl9d]s ( ! agglom]ate ( *emically-r$uc$ iron 9 p[d] & p>aff91 conta9+ respectively #e1 #aj1 #ae1 #bj1 #be & #ej p] c5t4 ( iron4 ,!n = control exp]im5ts3-- #aj4 ,a cyl9d] ( agglom]ate ( z9c p[d] 9 p>aff91 ) #dj p] c5t4 ( z9c4 #aa4 ,a cyl9d] ( brass fil+s 9 p>aff91 #bj p] c5t4 ( metal4 #ab4 ,a tube ( glass1 #de c5timetres diamet]1 fill$ ) v>i\s electrolytes4 ,illu/ration3 ,,fig4 #fg4 ,! mann] ( obs]v+ 0 z foll[s 7! exp]im5ts 7 done 9 ! laboratory ( ,h]tz73-- ,! resonator1 ) its spiral empty1 0 syntonis$ ) ! excit]1 & ! maximum sp>k measur$4 ,x 0 betwe5 #d & #i millimetres long 9 ^! exp]im5ts4 ,!n "o or o!r ( ! above cyl9d]s 0 introduc$ & ! sp>k l5g? measur$ afre%4 ,cyl9d] #a did n affect ! maximum sp>k l5g?4 ,cyl9d]s #b-d r$uc$ ! maximum sp>k to ? ( its =m] value2 #g & #h to _/?1 & ,no4 #i to _/? ( its =m] value 7viz41 f #i millimetres to #je millimetre74 ,nos4 #aj & #aa _h b a feeble action1 & r$uc$ ! sp>k f #h to #g millimetres4 ,tube ,no4 #ab1 fill$ ) di/ill$ wat]1 sc>cely affect$ ! sp>k l5g?2 ! p]iod ( ! second>y increases a little1 b ! maximum sp>k is ! same z be=e1 once syntony is re-e/abli%$4 ,fill$1 h[ev]1 ) dilute sulphuric acid1 conta9+ #aj1 #bj1 or #cj p] c5t41 ! tube r$uc$ ! sp>k consid]ably1 9 ea* case ab\t ! same1 viz41 f #i to #ac ab\t4 7,curr5ts induc$ by ,maxwellian radiation 9 electrolytes _h be5 already obs]v$ by ,j4 ,j4 ,?omson47 ,:ile try+ to re-e/abli% syntony betwe5 prim>y & second>y1 ,i f\nd t ! p]iod ( ! resonator 0 consid]ably increas$ by ! cyl9d]s #b-d1 b t ! maximum sp>k l5g? 0 mu* dim9i%$4 ,) ! cyl9d]s ,nos4 #e-i 9 ! spiral1 x 0 no long] possible to e/abli% syntony1 8a fact :i* is c]ta9ly due to _! consid]able absorption ( en]gy4 ,take1 = example1 cyl9d] #i3 electromagnetic en]gy mu/ conv]ge rapidly t[>ds x 9 ord] to be trans=m$1 & ! space f9ds itself empty ( en]gy z air is exhau/$ ( vap\r 9 pres5ce ( an absorb+ sub/ance40 8,?is absorption is probably due to hy/]esis 9 ! f]rug9\s cyl9d]s2 ! developm5t ( ,j\lian heat1 s typically %[n by cyl9d] #ab1 be+ und\bt$ly ( ! same ord] 9 cyl9d]s #c-i z 9 ,nos4 #aj1 #aa4 8,x is probably by reason ( ?is absorption t ,i h n succe$$ 9 e/abli%+ /ation>y magnetic waves 9 a circuit ( f]ro-p>aff940 ,if "o ( ! cyl9d]s #b-i1 is wrapp$ 9 t9n$ pap] be=e introduc+ x into ! spiral ,a1 its action is completely /opp$4 7,^! conduct+ cores dim9i% ! p]iod ( ! resonator2 x is mu* z if ! spiral ,a 7 p>tially %unt$ out2 b ! maximum sp>k returns z soon z syntony is re-e/abli%$47 ,to exam9e ?is fur!r he enclos$ ! cyl9d] 9 drums ( c>dbo>d hav+ f9e wires ei!r along g5]at+ l9es1 or along circul> p>allels4 ,! latt] susp5d$ ! action ( an int]ior f]rug9\s cyl9d]1 ! =m] did n4 ,to f9d to :at dep?s ! magnetism p5etrat$1 ,birkel& ins]t$ holl[ f]rug9\s drums into ,a1 measur$ _! effect1 & !n plung$ solid cyl9d]s into !m to see :e!r ! effect increas$4 ,he ?us f\nd t ! magnetisation easily trav]s$ #g millimetres ?ickness ( ! #aj p] c5t4 f]ro-p>aff91 & #e millimetres ( ! #be p] c5t4 ,! sub/ance is comp>able to a dieletric on ! !ory ( ,poisson-,mossotti4 8,! results obta9$ ) our magnetic dielectric invite to new rese>*es0--su* z ! me*anical =ce excit$ by electric waves on a delicately-susp5d$ f]ro-p>aff9 ne$le1 & ! rate ( propagation ( ,maxwellian waves ?r\gh su* a sub/ance4