file :i* includes ! orig9al illu/rations4 ,see #cdjeb-;h4htm or #cdjeb-;h4zip3 7https3_/_/www4gut5b]g4org_/ca*e_/epub_/ #cdjeb_/pg#cdjeb-;images4html7 or 7https3_/_/www4gut5b]g4org_/files_/#cdje b_/cdjeb-;h4zip7 ,images ( ! orig9al pages are available ?r\gh ,int]net ,ar*ive_/,canadian ,libr>ies4 ,see http3_/_/www4ar*ive4org_/details_/wirele s/ransmis#jjm>tu(t ,transcrib]'s note3 ,a c>at "* indicates t ! foll[+ "* 7or *>act]s 9 curly braces7 is a sup]script4 ,examples3 ,a#b 7,a rais$ to ! second p[]71 #aj-g 7#aj rais$ to ! -#g p[]74 ,text enclos$ betwe5 und]scores 0 italiciz$ 9 ! orig9al 7italics74 ,a s+le und]score indicates t ! foll[+ "* or *>act]s is a subscript4 ,example3 ,,cs#b 7! #b is a subscript74 ,numb]s enclos$ by curly braces )9 ! text are page numb]s 7example3 #ajj71 :i* h be5 incorporat$ to enable ! read] to use ! index4 ,,wireless ,,transmission ,,( ,,photographs ,illu/ration3 ,,fig4 #aj4 99 99 99 99 99 ,,wireless ,,transmission ,,( ,,photographs by ,,m>cus ,j4 ,,m>t9 ,,second ,,edition ,,revis$ ,,& ,,enl>g$ #aiai ,! ,wireless ,press1 ,ltd4 #ab-ac ,h5rietta ,/reet1 ,/r& ,london1 ,w4,c4 #b v ,,preface ,,to ,,second ,,edition ,al?\gh dur+ ! la/ few ye>s v little1 9 common ) o!r wireless "w1 has be5 possible 9 connection ) ! practical side ( ! wireless transmission ( photographs1 yet1 n[ t ! prospect ( exp]im5tal "w is once aga9 occupy+ ! m9ds ( all wireless work]s1 advantage has be5 tak5 ( a repr9t ( ?is little volume to amplify a few po9ts t 7 insuffici5tly dealt ) 9 ! fir/ edition1 & also to add "s fre% matt]4 ,to ,*apt] ,v4 has be5 add$ a %ort description ( ! ,n]n/ lamp1 & also "s useful in=mation reg>d+ photographic films1 & a few notes relat+ to enl>g+ includ$ 9 ! ,app5dix ,b4 ,a fre% app5dix deal+ ) ! pr9ciples ( optical l5ses has also be5 add$4 ,?is is a subject t plays an important "p 9 any sy/em ( wireless photography1 & to ^? exp]im5t]s ^: k ( optics is limit$ ?is section %\ld prove useful4 ,to s]i\s work]s engag$ on ! problem ( ! wireless transmission ( photographs1 att5tion vi is call$ to a s]ies ( articles :i* are be+ publi%$ f "t to "t 9 ! ,wireless ,_w1 on ! design & con/ruction ( wireless photographic app>atus4 ,m4 ,j4 ,m4 ,,maid/one1 #aiai4 vii ,,preface ,9 ^! progressive times x is only reasonable to expect t "s attempt w\ld be made to utilise ! e!r-waves = o!r purposes ?an t ( telegraphic communication1 & already _m clev] m9ds are at "w try+ to solve ! problems ( ! wireless control ( torp$oes & air%ips1 wireless telephony1 &1 la/ b n lea/1 ! wireless transmission ( photographs4 ,x may seem r premature to talk ab\t ! wireless transmission ( photographs at a "t :5 ! ord9>y sy/ems are n fully develop$2 b ! prospects ( wireless photography are ( a v enc\rag+ nature1 especially = long ov]-wat] di/ances1 z !re are great difficulties to be ov]come 9 long-di/ance transmission ov] ord9>y l& l9es & cables :i* w be entirely elim9at$ by wireless me?ods4 ,f a p]usal ( ,*apt] ,i4 ! read] w be able to und]/& some?+ ( ! difficulties t are to be enc\nt]$ 9 work+ ov] long di/ances1 & he w also be able to appreciate some?+ ( ! advantages t w\ld be d]iv$ viii f a reliable wireless sy/em4 ,ap>t f ! value ( su* a sy/em = transmitt+ news pictures1 x w\ld also be ( great advantage to transmit to %ips at sea photographs ( crim9als = id5tification purposes4 ,9 su* a small volume z ?is x w\ld be impossible to deal ) ! work+ ( wireless app>atus & ! _m sy/ems t h be5 devis$ = ! transmission ( photographs ov] metallic circuits4 ,! ,au?or has tak5 x = grant$ t o!r works h be5 /udi$ 9 connection ) ^! subjects1 & w !re=e only describe su* app>atus z is likely to be ( use 9 wireless transmission4 ,at pres5t ! transmission ( photographs by wireless me?ods is 9 a purely exp]im5tal /age1 & ?is book w h s]v$ its purpose if x helps to put future exp]im5t]s on ! "r track & prev5t !m f mak+ exp5sive & fruitless exp]im5ts1 by %[+ !m ! "r direction 9 :i* inve/igations are be+ c>ri$ out4 ,z !re is no claim to orig9ality 9 respect ( a good _m pieces ( app>atus1 etc41 describ$1 ,i h n ?\ght x necess>y to /ate ! v>i\s s\rces f :i* ! in=mation has be5 obta9$4 ,m4 ,j4 ,m4 ,,a%=d1 #aiaf4 99 99 99 99 99 ix ,,cont5ts ,,page ,,preface ,,to ,,second ,,edition v ,,preface vii ,,*apt] ,i ,,introductory #a ,=eword--,e>ly exp]im5ts--,advantages ( ,radio-,photography--,difficulties 9 ,cable work+--,b]no*i's ,sy/em--,knuds5's ,sy/em4 ,,*apt] ,,ii ,,transmitt+ ,,app>atus #ac ,wireless ,app>atus--,prep>+ ! ,photographs--,transmitt+ ,ma*9es--,transmitt+ ,app>atus--,effects ( ,arc+--,sp>k-,gaps--,contact ,break]s--,complete ,/ation--,pr(essor ,korn's ,app>atus--,p\ls5 ,company's ,photographic ,record]--,comp>ison ( v>i\s sy/ems--,practical applications4 ,,*apt] ,,iii ,,receiv+ ,,app>atus #cg ,me?ods ( ,receiv+--,au?or's ,photographic ,receiv]--,decoh]+ ,app>atus--,description ( ,e9?ov5 ,galvanomet]--,use ( ,galvanomet] 9 ,receiv+--,bel9's ,application ( ,blondel's ,oscillograph--,description ( ,*>bonelle's ,receiv]--,use ( ,telephone ,relay--,description ( ,telephone ,relay--,telephotographic ,receiv]--,pol>isation ,receiv]--,ka?ode-,ray ,receiv]--,electrolytic ,receiv]--,atmosph]ics 9 ,long-,di/ance work+4 x ,,*apt] ,,iv ,,syn*ronis+ ,,& ,,driv+ #fc ,driv+ ,motors--,iso*ronis+ ! ,electrolytic ,sy/em--,pr(essor ,korn's me?od--,description ( ,hughes ,gov]nor--,au?or's ,spe$ ,regulator--,problem ( ,syn*ronis+--,me?ods ( ,syn*ronis+--,advances made 9 ,radio-,photography4 ,,*apt] ,v ,,! ,,telephograph #gd ,au?or's ,sy/em ( ,radio-,photography--,requirem5ts--,adva ntages--,transmitt+ ma*9e--,description ( ,diff]5tial ,relay--,wireless ,receiv+ ,app>atus--,photo-,telegraphic ,receiv+ ,app>atus--,circuit ,break]--,friction ,brake--,magnetic ,clut*--,description ( ,iso*ronis]--,me?od ( work+--,types ( ,n]n/ ,lamp--,action ( ,n]n/ ,lamp--,comp>ison ( ,act9ic ,value--,in]tia ( ,photographic ,films--,*oos+ ,films--,spe$ ( ,films--,/&>d ( ,spe$--,comp>ative ,film ,spe$s--,effects ( ,m9imum ,exposure--,effects ( ,maximum ,exposure--,consid]ations 9 work+ & *oos+ ,films4 ,,app5dix ,a ,,sel5ium ,,cells #aji ,nature ( ,sel5ium--,prep>ation ( ,sel5ium--,=ms ( ,sel5ium ,cells--,action ( ,sel5ium ,cells--,*>act]i/ics ( ,sel5ium ,cells--,effects ( ,in]tia 9 ,photo-,telegraphy--,me?ods ( c\nt]act+ ,in]tia--,s5sitiv5ess ( ,sel5ium to ,light--,effect ( ,heat on ,sel5ium4 ,,app5dix ,b ,,prep>+ ,,! ,,metal ,,pr9ts #aae ,outl9e ( ,process--,l9e ,scre5s--,*oice ( ,cam]a--,fix+ ,l9e ,scre5 9 ,cam]a--,l5ses & ,/ops--,tak+ ! ,photograph--,copy+ ,/&s--,*oice ( ,photographic ,plates--,s\rces ( ,illum9ation--,metal ,pr9ts--,coat+ ! xi ,metal ,%eets--,s5sitis+ ,solution--,pr9t+ ,op]ations--,develop+--,int5sify+--,prec autions to be obs]v$ 9 work+--,prep>+ ,sket*es on ,metal--,app>atus = ,r$uc+ or ,enl>g+--,improvem5ts to ,copy+ ,bo>d--,l5ses = ,copy+--,=mula = ,copy+4 ,,app5dix ,c ,,l5ses #abf ,action ( ,light--,law ( ,refraction--,l5ses--,prisms--,action ( ,l5ses--,focal ,l5g? ( ,l5ses--,=mation ( ,images--,app>5t ,magnitude ( ,objects--,real & ,virtual ,images--,=mation ( ,virtual ,images--,p[] ( ,magnification--,defects ( ,l5ses--,ab]ration4 99 99 99 99 99 xiii ,,illu/rations ,,fig4 ,,page #a4 ,diagram %[+ effects ( capacity on an int]mitt5t curr5t #e #b4 ,b]no*i's wireless app>atus #g #c4 ,knuds5's wireless app>atus #aj #d4 ,wireless transmitt+ /ation #ac #e4 ,diagram ( exp]im5t illu/rat+ pr9ciple ( l9e photograph #af #f4 ,draw+ ( transmitt+ ma*9e #ag #g4 ,draw+ ( transmitt+ ma*9e #ah #h4 ,draw+ ( /ylus #ah #i4 ,electrical connections ( ma*9e #ai #aj4 ,photograph ( ,au?or's exp]im5tal ma*9e ,frontispiece #aj;a4 ,end view ( ,au?or's exp]im5tal ma*9e fac+ page #ba #aj;b4 ,view ( image brok5 up by a cross scre5 #aa4 ,connections ( complete transmitt+ app>atus #bc #ab4 ,draw+ ( ord9>y type ( sp>k-gap #bg #ac4 ,syn*ron\s rotat+ sp>k-gap #bh #ad4 ,non-syn*ron\s rotat+ sp>k-gap #bh #ae4 ,connections = complete wireless photographic /ation #cj #af4 ,connections ( ,pr(essor ,korn's app>atus #ca #ag4 ,connections ( ,p\ls5's photographic record] #cc #ah4 ,au?or's photographic receiv] #ch #ai4 ,enl>g$ draw+ ( cone #ci #bj4 ,end view ( ,au?or's photographic receiv] #ci #ba4 ,connections ( decoh]+ app>atus #da #bb4 ,connections = complete photographic receiv] #db xiv #bc4 ,arrangem5t ( ,e9?ov5 galvanomet] #de #bd4 ,e9?ov5 galvanomet] arrang$ = receiv+ #df #be4 ,connection ( telephone relay #di #bf4 ,draw+ ( ,au?or's improv$ photographic receiv] #ea #bg4 ,diagram giv+ ratio ( vibrat+ arm #ea #bh4 ,arrangem5t ( pol>isation receiv] #ec #bi4 ,arrangem5t ( ka?ode-ray receiv] #ed #cj4 ,connections ( electrolytic receiv] #ef #ca4 ,draw+ ( improv$ /ylus = receiv+ #eh #cb4 ,draw+ ( ,hughes telegraph gov]nor #ff #cc4 ,arrangem5t ( simple spe$ regulator #fh #cd4 ,diagram ( connections ( simple spe$ regulator #fh #ce4 ,au?or's arrangem5t = complete radio-photographic /ation #gg #cf4 ,draw+ ( transmitt+ ma*9e & circuit break] #gh #cg4 ,draw+ ( special transmitt+ /ylus %[+ adju/+ arrangem5ts #gi #cg;a4 ,end view ( transmitt+ /ylus #gi #ch4 ,connections ( new type ( relay design$ by ! ,au?or #hj #ci4 ,arrangem5t ( m]cury conta9]s & dipp+ rods = relay #hb #dj4 ,draw+ ( ,au?or's receiv] #hd #da4 ,enl>g$ draw+ ( diaphragm & /eel po9t #hd #da;a4 ,draw+ %[+ arrangem5t ( bu% & c\nt]-weight #hd #db4 ,optical arrangem5ts ( receiv] #he #dc4 ,optical arrangem5ts ( receiv] #hf #dd4 ,draw+ ( circuit break] #hh #de4 ,draw+ ( friction brake #hi #df4 ,sectional draw+ ( magnetic clut* #ij #dg4 ,plan ( magnetic clut* #ij #dh4 ,details ( ,iso*ronis] #ib #di4 ,connections ( ,iso*ronis] #id #ej4 ,dial ( ,iso*ronis] #id #ea4 ,diagram ( driv+ me*anism #if xv #eb4 ,diagram %[+ />t+ positions ( ma*9es #ig #eb;a4 ,arrangem5t ( small type ,n]n/ lamp #ii #eb;b4 ,balla/+ resi/ances = ,n]n/ lamps #ajj #eb;c4 ,arrangem5t ( l>ge type ,n]n/ lamp #aja #ec4 ,connections ( sel5ium cell elem5ts #aaj #ec;a4 ,=m ( sel5ium cell us$ by ,bell & ,ta9t] #aaj #ed4 ,diagram %[+ con/ruction ( mod]n cell #aaa #ee4 ,resi/ance curve ( sel5ium cell #aaa #ee;a4 ,actual curve ( sel5ium cell #aab #ef4 ,diagram ( ,pr(essor ,korn's me?od = c\nt]act+ in]tia #aac #eg4 ,arrangem5t ( plate %ea? & l9e scre5 #aag #eh4 ,details ( clips to hold l9e scre5 #aah #ei4 ,arrangem5t ( app>atus = copy+ #aai #fj4 ,draw+ %[+ me?od ( arrang+ cam]a & copy+ /& = adju/m5t #aai #fa4 ,photograph ( l9e scre5 & metal pr9t fac+ page #abd #fb4 ,photograph ( sket* drawn ^u metal foil #fc4 ,me?od ( m>k+ out copy+ bo>d #abd #fd4 ,diagram illu/rat+ law ( refraction #abg #fe4 ,=ms ( l5ses #abh #ff4 ,action ( light pass$ ?r\gh a prism #abi #fg4 ,diagram illu/rat+ action ( a l5s #acj #fh4 ,=mation ( pr9cipal focus ( a l5s #acj #fi4 ,=mation ( conjugate foci ( a l5s #aca #gj4 ,app>atus illu/rat+ pr9ciple ( cam]a #acb #ga4 ,=mation ( an image by a l5s #acc #gb4 ,diagram illu/rat+ app>5t magnitude #acd #gc4 ,=mation ( virtual image by a convex l5s #acg #gd4 ,=mation ( virtual image by a concave l5s #ach #ge4 ,diagram %[+ sph]ical ab]ration #aci #gf4 ,comb9ation ( plano-convex l5ses #aci #gg4 ,comb9ation ( m5iscus & convex l5ses #aci 99 99 99 99 99 #a ,,radio-,,photography ,,*apt] ,i ,,introductory ,^? :o desire to exp]im5t on radio-photography1 i4e4 transmitt+ photographs1 draw+s1 etc41 f "o place to ano!r )\t ! aid ( artificial conductors1 mu/ cultivate at lea/ an elem5t>y k ( optics1 *emi/ry1 me*anics1 & electricity2 photo-telegraphy call+ = a k ( all ^! sci5ces4 ,!re are1 no d\bt1 _m wireless work]s :o are int]e/$ 9 ?is subject1 b :o are det]r$ f exp]im5t+ ow+ to a lack ( k reg>d+ ! direction developm5ts are tak+1 besides :i*1 in=mation on ?is subject is v difficult to obta91 ! sci5ce ( photo-telegraphy be+1 at ! pres5t "t1 9 a purely exp]im5tal /age4 ,! wireless transmission ( photographs has1 no d\bt1 a great comm]cial value1 b = any sy/em to be comm]cially practicable1 x mu/ be simple1 rapid1 & reliable1 besides be+ able to "w #b 9 conjunction ) ! app>atus already in/all$ = ! purpose ( ord9>y wireless telegraphy4 ,z f> back z #ahdg exp]im5ts 7 c>ri$ out ) a view to solv+ ! problem ( transmitt+ pictures & writ+ by electrical me?ods ov] artificial conductors1 b no great inc5tive 0 held =? = developm5t ow+ to lack ( possible application2 b ow+ to ! great public dem& = illu/rat$ newspap]s t has rec5tly sprung into be+1 a l>ge field has be5 op5$ up4 ,dur+ ! la/ t5 ye>s1 h[ev]1 developm5t has be5 v rapid1 & "s excell5t results are n[ be+ obta9$ ov] a consid]able l5g? ( l9e4 ,! wireless transmission ( photographs is1 on ! o!r h&1 ( q rec5t gr[?1 ! fir/ practicable attempt be+ made by ,mr4 ,hans ,knuds5 9 #aijh4 ,x may seem r premature to talk ab\t ! wireless transmission at a "t :5 ! sy/ems = transmitt+ ov] ord9>y conductors are n p]fectly develop$1 b ev]y?+ po9ts to ! fact t = long-di/ance transmission a reliable wireless sy/em w prove to be bo? *eap] & quick] ?an transmission ov] ord9>y l& l9es & cables4 ,! effects ( capacity & inductance--prop]ties inh]5t to all telegraph sy/ems us+ metallic conductors--h a di/9ct be>+ ^u ! two que/ions1 h[ f> & h[ quickly c #c photographs be transmitt$8 ,ow+ to ! small curr5ts receiv$ & to prev5t int]f]5ce f e>? curr5ts x is necess>y to use a complete metallic circuit4 ,if an ov]head l9e c\ld be employ$ no difficulty w\ld be exp]i5c$ 9 work+ a di/ance ( ov] #ajjj miles1 b a l9e ( ?is l5g? is impossible--at lea/ 9 ?is c\ntry--& if transmission is attempt$ ) any o!r c\ntry1 a c]ta9 am\nt ( subm>9e cable is ess5tial4 ,x has be5 f\nd t ! electro/atic capacity ( "o mile ( subm>9e cable is equal to ! capacity ( #bj miles ( ov]head l9e1 & z ! effect ( capacity is to ret>d ! curr5t & r$uce ! spe$ ( work+1 x is evid5t t :]e !re is any great l5g? ( cable 9 ! circuit ! di/ance ( possible transmission is enorm\sly r$uc$4 ,if we take = an example ! ,london-,p>is telephone l9e ) a l5g? ( #caa miles & a capacity ( #aj4fb micr(>ads1 we f9d t ab\t half ?is capacity1 or #e4i micr(>ads1#a is contribut$ by ! #bc miles ( cable connect+ ,engl& ) ,france4 ,9 practice ! r$uction ( spe$ due to capacity has1 to a great ext5t1 be5 ov]come by means ( app>atus kn[n z a l9e-balanc]1 :i* ha/5s ! sl[ dis*>ge ( ! l9e & #d all[s ea* curr5t s5t out f ! transmitt]--! curr5t 9 sev]al sy/ems be+ int]mitt5t--to be record$ sep>ately on ! receiv]4 ,photographs suitable = press "w c n[ be s5t ov] a l9e :i* includes only a %ort l5g? ( cable = a di/ance ( q #djj miles 9 ab\t t5 m9utes1 ! "t1 ( c\rse1 dep5d+ ^u ! size ( ! photograph4 ,9 ext5d+ ! work+ to o!r c\ntries :]e !re is ne$ = a great l5g? ( cable1 z betwe5 ,engl& & ,irel&1 or ,am]ica1 ! ret>dation due to capacity is v great4 ,on a cable jo9+ ?is c\ntry ) ,am]ica ! curr5t is ret>d$ f\r-t5?s ( a second4 ,9 subm>9e telegraphy use is made ( only "o cable ) an e>? return1 b special means h _h to be adopt$ to ov]come int]f]5ce f e>? curr5ts1 z ! enorm\s co/ prohibits ! lay+ ( a second cable to provide a complete metallic circuit4 ,! curr5t available at ! cable ends = receiv+ is v small1 be+ only #a_/bjjjjj? "p ( an amp]e1 & ?is necessitates ! use ( app>atus ( a v s5sitive "*4 ,"o sy/em ( photo-telegraphy 9 use at ! pres5t "t1 employs :at is kn[n z an electrolytic receiv] 7see ,*apt] ,,iii47 :i* c record signals ov] a l5g? ( l9e 9 :i* ! capacity effects are v slight1 ) ! m>vell\s spe$ ( #ab1jjj a m9ute1 b ?is spe$ rapidly decreases ) an increase ( di/ance betwe5 ! #e ,illu/ration two /ations4 ,! effect ( capacity ^u an int]mitt5t curr5t is cle>ly %[n 9 ,fig4 #a4 ,if we 7 to s5d tw5ty brief curr5ts 9 rapid succession ov] a l9e ( mod]ate capacity 9 a giv5 "t1 we %\ld f9d t in/ead ( be+ record$ sep>ately & di/9ctly z at a1 ea* m>k w\ld be po9t$ at bo? ends & jo9$ toge!r z %[n at b1 :ile only p]haps fifte5 c\ld be record$4 ,if ! capacity be /ill f>!r increas$ z at c1 only p]haps half ! orig9al numb] ( curr5ts c\ld be record$ 9 ! same "t1 ow+ to ! fact t ) an increase ( resi/ance1 capacity1 & inductance ( ! l9e a long] "t is requir$ = x to *>ge up & dis*>ge1 !reby mat]ially less5+ ! rate at :i* x w all[ sep>ate signals to pass2 ! numb] ( signals t c !re=e be record$ 9 a giv5 "t is greatly dim9i%$4 ,if we 7 to attempt to s5d ! same numb] ( signals ov] a l9e ( great capacity1 z c\ld be s5t1 & record$ sep>ately & di/9ctly ov] a l9e ( small capacity--! "t limit be+ ( c\rse ! same 9 bo? in/ances--we %\ld f9d t ! #f signals w\ld be record$ practically z a cont9u\s l9e4 ,! two latt] cases b1 & c1 ,fig4 #a1 cle>ly %[s ! ret>dation t takes place at ! comm5cem5t ( a curr5t & ! prolongation t takes place at ! f9i%4 ,if ! photo-telegraphic sy/em previ\sly m5tion$ c\ld be r5d]$ s5sitive en\gh to "w on ! ,atlantic cables1 we %\ld f9d t only ab\t #abjj signals a m9ute c\ld be record$1 & ?is w\ld mean t a photograph :i* c\ld be transmitt$ ov] ord9>y l& l9es 9 ab\t t5 m9utes w\ld take at lea/ fifty m9utes ov] ! cable4 ,?is w\ld be bo? co/ly & impracticable1 & "t alone w %[ :e!r1 = long-di/ance "w1 transmission by wireless w be bo? *eap] & m rapid ?an any o!r me?od4 ,at pres5t wireless telegraphy has n sup]s$$ ! ord9>y me?ods ( communicat+ ov] l&1 b !re c be no d\bt t wireless telegraphy1 if free f ,gov]nm5t re/rictions1 w\ld 9 c]ta9 circum/ances v quickly sup]s$e l&-l9e telegraphy1 :ile x has prov$ a =midable comm]cial competitor to ! cable z a means ( connect+ ?is c\ntry ) ,am]ica4 ,likewise we _c say t no sy/em ( radio-photography w ev] come into g5]al use1 b :]e !re is any great di/ance to be bridg$1 especially ov] wat]1 wireless transmission is really ! only practical solution4 ,f ! #g =ego+ rem>ks1 x is evid5t t a reliable sy/em ( radio-photography w\ld secure a great victory 9 ! matt] ( "t & co/ alone1 besides :i*1 ! photo-telegraphic app>atus w\ld be m]ely an accessory to ! already exi/+ wireless in/allation4 ,illu/ration3 ,,fig4 #b4 ,!re h be5 num]\s sugge/ions put =w>d = ! wireless transmission ( photographs1 b !y are all m or less impracticable4 ,"o ( ! e>lie/ sy/ems 0 devis$ by de' ,b]no*i ( ,tur91 b 8 sy/em c only be reg>d$ int]e/+ f an hi/orical po9t ( view1 & z 9 all probability x c\ld only h be5 made to "w ov] a di/ance ( a few hundr$ y>ds x is ( no practical value4 ,fig4 #b w help to expla9 ! app>atus4 ,a glass cyl9d] ,a' is fa/5$ at "o end to a ?read$ /eel %aft1 :i* runs 9 two be>+s1 "o be>+ hav+ an int]nal ?read correspond+ ) t on ! #h %aft4 ,r\nd ! cyl9d] is wrapp$ a transp>5t film ^u :i* a photograph has be5 tak5 & develop$4 ,light f a p[]ful electric lamp ,l1 is focuss$ by means ( ! l5s1 ,n1 to a po9t ^u ! photographic film4 ,z ! cyl9d] is revolv$ by means ( a suitable motor1 x travels upw>ds simultane\sly by reason ( ! ?read$ %aft & be>+1 s t ! spot ( light traces a complete spiral ov] ! surface ( ! film4 ,! light1 on pass+ ?r\gh ! film 7! transmission ( :i* v>ies 9 int5sity accord+ to ! d5sity ( t portion ( ! photograph ?r\gh :i* x is pass+71 is refract$ by ! prism ,p on to ! sel5ium cell ,s :i* is 9 s]ies ) a batt]y ,b & ! prim>y ,x ( a =m ( induction coil4 ,z light ( diff]5t int5sities falls ^u ! sel5ium cell1#b ! resi/ance ( :i* alt]s 9 proportion1 curr5t is induc$ 9 ! second>y ,y ( ! coil & influ5ces ! light ( an arc lamp ( ^: circuit x is %unt$4 ,?is arc lamp ,t is plac$ at ! focus ( a p>abolic reflector ,r1 f :i* ! light is reflect$ 9 a p>allel beam to ! receiv+ /ation4 ,! receiv] consi/s ( a simil> reflector ,r' ) a sel5ium cell ,e plac$ at its focus1 ^: resi/ance is alt]$ by ! v>y+ light fall+ ^u x f ! reflector ,r4 ,! sel5ium cell #i ,e is 9 s]ies ) a batt]y ,f & ! mirror galvanomet] ,h4 ,light falls f a lamp ,d & is reflect$ by ! mirror ( ! galvanomet] on to a graduat$ ap]ture ,j & focuss$ by means ( ! aplanatic l5s ,u ^u ! receiv+ drum ,a#b1 :i* c>ries a s5sitis$ photographic film4 ,! two cyl9d]s mu/ be revolv$ syn*ron\sly4 ,! above app>atus is v clev]1 b _c be made to "w ov] a di/ance ( m ?an #bjj y>ds4 ,a sy/em bas$ on m practical l9es 0 t inv5t$ & demon/rat$ by ,mr4 ,hans ,knuds51 b ! app>atus :i* he employ$ = receiv+ has be5 disc>d$ 9 wireless "w1 z x is n suitable = work+ ) ! highly-tun$ sy/ems 9 use at ! pres5t "t4 ,knuds5's transmitt]1 a diagrammatic repres5tation ( :i* is giv5 9 ,fig4 #c1 consi/s ( a flat table to :i* a horizontal to-&-fro motion is giv5 by means ( a clockwork motor4 ,^u ?is table is fa/5$ a photographic plate :i* has be5 prep>$ 9 ! foll[+ mann]4 ,! plate ^u :i* ! photograph is to be tak5 has ! gelat9e film f ?ree to f\r times ?ick] ?an t commonly us$ 9 photography4 ,9 ! cam]a1 betwe5 ! l5s & ?is plate1 a s+le l9e scre5 is int]pos$1 :i* has ! effect ( break+ ! picture up into p>allel l9es4 ,^u ! plate be+ develop$ & be=e x is #aj ,illu/ration completely dry1 x is spr9kl$ ov] ) f9e iron du/4 ,) ?is type ( plate ! transp>5t p>ts dry mu* quick] ?an ! %ad$ or d>k p>ts1 & on ! iron du/ be+ spr9kl$ ov] ! plate x adh]es to ! d>k] portions ( ! film to a great] ext5t ?an x does to ! light] portions2 a picture p>tly compos$ ( iron du/ is ?us obta9$4 ,a /eel po9t atta*$ to a flat spr+ re/s ^u ?is plate & is made to travel at "r angles to ! motion ( ! table4 ,z ! picture is p>tly compos$ ( iron du/1 & z ! /eel ne$le is fa/5$ to a delicate spr+ x is evid5t t z ! plate passes to & fro "u ! ne$le1 bo? ! spr+ & ne$le are set 9 a /ate ( vibration4 ,?is vibrat+ spr+ makes #aa & breaks ! batt]y circuit ( a sp>k coil1 :i* 9 turn sets up sp>k+ 9 ! sp>k-gap ( ! wireless app>atus4 ,! receiv] consi/s ( a simil> table to t us$ = transmitt+1 & c>ries a glass plate t has be5 smok$ ^u "o side4 ,a simil> spr+ & ne$le is plac$ ov] ?is plate1 b is actuat$ by means ( a small electro-magnet 9 circuit ) a batt]y & a s5sitive coh]]4 ,z ! coh]] makes & breaks ! batt]y circuit by means ( ! int]mitt5t waves s5t out f ! transmitt+ a]ial1 ! ne$le is made to vibrate ^u ! smok$ glass plate 9 unison ) ! ne$le at ! transmitt+ end4 ,scrat*es are made ^u ! smok$ plate1 & ^! reproduce ! picture on ! orig9al plate4 ,a pr9t c be tak5 f ?is scrat*$ plate 9 a simil> mann] to an ord9>y photographic negative4 ,! two tables are syn*ronis$ 9 ! foll[+ mann]4 ,e "t ! transmitt+ table is ab\t to />t its =w>d /roke a p[]ful sp>k is produc$ at ! sp>k-gap4 ,! waves set up by ?is sp>k op]ate an ord9>y metal fil+s coh]] at ! receiv+ end :i* completes ! circuit ( an electro-magnet4 ,! armature ( ?is magnet on be+ attract$ imm$iately releases ! motor us$ = driv+1 all[+ x to op]ate ! table4 ,! "t tak5 to transmit a photograph1 qu>t]-plate size1 is ab\t fifte5 m9utes4 #ab ,al?\gh v +5i\s ?is sy/em w\ld n be practicable1 z besides spe$ ! quality ( ! receiv$ pictures is a great factor1 especially :]e !y are requir$ = reproduction purposes4 ,! results f ! above app>atus are said to be v crude1 z ) ! me?od us$ to prep>e ! photographs no v small detail c\ld be transmitt$4 99 99 99 99 99 #ac ,,*apt] ,,ii ,,transmitt+ ,,app>atus ,let u n[ consid] ! requirem5ts necess>y = transmitt+ photographs by means ( ! wireless app>atus 9 use at ! pres5t "t4 ,illu/ration3 ,,fig4 #d4 ,! connections = an exp]im5tal syntonic wireless transmitt+ /ation are %[n 9 ! diagram ,fig4 #d4 ,a is ! a]ial2 ,t1 ! inductance2 ,e1 e>?2 ,l1 hot-wire ammet]4 ,! clos$ oscillatory circuit consi/s ( an inductance ,f1 sp>k-gap ,g1 & a block cond5s] ,c4 ,h is a sp>k-coil = supply+ ! en]gy1 ! second>y ,j be+ connect$ to ! sp>k-gap4 ,a #ad m]cury break ,n & a batt]y ,b are plac$ 9 ! prim>y circuit ( ! coil4 ,! ,morse key ,k is = complet+ ! batt]y circuit = signall+ purposes4 ,:5 ! key ,k is depress$1 ! batt]y circuit is complet$1 & a sp>k passes betwe5 ! balls ( ! sp>k-gap ,g produc+ oscillations 9 ! clos$ circuit1 :i* are transpos$ to ! a]ial circuit by induction4 ,= signall+ purposes x is only necess>y = ! op]ator by means ( ! key ,k to s5d out a long or %ort tra9 ( waves 9 "s pre-arrang$ ord]1 to enable ! op]ator at ! receiv+ /ation to und]/& ! message t is be+ transmitt$4 ,if a photograph c\ld be prep>$ 9 su* a mann] t x w\ld s]ve ! purpose ( ! key ,k1 & c\ld s arrange matt]s t a m9ute portion ( ! photograph c\ld be transmitt$ sep>ately b 9 succession1 & t ea* portion ( ! photograph hav+ ! same d5sity c\ld be giv5 ! same signal1 !n x w\ld only be necess>y to h app>atus at ! receiv+ /ation capable ( arrang+ ! signals 9 prop] sequ5ce 7ea* signal record$ be+ ! same size & hav+ ! same d5sity z ! transmitt$ portion ( ! photograph7 9 ord] to receive a facsimile ( ! picture transmitt$4 ,! foll[+ me?od ( prep>+ ! photograph#c is "o t has be5 adopt$ 9 sev]al #ae sy/ems ( photo-telegraphy1 & is ! only "o at all suitable = wireless transmission4 ,! photograph or picture :i* is to be transmitt$ is fa/5$ out p]fectly flat ^u a copy+-bo>d4 ,a /rong light is plac$ on ei!r side ( ?is copy+ bo>d1 & is conc5trat$ ^u ! picture by means ( reflectors4 ,! cam]a :i* is us$ = copy+ has a s+le l9e scre5 int]pos$ betwe5 ! l5s & s5sitis$ plate1 & ! effect ( ?is scre5 is to break ! picture up into p>allel l9es4 ,?us a :ite portion ( ! photograph w\ld consi/ ( v n>r[ l9es wide ap>t1 :ile ! d>k portion w\ld be made up ( wide l9es close toge!r2 a black "p w\ld appe> solid & %[ no l9es at all4 ,f ?is l9e negative x w be necess>y to take (f a pr9t ^u a specially prep>$ %eet ( metal4 ,?is consi/s ( a %eet ( ?ick lead- or t9foil1 coat$ ^u "o side ) a ?9 film ( glue to :i* bi*romate ( pota% has be5 add$2 ! bi*romate possess+ ! prop]ty ( r5d]+ ! glue wat]pro( :5 act$ ^u by light4 ,! pr9t c be tak5 (f by artificial light 7arc lamps be+ g5]ally us$71 b ! exact "t to all[ = pr9t+ c only be f\nd by exp]im5t1 z x v>ies consid]ably accord+ to ! ?ickness ( ! film4 ,! pr9t+ f9i%$1 ! metal pr9t is wa%$ "u runn+ wat]1 :5 all ^? p>ts n act$ ^u by light1 i4e4 ! p>ts betwe5 ! l9es1 are #af wa%$ away1 leav+ ! b>e metal4 ,we h n[ an image compos$ ( num]\s b&s ( insulat+ mat]ial 7ea* b& v>y+ 9 wid? accord+ to ! d5sity ( ! photograph at any po9t f :i* x is prep>$7 atta*$ to a metal base1 s t ea* b& ( insulat+ mat]ial is sep>at$ by a b& ( conduct+ mat]ial4 ,x is1 ( c\rse1 obvi\s t ! l9es on ! pr9t _c be wid] ap>t1 c5tre to c5tre1 ?an ! l9es ( ! scre5 us$ 9 prep>+ x4 ,a good scre5 to use is "o hav+ #ej l9es to ! in*1 b "o is p]haps m suitable = exp]im5tal "w a little co>s]1 say #ce l9es to ! in*4 ,to use a scre5 hav+ #ej or m l9es to ! in*1 ! transmitt+ app>atus1 z w be evid5t lat] on1 w require to be v ne>ly p]fect4 ,illu/ration3 ,,fig4 #e4 ,be=e proce$+ fur!r x w p]haps be z well to make an exp]im5t4 ,if we take "o ( ! metal pr9ts or1 m simple1 draw a sket* 9 insulat+ ink ^u a %eet ( metal ,a1 ,fig4 #e1 & connect a batt]y ,b & ! galvanomet] ,d z %[n1 we %all f9d on draw+ ! free end ( ! wire across ! metal plate t all ! "t ! wire is 9 contact ) ! l9es ( insulat+ mat]ial ! ne$le ( ! galvanomet] w rema9 #ag at z]o1 b :]e x is 9 contact ) ! metal plate ! ne$le is deflect$4 ,f ?is exp]im5t x w be se5 t we h 9 our metal l9e pr9t1 :i* consi/s ( alt]nate l9es ( insulat+ & conduct+ mat]ial1 a me?od by :i* an electric circuit c be v easily made & brok54 ,x is1 ( c\rse1 necess>y to h "s arrangem5t :]eby ! :ole ( ! surface ( ! metal pr9t is utilis$ = ?is purpose to ! be/ advantage4 ,"o type ( transmitt+ ma*9e us$ = ?is purpose is repres5t$ by ! diagram1 ,fig4 #f4 ,! cyl9d] ,a is fa/5$ to ! /eel %aft ,b1 :i* runs 9 ! two be>+s ,d & ,d'1 ! be>+ ,d' hav+ an int]nal ?read correspond+ to t on ! %aft4 ,! /ylus 9 ?is class ( ma*9e is a fixture1 ! cyl9d] be+ giv5 a lat]al z well z a revolv+ movem5t4 ,z x is impossible to use a rigid drive1 a flexible c\pl+ ,f is employ$ betwe5 ! %aft ,b & ! motor4 ,illu/ration3 ,,fig4 #f4 ,ano!r type ( ma*9e is %[n 9 ,fig4 #g4 ,! drum 9 ?is case is /ation>y1 ! table ,t mov+ lat]ally by reason ( ! screw$ %aft #ah ,illu/ration & half nut ,f4 ,! table1 %[n sep>ate 9 ,fig4 #h1 c>ries a /iff brass spr+ ,a1 to :i* is atta*$ a hold] ,b made to take a h>d5$ /eel po9t4 ,! hold] is provid$ ) a set screw ,p = secur+ ! /eel po9t ,z4 ,! spr+ & ne$le are insulat$ f ! re/ ( ! ma*9e1 z %[n 9 ! draw+4 ,9 work+1 ! metal pr9t is wrapp$ tightly r\nd ! cyl9d] ( ! ma*9e1 ! glue image be+1 ( c\rse1 upp]mo/4 ,to fa/5 ! pr9t a little seccot9e %\ld be appli$ to "o edge1 & ! jo9t c>efully smoo!d d[n ) ! f+]s4 ,illu/ration ,if !re is any t5d5cy on ! "p ( ! pr9t to slip r\nd on ! drum1 a c\ple ( small spr+ clips plac$ ov] ! ends ( ! drum w act z a prev5tive4 ,x is necess>y to place ! pr9t ^u ! drum 9 su* a mann] t ! /ylus draws away f ! edge ( ! lap & n t[>ds x1 & ! metal pr9ts %\ld be ( su* a size t :5 plac$ r\nd ! drum ( ! #ai ma*9e a lap ( ab\t #c_/af?s ( an in* is all[$4 ,illu/ration3 ,,fig4 #i4 ,! /eel po9t ,z 7ord9>y gramophone ne$les may be us$ & w be f\nd to answ] ! purpose admirably7 is made to press lightly ^u ! metal pr9t1 & :ile ! pressure %\ld be suffici5t to make good electrical contact1 x %\ld n be suffici5t to cause ! ne$le to scrat* ! surface ( ! foil4 ,! pressure is regulat$ by means ( ! mill$ nut ,h4 ,! electrical connections are giv5 9 ,fig4 #i4 ,"o wire f ! batt]y ,m is tak5 to ! t]m9al ,t1 & ! o!r wires f ,m & ,f lead to ! relay ,r4 ,! curr5t fl[s f ! batt]y ,m ?r\gh ! spr+ ,y1 ?r\gh ! drum & metal pr9t1 ! /ylus ,z1 spr+ ,a1 d[n to ! relay ,r1 & f ,r back to ! batt]y ,m4 ,z ! drum c>ry+ ! s+le l9e half-tone pr9t is revolv$1 ! /ylus1 by reason ( ! lat]al movem5t giv5 to ! table or cyl9d] z ! case may be1 w trace a spiral pa? ov] ! entire surface ( ! pr9t4 ,z ! /ylus traces ov] a conduct+ /rip ! circuit is complet$1 & ! tongue ( ! relay ,r is attract$1 mak+ contact ) ! /op ,s4 #bj ,on pass+ ov] a /rip ( insulation ! circuit is brok5 & ! tongue ( ! relay ,r returns to its normal position4 ,z already /at$1 ! conduct+ & insulat+ b&s on ! pr9t v>y 9 wid? accord+ to ! d5sity ( ! photograph f :i* x is prep>$1 s t ! l5g? ( "t t ! tongue ( ! relay ,r is held aga9/ ! /op ,s1 is 9 proportion to ! wid? ( ! conduct+ /rip :i* is pass+ "u ! /ylus at any in/ant4 ,! function ( ! transmitt] is !re=e to s5d to ! relay ,r an int]mitt5t curr5t ( v>y+ duration4 ,! two photographs ,figs4 #aj & #aj;a are ( a ma*9e design$ & us$ by ! writ] 9 8 exp]im5ts4 ,9 ?is ma*9e ! drum is #c4e in*es long & #a4e in*es 9 diamet]4 ,! lead screw has #cj ?reads to ! in*1 & ! r$uction betwe5 x & ! drum is #c3a1 s t ! table has a movem5t ( #a_/ij? in* p] revolution ( ! drum4 ,f ! brief description ( ! v>i\s types ( ma*9es t h be5 giv5 x w be app>5t t 9 ! design ( ! ma*9e prop] !re is no?+ v complicat$1 al?\gh ! addition ( ! driv+ & syn*ronis+ app>atus complicates matt]s r consid]ably4 ,! que/ions ( driv+ & syn*ronis+ ! ma*9es at ! two /ations is fully dealt ) 9 ,*apt] ,,iv4 ,illu/ration3 ,,fig4 #aj;a4 ,illu/ration3 ,,fig4 #aj;b4 ,enl>g$ view ( an image brok5 up by a cross scre54 #ba ,al?\gh ! design ( ! ma*9es is r simple great att5tion mu/ be paid bo? to accuracy ( con/ruction & accuracy ( work+1 & ?is applies1 n only to ! ma*9es 7:e!r = transmitt+ or receiv+7 b = all ! v>i\s pieces ( app>atus t are us$4 ,too mu* c>e _c be be/[$ ^u ?is po9t1 z 9 ! wireless transmission ( photographs !re is a l>ge numb] ( in/rum5ts all requir+ c>eful adju/m5t1 & :i* h to "w toge!r 9 p]fect unison at a high spe$4 ,! ma*9e %[n 9 ,figs4 #aj & #aj;a 0 design$ & us$ by ! writ] solely = exp]im5tal "w4 ,x w be notic$ 9 ! description giv5 9 ! app5dix ( ! me?od ( prep>+ ! metal pr9ts t a #e x #d cam]a is recomm5d$1 :ile ! ma*9e1 ,fig4 #aj1 is design$ to take a pr9t procur$ f a qu>t]-plate negative4 ,?is size ( drum 0 adopt$ = sev]al reasons1 & al?\gh x w be f\nd q l>ge en\gh = g5]al exp]im5tal "w ! writ] has come to ! conclusion t = practical comm]cial "w a drum to take a pr9t #e x #d w give bett] results4 ,9 mak+ a negative ( a picture t is requir$ = reproduction purposes1 ! l9e scre5 9 ! cam]a is replac$ by a cross scre51 i4e4 two s+le l9e scre5s plac$ ) _! l9es at an angle ( #ij;deg to "o ano!r1 & ?is breaks ! #bb image up into small squ>es in/ead ( l9es4 ,by look+ at any ord9>y newspap] or book illu/ration ?r\gh a p[]ful magnify+ glass ! effects ( a cross scre5 w readily be se54 ,) a cross scre5 a c]ta9 am\nt ( detail is necess>ily lo/1 b ) a s+le l9e scre5 ! am\nt lo/ is mu* great]4 ,if !re is any v small detail 9 ! picture mo/ ( ?is w\ld be lo/ 9 a co>se scre51 h5ce ! necessity ( employ+ z f9e a l9e scre5 z practicable 9 ord] to get z mu* detail 9 z possible4 ,x is ma9ly on ?is acc\nt t a #e x #d pr9t is recomm5d$1 z1 if fairly bold subjects are us$ = copy+1 ! small detail 7?is is1 ( c\rse1 a v vague & indef9able t]m7 w n be too f9e1 & ! "t requir$ = transmitt+ reasonable4 ,= obvi\s reasons x is a great advantage to put ! pr9t "u pressure to cause ! glue image to s9k into ! s(t metal base & leave a p]fectly flat & smoo? surface4 ,x is ess5tial t ! b&s on ! pr9t lie along ! axis ( ! cyl9d]1 s t ! /ylus traces its pa? across !m1 & n ) !m4 ,we h n[ an arrangem5t t is capable ( tak+ ! place ( ! key ,k1 ,fig4 #d1 & ! diagram1 ,fig4 #aa1 gives ! connections = ! complete transmitt]4 ,a is ! a]ial1 ,e e>?1 ,t inductance1 ,l ammet]4 ,! clos$ oscillatory circuit consi/s ( a sp>k-gap ,g1 inductance ,f1 #bc ,illu/ration & a cond5s] ,c4 ,! second>y ,j ( ! coil ,h is connect$ to ! sp>k-gap1 & ! prim>y ,p is 9 circuit ) ! m]cury break ,n1 ! batt]y ,b1 & ! local contacts ( ! relay ,r4 ,! action is z foll[s4 ,:5 contact is made betwe5 ! /ylus ,z & ! drum ,v by means ( ! conduct+ b&s on ! l9e pr9t1 ! circuit ( ! relay ,r & ! batt]y ,m is complet$4 ,! clos+ ( ! local circuit ( ! relay ,r actuates ! second relay ,r'1 all[+ ! prim>y circuit ( ! coil ,h to be clos$4 ,z soon z ! prim>y circuit ( ! coil is complet$ sp>ks pass betwe5 ! electrodes ( ! sp>k-gap ,g1 caus+ waves to radiate f ! a]ial4 ,! duration ( ! wave-tra9s radiat$ dep5ds ^u ! duration ( contact made by ! relays #bd ,r & ,r'1 & ?is 9 turn dep5ds ^u ! wid? ( ! conduct+ /rip t is pass+ "u ! /ylus4 ,! batt]y ,m %\ld be ab\t #d volts1 & ! batt]y ,d ab\t #b volts4 ,! two-way swit* ,x is connect$ up s t ! relay ,r' c be ?r[n out & ! key ,k swit*$ 9 = ord9>y signall+ purposes4 ,if any sp>k+ takes place at ! po9t ( ! /ylus1 a small cond5s] ,c' 7ab\t #a micr(>ad capacity7 %\ld be connect$ z %[n4 ,9 ! pres5t in/ance ! cond5s] %\ld be us$ m z a prev5tive ?an z a cure1 z 9 all probability ! voltage f ,m w n be suffici5t to cause de/ructive 7if any7 sp>k+2 b1 z mo/ wireless work]s "k1 any?+ 9 ! nature ( a sp>k occurr+ 9 ! neighb\rhood ( a detector 7?is1 ( c\rse1 only applies :5 ! receiv+ app>atus is plac$ 9 close proximity to ! transmitt]7 is liable to de/roy ! adju/m5t4 ,9 transmitt+ ov] ord9>y conductors :]e ! initial voltage is fairly high & ! self-induction ( ! circuit v great1 ! use ( ! cond5s] w be f\nd to be absolutely ess5tial4 ,x has also be5 not$ t ! angle :i* ! /ylus pres5ts to ! drum has a m>k$ effect ^u ! sp>k+1 an angle ( ab\t #fj;deg be+ f\nd to give v good results4 ,if ! size ( ! s+le l9e pr9t us$ is #e in*es by #d in*es1 & a scre5 hav+ #ej l9es #be to ! in* is us$ = prep>+ x1 !n ! /ylus w h to make #bej contacts dur+ "o revolution ( ! drum4 ,assum+ ! drum to make "o revolution 9 ?ree seconds1 !n ! "t tak5 to transmit ! complete photograph c be f\nd f ! equation ,t w x t x s1 :]e w is ! wid? ( ! pr9t1 t ! travel ( ! /ylus dur+ "o revolution ( ! drum1 & s ! "t requir$ = "o revolution ( ! drum4 ,9 ! pres5t in/ance ?is w be ,t #d x #ij x #c #ajhj seconds #ah m9utes4 ,! numb] ( contacts made by ! /ylus p] m9ute is #ejjj1 & 9 work+ at ?is spe$ ! fir/ difficulty is enc\nt]$ 9 ! use ( ! two relays4 ,! relay ,r is lightly built1 & capable ( work+ at a fairly high spe$1 b ,r' is a heavi] patt]n1 & consequ5tly works at a slightly l[] rate4 ,?is relay mu/ necess>ily be heavi]1 z m sub/antial contacts are ne$$ 9 ord] to pass ! heavy curr5t tak5 by ! sp>k-coil4 ,relays s5sitive & accurate en\gh to "w at ?is spe$ w 9 all probability be beyond ! rea* ( ! majority ( work]s1 b !re are sev]al types ( relays on ! m>ket v reasonable 9 price t w answ] v well = exp]im5tal "w1 al?\gh ! spe$ ( work+ w no d\bt be sl[]4 ,= ! be/ results ! duration ( ! wave-tra9s s5t out %\ld be ( ! same duration z #bf ! contact made by ,r1 & !re=e equal to ! "t tak5 by ! /ylus to trace ov] a conduct+ /rip2 b if ! duration ( ! contact made by ,r is t1 !n t made by ,r' & consequ5tly ! duration ( ! gr\ps ( wave-tra9s w\ld be t - v :]e v equals ! extra "t requir$ by ,r' to complete its local circuit4 ,! diff]5ce 9 "t made by ! two relays1 al?\gh v slight1 w be f\nd to affect v consid]ably ! quality ( ! receiv$ pictures4 ,r5ew+ ! plat9um contacts is also a great exp5se1 z !y are soon burnt out :]e a heavy curr5t is pass$4 ,if ! di/ance exp]im5t$ ov] is %ort s t ! p[] requir$ to op]ate ! sp>k-coil is n v heavy1 "o relay w be suffici5t provid+ ! contacts are massive en\gh to c>ry ! curr5t safely4 ,x is useless to expect any ( ! ord9>y relays 9 g5]al use to "w satisfactorily at su* a high spe$1 & 9 ord] to comp5sate = ?is we mu/ ei!r increase ! "t ( transmitt+1 or1 z already sugge/$1 make use ( a co>s] l9e scre5 9 prep>+ ! photographs4 ,= reasons already expla9$1 all po9ts ( make & break %\ld be %unt$ by a cond5s]4 ,! effective work+ spe$ ( an ord9>y type ( relay may be any?+ f #ajjj to #bejj dots a m9ute1 dep5d+ ^u accuracy ( design & con/ruction4 ,9 ! wireless transmission ( photographs x #bg is absolutely ess5tial to use "s =m ( rot>y sp>k-gap1 z :]e sp>ks are pass$ 9 rapid succession ! ord9>y type ( gap is worse ?an useless4 ,:5 a sp>k passes betwe5 ! electrodes ( an ord9>y sp>k-gap1 ,fig4 #ab1 we f9d t = a fraction ( a second aft] ! fir/ sp>k has pass$1 ! normally high resi/ance ( ! gap has be5 l[]$ to less ?an "o ohm4 ,if ! column ( hot gas :i* con/itutes ! sp>k is n in/antly disp]s$1 b rema9s betwe5 ! electrodes1 x w provide an easy pa? = any fur!r dis*>ges1 & if sp>ks are pass$ at all rapidly1 :at 0 at fir/ a disruptive & oscillatory dis*>ge w deg5]ate into a hot1 non-oscillatory arc4#d ,illu/ration3 ,,fig4 #ab4 ,two =ms ( rotat+ sp>k-gaps are %[n 9 ,figs4 #ac & #ad1 & are kn[n z syn*ron\s & non-syn*ron\s gaps respectively4 ,9 ! syn*ron\s gap ! cog-:eel is m\nt$ on ! %aft ( ! alt]nator1 & a cog comes opposite ! fix$ electrode :5 ! maximum ( pot5tial is rea*$ 9 ! cond5s]1 ?us ensur+ a dis*>ge at e alt]nation ( curr5t4 ,) ?is type ( gap a sp>k ( pure tone is obta9$ :i* #bh ,illu/ration ,illu/ration is ( great value :]e ! signals are receiv$ by means ( a telephone1 b :]e ! signals are to be me*anically record$ ! tone ( ! sp>k is ( little consequ5ce4 ,9 a non-syn*ron\s gap a sep>ate motor is us$ = driv+ ! too!d :eel1 & c ei!r be m\nt$ on ! motor %aft or driv5 by means ( a b&1 !re be+ no reg>d giv5 to syn*ronism ) ! alt]nator4 ,! fix$ electrode is be/ made long en\gh to cov] ab\t two ( ! tee?1 z ?is ensures regul> sp>k+ & a uni=m sp>k+ di/ance2 ! #bi sp>k l5g? is d\ble ! l5g? ( ! sp>k-gap4 ,! too!d :eel %\ld revolve at a high spe$1 any?+ f #ejjj to #hjjj revolutions p] m9ute1 or ev5 m be+ requir$4 ,! %aft ( ! too!d :eel is pref]ably m\nt$ 9 ball-be>+s4 ,ow+ to ! l>ge numb] ( sp>ks t are requir$ p] m9ute 9 ord] to transmit a photograph at ev5 an ord9>y spe$1 x is necess>y t ! contact break] be capable ( work+ at a v high spe$ inde$4 ,! be/ break to use is :at is kn[n z a m]cury jet int]rupt]1 ! frequ5cy ( ! int]ruptions be+ 9 "s cases z high z #gj1jjj p] second4 ,no description ( ^! breaks w be giv51 z ! work+ ( !m is g5]ally well und]/ood4 ,9 "s cases an alt]nator is us$ 9 place ( ! batt]y ,b1 ,fig4 #d1 & :5 ?is is done ! break ,m c be disp5s$ )4 ,9 l>g] /ations ! coil ,h is replac$ ) a special trans=m]4 ,! writ] has design$ an improv$ relay :i* w respond to curr5ts la/+ only #a_/ajj? "p ( a second1 & capable ( deal+ ) r l>ge curr5ts 9 ! local circuit4#e ,?is relay has n yet be5 tri$1 b if x is successful ! two relays ,r & ,r' c be disp5s$ )1 & ! result w be m accurate & effective transmission4 #cj ,illu/ration3 ,,fig4 #ae4 ,! connections = a complete exp]im5tal /ation1 transmitt+ & receiv+ app>atus comb9$1 are giv5 9 ,fig4 #ae4 ,! t]m9als ,w1 ,w are = connect+ to ! photo-telegraphic receiv+ app>atus ,q1 be+ a d\ble pole two-way swit* = ?r[+ ei!r ! transmitt+ or receiv+ app>atus 9 circuit4 ,!re is ano!r sy/em ( transmitt+ devis$ by ,pr(essor ,korn1 :i* employs an entirely diff]5t me?od f ! =ego+4 ,by us+ ! app>atus j describ$1 ! waves g5]at$ are :at are kn[n z damp$ waves1 & by us+ ^! damp$ waves1 tun+1 :i* is s ess5tial to good comm]cial work+1 c be made to rea* a fairly high degree ( effici5cy4 #ca ,! "q ( damp$ v]sus undamp$ waves is a some:at burn+ "o1 & no attempt w be made "h to deal ) ! m]its or dem]its ( ! claims made = ! respective sy/ems4 ,a s]ies ( articles describ+ ! production ( undamp$ waves & _! effici5cy 9 work+ comp>$ ) damp$ waves w be f\nd 9 ! ,wireless ,_w1 ,nos4 #c & #d1 #aiac1 & are well wor? read+ by any "o int]e/$ 9 ! subject4 ,illu/ration3 ,,fig4 #af4 ,a diagrammatic repres5tation ( ! app>atus z arrang$ by ,pr(essor ,korn is giv5 9 ,fig4 #af4 ,! undamp$ or cont9u\s waves are g5]at$ by means ( a high-frequ5cy alt]nator or ,p\ls5 arc4 ,9 ,fig4 #af1 ,x is ! g5]ator1 ,f inductance1 ,c cond5s]2 ! a]ial inductance ,t is connect$ by ! a]ial ,a & e>? ,e4 ,by ?is means ! waves are tun$ to a c]ta9 p]iod4 #cb ,a metal pr9t1 simil> to :at has already be5 describ$1 is wrapp$ r\nd ! drum ,d ( ! ma*9e1 & :5 ! /ylus ,z traces ov] an insulat+ /rip ! waves g5]at$ are 9 tune ) ! receiv+ /ation1 b :5 x traces ov] a conduct+ /rip1 a portion ( ! inductance ,t is %ort-circuit$1 ! p]iod ( ! oscillations is alt]$1 & ! two /ations are ?r[n out ( tune4 ,! receiv+ /ation is provid$ ) an ap]iodic circuit1 :i* consi/s ( an inductance ,f'1 cond5s] ,c'1 & a !rmodetector ,n4 ,a /r+ galvanomet] ,h 7describ$ 9 ,*apt] ,,iii471 & ! self-induction coils ,b1 ,b' are connect$ z %[n1 ! coils ,b1 ,b' prev5t+ ! high-frequ5cy curr5ts1 :i* *ange _! direction1 f fl[+ ?r\gh ! galvanomet]4 ,! mann] 9 :i* ! /r+ galvanomet] is arrang$ to reproduce a transmitt$ picture is %[n 9 ,fig4 #bd4 ,! connections adopt$ by ! ,p\ls5 ,company = photographically record+ wireless messages are giv5 9 ,fig4 #ag1 a /r+ galvanomet] ( ! ,e9?ov5 type be+ us$4 ,! two self-induction coils ,s & ,s' are 9 circuit ) ! detector ,d & ! galvanomet] ,g4 ,! cond5s] ,c' prev5ts ! cont9u\s curr5t produc$ by ! detector f fl[+ ?r\gh ! high frequ5cy circuit2 ,p is ! prim>y ( ! a]ial #cc inductance & ,f ! second>y4 ,! me?od ( transmitt+ adopt$ by ,pr(essor ,korn appe>s to be a simple & reliable arrangem5t1 provid$ t an equally reliable me?od ( produc+ ! undamp$ waves c be f\nd4 ,ow+ to ! abs5ce ( me*anical in]tia x %\ld be capable ( work+ at a good spe$1 :ile ! abs5ce ( a numb] ( pieces ( delicate app>atus all requir+ c>eful adju/m5t add greatly to its reliability4 ,illu/ration3 ,,fig4 #ag4 ,9 any sp>k sy/em ) a prop]ly design$ a]ial a coil tak+ t5 amp]es is capable ( transmitt+ signals ov] a di/ance ( ?irty to fifty miles1 b :]e ! numb] ( int]ruptions ( ! break requir$ p] second is v high1 z 9 radio-photography1 x mu/ be rememb]$ t a mu* high] voltage is ne$$ to drive ! requisite am\nt ( curr5t ?r\gh ! prim>y w9d+ ( ! coil ?an w\ld be ! case if ! int]ruptions 7 sl[]4 ,x is possible to use plat9um #cd contacts = ! relays1 = curr5ts up to t5 amp]es1 b = heavi] curr5ts ?an ?is "s arrangem5t :]e contact is made ) m]cury w be f\nd to be m economical & reliable4 ,9 ! transmitt] already describ$ & giv5 9 ,fig4 #aa1 ! be/ results w\ld be obta9$ by f9d+ ! spe$ at :i* ! relay ,r' works be/1 & regulat+ ! numb] ( contacts made by ! /ylus accord+ly4 ,! me?od employ$ by ,de' ,b]no*i 7see ,*apt] ,i47 ( v>y+ ! int5sity ( a beam ( light by pass+ x ?r\gh a photographic film1 :i* 9 turn alt]s ! resi/ance ( a sel5ium cell1 has be5 v successfully employ$ 9 at lea/ "o sy/em ( photo-telegraphy4 ,its application has also be5 sugge/$ = wireless transmission1 & al?\gh ) any sy/em us+ cont9u\s waves ?is w\ld n be v difficult1 x c\ld h>dly be adapt$ to "w ) ! ord9>y sp>k sy/em4 ,! app>atus = receiv+ f ?is type ( transmitt] w\ld1 on ! o!r h&1 necess>ily be m elaborate ?an ! me?ods t are describ$ 9 ! next *apt]1 & z f> z ! writ]'s exp]i5ce goes1 exp]im5ts along ^! l9es w\ld n prove v pr(itable1 z simplicity is ! keynote ( success 9 any radio-photographic sy/em4 ,x has be5 sugge/$ t 9 ord] to decrease ! "t ( transmission a cyl9d] capable ( #ce tak+ a pr9t #g in*es by #e in*es be employ$1 ! pr9t be+ prep>$ f r a co>se l9e scre5--say #ce to ! in*--& a trav]se ( ab\t #a_/ej in* giv5 to ! /ylus1 ?us r$uc+ ! "t ( transmission to ab\t twelve m9utes4 ,x is que/ionable1 h[ev]1 :e!r ! increase 9 spe$ w\ld comp5sate = ! loss ( detail1 z only v bold subjects c\ld be transmitt$4 ,z already po9t$ out1 wireless transmission w\ld only be employ$ = fairly long di/ances1 & ! extra "t & exp5se requir$ to receive a fairly good detail$ picture is negligible :5 comp>$ ) ! enorm\s "t x w\ld take to receive ! orig9al photograph by any ord9>y means ( transit4 ,! public mu* pref] to h passable pictorial illu/rations ( curr5t ev5ts ?an wait sev]al days = a m p]fect picture--! orig9al1 & ! advantage ( any newspap] be+ able to publi% photographs sev]al days be=e its rivals is obvi\s4 ,!re c also be no d\bt b t a sy/em ( radio-photography1 if fairly reliable & capable ( work+ ov] a di/ance ( say ?irty miles1 w\ld be ( great milit>y use = transmitt+ maps & writt5 matt] ) a great sav+ ( "t & ev5 life4 ,writt5 matt] c\ld be transmitt$ ) ev5 great] safety ?an messages :i* are s5t 9 ! ord9>y way 9 ,morse ,code1 z ! signals receiv$ 9 ! receiv] #cf ( an ho/ile in/allation w\ld be b a mean+less jumble ( s\nds1 & ev5 7 !y possess$ ( radio-photographic app>atus ! receiv$ message w\ld be un9telligible1 unless !y knew ! exact spe$ at :i* ! ma*9es 7 runn+ & c\ld syn*ronise accurately4 99 99 99 99 99 #cg ,,*apt] ,,iii ,,receiv+ ,,app>atus ,!re are only two me?ods available at pres5t = receiv+ ! photographs1 & bo? h be5 us$ 9 ord9>y photo-telegraphic "w ) great success4 ,!y h disadvantages :5 appli$ to wireless "w1 h[ev]1 b ^! w no d\bt be ov]come ) future improvem5ts4 ,! two me?ods are 7#a7 by means ( an ord9>y photographic process1 & 7#b7 by means ( an electrolytic receiv]4 ,9 sev]al photo-telegraphic sy/ems ! ma*9e us$ = transmitt+ has ! cyl9d] twice ! size ( ! receiv+ cyl9d]1 ?us mak+ ! area ( ! receiv$ picture "o-qu>t] ! area ( ! picture transmitt$4 ,! extra quality ( ! receiv$ picture does n comp5sate = ! disadvantage ( hav+ to provide two ma*9es at ea* /ation1 & 9 ! writ]'s op9ion results1 q good en\gh = all practical purposes1 c be obta9$ by us+ a mod]ate size cyl9d] s t "o ma*9e answ]s = bo? transmitt+ #ch & receiv+1 & us+ z f9e a l9e scre5 z possible = prep>+ ! photographs4 ,illu/ration3 ,,fig4 #ah4 ,! writ]1 :5 fir/ exp]im5t+ 9 photo-telegraphy1 endeav\r$ to make ! receiv+ app>atus self-conta9$1 & "o idea :i* 0 work$ out is giv5 9 ,fig4 #ah4 ,! electric lamp ,l is ab\t #h c4p41 & is plac$ j )9 ! focus ( a l5s :i* has a focal l5g? ( #c_/d in*4 ,:5 a s\rce ( light is plac$ at "s po9t betwe5 a l5s & its pr9cipal focus1 ! light rays are n conv]g$1 b are transmitt$ 9 a p>allel beam ! same size z ! l5s4 ,x has be5 f\nd t ?is arrangem5t gives a %>p] l9e on ! drum ?an w\ld be ! case 7 ! light focuss$ direct ^u ! hole 9 ! cone ,a4 ,an enl>g$ draw+ ( ! cone is giv5 9 ,fig4 #ai4 ,! hole 9 ! tip ( ! cone ,a is a b>e #a_/ij in* 9 diamet]--! size ( ?is hole dep5ds ^u ! travel p] revolution ( ! drum or table ( ! ma*9e us$--& 9 work+1 ! cone is run z close z possible to ! #ci drum )\t be+ 9 actual contact4 ,! magnet ,m is w\nd full ) ,no4 #dj ,s4,c4,c4 wire1 & ! armature is made z light z possible4 ,! spr+ to :i* ! armature is atta*$ %\ld be ( su* a l5g? t its natural p]iod ( vibration is equal to ! numb] ( contacts made by ! transmitt+ /ylus4 ,! spr+ mu/ be /iff en\gh to br+ ! armature back ) a fairly crisp movem5t4 ,! spr+ & armature is %[n sep>ate 9 ,fig4 #bj4 ,illu/ration3 ,,fig4 #ai4 ,illu/ration3 ,,fig4 #bj4 ,! %utt] ,c is ab\t #a_/d in* squ>e & made f ?9 alum9ium4 ,! hole 9 ! c5tre is #a_/af x #a_/h in*1 & ! movem5t ( ! armature is limit$ to ab\t #c_/cb in*4 ,9 all arrangem5ts ( ?is k9d !re is a t5d5cy = ! armature spr+ to vibrate1 z x 71 s9usoidally1 if ! coil is magnetis$ & demagnetis$ at a high] rate ?an ! natural p]iod ( vibration ( ! spr+4 #dj ,?is causes an irregul>ity 9 ! rate ( ! vibrations :i* affects ! receiv$ image v consid]ably4 ,a photographic film is wrapp$ r\nd ! drum ( ! ma*9e1 be+ fa/5$ by means ( a little celluloid cem5t sme>$ along "o edge4 ,?is device1 al?\gh x w "w well ov] artificial conductors1 is n suitable = wireless "w1 z x is too co>se 9 its action2 x c be made s5sitive en\gh to "w at a spe$ ( #ajjj to #aejj contacts p] m9ute1 ) a curr5t ( 4#e milliamp]e4 ,x is impossible to obta9 a curr5t ( ?is magnitude f ! majority ( ! detectors 9 use1 s t if any attempt is made to use ?is device = radio-photography x w be necess>y to employ a ,m>coni coh]] 7fil+s71 z ?is is practically ! only coh]] f :i* s l>ge a curr5t c be obta9$4 ,!re h be5 _m attempts made to receive ) an ord9>y fil+s coh]]1 b z 0 po9t$ out 9 ,*apt] ,i4 ^! h n[ be5 disc>d$ 9 s]i\s wireless "w1 be+ only us$ 9 small amateur /ations or exp]im5tal sets4 ,z ! reasons = ?is are well kn[n to ! majority ( wireless work]s !re is no ne$ to enum]ate !m "h4 ,a me?od :]eby a fil+s coh]] c be decoh]$1 ! act ( decoh]+ clos+ a local circuit :i* conta9s ! photographic #da receiv+ app>atus1 is giv5 9 ! diagram ,fig4 #ba4 ,illu/ration3 ,,fig4 #ba4 ,9 ! figure1 ! coh]] ,c is fix$ 9 rigid supports1 "o support be+ provid$ ) a plat9um p9 ,f4 ,to ! coh]] is connect$ ! s5sitive electro-magnet ,m1 :i* becomes magnetis$ z soon z ! incom+ waves act ^u ! coh]]4 ,to ! armature ,b is atta*$ a light alum9ium arm ,s1 pivot$ at ,k1 & c>ry+ at ! o!r end ! /rik] ,g1 :i* is fitt$ ) a plat9um contact4 ,:5 ! armature ,b is attract$ ! coh]] is decoh]$ by ! =ce ( ! impact betwe5 ! contacts ,f & ,g4 ,to prev5t damage to ! coh]] ! =ce ( ! bl[ is tak5 (f by ! ability ( ! /rik] to "w back ?r\gh a hole 9 ! arm ,s1 ! spr+ #db ,n keep+ x normally 9 a fix$ position4 ,t & ,p are adju/+ screws1 & ! t]m9als ,j are = connect+ to ! receiv+ app>atus4 ,) ?is arrangem5t a v %ort wave-tra9 causes only "o tap ( ! contacts1 s t only "o m>k is regi/]$ on ! receiv+ drum = e contact made on ! transmitt]4 ,illu/ration3 ,,fig4 #bb4 ,! draw+1 ,fig4 #bb1 gives a diagrammatic repres5tation ( app>atus arrang$ = ano!r photographic me?od ( receiv+4 ,! ma*9e %[n 9 ,fig4 #f is us$ 9 ?is case4 ,a is ! a]ial1 ,e e>?1 ,p prim>y ( oscillation-trans=m]1 ,s second>y ( trans=m]1 ,c v>iable cond5s]1 ,c' block cond5s]1 ,d detector1 ,x two-way swit*1 ,t telephone4 ,a ,de' ,arsonval galvanomet] ,h is also connect$ to ! swit* ,x1 s t ei!r ! telephone or ! galvanomet] c be swit*$ 94 ,! #dc galvanomet] c be made s5sitive en\gh to "w ) a curr5t z small z #aj-g ( an amp]e1 ) a p]iod ( ab\t #a_/aej? ( a second4 ,! scre5 ,j has a small hole ab\t #a_/h in* diamet] drill$ 9 ! c5tre4 ,"u ! influ5ce ( ! brief curr5ts :i* pass ?r\gh ! detector e "t a gr\p ( waves is receiv$1 ! mirror ( ! galvanomet] sw+s to-&-fro 9 front ( ! scre5 ,j1 & all[s ! light reflect$ f ! s\rce ( light ,m to pass ?r\gh ! ap]ture 9 ! scre51 on to ! l5s ,n4 ,r\nd ! drum ,v ( ! ma*9e is wrapp$ a s5sitive photographic film1 & ?is records ! movem5ts ( ! mirror :i* correspond to ! contacts on ! half-tone pr9t us$ 9 transmitt+4 ,e "t curr5t passes ?r\gh ! galvanomet]1 ! light t is receiv$ f ,m1#f passes ?r\gh ! ap]ture 9 ! scre5 ,j1 & is focuss$ by ! l5s ,n to a po9t ^u ! revolv+ film4 ,z soon z ! curr5t ceases1 ! mirror sw+s back to its orig9al position1 & ! film is aga9 9 d>kness4 ,^u be+ develop$ a photograph1 simil> to ! negative us$ = prep>+ ! metal pr9t is obta9$4 ,if desir$ ! app>atus c be s arrang$ t ! receiv$ picture is a positive in/ead ( a negative4 #dd ,! detector us$ %\ld be a ,lodge :eel-coh]] or a ,m>coni valve-receiv]1 z ^! are ! only detectors t c be us$ ) a record+ in/rum5t4 ,if ! sw+ ( ! galvanomet] mirror is too great1 a small batt]y ) a regulat+ resi/ance c be ins]t$ 9 ord] to limit ! movem5t ( ! mirror to a v %ort range2 ! curr5t ( c\rse fl[+ 9 an opposite direction to ! curr5t fl[+ ?r\gh ! coh]]4 ,9 ?is1 z 9 all o!r me?ods ( receiv+1 ! results obta9$ dep5d ^u ! f95ess ( ! l9e scre5 us$ 9 prep>+ ! metal pr9ts2 & z already %[n ! f95ess ( ! scre5 t c be us$ is dep5d5t ^u ! me*anical effici5cy ( ! entire app>atus4 ,ano!r sy/em1 & "o t has be5 tri$ z a possible means ( record+ wireless messages1 is z foll[s4 ,! wireless arrangem5ts consi/ ( app>atus simil> to t %[n 9 ,fig4 #bb1 b in/ead ( a ,lodge coh]] a ,m>coni valve is us$1 & an ,e9?ov5 galvanomet] is sub/itut$ = ! reflect+ galvanomet]4 ,! ,e9?ov5 galvanomet] consi/s ( a v p[]ful electro-magnet1 ! pole pieces ( :i* conv]ge almo/ to po9ts4 ,a v f9e silv]$ qu>tz ?read is /ret*$ betwe5 ! pole pieces1 z %[n 9 ,fig4 #bc1 ! t5sion be+ adju/able4 ,! p]iod ( sw+ is ab\t #a_/bej? ( a second4 ,a hole is bor$ ?r\gh ! poles1 & "o ( !m is fitt$ #de ,illu/ration ) a slid+ tube :i* c>ries a %ort focus l5s ,n4 ,! light f ,m passes ?r\gh ! magnets1 & a magnifi$ image ( ! qu>tz ?read is ?r[n ^u ! ebonite scre5 ,j4 ,?is scre5 is provid$ ) a f9e slit1 & :5 ! galvanomet] is at re/ ! %ad[ ( ! ?read j cov]s ! slit 9 ! scre5 & prev5ts any light f ,m rea*+ ! photographic film4 ,^u signals be+ receiv$ ! %ad[ ( ! ?read moves to "o side = a long or %ort p]iod1 uncov]+ ! slit1 & all[+ light to pass ?r\gh4 ,! l5s ,r conc5trates ! collect$ light to a po9t ^u ! revolv+ film4 ,! connections = ! complete receiv] are giv5 9 ,fig4 #bd4 ,! modifi$ =m ( ! ,e9?ov5 galvanomet]1 z arrang$ by ,pr(essor ,korn = use ) 8 sel5ium ma*9es = photo-telegraphy ov] ord9>y l& l9es1 consi/s ( two f9e silv] wires :i* are displac$ 9 a lat]al direction betwe5 ! pole pieces :5 trav]s$ by a curr5t2 ! curr5t pass+ ?r\gh bo? wires 9 ! same #df direction4 ,a small %utt] ( alum9ium foil is atta*$ to ! wires at ! optical c5tre4 ,! silv] wires us$ are #a_/ajjj in* 9 diamet]1 ) a natural p]iod ( ab\t #a_/abj? ( a second2 ! l5g? ( wires free to sw+ be+ usually ab\t #e cm4 ,illu/ration3 ,,fig4 #bd4 ,! p]iod ( ! wires dep5ds to a great ext5t ^u _! l5g? & diamet]1 & also ^u _! t5sion4 ,by us+ %ort f9e wires ! p]iod c be made mu* small]1 b a great] curr5t is requir$ to produce a simil> displacem5t4 ,:]e ! curr5t available1 z 9 wireless telegraphy1 is v small1 & a def9ite displacem5t ( ! wires is requir$1 x is at once app>5t t ) wires ( a giv5 diamet] !re is a limit to _! l5g? & !re=e to ! p]iod4 ,f9] wires c be us$1 b "h aga9 !re is a practical limit to _! f95ess1 al?\gh galvanomet]s h be5 con/ruct$ ) a s+le silv]$ qu>tz ?read #a_/abjjj? ( an in* diamet]1 :i*1 :5 plac$ 9 a p[]ful field1 w give a good displacem5t ) a curr5t z small z #aj-h amp]e4 #dg ,) ! app>atus arrang$ by ! ,p\ls5 ,company1 giv5 9 ! diagram1 ,fig4 #ag1 = photographically record+ wireless signals1 ! curr5t requir$ to op]ate ! galvanomet] = signals transmitt$ at ! rate ( #aejj a m9ute is #a x #aj-f amp]e1 :ile = signals up to #bejj a m9ute a curr5t ab\t #e x #aj-f amp]e is necess>y4 ,ano!r v s5sitive in/rum5t1 employ$ by ,m4 ,bel91 & kn[n z ,blondel's oscillograph1 consi/s ( two f9e wires /ret*$ betwe5 ! poles ( a p[]ful electro-magnet1 a small & v light mirror be+ atta*$ to ! c5tre ( ! wires4 ,! curr5t passes d[n "o wire & up ! o!r1 & ! wires1 toge!r ) ! mirror1 are twi/$ to a degree dep5d+ ^u ! /r5g? ( ! receiv$ curr5t4 ,9 ord] to r5d] ! in/rum5t dead-beat ! mov+ p>ts are arrang$ to "w 9 oil4 ,! light reflect$ f ! mirror is made use ( 9 a mann] simil> to t %[n 9 ,fig4 #bb4 ,9 all photographic me?ods ( receiv+1 ! app>atus mu/ be enclos$ 9 "s way to prev5t any extrane\s light f rea*+ ! film1 or bett] /ill plac$ 9 a room light$ only by means ( a ruby light4 ,! foll[+ me?od is giv5 m z a sugge/ion ?an any?+ else1 z ,i d n ?9k x has be5 tri$ = wireless receiv+1 al?\gh x is /at$ to h giv5 "s good results ov] #dh ord9>y l& l9es4 ,x is ! inv5tion ( ,*>bonelle1 a ,fr5* eng9e]1 & is q an orig9al idea4 ,8 me?od consi/s ( plac+ a %eet ( c>bon pap] betwe5 two %eets ( ?9 :ite pap]1 & wrapp+ ! :ole tightly r\nd ! drum ( ! ma*9e4 ,a h>d5$ /eel po9t is fa/5$ to ! diaphragm ( a telephone receiv]1 & ?is receiv] is plac$ s t ! /eel po9t presses aga9/ ! %eets ( pap]4 ,z ! diaphragm & /eel po9t vibrates "u ! influ5ce ( ! receiv$ curr5ts m>ks are made by ! c>bon %eet on ! bottom pap]4 ,ov] a l9e :]e a fair am\nt ( curr5t is available at ! receiv]1 ! diaphragm w\ld h suffici5t movem5t to m>k ! pap]1 b ! movem5t w\ld be v small ) ! curr5t receiv$ f a detector4 ,?is difficulty c\ld no d\bt be ov]come to a c]ta9 ext5t by mak+ a special telephone receiv]1 ) a l>ge & v flexible diaphragm1 & w\nd = a v high resi/ance4 ,! movem5t ( an ord9>y telephone diaphragm = a b>ely audible s\nd is1 measur$ at ! c5tre1 ab\t #aj-f ( a c4m4 ,) a unit curr5t ! movem5t at ! c5tre is ab\t #a_/gjj? ( an in*4 ,great] movem5t ( ! diaphragm c\ld be obta9$ by connect+ a ,telephone relay to ! detector1 & us+ ! magnifi$ curr5t f ! relay to op]ate ! telephone4 #di ,illu/ration3 ,,fig4 #be4 ,! telephone relay consi/s ( a microphone ,c1 ,fig4 #be1 =m$ ( ! two pieces ( osmium iridium alloy4 ,! contact is sep>at$ to a m9ute degree p>tly by ! action ( ! local curr5t f ,f1 :i* fl[s ?r\gh x & also ?r\gh ! w9d+ ,w ( ! two magnet coils4 ,! local curr5t f ,f assi/s 9 =m+ ! microphone by r5d]+ ! space betwe5 ! contacts conductive4 ,! vibrat+ re$ ,p is fa/5$ to ! metal frame 7n %[n7 :i* c>ries a micromet] screw by :i* ! di/ance betwe5 ! contacts c be accurately regulat$4 ,x w be se5 f ,fig4 #be t ! local circuit consi/s ( a batt]y ,f 7ab\t #a4e volts71 ! microphone contacts ,c1 ! w9d+s ,w1 milliamp]e met] ,b1 & ! t]m9als ,t1 = connect+ to ! galvanomet] or telephone1 all 9 #ej s]ies4 ,on ! top ( ! magnet cores ,n1 ,s is a small] magnet ,d1 w\nd ) f9e wire = a resi/ance ( ab\t #dice ohms1 ! free ends ( ! coils be+ connect$ to ! detector t]m9als4 ,! work+ is z foll[s4 ,suppos+ ! curr5t f ! detector fl[s ?r\gh ,d 9 su* a way t its magnetism is increas$1 ! re$ ,p w be attract$1 ! contacts op5$1 & _! resi/ance increas$4 ,x w be se5 t ! curr5t f ,f is pass$ ?r\gh ! coils ,w1 9 su* a way z to increase ! magnetism ( ! p]man5t magnet1 s t any op5+ ( ! microphone contact increases _! resi/ance1 causes ! curr5t to fall1 & weak5s ! magnets to su* an ext5t t ! re$ ,p c spr+ back to its normal position4 ,on ! o!r h&1 if ! detector curr5t fl[s ?r\gh ,d 9 su* a direction z to decrease ! magnetism 9 ! p]man5t magnets1 ! re$ ,p w rise & make bett] contact ow+ to ! removal ( ! =ce oppos+ ! /iffness ( ! re$4 ,ow+ to ! decrease 9 ! resi/ance ( ! microphone1 ! /r5g? ( ! local curr5t w be increas$1 ! magnets /r5g!n$1 & ! re$ ,p w be pull$ back to its orig9al position4 ,?is relay gives a greatly magnifi$ curr5t :5 prop]ly adju/$1 ! curr5t be+ easily increas$ f #aj-d to #aj-b amp]es4 ,x is also v s5sitive1 b ne$s c>eful adju/m5t 9 ord] t ! be/ results may #ea be obta9$4 ,a great] range ( magnification c be obta9$ by plac+ two or m relays 9 s]ies4 ,illu/ration3 ,,fig4 #bf4 ,a v s5sitive receiv] design$ by ! writ] is giv5 9 ! figures #bf & #bg4 ,to ! c5tre ( a telephone diaphragm is fa/5$ a light /eel po9t ,p1 & ! movem5t ( ?is po9t is communicat$ to ! alum9ium arm ,d1 :i* is pivot$ at ,c4 ,z w be se5 ! telephone receiv] is ( special con/ruction1 x conta9+ only "o coil & !re=e only "o core2 by ?is means ! movem5t ( ! diaphragm is c5tralis$4 ,! coil is w\nd = a resi/ance ( ab\t #bjj ohms1 & ! diaphragm %\ld be fairly ?9 b v resilli5t4 ,illu/ration3 ,,fig4 #bg4 ,to ! free end ( ,d is fa/5$ ! mirror ,t1 made f ?9 diaphragm glass ab\t #a-a_/b c5timetres diamet]1 & hav+ a focal l5g? ( #dj in*es4 ,light f ! lamp ,l is transmitt$ by ! l5s ,n 9 a p>allel beam to ! mirror :i* #eb conc5trates x to a po9t ^u a hole #a_/ajj? ( an in* 9 diamet] 9 ! scre5 ,j4 ,z ! telephone diaphragm vibrates "u ! influ5ce ( ! receiv$ signals ! arm1 & consequ5tly ! mirror1 vibrates also1 & ! hole 9 ! scre5 ,j is con/antly be+ cov]$ & uncov]$ by ! spot ( light4 ,x w be se5 f ,fig4 #bg t ! ratio betwe5 ! c5tre ( ! mirror & ! pivot ,c1 & ,c & ! /eel po9t ,p is #aj3a1 s t if a movem5t ( #a_/bjjjj? ( an in* is obta9$ at ! c5tre ( ! diaphragm ! mirror w move #a_/bjjj? ( an in*2 & z ! focal l5g? ( ! mirror is #dj in*es a movem5t ( #a_/ej? in* is giv5 to ! spot ( light4 ,?is receiv] is capable ( work+ at a fairly high spe$1 z ! in]tia ( ! mov+ p>ts is practically negligible2 ! weight ( ! arm & mirror be+ less ?an #bj gra9s4 ,! hole 9 ! scre5 is made slightly less 9 diamet] ?an ! trav]se ( ! revolv+ cyl9d]1 ! slight di/ance betwe5 ! cyl9d] & ! scre5 all[+ ! light to disp]se suffici5tly to produce a l9e on ! film ( ab\t ! "r ?ickness4 ,!re are two o!r possible means ( photographically receiv+ ! picture t ^u inve/igation may yield "s results2 b x is d\btful :e!r ! curr5t available1 ev5 t obta9$ f a telephone relay1 w be suffici5t to produce ! desir$ magnetic effect1 & ! #ec ins]tion ( a second relay w\ld detract greatly f ! effici5cy by decreas+ ! spe$ ( work+4 ,if rays ( mono*romatic light f a lamp ,l1 ,fig4 #bh1 pass ?r\gh a ,nicol prism ,p 7pol>is+ prism71 !n ?r\gh a tube conta9+ ,,cs#b 7c>bon bisulphide71 aft]w>ds pass+ ?r\gh ! second prism ,p' 7analys+ prism71 & if ! two ,nicol prisms are set at ! pol>is+ angle1 no light f ,l w\ld rea* ! photographic film wrapp$ r\nd ! drum ,v ( ! ma*9e4 ,^u ! tube be+ subject$ to a field produc$ by a curr5t pass+ ?r\gh ! coil ,c1 ! refractive index ( ! liquid w be *ang$1 & light f ,l w rea* ! photographic film4#g ,illu/ration3 ,,fig4 #bh4 ,! second me?od is r m complicat$1 & is bas$ ^u ! fact t ! ka?ode rays 9 a ,crookes' tube c be deflect$ f _! c\rse by means ( a magnet4 ,9 ,fig4 #bi ! ka?ode ,k ( ! ,x-ray tube s5ds a ka?ode ray dis*>ge ?r\gh an ap]ture 9 ! anode ,a1 ?r\gh a small ap]ture 9 ! ebonite scre5 ,j #ed on to ! drum ,v ( ! ma*9e1 r\nd :i* is wrapp$ a photographic film2 ,a & ,k be+ connect$ to suitable electrical app>atus4 ,^u ! coil ,m be+ en]gis$1 ! ka?ode-ray is deflect$ f its /raight-l9e c\rse1 & ! drum ,v is left 9 d>kness4 ,illu/ration3 ,,fig4 #bi4 ,! me?od :i* is n[ go+ to be describ$ is v +5i\s1 z x makes use ( :at is kn[n z an electrolytic receiv]4 ,?is me?od ( receiv+ has prov$ to be ! mo/ practical & simple ( all ! photo-telegraphic sy/ems t h be5 devis$4 ,! application ( ?is sy/em to wireless reception is z foll[s4 ,! a]ial ,a1 & ! e>? ,e1 are jo9$ to ! prim>y ,p ( a trans=m]1 ! second>y ,s be+ connect$ to a ,m>coni valve receiv] ,c4 ,! valve receiv] is connect$ to ! batt]y ,b & silv]$ qu>tz ?read ,k ( an ,e9?ov5 galvanomet] 7already describ$74 ,! ?read is #a_/abjjj? ( an in* 9 diamet]1 & w respond to curr5ts z small z #aj-h ( #ee an amp]e4 ,! light f ,m ?r[s an enl>g$ %ad[ ( ! ?read ov] a slit 9 ! scre5 ,j1 & z ! ?read moves to "o side "u ! influ5ce ( a curr5t1 ! slit 9 ,j is uncov]$1 & ! light f ,m is ?r[n ^u a small sel5ium cell ,r4 ,9 ! d>k ! sel5ium cell has a v high resi/ance1 & !re=e no curr5t c fl[ f ! batt]y ,d to ! relay ,f4 ,:5 ! /r+ ( ! galvanomet] moves to "o side & uncov]s ! slit 9 ! scre5 ,j1 a c]ta9 am\nt ( light is ?r[n ^u ! sel5ium cell l[]+ its resi/ance1 all[+ suffici5t curr5t to pass ?r\gh to op]ate ! relay4 ,r\nd ! drum ( ! ma*9e 7%[n 9 ,fig4 #g7 is wrapp$ a %eet ( pap] t has be5 soak$ 9 c]ta9 *emicals t are decompos$ on ! passage ( an electric curr5t ?r\gh !m4 ,z soon z ! local circuit ( ! relay is clos$1 ! curr5t f ! batt]y ,z 7ab\t #ab volts7 fl[s ?r\gh ! pap] & produces a col\r$ m>k4 ,! picture1 !re=e1 is compos$ ( long or %ort m>ks :i* correspond to ! v>y+ /rips ( conduct+ mat]ial on ! s+le l9e pr9t4 ,9 ord] to r5d] ! m>ks %ort & crisp1 a small batt]y ,y1 & regulat+ resi/ance ,l1 is plac$ across ! drum & /ylus4 ,! diagram1 ,fig4 #cj1 gives ! connections = ! complete receiv]4 #ef ,! pap] us$ is soak$ 9 a solution consi/+ ( ,f]rocyanide ( potassium #a_/d oz4 ,ammoniac ,nitrate #a_/b oz4 ,di/ill$ wat]#h #d oz4 ,illu/ration3 ,,fig4 #cj4 ,! pap] has to be v c>efully *os51 z besides be+ absorb5t en\gh to rema9 moi/ dur+ ! :ole ( ! receiv+1 ! surface mu/ also rema9 fairly smoo?1 z ) a r\gh pap] ! gra9 %[s v di/9ctly1 & if !re is an excess ( solution ! electrolytic m>ks are incl9$ to spread & s cause a blurr$ image4 ,! writ] tri$ num]\s specim5s ( pap] be=e "o c\ld be f\nd t gave really satisfactory results4 ,x 0 also f\nd t :5 work+ 9 a w>m room ! pap] became ne>ly #eg dry be=e ! receiv+ 0 f9i%$1 & ! resi/ance ( ! pap] be+ greatly increas$ 7?is may be any?+ up to #ajjj ohms71 ! m>k+ became v fa9t4 ,a sponge moi/5$ ) ! solution & appli$ to ! undecompos$ portion ( ! pap]1 :ile /ill revolv+1 0 f\nd to help matt]s consid]ably4 ,ano!r exp]i5ce :i* happ5$ dur+ ! writ]'s e>ly exp]im5ts1 ! cause ( :i* ,i am /ill unable to expla91 occurr$ 9 connection ) ! /ylus4 ,! /ylus us$ consi/$ ( a %>ply po9t$ /eel ne$le1 & aft] work+ = ab\t ?ree m9utes x 0 notic$ t ! l9es 7 becom+ gradually wid]1 f9ally runn+ into ea* o!r4 ,^u exam9ation x 0 f\nd t ! po9t ( ! ne$le _h worn away consid]ably1 becom+ 9 fact1 almo/ a *isel po9t4 ,almo/ e ne$le tri$ act$ 9 a simil> mann]1 & to ov]come ?is difficulty ! /ylus %[n 9 ,fig4 #ca 0 devis$4 ,x w be se5 t x consi/s ( a hold] ,a1 some:at resembl+ a drill *uck1 fa/5$ to ! flat spr+ ,b 9 su* a mann] t ! angle ! /ylus makes to ! drum c be alt]$4 ,! ne$le consi/s ( a l5g? ( #cf-;gauge /eel wire1 & z ?is we>s away sl[ly ! jaws ( ! hold] c be loos5$ & a fre% l5g? pu%$ ?r\gh4 ,! wire %\ld n project beyond ! face ( ! hold] m ?an #a_/h? in*4 ,! gauge #eh ( wire *os5 w\ld n suit e ma*9e1 ! be/ gauge to use be+ f\nd by trial1 b 9 ! writ]'s ma*9e ! pit* ( ! decomposition m>ks is mu* f9] ?an ( ^? made by ! comm]cial ma*9es1 & ?is gauge1 ) ! slight b unavoidable spread+ ( ! m>ks1 w produce a m>k ( j ! "r ?ickness4 ,z already m5tion$1 no explanation ( ?is peculi>ity on ! "p ( ! /ylus c be giv51 z !re is no?+ v corrosive 9 ! solution us$1 & ! pressure ( ! /ylus ^u ! pap] is s slight z to be almo/ negligible4 ,illu/ration3 ,,fig4 #ca4 ,no special means are requir$ = fa/5+ ! pap] to ! drum1 ! moi/ pap] adh]+ q firmly4 ,c>e %\ld be tak51 h[ev]1 to fa/5 ! pap]--:i* %\ld be long en\gh to all[ = a lap ( ab\t #a_/d in*--9 su* a mann] t :5 work+ ! /ylus draws away f ! edge ( ! lap & n t[>ds x4 ,! curr5t requir$ to produce electrolysis is v small1 ab\t "o milliamp]e be+ suffici5t4 #ei ,provid+ t ! voltage is suffici5tly high1 decomposition w take place ) practically no curr5t1 x be+ possible to decompose ! solution ) ! dis*>ge f a small induction coil4 ,! quantity ( an elem5t lib]at$ is by weight ! product ( "t1 curr5t1 & ! electro-*emical equival5t ( t elem5t1 & is giv5 by ! equation ,w zct1 :]e ,w quantity ( elem5t lib]at$ 9 grammes4 z electro-*emical equival5t1 c curr5t 9 amp]es1 t "t 9 seconds4 ,! *emical action t takes place is !re=e v small1 z ! int]mitt5t curr5t s5t out f ! transmitt] 9 "s cases only la/s f #a_/ej? to #a_/ajj? a second4 ,! decompos$ m>ks on ! pap] are blue1 &1 z photograph]s "k1 blue is reproduc$ 9 a photograph z a :ite1 s t a photograph tak5 ( our electrolytic picture1 :i* w ( c\rse be a blue image ^u a :ite gr\nd1 w be reproduc$ almo/ l a blank %eet ( pap]4 ,if1 h[ev]1 a yell[ contra/ filt] is plac$ 9 front ( ! cam]a l5s1 & an or?o*romatic plate us$1 ! blue w be reproduc$ 9 ! photograph z a dead black4 ,!re is "o o!r po9t t requires att5tion4 ,x w be notic$ t ! metal pr9t us$ = #fj transmitt+ is a positive1 s9ce x is prep>$ f a negative4 ,! receiv$ picture w !re=e be a negative1 mak+ ! f9al reproduction1 if x is to be us$ = newspap] "w1 a negative also4 ,obvi\sly ?is is no good4 ,! f9al reproduction mu/ be a positive1 !re=e ! receiv$ picture mu/ be also a positive4 ,to ov]come ?is difficulty matt]s mu/ be s arrang$ at ! receiv+ /ation t 9 ! cases ( ,figs4 #ag1 #ah1 #bb1 & #bd1 ! film is kept p]man5tly illum9at$ :ile ! /ylus on ! transmitt] is trac+ ov] an insulat+ /rip1 & 9 d>kness :5 trac+ ov] a conduct+ /rip4 ,9 ,fig4 #cj ! relay ,f %\ld all[ a cont9u\s curr5t f ,z to fl[ ?r\gh ! electrolytic pap]1 & only brok5 :5 ! resi/ance ( ! sel5ium cell is suffici5tly r$uc$ to all[ ! curr5t f ,d to op]ate ! relay4 ,! au?or has endeav\r$ to make direct positives on glass ( ! picture to be transmitt$1 s t a negative metal pr9t c\ld be prep>$4 ,! results obta9$ 7 n v satisfactory1 b ! me?od tri$ is giv51 z x may p]haps be ( int]e/4 ,! plate us$ 9 ! cam]a has to be expos$ ?ree or f\r times long] ?an is requir$ = an ord9>y negative4 ,! expos$ plate is !n plac$ 9 a solution ( protoxalate ( iron 7f]r\s oxalate7 & left until ! image %[s pla9ly ?r\gh ! back ( ! plate4 ,x #fa is !n wa%$ 9 wat] & plac$ 9 a solution consi/+ ( ,di/ill$ wat] #ajjj cc4 ,nitric acid #b cc4 ,sulphuric acid #c cc4 ,bi*romate ( pota% #aje grammes4 ,alum #hj ,aft] be+ 9 ?is ba? = ab\t fifte5 m9utes ! plate is aga9 well wa%$ 9 wat]1 & develop$ 9 ! ord9>y way4 ,! fir/ two op]ations %\ld be p]=m$ 9 ! d>k room1 b ! rema9+ op]ations c be p]=m$ 9 daylight1 once ! plate has be5 plac$ 9 ! bi*romate ba?4 ,z already /at$1 ! results obta9$ 7 n v satisfactory1 & su* a me?od is n n[ wor? foll[+ up1 z x is comp>atively easy s to arrange matt]s at ! receiv+ /ation t a positive or negative image c be receiv$ at w4 ,x is necess>y to connect ! /ylus ( ! receiv+ ma*9e to ! positive pole ( ! batt]y ,z1 o!rwise ! m>ks w be made on ! und]side ( ! pap]4 ,! electrolytic receiv]1 ow+ to ! abs5ce ( me*anical & electro-magnetic in]tia1 is capable ( record+ signals at a v high spe$ inde$4 ,atmosph]ics1 :i* are su* a s]i\s nuisance 9 long-di/ance wireless telegraphy1 w also prove a nuisance 9 wireless photography1 #fb b _! effects w n be s s]i\s 9 a photographic me?od ( receiv+ z !y w\ld be 9 ! electrolytic sy/em4 ,9 a photographic receiv] :]e ! film is1 "u normal conditions1 con/antly illum9at$1 ! receiv$ signals 7bo? ! transmitt$ signals & ! atmosph]ic di/urbances7 w be record$1 aft] developm5t1 z transp>5t m>ks ^u ! film1 ! rema9d] ( ! film be+1 ( c\rse1 p]fectly opaque4 ,by c>eful ret\*+ ! m>ks due to ! di/urbances c be eradicat$1 a pr9t ^u s5sitis$ pap] hav+ be5 fir/ obta9$ to act z a guide dur+ ! process4 99 99 99 99 99 #fc ,,*apt] ,,iv ,,syn*ronis+ ,,& ,,driv+ ,clockwork & electro-motors are ! s\rce ( driv+ p[] t are mo/ suitable = photo-telegraphic "w1 & ea* has its sup]ior claims dep5d+ on ! type ( ma*9e t is be+ us$4 ,= g5]al exp]im5tal "w1 h[ev]1 an electro-motor is p]haps ! mo/ conv5i5t1 z ! spe$ c be regulat$ )9 v wide limits4 ,= a con/ant & accurate drive a fall+ weight has no equal1 b ! app>atus requir$ is v cumb]some & ! "w ( w9d+ bo? t$i\s & heavy4 ,?is me?od ( driv+ 0 at "o "t univ]sally employ$ ) ! ,hughes pr9t+ telegraph1 b x has n[ be5 disc>d$ 9 fav\r ( electro-motors1 :i* are m compact1 besides be+ *eap] to in/al 9 ! fir/ in/ance4 ,syn*ronis+ & iso*ronis+ ! two ma*9es are ! mo/ difficult problems t require solv+ 9 connection ) wireless photography1 & z previ\sly m5tion$1 ! #fd syn*ronis+ ( ! two /ations mu/ be v ne>ly p]fect 9 ord] to obta9 intelligible results4 ,! limit ( error 9 syn*ronis+ mu/ be ab\t #a 9 #ejj 9 ord] to obta9 results suitable = publication4 ,! electrolytic sy/em is p]haps ! easie/ to iso*ronise1 z ! receiv$ picture is visible4 ,on ! metal pr9t us$ = transmitt+1 & at ! comm5c+ edge a datum l9e is drawn across 9 insulat+ ink4 ,! reproduction ( ?is l9e is c>efully obs]v$ by ! op]ator 9 *>ge ( ! receiv+ in/rum5t1 & ! spe$ ( ! motor is regulat$ until ?is l9e lies close aga9/ a l9e drawn across ! electrolytic pap]4 ,al?\gh ?is may seem an ideal me?od !re are "o or two consid]ations to be tak5 into acc\nt4 ,unless ! decomposition m>ks are made ! correct l5g? & are prop]ly spac$1 h[ev] good ! iso*ronis+ may be1 ! result w be a blurr$ image4 ,any "o :o has work$ ) a sel5ium cell1 w "k t x _c *ange f its /ate ( high resi/ance to t ( l[ resi/ance ) inf9ite rapidity1 & ! effects ( ?is in]tia1 or fatigue z x has be5 call$1 are m pron\nc$ :5 work+ at a high spe$4 ,9 work+1 ! effects ( ?is in]tia w\ld be to increase ! "t ( contact ( ! relay ,f 7,fig4 #cj7 z ! curr5t f ,d w\ld fl[ = a slightly long] p]iod ?r\gh ,r to ,f ?an ! p]iod ( #fe illum9ation all[$ by ,k4 ,?is1 ( c\rse1 w\ld mean a l5g!n+ ( ! m>ks on ! pap]2 results w\ld also diff] greatly ) diff]5t sel5ium cells4 ,!re is a me?od ( comp5sation by :i* ! in]tia ( a cell c almo/ entirely be ov]come1 b x w\ld add greatly to ! complicacy ( ! receiv+ app>atus4 ,9 us+ an electro-motor ) any optical me?od ( receiv+ !re are two me?ods available4 ,! fir/ is an arrangem5t simil> to t us$ by ,pr(essor ,korn 9 8 e>ly exp]im5ts ) 8 sel5ium ma*9es4 ,! motor us$ = driv+ has sev]al coils 9 ! armature connect$ ) slip r+s1 f :i* an alt]nat+ curr5t may be tapp$ (f2 ! motor act+ p>tially z a g5]ator1 besides do+ good "w z a motor 9 driv+ ! ma*9e4 ,?is alt]nat+ curr5t is conduct$ to a frequ5cy met]1 :i* consi/s ( a p[]ful electro-magnet1 ov] :i* are plac$ magnetis$ /eel spr+s1 hav+ diff]5t natural p]iods ( vibration4 ,by means ( a regulat+ resi/ance ! motor is run until ! spr+ :i* has ! same p]iod z ! desir$ armature spe$ vibrates freely4 ,! spe$ ( ! motors at bo? /ations c ?us be adju/$ ) a fair am\nt ( accuracy4 ,ano!r me?od is to make use ( a gov]nor simil> to ^? employ$ 9 ! ,hughes pr9t+ telegraph sy/em4 ,a draw+ ( ! gov]nor is giv5 9 ,fig4 #cb4 ,x consi/s ( a ,illu/ration #fg metal frame :i* supports an upright /eel b> ,s1 ^: ends turn on pivots4 ,?is b> is rectangul> 9 section4 ,! ge>-:eel ,g is fa/5$ ne> ! bottom ( ?is rod & ge>s ) a simil> :eel on ! %aft ( ! driv+ motor 7n %[n74 ,susp5d$ f ! broad] sides ( ,s are ! two flexible arms ,d1 ea* c>ry+ a brass ball ,t4 ,^! balls are n fa/5$ to ! arms1 b c slide up & d[n1 be+ held 9 position by ! wire spr+s ,m1 "o end ( ea* spr+ be+ fa/5$ to ! screws ,c4 ,^! screws "w 9 a slot cut 9 ! upp] "p ( ,s1 & are connect$ to ! adju/+ screw ,e4 ,:5 ,e is turn$ ! screws are rais$ or l[]$ accord+ly1 & also ! balls on ! arms ,d4 ,fa/5$ to ! arms are two bru%es ( t[ ,b1 & ^! revolve inside b j cle>+ ! inn] surface ( ! /eel r+ ,z4 ,^u ! motor spe$ increas+ above ! normal ! arms ,d1 & consequ5tly ! balls ,t1 sw+ out1 mak+ a l>g] circle1 caus+ ! bru%es ,b to press aga9/ ! /eel r+ ,z1 sett+ up friction :i*1 h[ev]1 is r$uc$ z soon z ! motor rega9s its ord9>y work+ spe$4 ,by c>eful adju/m5t ! spe$ ( ! motors c be kept p]fectly con/ant4 ,! object ( hav+ ! balls ,t adju/able on ,d1 is to provide a means ( alt]+ ! motor spe$1 z ! l[] ! balls on ,d ! sl[] ! me*anism runs1 & vice v]sa4 #fh ,illu/ration ,a simple & effective spe$ regulator devis$ by ! writ] is giv5 9 draw+s #cc & #cd4 ,x comprises two p>ts1 ,a & ,b1 ! "p ,a be+ connect$ to ! driv+ motor1 & ! "p ,b work+ indep5d5tly4 ,! indep5d5t portion ,b consi/s ( an ord9>y clock movem5t ,m1 a /eel sp9dle ,j be+ ge>$ to "o ( ! sl[] mov+ :eels1 s t x makes j "o revolution 9 two seconds4 ,?is sp9dle1 :i* runs 9 two con$ be>+s1 c>ries at its out] end a light ,illu/ration po9t] ,d1 ab\t two in*es long1 to ! und]side ( :i* is fa/5$ ! ?9 brass contact spr+ ,s1 :i* presses lightly ^u ! ebonite r+ ,n4 #fi ,! portion ,a comprises a sp9dle1 po9t]1 & contact spr+ simil> to ^? employ$ 9 ,b1 ! sp9dle ,j' be+ ge>$ to ! driv+ motor by means ( ,f1 s t ! po9t] ,d' makes a little m ?an "o revolution 9 two seconds4 ,by means ( a special =m ( brake on ! driv+ motor1 ! spe$ is r$uc$1 s t bo? po9t]s travel at ! same rate1 viz4 "o revolution 9 two seconds4 ,by c>eful adju/m5t ! two po9t]s c be made to revolve 9 syn*ronism1#i & :5 ?is is obta9$ ! contact spr+s ,s1 ,s'1 pass ov] ! contacts ,c1 ,c'1 complet+ ! circuit ( ! batt]y ,b & lamp ,l4 ,:5 work+ prop]ly ! lamp ,l lights up regul>ly once e second4 ,?is regulator is an excell5t "o to use = exp]im5tal "w1 al?\gh x dep5ds a great deal ^u ! skill ( ! op]ator1 b good adju/m5t %\ld be obta9$ 9 ab\t two m9utes4 ,x is a good plan to ins]t a clut* ( "s description betwe5 ! driv+ motor & ! ma*9e1 s t ! regulator c be adju/$ prior to ! act ( receiv+ or transmitt+1 ! ma*9e be+ prev5t$ f revolv+ by means ( a cat*4 ,! motor us$ %\ld be p[]ful en\gh to take up ! "w ( driv+ ! ma*9e )\t any r$uction 9 spe$4 ,! clocks ,m c be regulat$ s t !y only ga9 or lose a few seconds 9 #gj tw5ty-f\r h\rs1 :i* gives an accuracy 9 work+ suffici5t = all practical purposes4 ,connection is made ) ! contact spr+s ,s1 ,s'1 by means ( ! spr+s ,t1 ,t'1 :i* press aga9/ ! sp9dles ,j1 ,j'4 ,ano!r important po9t is ! correct plac+ ( ! picture ^u ! receiv+ drum4 ,x is necess>y t ! two ma*9es besides revolv+ 9 p]fect iso*ronism %\ld syn*ronise z well1 i4e4 beg9 to transmit & record at exactly ! same position on ! cyl9d]s1 viz4 at ! edge ( ! lap1 s t ! compon5t p>ts ( ! receiv$ image %all occupy ! same position on ! pap] or film z !y d on ! metal pr9t4 ,if ! receiv+ cyl9d] _h1 let u suppose1 complet$ a qu>t] ( a revolution be=e x />t$ to reproduce1 ! reproduction :5 remov$ f ! ma*9e & op5$ out w be f\nd to be incorrectly plac$2 ! bottom portion ( ! picture be+ jo9$ to ! top portion1 or vice v]sa1 & ?is means t p]haps an important piece ( ! picture w\ld be r5d]$ useless ev5 if ! :ole is n spoilt4 ,x is evid5t1 !re=e1 t "s arrangem5t mu/ be employ$ :]eby syn*ronism1 z well z iso*ronism ( ! two in/rum5ts c be ma9ta9$4 ,!re are sev]al me?ods ( syn*ronis+ t are 9 con/ant use 9 high-spe$ telegraphy1 9 :i* ! limit ( error is r$uc$ to a m9imum1 #ga & "s modification ( ^! me?ods w p]haps solve ! problem1 b x mu/ be rememb]$ t syn*ronism is f> easi] to obta9 :]e ! two /ations are connect$ by a l5g? ( l9e ?an :]e ! two /ations are runn+ indep5d5tly4 ,9 "o sy/em ( ord9>y photo-telegraphy syn*ronism is obta9$ 9 ! foll[+ mann]4 ,! receiv+ cyl9d] travels at a spe$ slightly 9 excess ( ! transmitt+ cyl9d]1 & z its revolution is f9i%$ fir/ is prev5t$ f revolv+ by a *eck1 & :5 9 ?is position ! receiv+ app>atus is ?r[n out ( circuit & an electro-magnet :i* op]ates ! *eck is swit*$ 94 ,:5 ! transmitt+ cyl9d] has complet$ its revolution 7ab\t #a_/ajj? ( a second lat]7 ! transmitt+ app>atus1 by means ( a special arrangem5t1 is ?r[n out ( circuit = a p]iod1 j long en\gh = a p[]ful curr5t to be s5t ?r\gh ! l9e4 ,?is curr5t actuates ! electro-magnet4 ,! *eck is )drawn & ! receiv+ cyl9d] comm5ces a fre% revolution 9 p]fect syn*ronism ) ! transmitt+ cyl9d]4 ,z soon z ! *eck is )drawn ! receiv+ app>atus is aga9 plac$ 9 circuit until ano!r revolution is complet$4 ,z ! receiv] _c /op & />t abruptly at ! end ( ea* revolution a spr+ clut* is ins]t$ betwe5 ! driv+ motor & ! ma*9e4 #gb ,al?\gh a me?od ( syn*ronis+ simil> to ?is may lat] on be devis$ = wireless photography1 ! writ]1 f ! result ( 8 own exp]im5ts1 is l$ to believe t results good en\gh = all practical purposes c be obta9$ by fitt+ a syn*ronis+ device :]eby ! two ma*9es are />t$ "w at ! same in/ant1 & rely+ ^u ! p]fect regulation ( ! spe$ ( ! motors = correct work+4 ,! me?od ( iso*ronism mu/1 h[ev]1 be ne>ly p]fect 9 its action1 z x is easy to see t ) only a v slight diff]5ce 9 ! spe$ ( ei!r ma*9e ?is error w1 :5 multipli$ by #dj or #ej revolutions1 completely de/roy ! receiv$ picture = practical purposes4 ,f :at has be5 writt5 9 ?is & 9 ! prec$+ *apt]s x w be evid5t t ! successful solution ( transmitt+ photographs by wireless me?ods w necessitate ! use ( a great _m pieces ( app>atus all requir+ delicate adju/m5t1 & dep5d+ l>gely ^u ea* o!r = effici5t work+4 ,z previ\sly /at$1 !re is at pres5t no real sy/em ( wireless photography1 ! :ole sci5ce be+ 9 a purely exp]im5tal /age1 b already ,pr(essor ,korn has succe$$ 9 transmitt+ photographs betwe5 ,b]l9 & ,p>is1 a di/ance ( ov] #gjj miles4 ,if su* a di/ance c\ld be work$ ov] successfully1 !re is no reason to d\bt t be=e long #gc we %all be able to receive pictures f ,am]ica ) z great reliability & precision z we n[ receive messages4 ,9 ne>ly all wireless photographic sy/ems devis$ up to ! pres5t ! *ief portion ( ! receiv] consi/s ( a v s5sitive galvanomet]1 & al?\gh v good results h be5 obta9$ by _! use !y are m or less a nuisance1 z ! extreme delicacy ( _! con/ruction r5d]s !m liable to a lot ( unnecess>y movem5t caus$ by ext]nal di/urbances4 ,a galvanomet] ( ! ,de' ,arsonval patt]n1 us$ by ! writ]1 0 con/antly be+ di/urb$ by m]ely walk+ ab\t ! room1 al?\gh plac$ ^u a fairly sub/antial table2 & = ! same reason x 0 impossible to attempt to place ! driv+ motor ( ! ma*9e on ! same table z ! galvanomet]4 ,= %ip-bo>d "w x w be evid5t t ! use ( su* a s5sitive in/rum5t pres5ts a great difficulty to successful work+1 & a good op5+ exi/s = "s piece ( app>atus--to take ! place ( ! galvanomet]--t w be z s5sitive 9 its action b m robu/ 9 its con/ruction4 99 99 99 99 99 #gd ,,*apt] ,v ,,! ,,telephograph ,9 ! pres5t *apt] x is propos$ to give a brief description ( a sy/em ( radio-photography devis$ by ! au?or1 & :i* includes a greatly improv$ me?od ( transmitt+ & receiv+1 z well z an +5i\s arrangem5t = syn*ronis+ ! two /ations2 ! :ole be+ an attempt to produce a sy/em t w\ld be capable ( work+ comm]cially ov] fairly long di/ances4 ,! sy/em ab\t to be describ$1 & :i* ,i h designat$ ! telephograph1 is ! outcome ( sev]al ye>s' orig9al exp]im5tal "w1 _m difficulties t 7 manife/ 9 ! work+ ( ! e>li] sy/ems hav+ be5 ov]come by app>atus t has be5 expressly design$ = ! purpose4 ,9 any practical sy/em ( radio-photography ! foll[+ po9ts are ( great importance3 7#a7 ! spe$ ( transmission2 7#b7 ! quality ( ! receiv$ picture2 7#c7 ! me?od ( syn*ronis+ #ge ! two ma*9es s t transmission & reception beg9 simultane\sly2 7#d7 ! correct regulation ( ! spe$ ( ! driv+ motors2 7#e7 ! simplicity & reliability ( ! entire arrangem5t4 ,po9ts #a & #b are dep5d5t ^u sev]al factors2 ! numb] ( contacts made by ! /ylus p] m9ute2 ! size ( ! metal pr9t us$2 ! numb] ( l9es p] in* on ! scre5 us$ 9 prep>+ ! pr9t2 & ! accurate & h>moni\s work+ ( ! v>i\s pieces ( app>atus employ$4 ,9 ! sy/em "u discussion ! size ( ! metal pr9t us$ is #e in*es by #g in*es1 & a scre5 hav+ #ej l9es to ! in* is us$ = prep>+ x4 ,) ! drum ( ! ma*9e mak+ "o revolution 9 f\r seconds1 ! /ylus makes #hg contacts p] second1 or #ebbj a m9ute1 ! "t = complete transmission be+ tw5ty-five m9utes4 ,by ! use ( ord9>y relays n m ?an #bjjj contacts a m9ute c be obta9$1 & 9 ! pres5t sy/em x is only by means ( a specially design$ relay t su* a high rate ( work+ has be5 made possible4 ,simil>ly1 too1 ) ! receiv+ ( su* a l>ge numb] ( signals transmitt$ at su* a high spe$1 a special in/rum5t has be5 devis$ t c record ?is numb] ( signals )\t any tr\ble1 & c\ld ev5 record up to #hjjj signals a m9ute1 provid$ t a suitable transmitt] c\ld be design$4 #gf ,9 ! pres5t sy/em ! writ] does n claim to h completely solv$ ! problem ( ! wireless transmission ( photographs1 b x is a great advance on any sy/em previ\sly describ$1 & ! foll[+ advantages are put =w>d = recognition3 7#a7 a greatly improv$ me?od ( transmitt+ & receiv+2 7#b7 a simple me?od ( regulat+ ! spe$ ( ! driv+ motors & ma9ta9+ iso*ronism ) a limit ( error ( less ?an #a 9 #hjj2 7#c7 an arrangem5t = syn*ronis+ ! two ma*9es :]eby transmitt+ & receiv+ beg9 simultane\sly2 7#d7 ! use ( "o ma*9e only at ea* /ation4 ,,transmitt+ ,,app>atus ,a diagrammatic repres5tation ( ! app>atus requir$ = a complete /ation1 transmitt+ & receiv+ comb9$1 is giv5 9 ,fig4 #ce1 ! usual wireless equipm5t hav+ be5 omitt$ f ! diagram to avoid confusion4 ,! ,ma*9e4--,?is1 z w be se5 f ,fig4 #cf1 consi/s ( a base-plate ,m1 to :i* are atta*$ ! two be>+s ,b & ,b'4 ,! be>+ ,b' is fitt$ ) an int]nal ?read to correspond ) ! ?read$ portion ( ! %aft ,d4 ,! drum ,v is a brass ca/+1 be+ fa/5$ to ! %aft by set screws4 ,! %aft is ?read$ #ge to ! in*4 ,! be>+s are pref]ably ( ! conc5tric type4 ,! circuit break] ,c is s arrang$ t :5 #gg ! drum has trav]s$ ! requir$ di/ance1 ! end ( ! %aft pu%es back ! spr+ ,m1 break+ ! circuit ( ! driv+ ge> & /opp+ ! ma*9e4 ,! ma*9e is connect$ to ! driv+ ge> by ! flexible c\pl+ ,a4 ,illu/ration3 ,,fig4 #ce4 ,m1 motor2 ,y1 iso*ronis]2 ,f1 clut*2 ,a1 ma*9e2 ,r1 /ylus2 ,s1 relay2 ,x1 ge>+2 ,o1 circuit break]2 ,t1 receiv]2 ,c1 cond5s]2 ,u1 telephone relay2 ,k1 pol>is$ relay2 ,l1 contact break]2 ,d1 ,d#a1 ,d#b1 ,d#c1 batt]ies2 ,p1 friction brake2 ,b1 ,b#a1 d\ble-pole two-way swit*es2 ,n1 ,n#a1 ,n#b1 s+le swit*es2 ,w1 key2 ,e1 electric clock2 ,j1 telephones4 ,! drum measures #e in*es long by #b-a_/h in*es diamet]1 & ?is takes a metal pr9t #e in*es by #g in*es1 :i* all[s = a lap ( ab\t #a_/d in*4 ,9 work+1 ! pr9t is wrapp$ tightly r\nd ! drum1 be+ secur$ by means ( a little seccot9e sme>$ along "o edge4 ,c>e mu/ be tak5 t ! edge ( ! lap draws away f ! po9t ( #gh ! /ylus & n t[>ds x4 ,a m>g9 ( b>e foil1 ab\t #a_/h in* wide1 %\ld be left on ! pr9t at ! comm5c+ edge1 ! purpose ( :i* w be expla9$ lat]4 ,illu/ration3 ,,fig4 #cf4 ,! ,/ylus4--,z ! drum ( ! ma*9e travels lat]ally1 by reason ( ! ?read$ %aft & be>+1 ! /ylus mu/ necess>ily be a fixture4 ,x consi/s ( a hold] ,b1 drill$ to take a h>d5$ /eel po9t ,s1 atta*$ to ! spr+ ,m4 ,! spr+ is arrang$ to "w 9 ! guide ,f1 :i* is provid$ ) an adju/+ screw ,w = regulat+ ! pressure ( ! /ylus ^u ! pr9t2 ! pressure be+ suffici5t to enable good contact to be made1 b mu/ n be heavy en\gh to scrat* ! s(t foil4 ,! ne$le %\ld pres5t an angle ( ab\t #fj;deg to ! surface ( ! pr9t1 z ?is angle has be5 f\nd to give ! be/ results 9 work+4 ,to elim9ate any sp>k+ t may take place at ! po9t ( make & break1 due to ! self-induction ( ! relay coils1 a cond5s] ,c1 ab\t #a micr(>ad capacity1 %\ld be connect$ across #gi ! drum & /ylus4 ,! complete /ylus is giv5 9 ! draw+s1 ,figs4 #cg1 #cg;a1 & also 9 ! diagrams ,figs4 #h & #i4 ,illu/ration3 ,,fig4 #cg4 ,%[+ ! arrangem5t = slid+ ! /ylus to or f ! ma*9e4 ,illu/ration3 ,,fig4 #cg;a4 ,! ,relay4--,z w be se5 f ! diagram1 ,fig4 #ch1 ?is consi/s ( two electro-magnets hav+ v s(t iron cores1 ! magnet ,m be+ w\nd 9 ! usual mann]1 :ile ! magnet ,n is w\nd diff]5tially4 ,! armature ,a is made z light z possible1 & is pivot$ at ,p1 & :5 !re is no curr5t fl[+ ?r\gh any ( ! coils1 is held midway betwe5 ! magnet cores by ! two spiral spr+s ,s & ,t1 :i* are "u slight b equal t5sion4 ,! connections are z foll[s4 ,! wires f ! w9d+ on ,m are connect$ directly to ! relay t]m9als ,f & ,h1 z are also ! wires f "o w9d+ on ,n4 ,! o!r w9d+ on ,n is connect$ 9 s]ies ) ! batt]y ,c1 ammet] ,b1 & regulat+ resi/ance ,r4 #hj ,illu/ration3 ,,fig4 #ch4 ,:5 ! circuit ( ! batt]y ,c is complet$1 ! coil ( ,n1 to :i* x is connect$1 is en]gis$1 & ! armature ,a is attract$ aga9/ ! /op ,v4 ,:5 9 ?is position ! t5sion ( ! spr+ ,s is releas$1 :ile ! t5sion ( ! spr+ ,t is increas$4 ,z soon z ! circuit ( ! batt]y ,d is complet$ by means ( ! metal l9e pr9t on ! transmitt+ ma*9e1 ! curr5t divides at ! t]m9als ,f & ,h1 a portion fl[+ ?r\gh ! magnet coil ,m1 & a portion ?r\gh ! rema9+ w9d+ on ,n4 ,! curr5t :i* fl[s ?r\gh ! w9d+ on ,n produces a magnetis+ effect equal to t caus$ by ! o!r w9d+ on ,n1 b s9ce ! two w9d+s are ( equal l5g? & resi/ance1 & s9ce ! curr5t fl[+ ?r\gh ! two w9d+s is ( equal /r5g? b 9 opposite directions1 ! result is to neutralise #ha ! magnetis+ effects produc$ by ea* w9d+1 & consequ5tly no magnetism is produc$ 9 ! cores4 ,! o!r portion ( ! curr5t f ,d fl[s ?r\gh ! coil ,m1 & x becomes magnetis$ at ! same "t t ! coil ,n becomes demagnetis$4 ,! armature ,a is attract$ by ,m aga9/ ! /op ,x1 & ?is attraction is assi/$ by ! spr+ ,t1 :i* 0 "u increas$ t5sion4 ,! conditions ( ! spr+s are n[ rev]s$1 ! spr+ ,s be+ "u increas$ t5sion1 :ile ! t5sion ( ! spr+ ,t is releas$4 ,z soon z ! curr5t f ,d is brok51 ! magnetism disappe>s f ,m1 ! neutralis+ curr5t 9 ,n ceases1 & ,n once m becomes magnetis$1 ow+ to ! curr5t :i* /ill fl[s ?r\gh "o w9d+ f ,c2 ! armature is !re=e aga9 attract$ by ,n1 assi/$ by ! spr+ ,s4 ,! curr5t fl[+ ?r\gh ! two w9d+s ( ,n mu/ be p]fectly equal1 & ! regulat+ resi/ance ,r1 & ammet]s ,b & ,b'1 are ins]t$ = purposes ( adju/m5t4 ,! curr5t f ,c mu/ fl[ 9 a direction opposite to t :i* fl[s f ,d4 ,illu/ration3 ,,fig4 #ci4 ,h1 ,h'1 conta9]s2 ,m1 m]cury2 ,e1 p>aff9 oil2 ,t1 ,t'1 t]m9als2 ,c1 susp5d+ rod2 ,d1 base2 ,f1 ,f'1 dipp+ rods4 ,! local circuit ( ! relay is complet$ by means ( a copp] dipp] 9 m]cury1 some:at resembl+ an ord9>y m]cury break1 b modifi$ to suit ! pres5t requirem5ts4 ,! arrangem5t w be se5 f ,fig4 #ci4 ,! :ole ( ! #hb mov+ p>ts are made z light z possible1 & = ?is reason ! rod ,c & ! dipp]s ,f1 ,f' %\ld be made z %ort z conv5i5t4 ,! conta9]s ,h1 ,h' are sep>ate1 ( ca/ iron1 & rectangul> 9 %ape4 ,! dipp] is ( v ?9 copp] tube--an advantage :]e alt]nat+ curr5t is to be us$--& is made adju/able = height on ! susp5d+ rod ,c4 ,! leg ,f is ( su* a l5g? t p]man5t contact is made ) ! m]cury 9 ! conta9] ,h1 :ile ! leg ,f' cle>s ! surface ( ! m]cury by ab\t #a_/d in*1 :5 ! armature ( ! relay is 9 its normal position4 ,to prev5t undue *urn+ ( ! m]cury1 :i* w\ld necess>ily take place if ! dipp] ent]$ & left ! m]cury at ea* movem5t ( ! armature1 a po9t$ ebonite plug is ins]t$ 9 ! end ( ! tube4 ,?is w be f\nd to give good results at a high spe$1 ! m]cury be+ practically undi/urb$1 & ! production ( sludge r$uc$ to a m9imum4 ,to prev5t oxidation ( ! m]cury1 & to prev5t arc+1 ! surface is cov]$ ) p>aff9 oil4 ,if ?is is n suffici5t to prev5t arc+ a cond5s] %\ld be %unt$ across ! #hc conta9]s4 ,! volume ( m]cury1 & ! area ( ! dipp]s1 %\ld be suffici5t to c>ry ! curr5t us$ = a consid]able p]iod )\t heat+ up to any ext5t4 ,an adju/able weight ,j is provid$ 9 ord] to balance ! armature & dipp+ rod4 ,! rema9+ transmitt+ app>atus consi/s ( ! batt]y ,d#b & ! usual wireless app>atus4 ,! d\ble-pole two-way swit* ,b' is to enable ! photo-telegraphic set to be swit*$ out & ! h& key ,w swit*$ 9 = ord9>y signall+ purposes4 ,! batt]y ,d#b %\ld be ab\t #ab volts4 ,,receiv+ ,,app>atus ,! wireless portion ( ! receiv] is simil> to t giv5 9 ,fig4 #bb1 is ( ! usual syntonic type1 & comprises an oscillation trans=m]1 ,s be+ ! second>y1 & ,p ! prim>y2 ,c' is a block cond5s]1 & ,c a v>iable cond5s]4 ,! detector ,d is ( ! c>borundum cry/al or electrolytic patt]n4 ,a two-way swit* ,b is provid$ s t ! relay ,u c be swit*$ out & ! telephones ,j swit*$ 9 = ord9>y receiv+ purposes4 ,! relay ,u is a ,br[n's telephone relay4 ,illu/ration3 ,,fig4 #dj4 ,! ,receiv]4--,! magnifi$ curr5t f ! relay ,u is tak5 to a special telephone receiv]1 ! con/ruction ( :i* is giv5 9 ,fig4 #dj4 ,! diaphragm ,f is ab\t #b-a_/b in*es diamet]1 & %\ld be fairly ?9 b v resili5t4 ,only "o #hd ,illu/ration ,illu/ration coil is provid$1 & ?is %\ld be w\nd ) ,no4 #dg ,s4,s4,c4 copp] wire = a resi/ance ( ab\t #bjjj ohms4 ,by us+ only "o coil & !re=e only "o core1 ! movem5t ( ! diaphragm is c5tralis$4 ,to ! c5tre ( ! diaphragm a light /eel po9t is fa/5$1 ab\t #a_/b in* long1 & provid$ ) a project+ hook ,h4 ,an enl>g$ view ( ?is p9 is giv5 9 ,fig4 #da4 ,! movem5t ( ! diaphragm & consequ5tly ( ! /eel po9t ,p is communicat$ to a pivot$ rod ,r1 :i* is ( special con/ruction4 ,a piece ( alum9ium tube #c-c_/d in*es long1 & ( ! section giv5 at ,b1 is bu%$ at "o end ) a piece ( brass ( ! %ape %[n 9 ,fig4 #da;a4 ,a /iff /eel wire ,t ab\t #a in* long 7#bj gauge7 is screw$ into ! end ( ,z1 & c>ries a c\nt]balance weight ,c4 ,a h>d5$ #he /eel sp9dle1 po9t$ at bo? ends1 is fa/5$ at ,d1 & runs betwe5 two con$ be>+s1 "o ( :i* is adju/able4 ,! und]side ( ,z is flatt5$1 & a small con$ depression is made = ! reception ( ! po9t$ end ( ! p94 ,by means ( ! spr+ ,j ! two pieces1 ,z & ,p1 are held firmly toge!r1 at ! same "t all[+ p]fect fre$om ( movem5t4 ,! bridge ,g is made f a piece ( %eet alum9ium plac$ 9 a slot cut 9 ! tube ,r1 ! end ( ! tube be+ press$ tight ^u ,g1 & secur$ by means ( a small rivet4 ,! optical arrangem5ts are z foll[s4 ,by means ( ! ,n]n/ lamp ,l1 & ! l5ses ,b & ,b'1 ,figs4 #db & #dc1 a magnifi$ %ad[ ( ,g is ?r[n ^u ! scre5 ,j4 ,:5 ! %utt] ,g is 9 its normal position 7i4e4 at re/71 its %ad[ is j above ! small hole 9 ,j1 & light f ,l rea*es ! photographic film wrapp$ r\nd ! drum ,v ( ! ma*9e4 ,illu/ration3 ,,fig4 #db4 ,j1 scre52 ,l1 ,n]n/ lamp2 ,g1 %utt]2 ,b1 cond5s+ l5s2 ,b#a1 focuss+ l5s4 ,:51 h[ev]1 signals are s5t out f ! transmitt+ app>atus1 ! magnifi$ curr5t f ! relay ,u en]gises ! coil ( ! special telephone ,s1 attract+ ! diaphragm ,f1 & consequ5tly giv+ movem5t to ! pivot$ rod ,r4 ,z by means ( ! optical arrangem5ts a #hf magnifi$ movem5t z well z a magnifi$ image ( ,g is ?r[n ^u ! scre5 ,j1 ! %ad[ ( ,g w1 :5 ! telephone ,s is actuat$1 cov] ! hole 9 ! scre51 & prev5t any light f rea*+ ! film on ,v1 until curr5t f ! relay ,u ceases to fl[4 ,!re=e1 :5 ! /ylus ( ! transmitt] traces ov] a conduct+ /rip on ! metal pr9t1 no light rea*es ! film on ,v1 b :5 trac+ ov] an insulat+ /rip ! %ad[ ( ,g on ! scre5 ,j rises1 & ! light f ,l rea*es ! film4 ,by ?is means a positive picture is receiv$1 :i* is a great advantage :]e ! photographs are requir$ = reproduction4 ,atmosph]ics w\ld be repres5t$ by irregul> transp>5t m>ks on ! film aft] developm5t1 & ^! c be easily eradicat$ by ret\*+4 ,illu/ration3 ,,fig4 #dc4 ,e1 ebonite scre52 ,f1 focuss+ l5s2 ,g1 %utt]2 ,o1 cond5s+ l5s2 ,l1 ,n]n/ lamp4 ,! drum ( ! ma*9e moves lat]ally #a_/ge? ( an in* p] revolution1 & ! hole 9 ! scre5 is #a_/ij? ( an in* 9 diamet]4 ,z ! scre5 ,j is n 9 direct contact ) ! film1 ! slight diffusion ( ! light t takes place w produce #hg a m>k ( ab\t ! "r ?ickness4 ,) a movem5t ( ! diaphragm ( only #a_/djjjj? ( an in*1 ! actual movem5t ( ,g w be #a_/djjj? ( an in*4 ,if ! optical arrangem5ts h a magnify+ p[] ( #ajj1 !n ! movem5t ( ! %ad[ ^u ! scre5 w be #a_/dj? ( an in*1 :i* w be ample to cov] ! ap]ture4 ,! alum9ium rod ,r1 m9us ! c\nt]-weight1 c be made to weigh n m ?an #ab gra9s4 ,x is necess>y to enclose ! optical p>ts 9 a light tight box1 indicat$ by ! dott$ l9es 9 ,fig4 #dc1 9 ord] to prev5t any extrane\s light f rea*+ ! film4 ,! ,contact ,break]4--,! contact break] 7,l1 ,fig4 #ce71 z w be se5 f ,fig4 #dd1 consi/s ( an electro-magnet ,n1 ! w9d+s ( :i* are connect$ ) ! batt]y ,b & ! pol>is$ relay ,k4 ,! armature :i* is support$ by ! spr+ ,g c>ries a contact arm ,a1 :i* 9 its normal position makes p]man5t contact ) ! contact screw ,t1 & completes ! circuit betwe5 ! relay ,k & ! telephone relay ,u 7,fig4 #ce74 ,z soon z ! transmitt] s5ds out ! fir/ signal1 ! magnifi$ curr5t f ! telephone relay actuates ! relay ,k1 :i* 9 turn completes ! circuit ( ! contact break]4 ,directly ! armature ,m has be5 attract$1 ! contact ) ,t is brok51 & ,a makes fre% contact ) ! screw ,h1 by means ( ! spr+ ,z #hh fa/5$ to ! und]side ( ,a4 ,! armature1 once x has be5 attract$1 is held 9 p]man5t contact ) ,h by ! cat* ,s1 indep5d5t ( ! magnets ,n4 ,z soon z contact is made ) ,h1 ! clut* 7,f1 ,fig4 #ce7 circuit is complet$1 & ! circuit ( ! relay ,k is brok54 ,:5 ! circuit ( ! clut* ,f is brok5 by means ( ! circuit break] ,c on ! ma*9e 7,fig4 #cf71 ! /op ,s is pull$ back by h&1 all[+ ! contact arm ,a to rise1 & aga9 make fre% contact ) ! contact screw ,t4 ,illu/ration3 ,,fig4 #dd4 ,,driv+ ,,app>atus ,! ,friction ,brake4--,?is consi/s ( a /eel disc ,a1 ,fig4 #de1 ab\t #b-a_/b in*es diamet] & #c_/h in* or #a_/b in* wide on ! face1 secur$ to ! ma9 %aft ( ! driv+ motor4 ,! arm ,h1 pivot$ at ,c1 c>ries at "o end ! curv$ block ,b1 :i* is fac$ ) a pad ( t[ ,f4 ,! o!r extremity is pivot$ to ! /eel rod ,p1 :i* slides #hi ,illu/ration 9 holes bor$ 9 ! /&>ds ,j4 ,"o end ( ! rod ,p is screw$ ) a f9e ?read1 ab\t #ge to ! in*1 & is fitt$ ) a regulat+ :eel ,t1 by means ( :i* ! block ,b c be made to press ^u ! disc ,a ) any requir$ degree ( pressure4 ,a fairly /iff /eel spr+ ,r is plac$ ^u ! rod ,p1 betwe5 "o /&>d ,j & ! coll> ,n4 ,z ! spe$ ( ! driv+ motor is slightly 9 excess ( t requir$ by ! ma*9e1 ! block ,b1 by means ( ! :eel1 is made to press ^u ! disc ,a1 sett+ up friction :i* r$uces ! motor spe$ until ! iso*ronis] indicates t ! correct work+ spe$ has be5 atta9$4 ,! ,clut*4--,! details ( ?is w be se5 f ,figs4 #df & #dg4 ,x consi/s ( a /eel %aft con$ at bo? ends runn+ betwe5 two c\nt]sunk be>+s1 "o ( :i* is adju/able4 ,?is %aft c>ries ! two portions ( ! clut* ,a & ,b1 ! portion ,a be+ a fixture on ! %aft1 & ! portion ,b runn+ free ^u x4 ,! portion ,b is a gun-metal ca/+ bor$ to run accurately ^u ! /eel %aft4 ,a s(t iron annul> r+ is fa/5$ to ! face4 ,illu/ration3 ,,fig4 #df4 ,e1 sp9dle2 ,r1 bobb9s2 ,p1 iron cores2 ,d1 copp] r+s2 ,t1 bru%es2 ,n1 back plate2 ,v1 front plate2 ,j1 ge>+2 ,s1 spr+2 ,h1 coll>2 ,z1 iron r+2 ,f1 fix$ be>+2 ,c1 insulat+ bu%4 ,! portion ,a consi/s ( a gun-metal ca/+ #ij ,illu/ration bor$ a tight fit = ! %aft ,e1 secur$ by means ( a set screw4 ,! two magnet cores ,p are screw$ into ! front plate ,v1 :i* is also ( gun-metal1 & aft] ! bobb9s ,r h be5 slipp$ on1 ! %anks ( ! cores are pass$ ?r\gh holes drill$ 9 ! flange ,n ( ! ma9 ca/+ & held 9 place ) nuts4 ,! faces ( bo? ,a & ,b mu/ be turn$ p]fectly squ>e ) ! %aft1 s t !y run accurately toge!r4 ,! portion ,b is #ia kept 9 contact ) ,a by means ( a spr+ ,s1 ! pressure be+ regulat$ by ! coll> ,h4 ,curr5t is tak5 to ! magnets by means ( ! two insulat$ copp] r+s ,d m\nt$ ^u ! body ( ,a4 ,! ge>-:eels on bo? portions h tee? ( v f9e pit*1 ! numb] ( tee? on ea* be+ regulat$ by ! spe$ ( ! driv+ motor & ! requir$ ma*9e spe$4 ,connection ) ! circuit break] ,l & ! batt]y ,b#b is made ) ! collect+ r+s ,d by ! bru%es ,t4 ,! complete connections are giv5 9 ! diagram ,fig4 #ea4 ,! ,iso*ronis]4--,?is is a device = ensur+ ! correct spe$ regulation ( ! driv+ motors1 & is %[n 9 detail 9 ,fig4 #dh4 ,x comprises two portions1 "o portion be+ rotat$ at a def9ite spe$ by electrical means1 & ! o!r portion rotat$ by ! driv+ motor4 ,! ma9 portion consi/s ( a metal tube ,n1 bu%$ at bo? ends1 ! bottom end ( ! tube be+ arrang$ to "w on ball-be>+s4 ,an ebonite bu% ,c c>ries ?ree copp] r+s ,t1 ,t#a1 ,t#b1 & ! bru%es ,r1 ,r#a1 ,r#b are 9 electrical contact ) !m4 ,! ebonite plate ,j1 #c-a_/b in*es diamet]1 is secur$ to ! top end ( ,n1 & c>ries a contact piece ,q1 %[n sep>ate at ,e4 ,z w be se5 ?is is a block ( ebonite ) ?ree contacts arrang$ on ! top surface4 ,! middle contact ,p is #a_/fd? ( an in* wide1 & ! contacts ,p#a #ib & ,p#b are plac$ on ei!r side at a di/ance ( #a_/af in*2 ! contact /rips ,p#a1 ,p#b c>ry ! brass p9s ,d1 :i* are ab\t #a_/af in* diamet]1 & spac$ #c_/h in* ap>t4 ,a connect+ wire is c>ri$ f ! contact ,p to ! copp] r+ ,t1 ano!r f ,p#a to ,t#a1 & "o f ,p#b to ,t#b4 ,illu/ration3 ,,fig4 #dh4 ,n1 brass tube2 ,s1 bu%es2 ,g1 ball-be>+2 ,h1 ge>-:eel2 ,t1 ,t#a1 ,t#b1 copp] r+s2 ,c1 insulat+ block2 ,r1 ,r#a1 ,r#b1 bru%es2 ,j1 ebonite disc2 ,q1 contact block2 ,d1 metal p9s2 ,o1 pulley1 ,p1 ,p#a1 ,p#b1 contact plates2 ,k1 ne$le2 ,z1 spr+2 ,w1 /eel rod2 ,e1 c\nt]sunk be>+4 ,! bu%es ,s are bor$ a runn+ fit = ! /eel rod ,w 7%[n sep>ate at ,a71 :i* is con$ at bo? ends1 & runs betwe5 two c\nt]sunk be>+s1 ! bottom be>+ ,e be+ fix$ :ile #ic ! top be>+ 7n %[n7 is adju/able4 ,a ne$le ,k is fa/5$ ne> ! end ( ! rod ,w1 & atta*$ to ?is ne$le is ! spr+ ,z1 :i* presses lightly b firmly ^u ! contact block ,q4 ,to provide a level surface = ,z to "w ov]1 ! spaces betwe5 ! contact pieces are fill$ 9 ) an insulat+ mat]ial1 & ! :ole surface f9i%$ (f p]fectly smoo?4 ,! spr+ ,z is #a_/h in* wide = portion ( its l5g?1 b at ! po9t :]e x presses ^u ,q x is r$uc$ 9 wid? to #a_/fd? ( an in* 7see ,fig4 #dh74 ,! driv+ arrangem5ts are z foll[s4 ,a c\nt]-%aft ,q1 ,fig4 #ea1 fitt$ ) a groov$ pulley1 is run 9 be>+s p>allel ) ! %aft ,w1 & is connect$ by suitable ge>+ to ! %aft ( ! driv+ motor1 s t ! ne$le ,k makes "o revolution 9 ab\t #b-a_/b seconds4 ,a belt pass+ ov] ! pulleys connects ! two %afts1 & ! t5sion ( ! belt is regulat$ by means ( an adju/able jockey pulley4 ,! tube ,n1 c>ry+ ! disc ,j1 mu/ be rotat$ at a fix$ spe$1 & ?is is accompli%$ 9 ! foll[+ mann]4 ,an ord9>y electric clock impulse dial1 actuat$ f a ma/] clock1 is connect$ by suitable ge>+ ,h1 s t ! tube ,n makes exactly "o revolution 9 #b seconds2 x be+ possible to adju/ an electric clock ( ! ,syn*ronome type1 s t x only ga9s or loses ab\t #a second 9 #bd h\rs1 & ?is provides #id an accuracy suffici5t = all practical purposes4 ,! connections are giv5 9 ,fig4 #di1 & ! face ( ! in/rum5t 9 ,fig4 #ej4 ,x w be se5 t a connect+ wire is run f ! /eel sp9dle ,w to "o t]m9al ea* ( ! lamps ,l1 ,l#a1 ,l#b1 & f ! o!r t]m9al ( ! lamps to "o t]m9al ( ! batt]ies ,j1 ! batt]y compris+ a set ( ?ree #d-volt accumulators4 ,! o!r t]m9als ( ! batt]ies are jo9$ "o to ea* ( ! bru%es ,r1 ,r#a1 ,r#b4 ,illu/ration3 ,,fig4 #di4 ,illu/ration3 ,,fig4 #ej4 ,m1 t]m9als = connect+ to electric clock2 ,l1 :ite lamp2 ,l#a1 blue lamp2 ,l#b1 r$ lamp4 ,! lamps are col\r$1 ! lamp ,l be+ :ite1 & ! lamps ,l#a & ,l#b blue & r$ respectively1 & c>e mu/ be tak5 9 connect+ up t :5 ! ne$le ,k makes contact ) ! /ud ,p ! :ite lamp ,l is 9 circuit4 ,:5 ! ma*9es are work+1 ! op]ator1 by means ( ! brake 7already describ$71 r$uces ! spe$ ( ! driv+ motor until ! ne$le ,k travels 9 unison ) ! disc ,j1 mak+ p]man5t contact ) ,p on ! contact #ie block ,q1 :i* is evid5c$ by ! lamp ,l rema9+ alight4 ,if1 h[ev]1 ! ne$le travels fa/] ?an ! disc ,j1 contact ) ,p is brok5 & fre% contact is made ) ,p#b1 ! lamp ,l is ext+ui%$ & ! r$ lamp ,l#b lights up1 & rema9s alight until ! op]ator r$uces ! spe$4 ,simil>ly1 too1 if ! ne$le travels sl[] ?an ,j1 contact is made ) ,p#a1 & ! circuit ( ! blue lamp ,l#a is complet$4 ,:5 ! spe$ is ei!r above or bel[ ! normal1 ! ne$le ,k engages ) "o or ! o!r ( ! p9s ,d1 & z ! t5sion ( ! driv+ belt is only su* z is requir$ to drive ! ne$le1 ! belt slips on ! pulleys until ! normal spe$ is rega9$4 ,,me?od ,,( ,,work+ ,! clockwork motor ,m1 ,fig4 #ea1 %\ld be capable ( runn+ = sev]al h\rs ) "o w9d+1 & p[]ful en\gh to take up ! "w ( driv+ ! ma*9e )\t any appreciable ef=t4 ,! ma9 sp9dle ( ! motor is s arrang$ t x makes "o revolution 9 two m9utes1 & ! r$uction 9 spe$ betwe5 ! motor %aft & ! %aft to :i* ! c\pl+ ,a is atta*$ is #cj3a4 ,! metal l9e pr9t hav+ be5 wrapp$ r\nd ! drum ( ! ma*9e1 ! /ylus is put into position1 at ! edge ( ! lap1 & ) ! ne$le re/+ ab\t half-way on #if ! m>g9 ( ! b>e foil left at ! comm5c+ edge ( ! pr9t4 ,n[1 :5 ! two /ations are 9 p]fect read9ess = "w1 ! motors are />t$ & ! spe$ adju/$2 ! spe$ ( ! ma*9e be+ j "u "o revolution 9 f\r seconds4 ,illu/ration3 ,,fig4 #ea4 ,m1 clockwork motor2 ,s1 iso*ronis]2 ,e1 friction break2 ,t1 bru%es2 ,f1 electric clut*2 ,x1 ge>+2 ,d1 ,d#a1 swit*es2 ,a1 flexible c\pl+2 ,k1 pol>is$ relay2 ,l1 circuit break]2 ,b#a1 ,b#b1 ,b#c1 batt]ies2 ,p1 electric clock2 ,w1 t]m9als = connection to telephone relay2 ,h1 t]m9als = connection to t]m9als ,j1 on transmitt+ ma*9e4 ,! swit* ,d is !n clos$1 & ! arm ( ! swit* ,d#a plac$ on ! contact /ud 7#a71 at ! transmitt+ /ation only4 ,z soon z ! swit*es are clos$ ! clut* ,f comes into action1 & ! transmitt+ ma*9e beg9s to revolve4 ,:5 ! :ole ( ! l9e pr9t wrapp$ r\nd ! drum ( ! ma*9e has pass$ "u ! /ylus1 ! end ( ! %aft ,d1 ,fig4 #cf1 engages #ig ) ! spr+ m1 break+ ! clut* circuit & all[+ ! motor to run free4 ,z soon z ! ma*9e /ops1 ! swit* ,d is op5$ & ! ma*9e run back to its />t+ position by h&4 ,at ! receiv+ /ation ! swit* ,d is also clos$1 & ! arm ( ! swit* ,d#a plac$ on ! contact /ud 7#b74 ,! clos+ ( ^! swit*es does n br+ ! clut* ,f into op]ation until curr5t f ! telephone relay ,u connect$ to ! wireless receiv+ app>atus works ! s5sitive pol>is$ relay ,k1 :i* 9 turn completes ! circuit ( ! circuit-break] ,l4 ,:5 ! armature ( ,l is attract$1 ! circuit ( ! relay ,k is brok51 ! circuit ( ! clut* ,f is complet$1 & ! ma*9e />ts revolv+4 ,illu/ration3 ,,fig4 #eb4 ,! curr5t f ! relay ,u1 due to ! transmitt+ /ylus pass+ ov] "o contact /rip on ! metal pr9t1 is too brief to actuate ! heavi] me*anism ( ! relay ,k1 h5ce ! ne$ ( ! m>g9 ( b>e foil at ! comm5c+ edge ( ! metal pr9t1 s t a practically cont9u\s curr5t w fl[ to ! relay ,k until ! armature is attract$4 ,z1 h[ev]1 ! relay is n actuat$ at ! receipt ( ! fir/ signal1 & z x is necess>y = ! ma*9e to />t record+ at a c]ta9 po9t on ! film1 viz4 #ih at ! edge ( ! lap--! reason = ?is 0 giv5 9 ,*apt] ,,iv4--! />t+ position ( ! receiv+ drum w be simil> to t giv5 9 ! diagram ,fig4 #eb1 :]e ,x indicates ! lap ( ! photographic film1 & ! arr[ ! direction ( rotation4 ,x is1 ( c\rse1 obvi\s t a some:at simil> adju/m5t mu/ be made ) reg>d to ! position ( ! /ylus on ! metal pr9t at ! transmitt+ ma*9e4 ,9 ! pres5t sy/em1 z 9 almo/ e photographic me?od ( receiv+ t has be5 describ$1 ! ,n]n/ lamp is inv>iably m5tion$ z ! s\rce ( illum9ation4 ,s9ce ! adv5t ( ! high-voltage metal-filam5t lamps ! ,n]n/ lamp has fall5 some:at into disuse = comm]cial purposes1 b x possesses c]ta9 *>act]i/ics t r5d] x em95tly suitable = ! purpose "u discussion4 ,! ma9 pr9ciple ( ?is type ( lamp dep5ds ^u ! discov]y made by ,pr(essor ,n]n/ 9 #ahih1 aft] :om ! lamp is nam$1 t filam5ts ( c]ta9 e>?y bodies :5 rais$ to a r$ heat became conductive suffici5tly well to pass a curr5t :i* rais$ x to a :ite heat1 & fur!rmore t ! gl[+ filam5t emitt$ a bright] light = a giv5 am\nt ( curr5t ?an c>bon filam5ts4 ,illu/ration3 ,,fig4 #eb;a4 ,n]n/ lamps are made 9 two sizes1 ! l>g] #ii be+ int5d$ = ! same "w z usually done by arc lamps1 & ! small] to replace inc&esc5t lamps2 ! small] type be+ made to fit into ! ord9>y bayonet lamphold]s4 ,! pr9cipal p>ts ( a ,n]n/ lamp consi/ ( ! filam5t1 ! heat]1 ! automatic cut-out1 & ! resi/ance1 & _! arrangem5t 9 ! small] type ( lamp is giv5 9 ! diagram1 ,fig4 #eb;a4 ,! curr5t ent]s at ! positive t]m9al1 passes ?r\gh ! heat] ,m1 & out ?r\gh ! negative t]m9al4 ,! filam5t ,b1 :i* consi/s ( a %ort l5g? ( an infusible e>? made ( ! oxides ( sev]al r>e m9]als1 ( :i* zirconia is "o1 is a non-conductor at fir/1 b becomes a conductor ^u be+ rais$ to a high temp]ature by means ( ! heat] ,m4 ,z soon z ! filam5t becomes conductive ! curr5t !n passes ?r\gh ! automatic cut-out ,h1 & ! armature ,d is attract$1 ?us break+ ! heat] circuit4 ,! curr5t !n fl[s f ! positive t]m9al #ajj ,illu/ration ?r\gh ! cut-out ,h1 resi/ance ,j1 & filam5t ,b1 & f !nce out ( ! lamp4 ,s9ce ! resi/ance ( ! filam5t decreases ! hott] x gets1 x is necess>y to ins]t a balla/+ resi/ance 9 s]ies ) x :i* has ! opposite prop]ty ( increas+ its resi/ance z x gets hott]1 to prev5t ! filam5t tak+ too mu* curr5t & de/roy+ itself4 ,su* a resi/ance1 ,j1 consi/s ( a filam5t ( f9e iron wire1 :i*1 to prev5t oxidation f exposure to ! air1 is enclos$ 9 a glass bulb fill$ ) hydrog5 gas4 ,fig4 #eb;b %[s ! =m ( balla/ resi/ance us$ 9 ! small & l>ge type ( lamp respectively4 ,ei!r direct or alt]nat+ curr5t c be us$ ) ^! lamps1 & ) direct curr5t ! pol>ity mu/ be /rictly obs]v$1 & t ! positive wire is connect$ to ! positive & ! #aja negative wire to ! negative t]m9al4 ,) ! small] type ( lamp once x has be5 correctly plac$ 9 its hold] x is ess5tial t x %\ld n be turn$1 z a *ange 9 ! direction ( ! curr5t w rapidly de/roy ! filam5t4 ,illu/ration3 ,,fig4 #eb;c4 ,! arrangem5t ( ! l>g] type ( ,n]n/ lamp c be readily se5 f ! draw+1 ,fig4 #eb;c4 ,c>e mu/ be tak5 to see t ! voltage requir$ by ! burn] & resi/ance equals ! voltage ( ! supply circuit1 & t only p>ts ( ! same amp]age are us$ toge!r on ! same lamp4 ,no advantage is obta9$ by ov]-runn+ a ,n]n/ lamp1 ?is only %ort5+ its life )\t increas+ ! light4 ,"u normal conditions ! av]age life ( ! burn] is ab\t #gjj h\rs4 ,! effici5cy ( ! ,n]n/ lamp is fairly high1 be+ only #a4de to #a4ge watts p] c4p4 ,! light giv5 is rem>kably /eady1 & ! lamps are adaptable = all voltages f #ajj to #cjj4 ,9 "o ( ! l>ge type ( lamps = use on a #bce-volt #ajb circuit ! burn] takes #j4e amp]e at #bae volts1 & ! resi/ance #j4e amp]e at #bj volts1 :ile "o ( ! small] lamps = use on ! same circuit takes #j4be amp]e at #bae volts & #j4be amp]e at #bj volts = ! burn] & resi/ance respectively4 ,! burn] & heat] are v fragile1 & %\ld nev] be h&l$ except by ! porcela9 plate to :i* !y are atta*$4 ,! lamps burn 9 air & emit a brilliant :ite light ( high act9ic p[]1 ! intr9sic brilliancy 7c4p4_/squ>e in*7 v>y+ f #ajjj to #bejj1 z comp>$ ) #ajjj to #abjj = ord9>y metal filam5t lamps1 & #cjj to #ejj = c>bon filam5t lamps4 ,! *ief advantage ( ! ,n]n/ lamp f a photographic po9t ( view lies 9 ! fact t x produces abundantly ! blue & violet rays :i* h ! greate/ *emical effect ^u a photographic plate or film4 ,^! rays are kn[n z *emical or act9ic rays1 & are only slightly produc$ 9 "s types ( inc&esc5t electric lamps4 ,c>bon-filam5t lamps are v poor 9 ?is respect4 ,because a light is visually brilliant x mu/ by no means be assum$ t x is ! be/ to use = purposes ( photography1 & ?is is a po9t ov] :i* _m photograph]s /umble :5 us+ artificial light4 ,_m s\rces ( light1 :ile excell5t = illum9ation1 h v l[ act9ic p[]s1 :ile o!rs may h l[ illum9at+ b high #ajc act9ic p[]s4 ,a lamp giv+ a light yell[i% 9 col\r has usually l[ act9ic p[]1 :ile all ^? lamps giv+ a s(t :ite light are g5]ally f\nd to be highly act9ic4 ,9 addition to ! act9ic value ( ! s\rce ( illum9ation1 ! photographic film us$ mu/ be v c>efully *os51 z ! *emical in]tia ( ! s5sitis$ film plays an important "p 9 ! successful reproduction ( ! picture1 & also1 to a c]ta9 ext5t1 affects ! spe$ ( transmission4 ,! l5g? ( exposure1 ! am\nt ( light admitt$ to ! film1 & ! *>act]i/ics ( ! film itself1 are all factors :i* h a decid$ be>+ ^u ! quality ( ! results obta9$1 & ! film f\nd to be mo/ suitable 9 "o case w p]haps give v unsatisfactory results 9 ano!r4 ,9 photo-telegraphy ! l5g? ( exposure is det]m9$ by ! "t tak5 by ! transmitt+ /ylus to trace ov] a conduct+ /rip on ! metal pr9t1 & ?is "t1 ( c\rse1 v>ies ) ! d5sity ( ! image & also ) ! spe$ ( transmission4 ,! film 9 ord9>y photography is *os5 ) reg>d to ! subject & ! exi/+ light conditions1 & ! am\nt ( light admitt$ to ! film & ! l5g? ( exposure are regulat$ accord+ly4 ,no su* latitude is1 h[ev]1 possible 9 photo-telegraphy4 ,) ea* set ( app>atus #ajd ! v>i\s factors1 su* z ! light value1 ! am\nt ( light admitt$ to ! film1 & ! l5g? ( exposure1 w be practically fix$ quantities1 & ! film t w give ! mo/ satisfactory results "u ^! fix$ conditions c only be f\nd by ! r\gh-&-ready me?od ( trial & error4 ,! films 9 common use are manufactur$ 9 f\r qualities1 namely1 ord9>y1 /udio1 rapid1 & extra rapid4 ,^! t]ms %\ld really relate to ! light s5sitiv5ess ( ! film 7or1 z x is te*nically t]m$1 ! spe$71 b at ! be/ !y are a r\gh & v unsatisfactory guide1 = ! reason t "s unscrupul\s mak]s1 purely = bus9ess purposes1 d n hesitate to label _! films & plates z sl[1 rapid1 etc41 )\t tr\bl+ to make any te/s = correct classification4 ,! spe$ ( photographic films & plates is g5]ally indicat$ by a numb]1 & ! sy/em ( /&>disation adopt$ by ! majority ( mak]s 9 ?is c\ntry is t orig9at$ by ,messrs4 ,hurt] ,driffield1 abbreviat$ ,h4 ,d4 ,9 _! sy/em ! spe$ ( ! film & ! exposure v>ies 9 geometrical proportion1 a film m>k$ ,h4 ,d4 #ej requir+ d\ble ! exposure ( "o m>k$ ,h4 ,d4 #ajj4 ,! highe/ numb] always d5otes ! highe/ spe$1 & ! exposure v>ies inv]sely ) ! spe$4 ,besides ! ,hurt] ,driffield me?od ( #aje obta9+ ! spe$ numb]s ( plates & films adopt$ by a l>ge numb] ( mak]s 9 ?is c\ntry1 !re are also two /&>d ,engli% sy/ems kn[n z ! ,w4,p4 ,no4 7,watk9's p[] numb]7 & ,wynne ,f4 ,no41 bo? ( :i* are us$ to a fair ext5t4 ,! ,act9ograph numb] or spe$ numb] ( a plate 9 ! ,h4 ,d4 sy/em is f\nd by divid+ #cd by a numb] kn[n z ! ,in]tia1 ! ,in]tia1 :i* is a measure ( ! ins5sitiv5ess ( ! plate1 be+ det]m9$ accord+ to ! directions laid d[n by ,hurt] ,driffield--t is1 by us+ pyro-soda develop] & ! /raight portion only ( ! d5sity curve4 ,if1 = in/ance1 ! ,in]tia 0 f\nd to be "o-fif?1 !n ! spe$ numb] w\ld be #cd _/ #a_/e #agj1 & ! plate is ,h4 ,d4 #agj4 ,! ,w4,p4 ,no4 is f\nd by divid+ #ej by ! ,in]tia4 ,?us #ej _/ #a_/e #bej1 & ! plate is ,w4,p4 #bej1 b = all practical purposes ! ,w4,p4 ,no4 c be tak5 z "o & a half times ,h4 ,d4 ,! ,wynne ,f4 numb]s may be f\nd by multiply+ ! squ>e root ( ! ,watk9s numb] by #f4d4 ,?us sqrt#bej #ae4ha1 & #ae4ha x #f4d ,w4,f4 #aja4 ,= ^? photograph]s :o are 9 ! habit ( us+ an act9omet] giv+ ! plate spe$s 9 ,h4 ,d4 numb]s1 ! foll[+ table1 tak5 f ! ,photograph]'s ,daily ,companion1 is giv51 #ajf :i* %[s at a glance ! relative spe$ numb]s = ! v>i\s sy/ems4 ,! ,watk9s & ,wynne numb]s only hold good1 h[ev]1 :5 ! in]tia has be5 f\nd by ! ,h4 ,d4 me?od4 ,,table ,,( ,,comp>ative ,,spe$ ,,numb]s ,,= ,,plates ,,& ,,films ---------------------------------------- -------------- ,h4 ,d4,w4,p4 ,no4,w4,f4 ,no4,h4 ,d4,w4,p4 ,no4,w4,f4 ,no4 ---------------------------------------- ---------- #aj #ae #bd #bbj #cbc #aad #bj #cj #bh #bdj #ceb #abj #dj #fj #di #bfj #chb #abd #hj #abj #fi #bhj #dab #abi #ajj #adg #gg #cjj #dda #acd #abj #agf #hd #cbj #dgj #ach #adj #bjf #ia #cdj #ejj #adb #afj #bce #ajc #chj #eeh #aej #bjj #bid #aji #djj #ehh #aed ---------------------------------------- -------------- ,al?\gh !oretically ! high] ! spe$ ( ! film ! less ! duration ( exposure requir$1 !re is a practical limit1 z besides ! int5sity & act9ic value ( ! light admitt$ to ! film a def9ite "t is necess>y = x to ov]come ! *emical in]tia ( ! s5sitis$ coat+ & produce a useful effect4 ,) e make ( film x is possible to give s %ort an exposure t al?\gh light does fall ^u ! film x does no "w at all--9 o!r words1 we c say t = e film !re is a m9imum am\nt ( light action1 & any?+ bel[ ?is is ( no use4 ,! exposure t enables ! smalle/ am\nt ( light action to take place is t]m$ ! limit ( ! smalle/ useful exposure4 #ajg ,!re is also a maximum exposure 9 :i* ! light affects practically all ! silv] 9 ! film1 & any increas$ light action has no increas$ effect4 ,?is is ! limit ( ! greate/ useful exposure4 ,9 photo-telegraphy ! duration ( exposure1 z already po9t$ out1 is det]m9$ by c]ta9 conditions connect$ ) ! transmitt+ app>atus1 & ) conditions simil> to ^? m5tion$ on page #ge ! l5g? ( exposure w v>y r\ghly f #a-ej? to #a-aej? ( a second4 ,! mo/ suitable film to use = purposes ( photo-telegraphy is "o hav+ a fairly sl[ spe$ 9 :i* ! range ( exposure requir$ comes well )9 ! limits ( ! film4 ,!re is no advantage 9 us+ a film hav+ a spe$ (1 say1 ,h4 ,d4 #cjj if good results c be obta9$ f "o ) a spe$ (1 say1 ,h4 ,d4 #bjj1 z ! use ( ! high] spe$ increases ! risk ( ov]exposure4 ,) ! high-spe$$ films ! difficulties ( developm5t are also greatly increas$1 !re be+ m latitude 9 bo? exposure & developm5t ) ! sl[] spe$s1 & consequ5tly a bett] *ance ( obta9+ a good negative4 ,ano!r po9t1 (t5 puzzl+ to ! beg9n]1 & :i* increases ! difficulty ( *oos+ a suitable make ( film1 is t1 al?\gh "o make ( film m>k$ ,h4 ,d4 #ajj w give good results1 ano!r make1 also m>k$ ,h4 ,d4 #ajj1 w give #ajh v poor results4 ,?is is ow+1 n to a poor quality film1 z _m suppose1 b to ! almo/ insurm\ntable difficulty ( mak]s be+ able to employ exactly ! same /&>d ( light = te/+ purposes1 s t al?\gh v>i\s makes may all be /&>dis$ by ! ,h4 ,d4 me?od1 films be>+ ! same spe$ numb]s may v>y 9 _! actual spe$ by z mu* z #cj to #ej p] c5t4 99 99 99 99 99 #aji ,,app5dix ,a ,,sel5ium ,,cells ,sel5ium is a non-metallic elem5t1 & 0 fir/ discov]$ by ,b]zelius 9 #ahag1 9 ! deposit f sulphuric acid *amb]s1 :i* /ill cont9ues ! s\rce f :i* x is obta9$ = comm]cial purposes1 al?\gh x is f\nd to a small ext5t 9 native sulphur4 ,its at4 wt4 is #gi4b1 & its sp4 gr4 #d4h4 ,symbol1 ,se4 ,9 its natural /ate sel5ium is practically a non-conductor ( electricity1 its resi/ance be+ =ty ?\s& million times great] ?an copp]4 ,its practical value lies 9 ! prop]ty :i* x possesses1 t :5 9 a prep>$ condition x is capable ( v>y+ its electrical resi/ance accord+ to ! am\nt ( light to :i* x is expos$1 ! resi/ance decreas+ z ! light increases4 ,sel5ium is prep>$ by heat+ x to a temp]ature ( #abj;deg ,c41 keep+ x !re = "s h\rs1 & all[+ x to cool sl[ly1 :5 x assumes a cry/all9e =m & *anges f a blui% grey to a dull slate col\r4 ,a sel5ium cell 9 its simple/ =m consi/s m]ely ( "s prep>$ sel5ium plac$ betwe5 two or m metal electrodes1 ! sel5ium act+ z a high resi/ance conductor betwe5 !m4 ,! =m giv5 by ,bell & ,ta9t] to ! cells us$ 9 _! exp]im5ts is giv5 9 ,figs4 #ec & #ec;a4 ,x consi/s ( a numb] ( rectangul> brass plates ,p1 ,p'1 sep>at$ by v ?9 %eets ( mica ,m1 ! mica %eets be+ slightly n>r[] ?an ! brass plates1 ! :ole be+ clamp$ toge!r 9 ! frame ,f by ! two bolts ,b4 #aaj ,by means ( a s&-ba? ! cell is rais$ to ! desir$ temp]ature1 & sel5ium is rubb$ ov] ! surface1 :i* melts & fills ! small spaces betwe5 ! brass plates4 ,all ! plates ,p are connect$ toge!r to =m "o t]m9al1 & ! plates ,p' to =m ! o!r4 ,by us+ v ?9 mica %eets1 & a l>ge numb] ( elem5ts1 a v n>r[ transv]se section ( sel5ium1 toge!r ) a l>ge active surface1 c be obta9$4 ,! cell us$ = comm]cial purposes is usually con/ruct$ z foll[s4 ,a small rectangul> piece ( porcela91 slate1 mica1 or o!r insulator1 is w\nd ) _m turns ( f9e plat9um wire4 ,! wire is w\nd d\ble1 z %[n 9 ,fig4 #ed1 ! spaces betwe5 ! turns be+ fill$ ) prep>$ sel5ium4 ,a ?9 glass cov] is sometimes plac$ ov] ! cell to protect ! surface f injury4 ,illu/ration3 ,,fig4 #ec4 ,p1 ,p'1 plates2 ,m1 mica2 ,s1 sel5ium4 ,illu/ration3 ,,fig4 #ec;a4 ,a /rong light fall+ ^u a cell l[]s its resi/ance1 & vice v]sa1 ! resi/ance ( a cell be+ at its highe/ :5 unexpos$ to light2 ! light is app>5tly absorb$ & made to d "w by v>y+ ! electrical resi/ance ( ! sel5ium4 ,sel5ium cells v>y v consid]ably z reg>ds _! quality z well z 9 _! electrical resi/ance1 x be+ possible to obta9 cells ( ! same size = any resi/ance betwe5 #aj & #a1jjj1jjj ohms1 & also1 a cell may rema9 9 good work+ condition = sev]al mon?s1 :ile ano!r w become useless 9 z _m weeks4 ,! ability ( a cell to respond to v rapid *anges 9 ! illum9ation to :i* x is expos$ is det]m9$ l>gely ^u its in]tia1 x be+ tak5 z a g5]al rule #aaa t ! high] ! resi/ance ( a cell ! less ! in]tia1 & vice v]sa1 & also1 t ! high] ! resi/ance ! great] ! ratio ( s5sitiv5ess4 ,in]tia plays an important "p 9 ! work+ ( a cell1 slightly oppos+ ! drop 9 resi/ance :5 illum9at$1 & oppos+ to a ,illu/ration mu* great] degree ! return to normal = no-illum9ation4 ,! effects ( in]tia or lag1 z x is t]m$1 c readily be se5 by ref]5ce to ,fig4 #ee4 ,x w be notic$ t ! curr5t value rapidly increases :5 ! cell is fir/ illum9at$1 b if aft] a %ort "t t ! light is cut (f1 ! curr5t value1 in/ead ( return+ at once to normal = no-illum9ation1 only p>tially rises ow+ to ! int]f]5ce ( ! in]tia1 & "s "t elapses be=e ! cell returns to its normal condition2 ! "t v>y+ f a few seconds to sev]al m9utes1 dep5d+ ^u ! *>act]i/ics ( ! cell & ! am\nt ( light to :i* x is expos$4 ,an actual curve is giv5 9 ,fig4 #ee;a4 ,! in]tia or lag ( a cell produces ^u an int]mitt5t curr5t an effect simil> to t produc$ by ! capacity ,illu/ration ( a l9e1 z 0 not$ 9 ,*apt] ,i41 prev5t+ ! incom+ signals f be+ record$ sep>ately1 & di/9ctly4 ,to obta9 ! be/ results 9 photo-telegraphy1 ! resi/ance ( a cell %\ld only be decreas$ to an ext5t suffici5t to pass ! curr5t requir$ to op]ate ! record+ app>atus1 & ! illum9ation %\ld be regulat$ s t ?is condition ( ! cell takes place4 ,! comp>ative sl[ness ( sel5ium 9 respond+ to #aab any great *anges 9 ! illum9ation (f]s a s]i\s difficulty to its use 9 photo-telegraphy1 b v>i\s me?ods h be5 devis$ :]eby ! effects ( in]tia c be c\nt]act$4 ,9 ! sy/em ( ,de' ,b]no*i 7see ,*apt] ,i47 ! *anges 9 ! illum9ation are nei!r v rapid nor v great1 & ! in]tia effects w\ld !re=e be v slight2 b 9 any photo-telegraphic sy/em 9 :i* a metal l9e pr9t is us$ = transmitt+1 :]e ! s\rce ( illum9ation is con/ant & ! resi/ance ( ! cell is requir$ to drop to a def9ite value & return to normal in/antly1 _m times 9 succession1 ! in]tia effects are v pron\nc$4 ,! mo/ successful me?od ( c\nt]act+ ! in]tia is t adopt$ by ,pr(essor ,korn ( always keep+ ! cell suffici5tly illum9at$ to ov]come x1 s t any additional light acts v rapidly4 ,ano!r me?od work$ out & pat5t$ by ,pr(essor ,korn1 & kn[n z ! comp5sat+ cell me?od1 gives a practically dead beat action1 ! resi/ance return+ to its normal condition z soon z ! illum9ation ceases4 ,! arrangem5t is giv5 9 ! diagram ,fig4 #ef4 ,illu/ration3 ,,fig4 #ee;a4 ,light f ! transmitt+ or receiv+ app>atus1 z ! case may be1 falls ^u ! sel5ium cell ,s#a1 :i* is #aac plac$ on "o arm ( a ,:eat/one bridge1 a second cell ,s#b be+ plac$ on ! opposite arm4 ,! sel5ium cell ,s#a %\ld h great s5sitiv5ess & small in]tia1 ! comp5sat+ cell ,s#b hav+ proportionally small s5sitiv5ess & l>ge in]tia4 ,two batt]ies ,b1 ,b'1 ( ab\t #ajj volts1 are connect$ z %[n1 ,b be+ provid$ ) a comp5sat+ v>iable resi/ance ,w2 ,w' is also a regulat+ resi/ance4 ,:5 no light is fall+ ^u ! cell ,s#a1 light f ,l is prev5t$ f rea*+ ! second cell ,s#b by a small %utt] :i* is fa/5$ to ! /r+s ( ! ,e9?ov5 galvanomet] 7describ$ 9 ,*apt] ,,iii471 & ! piece ( app>atus ,c--relay or galvanomet] z ! case may be--rema9s 9 a normal condition4 ,:51 h[ev]1 light falls ^u ! cell ,s#a1 ! balance ( ! bridge is upset1 & light f ,l falls a fraction ( a second lat] ^u ! second cell ,s#b1 & ! curr5t fl[+ ?r\gh ,c completes ! circuit4 ,ne$less to say x is necess>y t ! two cells be well mat*$1 z x is v easy to h ov]-comp5sation1 9 :i* case ! curr5t is br\ght bel[ z]o4 ,illu/ration3 ,,fig4 #ef4 ,x is also /at$ t by enclos+ ! cells 9 exhau/$ glass tubes1 _! in]tia c be greatly r$uc$ & _! life consid]ably prolong$4 ,! s5sitiv5ess ( a cell is ! ratio betwe5 its resi/ance 9 ! d>k & its resi/ance :5 illum9at$4 ,! majority ( cells h a ratio betwe5 #b3a & #c3a1 b ,pr(essor ,korn has %[n ma!matically t by con=m+ to c]ta9 conditions reg>d+ ! con/ruction ! ratio ( s5sitiv5ess may be betwe5 #d3a & #e3a4 ,?us a cell ( ,r #bej1jjj ohms c be r$uc$ to #fj1jjj ohms f ! light ( a #af c4p4 lamp plac$ only a %ort di/ance away2 ! resi/ance may be /ill #aad fur!r decreas$ by cont9u+ ! illum9ation1 b ?is produces a p]man5t defect 9 ! cells t]m$ fatigue1 ! cells becom+ v sluggi% 9 _! action & _! s5sitiv5ess gradually becom+ less1 ! ratio betwe5 _! resi/ance 9 ! d>k & _! resi/ance :5 illum9at$ be+ r$uc$ by z mu* z #cj p] c5t4 ,excessive illum9ation w also produce simil> results4 ,! in]tia ( a cell is practically unaffect$ by ! wavel5g? ( ! light us$1 b ! maximum s5sitiv5ess ( a cell is t[>ds ! yell[-orange portion ( ! spectrum4 ,9 addition to light1 heat has also be5 f\nd to v>y ! electrical resi/ance ( sel5ium 9 a v rem>kable mann]4 ,at #hj;deg ,c4 sel5ium is a non-conductor1 b up to #baj;deg ,c4 ! conductivity gradually increases1 aft] :i* x aga9 dim9i%es4 99 99 99 99 99 #aae ,,app5dix ,b ,,prep>+ ,,! ,,metal ,,pr9ts ,electricians :o desire to exp]im5t 9 photo-telegraphy1 b :o h no k ( photography1 may p]haps f9d ! foll[+ detail$ description ( prep>+ ! metal pr9ts ( "s value4 ,! w\ld-be exp]im5t] may feel some:at al>m$ at ! am\nt ( "w entail$1 b once ! v>i\s op]ations are ?or\ghly grasp$1 & ) a little pati5ce & practice1 no v great difficulty %\ld be exp]i5c$4 ,! simpl] photographic op]ations1 su* z develop+1 fix+1 etc41 _c be describ$ "h1 & ! beg9n] is advis$ to /udy a good text-book on ! subject4 ,! me?od to be giv5 ( prep>+ ! photographs is practically ! only "o available = wireless transmission1 & al?\gh ! mann] giv5 ( prep>+ is p]haps n /rictly pr(essional1 hav+ be5 modifi$ 9 ord] to meet ! requirem5ts ( ! ord9>y amateur exp]im5t]1 ! results obta9$ w be f\nd p]fectly satisfactory4 ,z w h be5 ga!r$ f ,*apt] ,,ii41 ! cam]a us$ = copy+ has to h a s+le l9e scre5 plac$ a c]ta9 di/ance 9 front ( ! photographic plate1 & ! object ( ?is scre5 is to break ! image up into p>allel b&s1 ea* b& v>y+ 9 wid? accord+ to ! d5sity ( ! photograph f :i* x has be5 prep>$4 ,?us a :ite portion ( ! photograph w\ld consi/ ( v n>r[ l9es wide ap>t1 :ile a d>k portion w\ld be made up ( wide l9es close toge!r2 a black "p w\ld appe> solid & %[ no l9es at all4 ,x is1 ( c\rse1 obvi\s #aaf t ! l9es on ! negative _c be wid] ap>t1 c5tre to c5tre1 ?an ! l9es ( ! scre54 ,a good scre5 di/ance has be5 f\nd to be #a to #fd1 i4e4 ! diamet] ( ! /op is #a_/fd? ( ! cam]a ext5sion1 & ! di/ance ( ! scre5 l9es f ! photographic plate is #fd times ! size ( ! scre5 op5+4 ,! foll[+ table %[s :at ?is di/ance is = ! scre5 mo/ likely to be us$4 ,! l9e scre5s us$ consi/ ( glass plates ^u :i* a numb] ( l9es are accurately rul$1 ! wid? ( ! l9es & ! spaces betwe5 be+ equal2 ! l9es are fill$ 9 ) an opaque sub/ance4 ,^! rul$ scre5s are v exp5sive1 & are only made to ord]1#aj a scre5 half-plate size co/+ f #bas4 to #bgs4 #f;d4 ,an effici5t sub/itute = a rul$ scre5 c be made by tak+ a r l>ge %eet ( ,bri/ol bo>d & rul+ l9es across 9 pure black draw+ ink1 ! wid? ( ! l9es & ! spaces betwe5 be+ #a_/ab? ( an in* respectively4 ,a photograph mu/ be tak5 ( ?is c>d1 ! r$uction 9 size det]m9+ ! numb] ( l9es to ! in*4 ,a c>d #bj x #ae in*es1 ) #ab l9es to ! in*1 w\ld1 if r$uc$ to #e x #d in*es1 make a scre5 hav+ #dh l9es to ! in*4 ,prep>+ ! bo>d is r a t$i\s op]ation1 b ! l9e negative produc$ w be f\nd to give results almo/ z good z ^? obta9$ f a pur*as$ scre54 ,,diamet] ,,( ,,/op ,,us$ #a_/fd,,? ,,( ,,cam]a ,,ext5sion4 ---------------------------------------- ---------------------- ,scre5 rul+ ,actual space ,di/ance ( ,9 #a_/cb;,9 milli- l9es p] in*4 9 in*es4 scre5 rul+ in*es metres4 9 in*es4 ---------------------------------------- ---------------- #ce #a_/gj 4#ia #bh4h #ba4h #ej #a_/ajj 4#fd #bj4e #af4b #fe #a_/acj 4#di #ae4g #ab4d ---------------------------------------- ---------------------- ,z x is impossible = _m to h ! use ( pr(essional app>atus design$ = ?is p>ticul> k9d ( "w1 #aag ! fix+ ( ! scre5 into an ord9>y cam]a mu/ be left to ! +5uity ( ! work]4 ,a half-plate back focuss+ cam]a w be f\nd suitable = g5]al exp]im5tal "w1 b if ?is is n available1 a l>ge box cam]a c be press$ into s]vice4 ,illu/ration3 ,,fig4 #eg4 ,! writ] has nev] se5 a half-plate box cam]a1 b "o tak+ a #e x #d in* plate c be obta9$ second-h& v *eaply4 ,x is a comp>atively simple matt] to fix ! l9e scre5 into a cam]a ( ?is description1 ! draw+s ,figs4 #eg & #eh %[+ ! me?od adopt$ by ! writ]4 ,! two clips ,d1 made f fairly /\t brass ab\t #a_/b in* wide1 are b5t to ! %ape %[n 7an enl>g$ section is giv5 at ,c7 & sold]$ at ! top & bottom ( "o ( ! metal %ea?s provid$ = hold+ ! plates4 ,! di/ance betwe5 ! front ( ! photographic plate 7! film side7 & ! back ( ! l9e scre5 7also ! film side71 indicat$ by ! arr[ at ,a1 is det]m9$ by ! numb] ( l9es on ! scre54 ,z w be se5 f ! table giv51 ! di/ance = a scre5 hav+ #ej l9es to ! in* w be #da_/fd?s ( an in*4 ,illu/ration3 ,,fig4 #eh4 ,m1 %ea?2 ,p1 photographic plate2 ,d1 clips2 ,s1 l9e scre54 ,9 all probability !re w be en\gh cle>ance betwe5 ! top ( ! %ea? & ! top ( ! cam]a to all[ = ! ?ickness ( ! clip1 b if n1 a %all[ groove a little wid] ?an ! clip %\ld be c>efully cut 9 ! top ( ! cam]a1 s t x w slide 9 easily4 ,! scre5 %\ld be plac$ betwe5 ! clips1 ! film side on ! #aah inside1 i4e4 fac+ ! photographic plate4 ,z ) a box cam]a ! ext5sion is a fixture1 ! size ( /op to be us$ is a fixture also4 ,! ext5sion ( a cam]a 7?is t]m really applies to a bell[s cam]a7 is measur$ f ! front ( ! photographic plate to ! diaphragm1 & if ?is di/ance 9 our cam]a is #h in*es1 !n ! diamet] ( ! /op to give ! be/ results w\ld be #a_/fd? ( ?is1 or #a_/h? in*4 ,al?\gh = all ord9>y exp]im5tal "w ! l5s fitt$ to ! cam]a w be suitable1 ! be/ type ( l5s = process "w ( all k9ds is ! ,ana/igmat4 ,! picture or photograph f :i* x is desir$ to make a pr9t %\ld be fa/5$ out p]fectly flat ^u a bo>d ) draw+ p9s1 & if a copy+ /& is n available x mu/ be plac$ upright 9 "s conv5i5t position4 ,! diagram ,fig4 #ei gives ! disposition ( ! app>atus requir$ = copy+4 ,a simple & inexp5sive copy+ /& is %[n 9 ,fig4 #fj4 ,! blackbo>d ,a %\ld be ab\t #cj in*es squ>e1 & mu/ be fa/5$ p]fectly upright ^u ! base-bo>d ,b4 ,! /& ,c %\ld be made s t x slides )\t any side play betwe5 ! guides ,d1 & %\ld be ( su* a height t ! l5s ( ! cam]a comes exactly opposite ! #aai ,illu/ration ,illu/ration c5tre ( ! bo>d ,a4 ,! cam]a1 if ( ! box type1 c be secur$ to ! /& by means ( a screw & w+nut1 ! screw be+ pass$ f ! inside z %[n4 ,! beg9n] is advis$ to photograph only v bold & simple subjects1 su* z black & :ite draw+s or enl>gem5ts4 ,x is n safe to tru/ to ! view-f9d]s z to :e!r ! :ole ( ! picture is includ$ on ! plate1 a piece ( gr\nd glass ! same size z ! plate %ea?s1 & us$ z a focuss+ scre51 be+ mu* m reliable4 ,x is a good plan to focus ! cam]a = a numb] ( diff]5t-siz$ pictures1 m>k+ ! bo>d ,a1 & ! #abj guides ,d1 s t adju/m5t is aft]w>ds a v simple matt]4 ,! make ( plate us$ is also a great factor 9 gett+ a good negative1 & ,wratt5 ,process ,plates w be f\nd excell5t4 ,z already m5tion$1 su* subjects z ! exposure & ! developm5t ( ! plate _c be dealt ) "h1 ^! subjects hav+ be5 exhau/ively treat$ 9 sev]al text-books on photography4 ,) an arc lamp ! exposure is ab\t twice z long z 9 daylight1 b ! exposure v>ies ) ! am\nt ( light admitt$ to ! plate1 "* ( ! s\rce ( light1 & ! s5sitiv5ess ( ! plate us$1 etc4 ,! writ] has us$ acetyl5e gas lamps = ?is purpose ) great success4 ,! beg9n] is advis$ to use artificial light1 z ?is c be kept p]fectly ev54 ,) daylight1 h[ev]1 ! light is con/antly fluctuat+1 & ?is r5d]s ! use ( an act9omet] a necessity = correct exposure4 ,aft] developm5t1 if ! plate is requir$ = imm$iate use1 x c be quickly dri$ by soak+ = a few m9utes 9 me?ylat$ _s4 ,hav+ obta9$ a good negative1 ! next op]ation is to prep>e :at is kn[n z a metal pr9t4 ,= ?is we %all require "s /\t t9-foil or lead-foil1 ab\t #ab or #ae squ>e feet to ! p\nd1 & ?is %\ld be cut into pieces ( su* a size t x all[s a lap ( #c_/af in* :5 wrapp$ r\nd ! drum ( ! transmitt+ ma*9e4 ,obta9 "s good fi%-glue & add a saturat$ solution ( bi*romate ( pota% 9 ! proportion ( #d p>ts ( pota% to #dj or #ej p>ts ( glue4 ,p\r a little ( ?is glue into a %all[ di%1 lay a %eet ( foil ^u a flat bo>d1 & ) a fairly /iff bru% 7a flat hog's-hair z wide z possible7 proce$ to coat ! %eet ( foil ) a ?9 b p]fectly ev5 coat+ ( glue4 ,! ?ickness ( ! coat+ c only be f\nd by trial1 = if ! coat+ is too ?ick a long] "t w be requir$ = pr9t+2 b x mu/ n be ?9 en\gh to %[ int]f]5ce col\rs4 ,aft] ! coat+ has be5 laid on1 a s(t bru%1 su* z photograph]s use = du/+ dry #aba plates1 %\ld be pass$ up & d[n1 & across & across1 ) light1 ev5 /rokes to remove any unev5ness4 ,a glue solution us$ by pr(essional photo-engrav]s is z foll[s3 ,fi%-glue #ab oz4 ,bi*romate ( ,ammonia #c_/d oz4 ,wat] #ah to #bd oz4 ,ammonia 4#hhj #cj m9ims4 ,! bi*romate %\ld be dissolv$ 9 ! wat]1 &1 :5 add$ to ! glue1 /ir v ?or\ghly 9 ord] t complete mix+ may take place4 ,! coat+ may be done 9 a good light1 n bright sunlight1 b x mu/ be dri$ 9 ! d>k1 because1 al?\gh ins5sitive :ile 9 a moi/ condition1 x becomes s5sitive imm$iately on desiccation4 ,if all[$ to dry 9 ! light ! :ole coat+ w become insoluble1 & = ?is reason ! bru%es us$ %\ld be wa%$ out z soon z !y are f9i%$ )4 ,! %eets w take ab\t #ae m9utes to dry 9 a p]fectly dry room1 b x is n advisable to prep>e _m %eets at once1 z !y w n keep = m ?an two or ?ree days4 ,! prep>$ negative mu/ n[ be plac$ 9 an ord9>y pr9t+ frame1 & a pr9t tak5 (f ^u "o ( ! metal %eets 9 ! same way z a pr9t is tak5 (f ^u ord9>y s5sitis$ pap]4 ,9 daylight ! exposure v>ies f #e to #bj m9utes1 b 9 artificial light v>i\s trials w h to be made 9 ord] to get ! be/ results1 ! exposure v>y+ ) ! am\nt ( bi*romate 9 ! coat+2 ! proportion ( ! bi*romate to ! glue %\ld rema9 ab\t #f p] c5t4 ,light f a #be amp]e arc lamp = #b to #e m9utes1 at a di/ance ( #ah in*es1 w g5]ally suffice to pr9t ! impression on ! metal %eets4 ,! pr9t+ f9i%$1 ! metal pr9t %\ld be laid ^u a %eet ( glass & held "u a runn+ /ream ( wat]4 ,! wa%+ is complete z soon z ! unexpos$ p>ts ( ! glue coat+ h be5 entirely wa%$ away leav+ ! b>e metal1 & ?is w take any?+ f #c to #g #abb m9utes1 dep5d+ ^u ! ?ickness ( ! film4 ,z soon z x is dry ! pr9t is ready = use4 ,z already m5tion$1 ! negative f :i* ! metal pr9t is made requires t ! l9es be p]fectly %>p & opaque1 & ! spaces betwe5 p]fectly transp>5t4 ,ord9>y dry plates are too rapid1 a r sl[ plate be+ requir$4 ,wratt5 ,process ,plates give excell5t results1 & ! foll[+ is a good develop] to use ) !m3 ,glyc9 #ae grammes #a oz4 ,sulphite ( ,soda #dj 11 #b-a_/b 11 ,c>bonate ( ,pota% #hj 11 #e 11 ,wat] #ajjj c4c4 #fj 11 ,?is develop] %\ld be us$ = #f m9utes at a temp]ature ( #ej;deg ,f41 #c-a_/b m9utes at #fe;deg1 & #a-c_/d m9utes at #hj;deg4 ,x is be/ only us$ once4 ,if an int5sifi] is requir$1 ! foll[+ =mula w be f\nd to give satisfactory results3 ,bi*loride ( ,m]cury #a oz4 #fj grammes4 ,hot ,wat] #af 11 #ajjj c4c4 ,all[ to cool1 completely p\r (f f any cry/als1 & add3 ,hydro*loric ,acid #cj m9ims #d c4c4 ,all[ negative to blea* ?or\ghly1 wa% well 9 wat]1 & black5 9 #aj p] c5t ammonia 4#hhj1 or #e p] c5t sodium sulphide4 ,9 prep>+ ! negatives & metal pr9ts ! foll[+ po9ts %\ld be obs]v$3 ,a good negative %\ld h ! l9es p]fectly %>p & opaque2 !re %\ld be no fluff betwe5 ! l9es ev5 :5 !y are close toge!r4 ,a prop]ly expos$ & develop$ negative %\ld n require any r$uc+ or int5sify+4 ,if ! lamps us$ = illum9at+ ! copy+ bo>d are plac$ #b feet away1 & ! exposure requir$ is #e m9utes1 ! exposure1 if ! lamps are plac$ #d feet away1 w be #abc #bj m9utes1 z ! am\nt ( light :i* falls ^u an object decreases z ! inv]se squ>e ( ! di/ance4 ,get ! coat+ on ! foil z ?9 z possible1 & err on ! side ( ov]-exposure1 = if ! coat+ is ?ick & has be5 "u-expos$1 excessive wa%+ w dissolve ! :ole coat+2 =1 unless insolubilisation has tak5 place "r up to ! metal base1 ! "u p>ts w rema9 9 a m or less soluble condition4 ,on no acc\nt mu/ ! unexpos$ %eets be plac$ ne> a fire1 o!rwise !y w be spoilt1 ! :ole coat+ becom+ insoluble2 heat act+ 9 ! same mann] z light4 ,9 wa%+1 keep ! pr9t mov+ s t ! /ream ( wat] does n fall cont9ually 9 "o place4 ,x is be/ to hold ! pr9t s t ! wat] runs (f 9 ! direction ( ! l9es4 ,to dry ! pr9ts aft] wa%+ !y c be laid out flat 9 a mod]ately w>m ov51 or be=e a /ove1 ! heat ( c\rse n be+ suffici5t to cause ! coat+ to peel4 ,to r5d] ! glue image m di/9ct ! pr9t %\ld be imm]s$ = a few seconds 9 an anil9e dye solution1 ! glue tak+ up ! col\r readily4 ,^! dyes are soluble 9 ei!r wat] or alcohol4 ,a dye kn[n z mag5ta is v good4 ,! process ( coat+ ! metal %eets mu/ be p]=m$ z quickly z possible 7ab\t #aj seconds71 z ow+ to ! peculi> nature ( ! bi*romat$ glue x soon sets1 & once ?is has tak5 place x is impossible to smoo? d[n any unev5ness4 ,see t ! negative & metal %eet make good contact :ile pr9t+4 ,if ! glue solution does n adh]e to ! surface ( ! foil 9 a p]fectly ev5 film1 b assumes a /reaky appe>ance1 a little liquid ammonia1 or a weak solution ( nitric acid1 rubb$ ov] ! surface ( ! foil1 :i* is aft]w>ds g5tly sc\r$ ) precipitat$ *alk on a tuft ( cotton #abd wool1 w remove ! grease :i* is ! cause ( ! difficulty4 ,a photograph ( a picture prep>$ f a l9e negative is giv5 9 ,fig4 #fa4 ,= a great _m exp]im5ts1 & 9 ord] to save "t1 tr\ble1 & exp5se1 sket*es drawn ^u /\t lead-foil 9 an insulat+ ink w answ] ! purpose admirably1 b if any exact "w is to be done a s+le l9e pr9t is ( c\rse absolutely necess>y4 ,! insulat+ ink c be prep>$ by dissolv+ %ellac 9 me?ylat$ _s1 or ord9>y gum c be us$4 ,a v f9e bru% %\ld be us$ 9 place ( a p51 z ! gum w n fl[ freely f an ord9>y nib unless great] pressure ?an ! foil w safely /& be appli$4 ,a sket* prep>$ 9 ?is mann] is %[n 9 ,fig4 #fb4 ,a little anil9e dye %\ld be add$ to ! gum to r5d] x m visible1 or a mixture ( gum & liquid indian ink w be f\nd suitable4 ,illu/ration3 ,,fig4 #fc4 ,) ! copy+ arrangem5t already describ$ x is only possible to employ x = r$uc+1 x be+ necess>y to employ a bell[s cam]a ) a back focuss+ atta*m5t = purposes ( enl>g+1 & ?is con/itutes ! *ief drawback to ! use ( a fix$ focus cam]a4 ,by replac+ ! box cam]a ) a focuss+ cam]a ( ! same size1 we %all h a piece ( app>atus capable ( r$uc+ or enl>g+1 only 9 ?is case ! cam]a %\ld be a fixture & ! bo>d1 ,a1 arrang$ to slide backw>ds & =w>ds in/ead4 ,illu/ration3 ,,fig4 #fa4 ,portions ( photographs 7full size7 ( s+le l9e scre51 & s+le l9e pr9t4 ,scre5 #dj l9es to ! in*4 ,illu/ration3 ,,fig4 #fb4 #abe ,an extra improvem5t w\ld be to rule ! surface ( ! copy+ bo>d1 ,a1 9 a mann] simil> to t %[n 9 ! diagram1 ,fig4 #fc4 ,! rul+s %\ld be m>k$ (f f ! c5tre ( ! bo>d1 & %\ld enclose p>allelograms ( ! v>i\s plate sizes rang+ f #c-a_/d x #d-a_/d in*es up to ! full size ( ! bo>d4 ,by fa/5+ ! picture or photograph to be copi$ 9 ! space on ! bo>d correspond+ 9 size1 we c ensure t x is 9 ! correct position = ! :ole to be includ$ on ! photographic plate1 provid+1 ( c\rse1 t ! c5tre ( l5s & bo>d co9cide4 ,) reg>d to ! l5s requir$1 ! practice adh]$ to by mo/ photograph]s is to use a l5s hav+ a focal l5g? equal to ! diagonal ( ! plate us$4 ,?us = a #a_/d-plate cam]a a #e-;in* l5s %\ld be us$1 & = a #a_/b-plate an #h-;in* l5s1 & s on4 ,= a #e x #d in* cam]a a #f-;in* l5s w be requir$4 ,! foll[+ is a simple rule = f9d+ ! conjugate foci ( a l5s1 & is useful 9 obta9+ ! di/ance f ! l5s to ! photographic plate & ! picture to be copi$4 ,let u suppose t we wi% to make a #a-a_/b times enl>g$ l9e negative f a #d-a_/d x #c-a_/d in* pr9t4 ,add #a to ! numb] ( times x is requir$ to enl>ge & multiply ! result by ! focal l5g? ( ! l5s 9 in*es4 ,9 ! pres5t case ?is w be #a-a_/b #a #b-a_/b2 & if a #f-;in* l5s is us$1 #b-a_/b x #f #ae in*es w be ! di/ance ( ! l5s f ! plate4 ,divide ?is numb] by ! numb] ( times x is desir$ to enl>ge1 & ! di/ance ( ! l5s f ! picture to be copi$ is obta9$2 9 ?is in/ance #ae _/ #a-a_/b #aj in*es4 ,! same rule c be foll[$ :5 x is requir$ to r$uce any giv5 numb] ( times1 only 9 ?is case ! great] numb] w repres5t ! di/ance betwe5 ! l5s & ! picture to be copi$1 & ! less] numb] ! di/ance betwe5 ! l5s & ! plate4 ,9 r$uc+1 a #a_/d-plate l5s w be f\nd to fully cov] a #e x #d in* plate1 provid+ ! r$uction is n great] ?an ?ree to "o4 99 99 99 99 99 #abf ,,app5dix ,c ,,l5ses ,9 ?is small volume x is n desirable1 nei!r is x int5d$1 to give an exhau/ive treatm5t on ! subject ( l5ses & _! action1 b z optics plays an important "p 9 ! transmission ( photographs1 bo? by wireless & ov] ord9>y conductors1 ! foll[+ notes relat+ to a few necess>y pr9ciples h be5 includ$ z likely to prove ( int]e/4 ,light always travels 9 /raight l9es :5 9 a m$ium ( uni=m d5sity1 su* z wat]1 air1 glass1 etc41 b on pass+ f "o m$ium to ano!r1 su* z f air to wat]1 or air to glass1 ! direction ( ! light rays is *ang$1 or1 to use ! correct t]m1 refract$4 ,?is refraction ( ! rays ( light only takes place :5 ! incid5t rays are pass$ obliquely2 if ! incid5t rays are p]p5dicul> to ! surface sep>at+ ! two m$ia !y are n refract$1 b cont9ue _! c\rse 9 a /raight l9e4 ,all liquid & solid bodies t are suffici5tly transp>5t to all[ light rays to pass ?r\gh !m possess ! p[] ( b5d+ or refract+ ! rays1 ! degree ( refraction1 z already expla9$1 dep5d+ ^u ! nature ( ! body4 ,! law relat+ to refraction w p]haps be bett] und]/ood by means ( ! foll[+ diagram4 ,9 ,fig4 #fd let ! l9e ,,ab repres5t ! surface ( a vessel ( wat]4 ,! l9e ,,cd1 :i* is p]p5dicul> to ! surface ( ! #abg wat]1 is t]m$ ! normal1 & a ray ( light pass$ 9 ?is direction w cont9ue 9 a /raight l9e to ! po9t ,e4 ,if1 h[ev]1 ! ray is pass$ 9 an oblique direction1 su* z ,,nd1 x w be se5 t ! ray is b5t or refract$ 9 ! direction ,,dm2 if ! ray ( light is pass$ 9 any o!r oblique direction1 su* z ,,jd1 ! refract$ ray w be 9 ! direction ,,dk4 ,! angle ,,ndc is call$ ! angle ( incid5ce & ,,mde ! angle ( refraction4 ,if we measure accurately ! l9e ,,nc1 we %all f9d t x is #a-a_/c1 or m exactly #a4ccf1 times great] ?an ! l9e ,,em4 ,if we repeat ?is measurem5t ) ! l9es ,,jh & ,,pk we %all f9d t ! l9e ,,jh also be>s ! proportion ( #a4ccf to ! l9e ,,pk4 ,! l9e ,,nc is call$ ! s9e ( ! angle ( incid5ce ,,ndc1 & ,,em ! s9e ( ! angle ( refraction ,,mde4 ,illu/ration3 ,,fig4 #fd4 ,!re=e 9 wat] ! s9e ( ! angle ( incid5ce is to ! s9e ( ! angle ( refraction z #a4ccf is to #a1 & ?is is true :atev] ! position ( ! incid5t ray ) respect to ! surface ( ! wat]4 ,f ?is we say t ! s9es ( ! angles ( incid5ce & refraction h a con/ant proportion or ratio to "o ano!r4 ,! numb] #a4ccf is t]m$ ! refractive index1 or coeffici5t1 or ! refractive p[] ( wat]4 ,! refractive p[] v>ies1 h[ev]1 ) o!r fluids & solids1 & a complete table w be f\nd 9 any good "w on optics4 ,glass is ! sub/ance mo/ commonly us$ = refract+ ! rays ( light 9 optical "w1 ! glass be+ work$ up into diff]5t =ms accord+ to ! purpose = :i* x #abh is int5d$4 ,solids =m$ 9 ?is way are t]m$ l5ses4 ,a l5s c be def9$ z a transp>5t m$ium :i*1 ow+ to ! curvature ( its surfaces1 is capable ( conv]g+ or div]g+ ! rays ( light pass$ ?r\gh x4 ,accord+ to its curvature x is ei!r sph]ical1 cyl9drical1 elliptical1 or p>abolic4 ,! l5ses us$ 9 optics are always exclusively sph]ical1 ! glass us$ 9 _! con/ruction be+ ei!r cr[n glass1 :i* is free f lead1 or fl9t glass1 :i* conta9s lead & is m refractive ?an cr[n glass4 ,! refractive p[] ( cr[n glass is f #a4ecd to #a4ebe1 & ( fl9t glass f #a4fbe to #a4eij4 ,sph]ical surfaces 9 comb9ation ) ea* o!r or ) plane surfaces give rise to six diff]5t =ms ( l5ses1 sections ( :i* are giv5 9 ,fig4 #fe4 ,illu/ration3 ,,fig4 #fe4 ,all l5ses c be divid$ into two classes1 convex or conv]g+1 or concave or div]g+4 ,9 ! figure1 b1 c1 g are conv]g+ l5ses1 be+ ?ick] at ! middle ?an at ! bord]s1 & d1 e1 f1 :i* are ?9n] at ! middle1 be+ div]g+ l5ses4 ,! l5ses e & g are also t]m$ m5iscus l5ses1 & a repres5ts a prism4 ,! l9e ,,xy is ! axis or normal ( ^! l5ses to :i* _! plane surfaces are p]p5dicul>4 ,let u fir/ ( all notice ! action ( a ray ( light :5 pass$ ?r\gh a prism4 ,! prism1 ,fig4 #ff1 is repres5t$ by ! triangle ,,bbb1 & ! incid5t ray by ! l9e ,,ta4 #abi ,:]e x ent]s ! prism at ,a its direction is *ang$ & x is b5t or refract$ t[>ds ! base ( ! prism1 or t[>ds ! normal1 ?is be+ always ! case :5 light passes f a r>e m$ium to a d5se "o1 & :]e ! light leaves ! opposite face ( ! prism at ,d x is aga9 refract$1 b away f ! normal 9 an opposite direction to ! incid5t ray1 s9ce x is pass+ f a d5se to a r>e m$ium4 ,! l9e ,,dp is call$ ! em]g5t or refract$ ray4 ,if ! eye is plac$ at ,t1 & a bright object at ,p1 ! object is se5 n at ,p1 b at ! po9t ,h1 s9ce ! eye _c foll[ ! c\rse tak5 by ! refract$ rays4 ,9 o!r words1 objects view$ ?r\gh a prism always appe> deflect$ t[>ds its summit4 ,illu/ration3 ,,fig4 #ff4 ,9 consid]+ ! action ( a l5s we c reg>d any l5s z be+ built up ( a numb] ( prisms ) curv$ faces 9 contact4 ,su* a l5s is %[n 9 ,fig4 #fg1 ! light rays be+ refract$ t[>ds ! base ( ! prisms or t[>ds ! normal1 z already expla9$2 :ile ! top half ( ! l5s w refract all ! light d[nw>ds1 ! bottom half w act z a s]ies ( inv]t$ prisms & refract all ! light upw>ds4 ,illu/ration3 ,,fig4 #fg4 ,illu/ration3 ,,fig4 #fh4 ,if a beam ( p>allel light--su* z light f ! sun--be pass$ ?r\gh a d\ble convex l5s ,l1 ,fig4 #fh1 we %all f9d t ! rays h be5 refract$ f _! p>allel c\rse & br\ght toge!r at a po9t ,f4 ,?is po9t ,f is #acj t]m$ ! pr9cipal focus ( ! l5s1 & its di/ance f ! l5s is kn[n z ! focal l5g? ( t l5s4 ,9 a d\ble & equally convex l5s ( glass ! focal l5g? is equal to ! radius ( ! sph]ical surfaces ( ! l5s4 ,if ! l5s is a plano-convex ! focal l5g? is twice ! radius ( its sph]ical surfaces4 ,if ! l5s is unequally convex ! focal l5g? is f\nd by ! foll[+ rule3 multiply ! two radii ( its surfaces & divide twice t product by ! sum ( ! two radii1 & ! quoti5t w #aca be ! focal l5g? requir$4 ,conv]sely1 by plac+ a s\rce ( light at ! po9t ,f ! rays w be project$ 9 a p>allel beam ! same diamet] z ! l5s4 ,if1 h[ev]1 in/ead ( be+ p>allel1 ! rays proce$ f a po9t f>!r f ! l5s ?an ! pr9cipal focus1 z at ,a1 ,fig4 #fi1 !y are t]m$ div]g5t rays1 b !y also w be br\ght to a focus at ! o!r side ( ! l5s at ! po9t a4 ,if ! s\rce ( light ,a is mov$ ne>] to ! pr9cipal focus ( ! l5s to a po9t ,a#a ! rays w come to a focus at ! po9t a#a1 & simil>ly :5 ! light is at ,a#b ! rays w come to a focus at ! po9t a#b4 ,x c be f\nd by direct exp]im5t t ! di/ance fa increases 9 ! same proportion z ,,af dim9i%es1 & dim9i%es 9 ! same proportion z ,,af increases4 ,! relation%ip :i* exi/s betwe5 pairs ( po9ts 9 ?is mann] is t]m$ ! conjugate foci ( a l5s1 & ?\gh e l5s has only "o pr9cipal focus1 yet its conjugate foci are innum]able4 ,illu/ration3 ,,fig4 #fi4 ,! =mation ( an image ( "s di/ant object 9 its pr9cipal focus is "o ( ! mo/ useful prop]ties ( a convex l5s1 & x is ?is prop]ty t =ms ! basis ( sev]al well-kn[n optical in/rum5ts1 includ+ ! cam]a1 telescope1 microscope1 etc4 ,if we take an oblong wood5 box1 ,,aa1 & sub/itute a %eet ( gr\nd glass1 ,c1 = "o end1 & drill a small p9hole1 ,h1 9 ! c5tre ( ! o!r end opposite ! #acb glass plate1 we %all f9d t a tol]ably good image ( any object plac$ 9 front ( ! box w be =m$ ^u ! glass plate4 ,! light rays f all po9ts ( ! object1 ,,bd1 ,fig4 #gj1 w pass /raight ?r\gh ! hole ,h1 & illum9ate ! gr\nd glass scre5 at po9ts imm$iately opposite !m1 =m+ a fa9t inv]t$ image ( ! object ,,bd4 ,! purpose ( ! hole ,h is to prev5t ! rays f any "o po9t ( ! object f fall+ ^u any o!r po9t on ! glass scre5 ?an ! po9t imm$iately opposite to x1 !re=e ! small] we make ,h1 ! m di/9ct w be ! image obta9$4 ,r$uc+ ! size ( ,h 9 ord] to produce a m di/9ct image has ! effect ( caus+ ! image to become v fa9t1 z ! small] ! hole 9 ,h1 ! small] ! numb] ( rays t c pass ?r\gh f any po9t ( ! object4 ,by enl>g+ ! hole ,h gradually1 ! image w become m & m indi/9ct until su* a size is rea*$ t x disappe>s altoge!r4 ,illu/ration3 ,,fig4 #gj4 ,if 9 ?is enl>g$ hole we place a d\ble convex l5s1 ,,ll1 ,fig4 #ga1 ^: focal l5g? suits ! l5g? ( ! box1 ! image produc$ w be bright] & m di/9ct ?an t =m$ by ! ap]ture1 ,h1 s9ce ! rays :i* proce$ f any po9t ( ! object w be br\ght by ! l5s to a focus on ! glass scre51 =m+ a bright #acc di/9ct image ( ! po9t f :i* !y come4 ,! image owes its increas$ di/9ctness to ! fact t ! rays f any "o po9t ( ! object _c int]f]e ) ! rays f any o!r po9t1 & its increas$ brightness to ! great numb] ( rays t are collect$ by ! l5s f ea* po9t ( ! object & focuss$ 9 ! correspond+ po9t ( ! image4 ,x w be evid5t f a /udy ( ,fig4 #ga t ! image =m$ by a convex l5s mu/ necess>ily be inv]t$1 s9ce x is impossible = ! rays f ! end1 ,m1 ( ! object to be c>ri$ by refraction to ! upp] end ( ! image at n4 ,! relative positions ( ! object & image :5 plac$ at diff]5t di/ances f ! l5s are exactly ! same z ! conjugate foci ( light rays z %[n 9 ,fig4 #fi4 ,illu/ration3 ,,fig4 #ga4 ,! l5g? ( ! image =m$ by a convex l5s is to ! l5g? ( ! object z ! di/ance ( ! image is to ! di/ance ( ! object f ! l5s4 ,= example1 if a l5s hav+ a focal l5g? ( #ab in*es is plac$ at a di/ance ( #ajjj feet f "s object1 !n ! size ( ! image w be to t ( ! object z #ab in*es to #ajjj feet1 or #ajjj times small] ?an ! object2 & if ! l5g? ( ! object is #ejj in*es1 !n ! l5g? ( ! image w be ! #a_/ajjj? "p ( #ejj in*es1 or #a_/b in*4 #acd ,! image =m$ by ! convex l5s 9 ,fig4 #ga is kn[n z a real image1 b 9 addition convex l5ses possess ! prop]ty ( =m+ :at are t]m$ virtual images4 ,! di/9ction c be express$ by say+1 real images are ^? =m$ by ! refract$ rays !mselves1 & virtual images ^? =m$ by _! prolongations4 ,:ile a real image =m$ by a convex l5s is always inv]t$ & small] ?an ! object1 ! virtual image is always erect & l>g] ?an ! object4 ,! p[] possess$ by convex l5ses ( =m+ virtual images is made use ( 9 t useful b common piece ( app>atus kn[n z a read+ or magnify+ glass1 by :i* objects plac$ )9 its focus are made l>g] or magnifi$ :5 view$ ?r\gh x2 b 9 ord] to prop]ly und]/& h[ objects seem to be br\ght ne>] & app>5tly increas$ 9 size1 we mu/ fir/ ( all und]/& :at is meant by ! expression1 ! app>5t magnitude ( objects4 ,illu/ration3 ,,fig4 #gb4 ,! app>5t magnitude ( an object dep5ds ^u ! angle :i* x subt5ds to ! eye ( ! obs]v]4 ,! image at ,a1 ,fig4 #gb1 pres5ts a small] angle to ! eye ?an ! angle pres5t$ by ! object :5 mov$ to ,b1 & ! image !re=e appe>s small]4 ,:5 ! object is mov$ to ei!r ,b or ,c1 x is view$ "u a mu* #ace great] angle1 caus+ ! image to appe> mu* l>g]4 ,if we take a wat* or o!r small circul> object & place x at ,a1 :i* we w suppose is a di/ance ( #ej y>ds1 we %all f9d t x w be only visible z a circul> object1 & its app>5t magnitude or ! angle "u :i* x is view$ is !n /at$ to be v small4 ,if ! object is n[ mov$ to ! po9t ,b1 :i* is only #e feet f ! eye1 its app>5t magnitude w be f\nd to h increas$ to su* an ext5t t we c di/+ui% n only its %ape1 b also "s ( ! m>k+4 ,:5 mov$ to )9 a few in*es f ! eye z at ,c1 we see x "u an angle s great t all ! detail c be di/9ctly se54 ,by hav+ br\ght ! object ne>] ! eye1 ?us r5d]+ all its p>ts cle>ly visible1 we h actually magnifi$ x1 or made x appe> l>g]1 al?\gh its actual size rema9s exactly ! same4 ,:5 ! di/ance betwe5 ! object & ! obs]v] is kn[n1 ! app>5t magnitude ( ! object v>ies inv]sely z ! di/ance f ! obs]v]4 ,let u suppose t we wi% to produce an image ( a tree situat$ at a di/ance ( #ejjj feet4 ,at ?is di/ance ! light rays f ! tree w be ne>ly p>allel1 s t if a l5s hav+ a focal l5g? ( #e feet is fa/5$ 9 any conv5i5t mann] 9 ! wall ( a d>k5$ room ! image w be =m$ #e feet beh9d ! l5s at its pr9cipal focus4 ,if a scre5 ( :ite c>dbo>d be plac$ at ?is po9t we %all f9d t a small b inv]t$ image ( ! tree w be focuss$ ^u x4 ,z ! di/ance ( ! object is #ejjj feet1 & z ! size ( ! receiv$ image is 9 proportion to ?is di/ance divid$ by ! focal l5g? ( ! l5s1 ! image w be z #ejjj _/ #e1 or #ajjj times small] ?an ! object4 ,if n[ ! eye is plac$ six in*es beh9d ! scre5 & ! scre5 remov$1 s t we c view ! small image di/9ctly 9 ! air1 we %all see x ) an app>5t magnitude z mu* great] ?an if ! same small image 7 equally f> (f ) ! tree1 z #f in*es is to #ejjj #acf feet1 t is #aj1jjj times4 ,?us we see t al?\gh ! image produc$ on ! scre5 is #ajjj times less ?an ! tree f "o cause1 yet on acc\nt ( x be+ br\ght ne> to ! eye x is #aj1jjj times great] 9 app>5t magnitude2 !re=e its app>5t magnitude is increas$ z #aj1jjj _/ #ajjj1 or #aj times4 ,?is means t by means ( ! l5s x has actually be5 magnifi$ #aj times4 ,?is magnify+ p[] ( a l5s is always equal to ! focal l5g? divid$ by ! di/ance at :i* we see small objects mo/ di/9ctly1 viz4 #f in*es1 & 9 ! pres5t in/ance is #fj _/ #f1 or #aj times4 ,:5 ! image is receiv$ ^u a scre5 ! app>atus is call$ a cam]a obscura1 b :5 ! eye is us$ & sees ! inv]t$ image 9 ! air1 !n ! app>atus is t]m$ a telescope4 ,! image =m$ by a convex l5s c be reg>d$ z a new object1 & if a second l5s is plac$ beh9d x a second image w be =m$ 9 ! same mann] z if ! fir/ image 7 a real object4 ,a succession ( images c ?us be =m$ by convex l5ses1 ! la/ image be+ always treat$ z a fre% object1 & be+ always an inv]t$ image ( ! "o be=e4 ,f ?is x w be evid5t t additional magnify+ p[] c be giv5 to our telescope ) "o l5s by br++ ! image ne>] ! eye1 & ?is is accompli%$ by plac+ a %ort focus l5s betwe5 ! image & ! eye4 ,by us+ a l5s hav+ a focal l5g? ( #a in*1 & su* a l5s w magnify #f times1 ! total magnify+ p[] ( ! two l5ses w be #aj x #f #fj times1 or #aj times by ! fir/ l5s & #f times by ! second4 ,su* an in/rum5t is kn[n z a comp\nd or a/ronomical telescope1 & ! fir/ l5s is call$ ! object glass & ! second l5s ! magnify+ glass1 or eye-piece4 ,we are n[ 9 a position to und]/& h[ virtual images are =m$1 & ! =mation ( a virtual image by means ( a convex l5s w be readily foll[$ f a #acg /udy ( ,fig4 #gc4 ,let ,l repres5t a d\ble convex l5s1 ) an object1 ,,ab1 plac$ betwe5 x & ! po9t ,f1 :i* is ! pr9cipal focus ( ! l5s4 ,! rays f ! object ,,ab are refract$ on pass+ ?r\gh ! l5s1 & aga9 refract$ on leav+ ! l5s1 s t an image ( ! object is =m$ at ! eye1 ,n4 ,z x is impossible = ! eye to foll[ ! b5t rays f ! object1 a virtual image is =m$ & is se5 at ,a#a;,b#a1 & is really a cont9uation ( ! em]g5t rays4 ,! magnify+ p[] ( su* a l5s may be f\nd by divid+ #f in*es by ! focal l5g? ( ! l5s1 #f in*es be+ ! di/ance at :i* we see small objects mo/ di/9ctly4 ,a l5s hav+ a focal l5g? ( #a_/d in* w\ld magnify #bd times1 & "o ) a focal l5g? ( #a_/ajj? ( an in* #fjj times1 & s on4 ,! magnify+ p[] is great] z ! l5s is m convex & ! object ne> to ! pr9cipal focus4 ,:5 a s+le l5s is appli$ 9 ?is mann] x is t]m$ a s+le microscope1 b :5 m ?an "o l5s is employ$ 9 ord] to increase ! magnify+ p[]1 z 9 ! telescope1 !n ! app>atus is t]m$ a comp\nd microscope4 ,illu/ration3 ,,fig4 #gc4 ,unlike a convex l5s1 :i* c =m bo? real & virtual images1 a concave l5s c only produce a virtual image2 & :ile ! convex l5s =ms an image l>g] #ach ?an ! object1 ! concave l5s =ms an image small] ?an ! object4 ,let ,l1 ,fig4 #gd1 repres5t a d\ble concave l5s1 & ,,ab ! object4 ,! rays f ,,ab on pass+ ?r\gh ! l5s are refract$1 & !y div]ge 9 ! direction ,,rrrr1 z if !y proce$$ f ! po9t ,f1 :i* is ! pr9cipal focus ( ! l5s1 & ! prolongations ( ^! div]g5t rays produce a virtual image1 erect & small] ?an ! object1 at ,a#a;,b#a4 ,! pr9cipal focal di/ance ( concave l5ses is f\nd by exactly ! same rule z t giv5 = convex l5ses4 ,illu/ration3 ,,fig4 #gd4 ,up to ! pres5t we h assum$ t all ! rays ( light pass$ ?r\gh a convex l5s 7 br\ght to a focus at a po9t common to all ! rays1 b ?is is really only ! case ) a l5s ^: ap]ture does n exce$ #ab;deg4 ,by ap]ture is meant ! angle obta9$ by jo9+ ! edges ( a l5s ) ! pr9cipal focus4 ,) l5ses hav+ a l>g] ap]ture ! am\nt ( refraction is great] at ! edges ?an at ! c5tre1 & consequ5tly ! rays t pass ?r\gh ! edges ( ! l5s are br\ght to a focus ne>] ! l5s ?an ! rays t pass ?r\gh ! c5tre4 ,s9ce ?is defect arises f ! sph]ical =m ( ! l5s x is t]m$ sph]ical ab]ration1 & 9 l5ses t #aci are us$ = photographic purposes ! ab]ration has to be v c>efully correct$4 ,! di/ortion ( an image =m$ by a convex l5s is %[n by ! diagram1 ,fig4 #ge4 ,if we receive ! image ^u a %eet ( :ite c>dbo>d plac$ at ,a1 we %all f9d t :ile ! outside edges w be cle> & di/9ct1 ! inside w be blurr$1 ! rev]se be+ ! case :5 ! c>dbo>d is mov$ to ! po9t ,b4 ,illu/ration3 ,,fig4 #ge4 ,illu/ration3 ,,fig4 #gf4 ,illu/ration3 ,,fig4 #gg4 ,ab]ration is to a great ext5t m9imis$ by giv+ to ! l5s a m5iscus in/ead ( a biconvex =m1 b z x is desirable to r$uce ! ab]ration to bel[ once ! #adj ?ickness ( ! l5s1 & z ?is _c be done by a s+le l5s1 we mu/ h rec\rse to two l5ses put toge!r4 ,! ?ickness ( a l5s is ! diff]5ce betwe5 its ?ickness at ! middle & at ! circumf]5ce4 ,9 a d\ble convex l5s ) equal convexities ! ab]ration is #a-fg_/ajj?s ( its ?ickness4 ,9 a plano-convex l5s ) ! plane side turn$ t[>ds p>allel rays ! ab]ration is #d-a_/b times its ?ickness1 b ) ! convex side turn$ t[>ds p>allel rays ! ab]ration is only #a-ag_/ajj?s ( its ?ickness4 ,by mak+ use ( two plano-convex l5ses plac$ toge!r z at ,fig4 #gf1 ! ab]ration w be "o-f\r? ( t ( a s+le l5s1 b ! focal l5g? ( ! l5s1 ,l#a1 mu/ be half z mu* aga9 z t ( ,l4 ,if _! focal l5g?s are equal ! ab]ration w only be a little m ?an half r$uc$4 ,sph]ical ab]ration1 h[ev]1 may be entirely de/roy$ by comb9+ a m5iscus & d\ble convex l5s1 z %[n 9 ,fig4 #gg1 ! convex side be+ turn$ to ! eye :5 us$ z a l5s1 & to p>allel rays :5 us$ z a burn+ glass or cond5s]4 99 99 99 99 99 #ada ,,index ,ab]ration1 #aci sph]ical1 #ach1 #adj ,accuracy ( work+1 #gj1 #gb ,acetyl5e gas lamps1 #abj ,act9ic p[]1 #ajb ,act9ograph1 #aje ,act9omet]1 #abj ,alt]nat+ curr5t1 #hb1 #ajj ,ammonia1 #abc ,angle ( /ylus1 #bd1 #gh ,anil9e dye1 #abc ,arc+1 #bg1 #hb ,arc lamps1 #ae1 #abj1 #aba ,atmosph]ics1 #fa1 #he ,balla/+ resi/ance1 #ajj ,bel91 #dg ,b]no*i1 #g1 #aab sy/em (1 #g1 #cd ,b]zelius1 #aji ,bi*romate ( pota%1 #abj ,blondel's oscillograph1 #dg ,cam]a obscura1 #acf ext5sion1 #aaf1 #aah *oice (1 #aag ,capacity ( cond5s]1 #bd1 #gh electro/atic1 #c1 #e ( cable1 #c ( ,london-,p>is telephone l9e1 #c ,c>bon bisulphide1 #ec ,*>bonelle1 #dh receiv] (1 #dh ,*emical solution1 #ef ,circuit break]1 #gf ,clut*1 details (1 #hh1 #hi1 #ia spr+1 #ga ,coat+ ! metal %eets1 #abj ,coh]]1 #aa1 #dj ,collect+ r+s1 #ia ,comm]cial value ( photo-telegraphy1 #a ,comp5sat+ sel5ium cell1 #aab ,contact break]1 #cg ,copy+ arrangem5ts1 #aah1 #abe ,cross scre51 #ba ,de' ,arsonval galvanomet]1 #dg1 #gc ,decoh]]1 #da ,design ( ma*9es1 #ba ,detectors1 #hc ,develop+ solutions1 #aje1 #abb ,diaphragm1 movem5t (1 #dh1 #eb1 #hd1 #hg ,dipp+ rods1 #ha1 #hc ,di/ance ( transmission1 #cc ,duration ( wave-tra9s1 #bb1 #be ,e>ly exp]im5ts1 #b ,e9?ov5 galvanomet]1 #cb1 #dd1 #de1 #ed1 #aac ,electric clock1 #ic ,electrolytic receiv]1 #d1 #cg1 #ed1 #fa1 #fd ,enl>g+ arrangem5ts1 #abd1 #abe ,exp]im5tal ma*9e1 #bj ,extrane\s light1 #dg ,fa/5+ electrolytic pap]1 #eh ,fatigue ( sel5ium cell1 #fd1 #aad ,fi% glue1 #abj ,flexible c\pl+s1 #gg ,frequ5cy met]1 #fe ,friction brake1 #hh #adb ,high spe$ telegraphy1 #gj ,hughes gov]nor1 #fe ,hughes pr9t+ telegraph1 #fc ,hurt] & ,driffield1 #ajd ,hydrog51 #ajj ,incid5ce1 angle (1 #abg ,in]tia1 #fd1 #fe1 #aaa effects 9 photo-telegraphy1 #aaj me?od ( c\nt]act+1 #ajc1 #aab1 #aac effect ( wave-l5g? ( light on1 #aad ,int5sify+ solution1 #abb ,iso*ronis]1 #hi1 #ia details (1 #ia1 #ib1 #ie ,iso*ronism1 #fd1 #fi1 #gj1 #ga ,ka?ode rays1 #ec ,knuds51 #b app>atus (1 #i ,korn1 #cj1 #cc1 #de1 #fe1 #gb app>atus (1 #ca ,lamps1 col\r$1 #id ,l5ses1 #he1 #abe1 #abh pr9cipal focus (1 #acj conjugate foci (1 #aca action (1 #abi convex1 #abh1 #aca1 #acf concave1 #abh1 #ach focal l5g? (1 #acj1 #ach ap]ture1 #ach m5iscus1 #aci ,light1 diffusion (1 #hf extrane\s1 #hg ,limit ( error 9 syn*ronis+1 #fd ,l9e balanc]1 #c ,l9e scre5s1 #i1 #ae1 #af1 #aaf mak+1 #aaf ,magnify+ p[]1 #acf1 #acg ,m>coni valve1 #dd1 #ed coh]]1 #dj ,me*anical in]tia1 #cc ,m]cury break1 #ha *urn+ (1 #hb conta9]s1 #hb ,m]cury jet int]rupt]1 #bi ,metal pr9ts1 #ae1 #ah1 #cb1 #ei1 #fd1 #ie1 #abj1 #abd dry+ !1 #aba1 #abc exposure (1 #aba size (1 #bb1 #bd1 #ge1 #gg press+ !1 #bb ,microscope1 #aca1 #acg ,milit>y uses1 #ce ,mirror galvanomet]1 #i1 #db1 #gc ,mirror1 #dg1 #ea ,morse code1 #ce ,motor spe$1 #hi1 #ie driv+1 #ia1 #ic1 #ie clockwork1 #fc electric1 #fc ,n]n/ lamps1 #dc1 #he1 #ih heat] (1 #ii filam5t (1 #ii pr9ciple (1 #ih resi/ance (1 #ajj effici5cy (1 #aja1 #ajb ov]runn+1 #aja ,nicol prism1 #ec ,pap] = electrolytic receiv]1 #ef ,p>abolic reflector1 #h ,p]iod ( galvanomet]1 #dc1 #dd1 #df ,photographic ,daily ,companion1 #aje ,photographic films1 #dj1 #dc1 #de1 #ec1 #ed1 #fb1 #he1 #hf1 #ih process1 #cg *emical in]tia1 #ajc exposure (1 #ajc1 #ajg spe$ (1 #ajd1 #aje plates1 or?o*romatic1 #ei plates1 #abj ,po9ts to be obs]v$ 9 prep>+ metal pr9ts1 #abc ,p\ls5 ,company1 #cb1 #dg arc1 #ca ,prep>+ sel5ium1 #aji photographs = transmitt+1 #ae1 #aae sket*es on metal foil1 #abd ,prism1 #abh action (1 #abi ,process plates1 #abb ,pr(essor ,n]n/1 #ih #adc ,radio-photography1 requirem5ts (1 #gd ,refraction1 angle (1 #abg ,refractive p[]1 #abg ,relay1 #be1 #ci1 #di1 #ec1 #ee1 #fj1 #ge diff]5tial1 #gi pol>is$1 #ig work+ spe$ (1 #bf1 #ge ,reproduc+ = newspap]s1 #fj ,resi/ance ( sel5ium1 #aji ( sel5ium cells1 #aaj regulat+1 #aac ,ret>dation ( curr5t1 #f ,ret\*+1 #fb ,rot>y sp>k-gap1 #bh ,sel5ium1 #ii cells1 #h1 #cd1 #ee1 #fj1 #fd1 #aji1 #aaj ma*9es1 #de ,self-induction1 #bd1 #gh ,s5sitiv5ess ( sel5ium cells1 #aac ratio (1 #aac ,silv]$ qu>tz ?reads1 #dd1 #df ,sp>k-gap1 #bg ,spe$ regulator1 #fh adju/m5ts (1 #fi ,spr+ clut*1 #ga ,/>t+ position ( ma*9es1 #ih ,/r+ galvanomet]1 #cb ,/ylus1 #ag1 #ah1 #eg1 #fa1 #gh1 #ie1 #ajc sp>k+ at1 #bd ,/ylus1 angle (1 #bd1 #gh defects (1 #eg ,subm>9e cable1 #d ,syn*ronism1 #aa1 #bj1 #cf1 #fd1 #fi1 #ga ,telephograph1 #gd advantages (1 #gf me?od ( work+1 #if ,telephone receiv]1 #hc1 #he diaphragm1 #dh improv$1 #ea ,telephone relay1 #dh1 #ej1 #eb1 #hc1 #he1 #ig ,telescope1 #aca1 #acf ,!rmodetector1 #cb ,t[1 #hh ,transmission1 di/ance (1 #ce1 #gb spe$ (1 #be1 #ce1 #ge ,vibration1 natural p]iod (1 #ci ,watk9s1 #aje p[] numb]1 #aje ,waves1 damp$1 #cj undamp$1 #cj1 #ca ,:eat/one bridge1 #aac ,wireless app>atus1 #ac ,wireless ,_w1 #ca ,wynne1 #aje ,zirconia1 #ii ,,! 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,,elem5t>y ,,pr9ciples ,,( ,,wireless ,,telegraphy4 ,by ,r4 ,d4 ,,bangay4 ,9 two ,p>ts4 ,price #c,s4 ea*4 7,,po/age #d;,d47 ,or 9 "o ,volume1 price #g,s4 net4 7,,po/age #f;,d47 ,us$ by ,h4,m4 ,gov]nm5t = in/ructional purposes4 ,,pr9cipios ,,elem5t ,,ales ,,de ,,telegrafia ,,s9 ,,hilos4 ,por ,r4 ,d4 ,,bangay4 7,p>tes #a;a y #b;a en un ,volum547 ,,precio3 ,espana1 #aj pesetas2 ,franqueo1 #a peseta extra4 ,am]ica ,lat9a1 #b4be1 oro1 neto2 ,franqueo1 #be c5ts extra4 7,great ,brita91 #i,s42 ,,po/age #f;,d47 ,,pr9cipes ,,elem5taires ,,de ,,telegraphie ,,sans ,,fil4 ,p> ,r4 ,d4 ,,bangay4 7,great ,brita91 #i,s42 ,,po/age #f;,d47 ,,magnetism ,,& ,,electricity ,,= ,,home ,,/udy4 ,by ,h4 ,e4 ,,p5rose4 ,cr[n #hvo4 ,ov] #ejj pages4 ,price #e,s4 net1 7,,po/age #f;,d47 ,conta9s fifty complete lessons4 ,,! ,,calculation ,,& ,,measurem5t ,,( ,,inductance ,,& ,,capacity4 ,by ,w4 ,h4 ,,nottage1 ,b4,sc4 ,invaluable to all engag$ 9 ,telegraph ,eng9e]+4 ,indisp5sable to ! ,wireless ,eng9e]1 ,/ud5t & ,exp]im5t]4 ,price #c,s4 #f;,d4 net4 7,,po/age #e;,d47 ,a ,,%ort ,,c\rse ,,9 ,,elem5t>y ,,ma!matics ,,& ,,_! ,,application ,,to ,,wireless ,,telegraphy4 ,by ,s4 ,j4 ,,willis4 ,to ,/ud5ts 9 ,wireless ,telegraphy1 z well z ^? engag$ 9 ! practical application ( ?is ,sci5ce1 ?is book %\ld prove ( real value4 ,price #c,s4 #f;,d4 net4 7,,po/age #f;,d47 ,,! ,,m>coni ,,(ficial ,,gramophone ,,records4 ,= self-tuition 9 receiv+ ,morse ,signals4 ,price #d,s4 ea*1 d\ble-sid$4 7,,po/age #i;,d47 ,set ( ,six ,records1 #bd,s4 po/ ,,free4 ,,! ,,ma9t5ance ,,( ,,wireless ,,telegraph ,,app>atus4 ,by ,p4 ,w4 ,,h>ris4 ,an up-to-date ,manual1 full ( practical h9ts & explanations4 ,diagrams ( all %ip in/allations1 f #a_/d kw4 to #e kw4 ,price #b,s4 #f;,d4 net4 7,,po/age #d;,d47 ,,diction>y ,,( ,,te*nical ,,t]ms ,,us$ ,,9 ,,wireless ,,telegraphy4 ,by ,,h>old ,,w>d4 ,ve/ ,pocket ,edition4 #bnd ,edition1 revis$ & enl>g$4 ,conta9s ov] #aejj def9itions4 ,price #b,s4 #f;,d4 net4 7,,po/age #b;,d47 ,,armature ,,model ,,= #a-a_/b ,,kw4 ,,rot>y ,,conv]t]4 ,%[s e ,w9d+ ( ! ,conv]t] ,armature f />t to f9i%4 ,price #a,s4 net4 7,,po/age #c;,d47 ,,morse ,,made ,,easy4 ,by ,a4 ,l4 ,,rye4 ,l95 back$1 = rapidly le>n+ ! ,morse ,code4 ,price #c;,d4 net1 or po/ free #c-a_/b;,d4 ,,morse ,,code ,,c>d4 ,conta9s full alphabet1 ) punctuation m>ks1 figures1 abbreviations & contractions4 ,price #b;,d41 po/ free4 ,,practical ,,wireless ,,telegraphy4 ,by ,e4 ,e4 ,,bu*]4 #ceb pages4 #cdj ,illu/rations4 ,price #ab,s4 #f;,d4 7,,po/age #f;,d47 ,,radio-,,telephony4 ,by ,,alfr$ ,n4 ,,goldsmi?1 ,ph4,d4 #bef pages4 #bbf ,illu/rations4 ,price #ae,s4 net4 7,,po/age #f;,d47 ,,/&>d ,,tables ,,& ,,equations ,,9 ,,radio-,,telegraphy4 ,by ,,b]tram ,,hoyle1 ,m4,sc4,te*41 ,a4,m4,i4,e4,e4 #aei pages4 ,price #i,s4 net4 7,,po/age #f;,d47 ,,vacuum ,,tubes ,,9 ,,wireless ,,communication4 ,by ,e4 ,e4 ,,bu*]4 ,deals ) ! ,oscillation ,valve4 #agh pages4 #acj ,illu/rations4 ,price #ab,s4 #f;,d4 net4 7,,po/age #f;,d47 ,,useful ,,notes ,,on ,,wireless ,,telegraphy4 7,/ud5ts' ,libr>y47 ,by ,,h>old ,e4 ,,p5rose4 ,price #a,s4 #d;,d4 net ea*4 7,,po/age #b;,d47 ,book ,i4 ,,direct ,,curr5t4 ,book ,,ii4 ,,alt]nat+ ,,curr5t4 ,book ,,iii4 ,,high-,,frequ5cy ,,curr5t ,,& ,,wave ,,production4 ,book ,,iv4 ,,! #a-a_/b ,,kw4 ,,%ip ,,set4 ,book ,v4 ,,! ,,oscillation ,,valve4 ,,! ,,oscillation ,,valve3 ,,! ,,elem5t>y ,,pr9ciples ,,( ,,its ,,application ,,to ,,wireless ,,telegraphy4 ,by ,r4 ,d4 ,,bangay4 #bae pages4 ,price #e,s4 7,,po/age #c;,d47 ,,! ,,!rmionic ,,valve ,,& ,,its ,,developm5ts ,,9 ,,radio-,,telegraphy ,,& ,,telephony4 ,by ,dr4 ,j4 ,a4 ,,flem+1 ,m4,a41 ,d4,sc41 ,f4,r4,s41 ,m4,in/4,e4,e41 etc4 #bgi pages4 ,price #ae,s4 7,,po/age #f;,d47 ,,alt]nat+ ,,curr5t ,,"w3 ,,an ,,outl9e ,,= ,,/ud5ts ,,( ,,wireless ,,telegraphy4 ,by ,a4 ,,%ore4 #afc pages4 ,price #c,s4 #f;,d4 7,,po/age #d;,d47 ,,telephony ,,)\t ,,wires4 ,by ,,philip ,r4 ,,c\rsey1 ,b4,sc41 ,a4,m4,i4,e4,e41 ,f4,p4,s4,l4 #dad pages4 ,price #ae,s4 7,,po/age #f;,d47 ,,! ,,wireless ,,_w4 ,a ,mon?ly ,magaz9e devot$ to ,wireless ,telegraphy & ,telephony4 ,price #i;,d4 7,,po/age #c;,d47 ,annual ,subscription1 #aa,s4 po/ free4 ,,! ,,radio ,,review4 ,a ,mon?ly ,record ( ,sci5tific ,progress 9 ,radio-telegraphy & ,telephony4 ,price #b,s4 #f;,d4 7,,po/age #c;,d47 ,annual ,subscription1 #cj,s4 po/ free4 ,,conque/4 ,a ,popul> ,illu/rat$ ,mon?ly ,magaz9e deal+ ) ,sci5ce1 ,indu/ry & ,inv5tion4 ,price #a,s4 7,,po/age #c;,d47 ,annual ,subscription1 #ae,s4 po/ free4 ,,cont9u\s ,,wave ,,wireless ,,telegraphy4 ,"p ,i4 ,by ,dr4 ,w4 ,h4 ,,eccles1 ,d4,sc41 ,a4,r4,c4,s41 ,m4,i4,e4,e4 ,9 ! ,press4 99 99 99 99 99 ,,complete ,,catalogue ,,po/ ,,free4 99 99 99 99 99 ,notes #a ,^! measurem5ts only apply to a s+le l9e4 ,:]e a d\ble l9e is employ$ ! capacity is halv$4 #b ,see ,app5dix ,a4 #c ,see ,app5dix ,b4 #d ,9 wireless telegraphy arc+ is pr9cipally caus$ by ! cont9uation ( ! supply curr5t 9 ! sp>k-gap aft] ! capacity has be5 *>g$ to a pot5tial suffici5t to break d[n ! insulation ( ! gap4 #e ,see ,*apt] ,v4 #f ,n]n/ lamps are ! be/ to use1 z !y produce abundantly ! blue & violet rays :i* h ! greate/ *emical effect ^u a photographic film4 ,c>bon filam5t lamps are v poor 9 ?is respect4 #g ,a description ( ! app>atus requir$ w be f\nd 9 ,ganot's ,physics4 #h ,great c>e mu/ be ex]cis$ 9 us+ ?is solution1 z x is exce$+ly poison\s4 #i ,two clocks w\ld iso*ronise if _! h&s travell$ at precisely ! same rate r\nd ! dials1 b w\ld n syn*ronise unless !y bo? regi/]$ ! same "t z well4 #aj ,l9e scre5s c be obta9$ f ,messrs4 ,p5rose1 #aji ,f>r+don ,/reet1 ,london2 or ,messrs4 ,fall[field1 #adf ,*>+ ,cross ,road1 ,london4