,?is file 0 produc$ f page images at ,google ,books4 ,transcrib]'s ,note ,?is book 0 transcrib$ f scans ( ! orig9al f\nd at ,google ,books4 ,i h rotat$ "s images4 ,! m complex tables are treat$ z images4 ,illu/ration3 ,a ,,boy',s ,,wireless ,,outfit ,,made ,,up ,,( ,,! ,,app>atus ,,describ$ ,,9 ,,*apt] ,,xiv4 ,,! ,,junior ,,dynamo ,,& ,a ,,coh]] ,,outfit ,,c ,,be ,,se5 ,,on ,,! ,,l[] ,,"p ,,( ,,! ,,table4 ,! ,boy ,electrician ,practical ,plans = ,electrical ,app>atus = "w & play1 ) an explanation ,( ! pr9ciples ( e-day electricity4 ,by ,,alfr$ ,p ,,morgan ,) illu/rations by ! au?or ,,bo/on ,,lo?rop1 ,,lee ,,%ep>d ,,co4 ,copyright1 #aiac1 by ,lo?rop1 ,lee ,%ep>d ,co4 ,ent]$ at ,/ation]s' ,hall1 ,london ,publi%$ ,july1 #aiad ,all rights res]v$ ,,! ,,boy ,,electrician ,,norwood ,,press ,b]wick ,smi? ,co4 ,norwood1 ,mass4 ,u4,s4,a4 ,,to ,,! ,,self-,,reliant 99,,boys ,,( ,,am]ica199 ,,our ,,future ,,eng9e]s ,,& ,,sci5ti/s1 ,,?an ,,:om ,,none ,,9 ,,! ,,:ole ,,_w ,,are ,,bett] ,,able ,,to ,,"w ,,out ,,& ,,solve ,,! ,,problems ,,t ,,ev] ,,confront ,,"y ,,manhood1 ,,?is ,,book ,,is ,,cordially ,,d$icat$4 ,,! ,,boy ,,electrician ,,introduction ,once ^u a "t1 & ?is is a true tale1 a boy _h a :ole railroad sy/em = a toy4 ,! tra9 ran automatically1 propell$ by t9y electric motors1 ! signals w5t up & d[n1 ! /ation 0 rea*$1 a bell rang1 ! tra9 mov$ on aga9 & 0 (f on its j\rney ar\nd _m feet ( track to come back ov] ! old r\te4 ,! boy view$ 8 gift ) raptur$ eyes1 & !n 8 face *ang$ & he cri$ out 9 ! bitt]ness ( 8 disappo9tm5t3 ,b :at d ,i d8 ,! toy 0 s elaborate t ! boy 0 left entirely out ( ! play4 ,( c\rse he did n l x4 ,8 cry tells a long /ory4 ,! prime in/9ct ( almo/ any boy at play is to make & to create4 ,he w make ?+s ( su* mat]ials z he has at h&1 & use ! :ole =ce ( dream & fancy to create some?+ out ( no?+4 ,! five-ye>-old w lay half a doz5 wood5 blocks toge!r ) a spool on "o end & tell y x is a /eam tra94 ,& x is4 ,he has bo? made & creat$ an eng9e1 :i* he sees b :i* y don't1 = ! blocks & spool are only a symbol ( 8 creation4 ,give 8 old] bro!r a telephone receiv]1 "s wire & bits ( brass1 & he w make a wireless telegraph outfit & li/5 to a /eam%ip hundr$s ( miles away spell out its message to ! %ore4 ,! wireless outfit is n a symbol1 b some?+ t y c bo? he> & see 9 op]ation ev5 ?\gh y may n und]/& ! :isp]+ ( ! dots & da%es4 ,& z soon z ! my/]y ( ?is mod]n wond] m firmly grips y\r imag9ation1 y p]haps may come to realize t we are liv+ m & m 9 ! age ( electricity & me*anism4 ,electricity propels our tra9s1 lights our h\ses & /reets1 makes our clo!s1 cures our ills1 w>ms u1 cooks = u & p]=ms an innum]able numb] ( o!r tasks at ! turn+ ( a little swit*4 ,a m]e li/ is impossible4 ,almo/ e boy exp]im5ts at "o "t or ano!r ) electricity & electrical app>atus4 ,x is my purpose 9 writ+ ?is book to op5 ?is wond]l& ( sci5ce & pres5t x 9 a mann] :i* c be readily und]/ood1 & :]e9 a boy may d some?+4 ,( c\rse !re are o!r books ) ! same purport1 b !y d n accompli% _! end4 ,!y are n practical4 ,i c say ?is because z a boy ,i h read & /udi$ !m & !y h fall5 f> %ort ( tea*+ me or my companions ! ?+s t we 7 seek+ to le>n4 ,if !y h fail$ 9 ?is respect1 !y h done s p]haps n ?r\gh any inability ( ! au?or1 b f ! fact t !y h n be5 writt5 f ! boy's /&po9t4 ,!y tell :at ! au?or ?\ght a boy ought to "k b n :at he really does want to "k4 ,! app>atus describ$ !re9 is = ! mo/ "p imag9>y4 ,! au?or ?\ght x might be possible = a boy to build motors1 telegraph in/rum5ts1 etc41 out ( old bolts & t9 cans1 b he nev] tri$ to d s himself4 ,! app>atus & exp]im5ts t ,i h describ$ h be5 con/ruct$ & c>ri$ out by boys4 ,_! problems & _! que/ions h be5 /udi$ & rem$i$4 ,i h tri$ to pres5t practical matt] consid]$ :olly f a boy's /&po9t1 & to %[ ! "y exp]im5t] j :at he c d ) ! tools & mat]ials 9 8 possession or n h>d to obta94 ,to ! boy int]e/$ 9 sci5ce1 a wide field is op54 ,!re is no bett] education = any boy ?an to beg9 at ! bottom ( ! ladd] & climb ! rungs ( sci5tific k1 /ep by /ep4 ,x equips him ) in=mation :i* may prove ( ine/imable wor? 9 an opportune mom5t4 ,!re is an apt illu/ration 9 ! boy :o wat*$ 8 "m empty a jug ( molasses into a b[l & replace ! cork4 ,8 "m told him n to di/urb ! jug1 z x 0 empty4 ,he p]si/$1 h[ev]1 & turn$ ! jug upside d[n4 ,no m molasses came1 b out crawl$ a fly4 ,new developm5ts 9 sci5ce w nev] cease4 ,inv5tion w foll[ inv5tion4 ,! unexpect$ is (t5 a valuable clue4 ,! ,edisons & ,teslas ( to-day h n discov]$ ev]y?+4 ,!re is a fly 9 ! molasses1 to be _h by p]si/5ce4 ,inspiration is b a />t+-po9t4 ,success means "w1 days1 nights1 weeks1 & ye>s4 ,!re c be no boy :o w foll[ exactly any directions giv5 to him1 or d exactly z he is told1 ( 8 own free w4 ,he w bolt at ! fir/ opportunity4 ,if =c$ or oblig$ to d z he is direct$1 8 action w be accompani$ by _m a :y8 ,!re=e 9 pres5t+ ! foll[+ *apt]s ,i h n only told h[ to make ! v>i\s motors1 telegraphs1 telephones1 radio receiv]s1 etc4 b h also expla9$ ! pr9ciples ( electricity ^u :i* !y dep5d = _! op]ation1 & h[ ! same ?+ is accompli%$ 9 ! e-day _w4 ,9 giv+ directions or (f]+ cautions1 ,i h usually /at$ ! reason = s do+1 9 ! hope t ?is in=mation may be a /imulant to ! imag9ation ( ! "y exp]im5t] & a useful guide 9 enabl+ him to proce$ along "s ( ! /range roads on :i* he w surely g4 ,,alfr$ ,p4 ,,morgan ,,upp] ,,montclair1 ,n4 ,j4 ,,! ,,boy ,,electrician 4444444444444444444444444444444444444444 4444444 ,,introduction 4444444444444444444444444444444444444444 444444444444 ,,*apt] ,i ,,magnets ,,& ,,magnetism 444444444444444444444444444444444 ,,*apt] ,,ii ,,/atic ,,electricity 44444444444444444444444444444444444 ,,*apt] ,,iii ,,/atic ,,electric ,,ma*9es 4444444444444444444444444444 ,,*apt] ,,iv ,,cells ,,& ,,batt]ies 4444444444444444444444444444444444 ,,*apt] ,v ,,electro-,,magnetism ,,& ,,magnetic ,,induction 44444444444444 ,,*apt] ,,vi ,,electrical ,,units 4444444444444444444444444444444444444 ,,*apt] ,,vii ,,electrical ,,appurt5ances 4444444444444444444444444444 ,,*apt] ,,viii ,,electrical ,,measur+ ,,in/rum5ts 4444444444444444444 ,,*apt] ,,ix ,,bells1 ,,al>ms1 ,,& ,,annunciators 4444444444444444444444 ,,*apt] ,x ,,electric ,,telegraphs 44444444444444444444444444444444444 ,,*apt] ,,xi ,,microphones ,,& ,,telephones 444444444444444444444444444 ,,*apt] ,,xii ,,induction ,,coils 4444444444444444444444444444444444444 ,,*apt] ,,xiii ,,trans=m]s 444444444444444444444444444444444444444 ,,*apt] ,,viv ,,wireless ,,telegraphy 444444444444444444444444444444444 ,,*apt] ,,xv ,a ,,wireless ,,telephone 444444444444444444444444444444444 ,,*apt] ,,xvi ,,electric ,,motors 4444444444444444444444444444444444444 ,,*apt] ,,xvii ,,dynamos 4444444444444444444444444444444444444444 4444 ,,*apt] ,,xviii ,,an ,,electric ,,railway 4444444444444444444444444444444 ,,*apt] ,,xix ,,m9iature ,,light+ 4444444444444444444444444444444444 ,,*apt] ,,xx ,,miscellane\s ,,electrical ,,app>atus 4444444444444444444 ,! ,full ,project ,gut5b]g ,lic5se 44444444444444444444444444444444 ,section #a4 ,g5]al ,t]ms ( ,use ,r$i/ribut+ ,project ,gut5b]g electronic works 4444444444444444444444444444444444444 ,section #b4 ,in=mation ab\t ! ,mission ( ,project ,gut5b]g 44 ,section #c4 ,in=mation ab\t ! ,project ,gut5b]g ,lit]>y ,ar*ive ,f\ndation 4444444444444444444444444444444444444444 444444 ,section #d4 ,in=mation ab\t ,donations to ! ,project ,gut5b]g ,lit]>y ,ar*ive ,f\ndation 4444444444444444444444444444444444444 ,section #e4 ,g5]al ,in=mation ,ab\t ,project ,gut5b]g electronic works4 4444444444444444444444444444444444444444 444444444444444444 ,a ,,boy',s ,,wireless ,,outfit ,,made ,,up ,,( ,,! ,,app>atus ,,describ$ ,,9 ,,*apt] ,,xiv4 ,,! ,,junior ,,dynamo ,,& ,a ,,coh]] ,,outfit ,,c ,,be ,,se5 ,,on ,,! ,,l[] ,,"p ,,( ,,! ,,table4 44444444444444444444444444444444444444 ,fig4 #a4--,! ,c>d ( a ,m>9]'s ,compass1 ,%[+ ! ,po9ts4 4444 ,fig4 #b4--;,a ,b> ,magnet 4444444444444444444444444444444444444444 444444 ,fig4 #c4--;,a ,horse%oe ,magnet 4444444444444444444444444444444444444444 ,fig4 #d4--;,a ,magnetiz$ ,ne$le & a ,b> ,magnet :i* h be5 dipp$ 9 ,iron ,fil+s4 4444444444444444444444444444444444444444 4444444444 ,fig4 #e4--,! ,lift+ ,p[] ( a ,b> ,magnet4 ,x mu/ be br\ght clos] to ! nails ?an ! tacks because !y are heavi]4 44444 ,fig4 #f4--;,a ,simple ,compass4 4444444444444444444444444444444444444444 4 ,fig4 #g4--,sev]al ,diff]5t ,me?ods ( ,mak+ a ,simple ,compass4 44444 ,fig4 #h4--,! ,attraction ( an ,iron ,nail ?r\gh ,glass4 44444444444 ,fig4 #i4--;,a ,magnetic ,*a94 4444444444444444444444444444444444444444 4 ,fig4 #aj4--;,an ,exp]im5t ,illu/rat+ t ,l ,poles ,repel ,ea* ,o!r & ,unlike ,poles ,attract4 4444444444444444444444444444444444444444 4 ,fig4 #aa4--;,a ,magnetic ,boat4 4444444444444444444444444444444444444444 4 ,fig4 #ab4--,repulsion betwe5 ,simil> ,poles1 ,%[n by ,float+ ,ne$les4 ,fig4 #ac4--;,a ,magnetic ,phantom1 ,%[+ ! ,field ( ,=ce ab\t a ,magnet4 4444444444444444444444444444444444444444 4444444444444444444 ,fig4 #ad4--,magnetic ,phantom %[+ ! ,l9es ( ,=ce ab\t a ,horse%oe ,magnet4 4444444444444444444444444444444444444444 444444444 ,fig4 #ae4--,l9es ( ,=ce betwe5 ,l & ,unlike ,poles4 444444444444 ,fig4 #af4--;,a ,simple ,dipp+ ,ne$le4 444444444444444444444444444444444 ,fig4 #ag4--;,an ,electrifi$ ,glass ,rod w ,attract ,small ,bits ( ,pap]4 ,f ! au?or's ,wireless ,telegraphy & ,telephony by p]mission4 99,a ,d\ble ,lightn+ ,dis*>ge f a ,cl\d to ! ,e>?499 4444444444444444444444444444444444444444 4444444444444444444 ,fig4 #ai4--;,a ,piece ( ,dry ,writ+-,pap] may be ,electrifi$ by ,rubb+4 ,fig4 #bj4--;,a ,surprise = ! ,cat4 4444444444444444444444444444444444 ,fig4 #ba4--;,a ,pap] ,electroscope4 444444444444444444444444444444444444 ,fig4 #bb4--;,a ,pi?-,ball ,electroscope4 44444444444444444444444444444444 ,fig4 #bc4--;,a ,d\ble ,pi?-,ball ,electroscope4 4444444444444444444444444 ,fig4 #bd4--;,a ,gold-,leaf ,electroscope4 44444444444444444444444444444444 ,fig4 #be4--,me?od ( ,susp5d+ an ,electrifi$ ,rod 9 a ,wire ,/irrup4 ,fig4 #bf4--,simil>ly ,electrifi$ ,bodies ,repel ,ea* ,o!r4 ,dissimil>ly ,electrifi$ ,ones ,attract ,ea* ,o!r4 444444444444444444444444444444 ,fig4 #bg4--,! ,electrophor\s 444444444444444444444444444444444444444 ,fig4 #bh4--;,an ,electric ,frog-,pond4 44444444444444444444444444444444444 ,fig4 #bi4--;,front ,view ( a ,cyl9d] ,electric ,ma*9e4 444444444444444 ,fig4 #cj4--,me?od ( ,f9d+ ! ,c5t] ( a ,circle4 4444444444444444 ,fig4 #ca4--,! ,rubb]4 4444444444444444444444444444444444444444 4444 ,fig4 #cb4--,! ,prime ,conductor or ,collector4 444444444444444444444444 ,fig4 #cc4--,! ,complete ,cyl9d] ,electric ,ma*9e4 444444444444444444 ,fig4 #cd4--,pap] ,patt]n = lay+ out ! ,plates4 44444444444444444 ,fig4 #ce4--,plate ) ,sectors 9 ,position1 & a ,patt]n = ! ,sectors4 4444444444444444444444444444444444444444 444444444444444444 ,fig4 #cf4--;,a ,side ,view ( "o ( ! ,bosses1 %[+ ! ,brass ,bu%+ us$4 4444444444444444444444444444444444444444 444444444444444444444 ,fig4 #cg4--,! ,frame4 4444444444444444444444444444444444444444 4444444 ,fig4 #ch4--,! ,upright4 4444444444444444444444444444444444444444 44444 ,fig4 #ci4--,! ,driv+-,:eels & ,axle4 44444444444444444444444444444 ,fig4 #dj--,! ,boss & ,axle4 ,= sake ( cle>ness1 ! ,plate is n %[n4 4444444444444444444444444444444444444444 44444444444444444444 ,fig4 #da--,%[+ h[ ! ,ball1 ,comb1 etc41 are m\nt$ on ! ,glass ,rod4 4444444444444444444444444444444444444444 4444444444444444444444 ,fig4 #db4--;,a ,comb or ,collector4 4444444444444444444444444444444444444 ,fig4 #dc4--,%[+ h[ ! ,t9sel ,bru%es are arrang$ on ! ,neutraliz] ,rods4 4444444444444444444444444444444444444444 4444444 ,fig4 #dd4--,! ,complete ,wim%ur/ ,electric ,ma*9e4 ,b ,b ,b ,b1 ,bru%es4 ,c ,c1 ,combs4 ,d ,b1 ,dis*>ge ,ball4 ,i ,i1 ,glass ,rods4 ,h1 ,h&le4 ,q ,q1 ,quadrant ,rods4 ,s ,s ,s ,s ,s1 ,sectors4 ,s ,g1 ,sp>k-,gap4 ,p ,p1 ,driv+-,:eels4 ,= ! sake ( cle>ness1 sev]al ( ! sectors are n %[n4 44444444444444444444444444444 ,fig4 #de4--,! ,leyd5 ,j>4 4444444444444444444444444444444444444444 44 ,fig4 #df4--;,a ,wood5 ,mort> = ,ignit+ ,gunp[d]4 444444444444444444 ,fig4 #dg4--;,an ,electric ,umbrella4 444444444444444444444444444444444444 ,fig4 #dh4--;,a ,lightn+ ,bo>d4 444444444444444444444444444444444444444 ,fig4 #di4--;,an ,electric ,dance4 444444444444444444444444444444444444444 ,fig4 #ej4--;,an ,electric ,:irl4 444444444444444444444444444444444444444 ,fig4 #ea4--,li*t5b]g's ,figures4 44444444444444444444444444444444444 ,fig4 #eb4--,! ,voltaic ,cell4 4444444444444444444444444444444444444444 ,fig4 #ec4--,! ,elem5ts ( ,simple ,voltaic ,cell4 444444444444444444444 ,fig4 #ed4--;,a ,home-,made ,voltaic ,cell4 44444444444444444444444444444444 ,fig4 #ee4--;,c>bon-,cyl9d] ,cell1 & ,cyl9d]4 4444444444444444444444 ,fig4 #ef4--;,a ,leclan*e ,cell1 %[+ ! ,por\s ,cup4 4444444444444444 ,fig4 #eg4--;,a ,dry ,cell4 4444444444444444444444444444444444444444 444444 ,fig4 #eh4--,! ,diff]5t ,op]ations involv$ 9 ,mak+ a ,dry ,cell4 44 ,fig4 #ei4--;,a ,z9c-,c>bon ,elem5t1 made f ,heavy plates4 44444444444 ,fig4 #fj4--;,a ,me?od ( mak+ a ,cell ,elem5t f ,c>bon ,rods4 444444 ,fig4 #fa4 ,an ,elem5t made f two ,c>bon ,plates & a ,z9c ,rod4 444 ,fig4 #fb4 ,a ,me?od ( ,m\nt+ f\r ,c>bon ,plates4 44444444444444444 ,fig4 #fc4--;,a ,batt]y ,elem5t arrang$ = ?ree ,cells4 44444444444444 ,fig4 #fd4--;,a ,plunge ,batt]y1 ) ,w9dlass4 4444444444444444444444444 ,fig4 #fe4--;,a ,plunge ,batt]y adapt$ to a ,set ( ,elem5ts1 z %[n 9 ,figure #fc4 ,!y may be lift$ out & plac$ on ! ,arms to dra94 ,fig4 #ff4--;,an ,edison-,lal&e ,cell4 4444444444444444444444444444444444 ,fig4 #fg4--;,a ,tomato-,c ,cell2 ,sectional ,view4 44444444444444444444444 ,fig4 #fh4--,! ,tomato-,c ,cell ,complete4 4444444444444444444444444444 ,fig4 #fi4--,two ,me?ods ( ,connect+ ,cells s z to obta9 ,diff]5t ,voltage & ,amp]age ,values4 44444444444444444444444444444444444444 ,fig4 #gj4--,small ,/orage ,cells4 4444444444444444444444444444444444444 ,fig4 #ga4--;,h[ to make ! ,plates = a ,/orage ,cell4 444444444444444 ,fig4 #gb4--,! ,wood ,sep>ator4 44444444444444444444444444444444444444 ,fig4 #gc4--,! ,complete ,elem5t = a ,/orage ,cell4 44444444444444444 ,fig4 #gd4--;,a ,batt]y ( ,home-,made ,/orage ,cells4 44444444444444444444 ,fig4 #ge4--;,gravity ,cells4 ,^! consi/ ( z9c & copp] elem5ts1 imm]s$ 9 a z9c-copp] sulphate solution4 ,!y _c be easily made1 & are be/ pur*as$4 ,! illu/ration also %[s ! />-%ap$ copp] & cr[foot z9c elem5t us$ 9 a gravity cell4 4444444444444444444444444444444444444444 444444444444444444444 ,fig4 #gf4--;,a ,curr5t ( ,electricity fl[+ ?r\gh a ,wire w deflect a ,compass ,ne$le4 4444444444444444444444444444444444444444 4 ,fig4 #gg4--;,if a ,loop ( ,wire is =m$ ab\t a ,compass ,ne$le1 ! ,deflection w be great]4 444444444444444444444444444444444444444 ,fig4 #gh4--;,iron ,fil+s clu/]$ on a ,wire c>ry+ a ,curr5t ( ,electricity4 4444444444444444444444444444444444444444 44444444444444 ,fig4 #gi4--,magnetic ,phantom =m$ ab\t a ,wire c>ry+ a ,curr5t ( ,electricity4 4444444444444444444444444444444444444444 44444444444444 ,fig4 #hj4--,magnetic ,phantom =m$ ab\t sev]al ,turns ( wire4 44444 ,fig4 #ha4--,pap] ,tube wrapp$ ) ,wire = ,exp]im5tal ,purposes4 44 ,fig4 #hb4--,%[+ h[ ! ,l9es ( ,=ce ,leak at ! sides ( ! coil1 f a ,coil ( ,wire1 & h[ !y are conc5trat$ by an ,iron ,core4 4444444444444444444444444444444444444444 444444444444444444444 ,fig4 #hc4--,! ,pr9ciple ( an ,electro-,magnet4 4444444444444444444444 ,fig4 #hd4--;if y wrap "s insulat$ ,wire ar\nd an ,ord9>y ,nail & connect x to a ,batt]y1 x w become an ,electro-,magnet4 44444444 ,fig4 #he4--;,if y w9d ! ,wire ar\nd a small ,pap] ,tube into :i* a ,nail w slide easily1 ! ,coil w draw ! ,nail 9 :5 ! ,curr5t is turn$ on4 4444444444444444444444444444444444444444 44444 ,by p]mission1 f ,sol5oids by ,c4 ,r4 ,und]hill4 ,lift+-,magnets ( ! type kn[n z ,plate1 ,billet1 & ,+ot ,magnets4 4444444444444444444444444444444444444444 444444444444444444 ,fig4 #hf4--,%[+ h[ a ,curr5t ( ,electricity may be induc$ by a ,b> ,magnet & a ,coil4 4444444444444444444444444444444444444444 4444 ,fig4 #hg4--;,a ,horse%oe ,magnet & a ,coil arrang$ to produce ,electric ,curr5ts by ,induction4 4444444444444444444444444444444444444444 44 ,fig4 #hh4--;,graphic ,repres5tation ( a ,direct & an ,alt]nat+ ,curr5t4 4444444444444444444444444444444444444444 444444444444444444 ,fig4 #hi4--,/aples & ,wood5 ,cleat us$ = runn+ ,l[ ,voltage ,wires4 4444444444444444444444444444444444444444 44444444444444444444 ,fig4 #ij4--,porcela9 ,insulators to support ,electric ,light ,wires4 4444 ,fig4 #ia4--;,glass ,insulator ,b9d+-,po/s & ,p9 us$ to support ,telegraph & ,telephone wires4 444444444444444444444444444444444444 ,fig4 #ib4--,types ( ,b9d+-,po/s4 4444444444444444444444444444444444 ,fig4 #ic4--;,home-made ,b9d+-,po/s4 444444444444444444444444444444444 ,fig4 #id4--;,b9d+-,po/ remov$ f ! ,c>bon ( a ,dry ,cell4 444444 ,fig4 #ie4--,simple ,swit*es4 ,a1 ,s+le-,po9t ,swit*4 ,b1 ,two-,po9t ,swit*4 ,c1 ,?ree-,po9t ,swit*4 ,d1 ,five-,po9t ,swit*4 ,e1 ,lev] ) ,end ,roll$ up to =m ,h&le4 ,f1 ,lev] ) ,h&le made f "p ( a ,spool4 4444444444444444444444444444444444444444 4444444444 ,fig4 #if4--,knife ,swit*es4 4444444444444444444444444444444444444444 44 ,fig4 #ig4--,metal ,p>ts = ! ,knife ,swit*es4 4444444444444444444444 ,fig4 #ih4--,simple ,fuses4 ,a1 ,fuse-,block ) pla9 ,wire ,fuse4 ,d1 ,fuse-,block ) ,mica ,fuse 9 position4 4444444444444444444444444444 ,fig4 #ii4--,lightn+-,arre/] & ,gr\nd-,wire ,swit*4 444444444444444 ,fig4 #ajj4--;,home-made ,lightn+-,arre/]4 444444444444444444444444444 ,fig4 #aja4--,lightn+-,arre/] = ,telephone ,wires4 44444444444444444 ,fig4 #ajb4--;,a1 ,base1 %[+ ,slot4 ,b & ,c1 ,sides & ,top ( ! ,bobb94 ,d1 ,base & ,bobb9 9 ,position4 4444444444444444444444444 ,fig4 #ajc4--;,arrangem5t ( ! ,ne$le & ,po9t]4 444444444444444444 ,fig4 #ajd4--;,a1 ,be>+s4 ,b1 ,h[ ! ,ne$le is m\nt$4 4444444444 ,fig4 #aje4--,! ,complet$ ,met]4 444444444444444444444444444444444444 ,fig4 #ajf4--;,details ( ! ,bobb94 4444444444444444444444444444444444 ,fig4 #ajg4--,! ,bobb9 p>tly cut away s z to %[ ! ,be>+4 ,details ( ! ,armature & ,%aft4 44444444444444444444444444444444 ,fig4 #ajh4--;,complet$ ,voltmet]4 444444444444444444444444444444444444 ,fig4 #aji4--;,circuits = ,calibrat+ ! ,ammet] & ,voltmet]4 44444 ,fig4 #aaj4--,simple ,compass ,galvanoscope4 4444444444444444444444444444 ,fig4 #aaa4--;,galvanoscope4 4444444444444444444444444444444444444444 444 ,fig4 #aab4--;,a/atic ,galvanoscope4 44444444444444444444444444444444444 ,fig4 #aac4--;,a/atic ,ne$les4 4444444444444444444444444444444444444444 ,fig4 #aad4--;,bobb9 = ,a/atic ,galvanomet]4 444444444444444444444444 ,fig4 #aae4--;,complet$ ,a/atic ,galvanomet]4 4444444444444444444444444 ,fig4 #aaf4--,:eat/one ,bridge4 44444444444444444444444444444444444444 ,fig4 #aag4--,knife-,contact4 4444444444444444444444444444444444444444 44 ,fig4 #aah4--,resi/ance-,coil4 ,a %[s h[ ! ,wire is d\bl$ & w\nd on ! ,spool4 ,b is ! complet$ ,coil4 44444444444444444444 ,fig4 #aai4--;,details ( ! ,magnet ,spools1 & ,yoke = an ,electric ,bell4 4444444444444444444444444444444444444444 444444444444444444444 ,fig4 #abj4--;,details ( ! ,armature1 & ,contact ,screw4 4444444444444 ,fig4 #aba4--,! ,complet$ ,bell4 4444444444444444444444444444444444444 ,fig4 #abb4--;,diagram %[+ h[ to connect a ,bell1 ,batt]y1 & ,pu%-,button4 4444444444444444444444444444444444444444 44444444444444 ,fig4 #abc4--,two ,simple ,pu%-,buttons4 44444444444444444444444444444444 ,fig4 #abd4--;,diagram %[+ h[ to arrange a ,bell ,sy/em ( ,return ,signals4 4444444444444444444444444444444444444444 444444444444444444 ,fig4 #abe4--;,burgl>-,al>m ,trap4 4444444444444444444444444444444444444 ,fig4 #abf4--;,an ,e>ly-,ris]'s ,electric ,al>m ,atta*m5t = a ,clock4 4 ,fig4 #abg4--;,details ( ! ,*a9 ,electrodes1 etc4 4444444444444444444 ,fig4 #abh4--;,an ,annunciator ,drop4 444444444444444444444444444444444444 ,fig #abi4--;,details ( ! ,drop-,frame & ,armature4 444444444444444444 ,fig4 #acj4--;,a ,typical ,telegraph ,key1 %[+ ! ,v>i\s ,p>ts4 44444 ,fig4 #aca4--;,a ,typical ,telegraph ,s\nd]1 %[+ ! ,v>i\s ,p>ts4 4 ,fig4 #acb4--;,a ,simple ,home-made ,telegraph ,key4 44444444444444444444444 ,fig4 #acc4--;,a ,simple ,home-made ,telegraph ,s\nd]4 4444444444444444444 ,fig4 #acd4--;,a ,diagram %[+ h[ to connect two ,simple ,telegraph ,/ations4 4444444444444444444444444444444444444444 44444444444444444 ,fig4 #ace4--;,a ,complete ,telegraph ,set1 consi/+ ( a ,keybo>d & a ,s\nd]4 4444444444444444444444444444444444444444 444444444444444444 ,fig4 #acf4--;,details ( ! ,telegraph ,set %[n 9 ,figure #ace4 4444444 ,fig4 #acg4--;,a ,diagram %[+ h[ to connect two ,complete ,telegraph ,sets1 us+ "o ,l9e ,wire & a ,gr\nd4 ,! ,two-,po9t ,swit*es ?r[ ! ,batt]ies out ( ,circuit :5 ! ,l9e is n 9 use4 444444444 ,fig4 #ach4--;,details ( ! ,relay ,p>ts4 44444444444444444444444444444 ,fig4 #aci4--,! ,complet$ ,relay4 444444444444444444444444444444444444 ,fig4 #adj4--;,a ,diagram %[+ h[ to connect a ,relay1 ,s\nd]1 & ,key4 ,clos+ ! ,key w op]ate ! ,relay4 ,! ,relay w !n op]ate ! ,s\nd] 9 turn4 44444444444444444444444444444444444444 ,fig4 #ada4--;,h[ to hold a ,telegraph ,key4 4444444444444444444444444444 ,fig4 #adb4--,! ,morse ,telegraphic ,code4 44444444444444444444444444444 ,fig4 #adc4--;,a ,microphone connect$ to a ,telephone ,receiv]1 & a ,batt]y4 4444444444444444444444444444444444444444 444444444444444444 ,fig4 #add4--;,a ,v ,s5sitive ,=m ( ,microphone1 ) :i* ! ,foot/eps ( a ,fly c be he>d4 4444444444444444444444444444444444 ,fig4 #ade4--;,a ,telephone ,sy/em1 consi/+ ( a ,receiv]1 ,transmitt]1 & a ,batt]y connect$ 9 ,s]ies4 ,words spok5 into ! ,transmitt] are reproduc$ by ! ,receiv]4 44444444444444444444444444444444444 ,fig4 #adf4--;,a ,wat*-,case ,telephone ,receiv]4 444444444444444444444444 ,fig4 #adg4--;,a ,simple ,=m ( ,telephone ,receiv]4 44444444444444444444 ,fig4 #adh4--;,a ,home-made ,telephone ,transmitt]4 4444444444444444444444 ,fig4 #adi4--;,a ,complete ,telephone ,in/rum5t4 ,two ,in/rum5ts su* z ?is are necess>y to =m a simple ,telephone ,sy/em4 4444444444444 ,fig4 #aej4--;,diagram ( ,connection = ! ,telephone ,in/rum5t %[n 9 ,fig4 #adi4 4444444444444444444444444444444444444444 44444444444444 ,fig4 #aea4--;,a ,desk-,/& ,type ( ,telephone4 4444444444444444444444444 ,fig4 #aeb4--;,a ,telephone ,induction ,coil4 44444444444444444444444444444 ,fig4 #aec4--;,diagram ( ,connection = a ,telephone ,sy/em employ+ an ,induction ,coil at ea* ,/ation4 44444444444444444444444444444444444 ,fig4 #aed4--;,details ( ,v>i\s ,p>ts ( a ,m$ical ,coil4 4444444444444 ,fig4 #aee4--;,details ( ,int]rupt] = ,m$ical ,coil4 4444444444444444 ,fig4 #aef4--;,complet$ ,m$ical ,coil4 444444444444444444444444444444444 ,fig4 #aeg4--;,diagram %[+ ,ess5tial ,p>ts ( ,induction ,coil4 444444 ,fig4 #aeh4--;,empty ,pap] ,tube1 & ,tube fill$ ) ,core ,wire prep>atory to w9d+ on ! ,prim>y4 4444444444444444444444444444 ,fig4 #aei4--;,illu/rat+ ! ,v>i\s ,/eps 9 w9d+ on ! ,prim>y & fa/5+ ! ,ends ( ! ,wire4 4444444444444444444444444444444 ,fig4 #afj4--;,complete ,prim>y ,w9d+ & ,core4 4444444444444444444444 ,fig4 #afa4--,! ,prim>y cov]$ ) ,insulat+ ,lay] ( ,pap] ready = ! ,second>y4 4444444444444444444444444444444444444444 44444444 ,fig4 #afb4--,simple ,w9d+ ,device = w9d+ ! ,second>y4 44444444 ,fig4 #afc4--;,complet$ ,second>y ,w9d+4 4444444444444444444444444444 ,fig4 #afd4--;,int]rupt] ,p>ts4 44444444444444444444444444444444444444 ,fig4 #afe4--;,cond5s]4 4444444444444444444444444444444444444444 444444 ,fig4 #aff4--;,complet$ ,coil4 4444444444444444444444444444444444444444 4 ,fig4 #afg4--;,diagram %[+ h[ to connect ! ,app>atus = ! ,electric ,h&s ,exp]im5t4 44444444444444444444444444444444444444 ,fig4 #afh4--;,geissl] ,tubes4 4444444444444444444444444444444444444444 4 ,fig4 #afi4--,! ,bulb w emit a ,peculi> ,gre5i% ,light4 44444444444 ,fig4 #agj4--;,an ,electrifi$ ,g>bage-c4 44444444444444444444444444444 ,fig4 #aga4--;,jacob's ,ladd]4 4444444444444444444444444444444444444444 4 ,fig4 #agb4--;,an ,x-,ray ,tube4 4444444444444444444444444444444444444444 44 ,fig4 #agc4--;,fluoroscope4 4444444444444444444444444444444444444444 4444 ,fig4 #agd4--;,h[ to connect an ,x-,ray ,tube to a ,sp>k-,coil4 44444444444 ,an ,x-,ray ,photograph ( ! h& tak5 ) ! ,outfit %[n 9 ,figure #agd4 ,! arr[s po9t to injuries to ! bone ( ! ?ird f+] ne> ! middle ,jo9t ,result+ 9 a ,/iff ,jo9t4 4444444444 ,fig4 #age4--;,comp>ison betwe5 ,electric ,curr5t & ,fl[ ( ,wat]4 44 ,fig4 #agf4--;,alt]nat+ ,curr5t ,sy/em = ,light & ,p[]4 444444444 ,fig4 #agg4--,motor ,g5]ator ,set = *ang+ ,alt]nat+ ,curr5t to ,direct ,curr5t4 4444444444444444444444444444444444444444 44444444444 ,fig4 #agh4--,/ep-,up ,trans=m]4 444444444444444444444444444444444444 ,fig4 #agi4--,/ep-,d[n ,trans=m]4 4444444444444444444444444444444444 ,fig4 #ahj4--;,core ,dim5sions4 4444444444444444444444444444444444444444 ,fig4 #aha4--,! ,core1 ,assembl$ & ,tap$4 44444444444444444444444444 ,fig4 #ahb4--,trans=m] ,leg4 4444444444444444444444444444444444444444 ,fig4 #ahc4--;,fib] ,head4 4444444444444444444444444444444444444444 44444 ,fig4 #ahd4--,leg ) ,heads 9 ,position = ,w9d+4 44444444444444444 ,fig4 #ahe4--;,h[ to make a ,tap 9 ! ,prim>y by sold]+ a ,copp] ,/rip to ! ,wire4 4444444444444444444444444444444444444444 44444444 ,fig4 #ahf4--,! ,trans=m] completely ,w\nd & ready = ,assembl+4 ,fig4 #ahg4--,wood5 ,/rips = m\nt+ ! ,trans=m] on ! ,base4 4 ,fig4 #ahh4--;,details ( ! ,swit* ,p>ts4 4444444444444444444444444444 ,fig4 #ahi4--,! ,complete ,swit*4 444444444444444444444444444444444444 ,fig4 #aij4--;,diagram ( ,connections4 444444444444444444444444444444444 ,fig4 #aia4--,top ,view ( ! ,trans=m]4 4444444444444444444444444444 ,fig4 #aib4--,side ,view ( ! ,trans=m]4 444444444444444444444444444 ,fig4 #aic4--,little ,waves spread out f ! ,spot4 444444444444444444 ,fig4 #aid4--;,a ,simple ,transmitt]4 44444444444444444444444444444444444 ,fig4 #aie4--;,a ,simple ,receptor4 44444444444444444444444444444444444444 ,fig4 #aif4--,mold$ ,a]ial ,insulator 444444444444444444444444444444444 ,fig4 #aig4--;,a ,porcela9 ,cleat w make a ,good ,insulator = ,small ,a]ials4 4444444444444444444444444444444444444444 444444444444444444 ,fig4 #aih4--,me?od ( ,arrang+ ! ,wires & ,insulat+ !m f ! ,cross ,arm or ,spread]4 4444444444444444444444444444444444444444 4444 ,fig4 #aii4--,v>i\s ,types ( ,a]ials4 4444444444444444444444444444444 ,fig4 #bjj4--;,a ,gr\nd ,clamp = ,pipes4 4444444444444444444444444444444 ,fig4 #bja4--;,details ( ! ,tun+ ,coil4 44444444444444444444444444444 ,fig4 #bjb4--,side & ,end ,views ( ! ,tun+ ,coil4 444444444444444444 ,fig4 #bjc4--;,complete ,d\ble-,slid] ,tun+ ,coil4 444444444444444444444 ,fig4 #bjd4--;,a ,simple ,loose ,c\pl]4 444444444444444444444444444444444 ,fig4 #bje4--;,details ( ! ,wood5 ,p>ts4 4444444444444444444444444444 ,fig4 #bjf4--,side ,view ( ! ,loose ,c\pl]4 4444444444444444444444444 ,fig4 #bjg4--,top ,view ( ! ,loose ,c\pl]4 44444444444444444444444444 ,fig4 #bjh4--;,end ,views ( ! ,loose ,c\pl]4 4444444444444444444444444 ,fig4 #bji4--;,complete ,loose ,c\pl]4 444444444444444444444444444444444 ,fig4 #baj4--;,a ,cry/al ,detector4 4444444444444444444444444444444444444 ,fig4 #baa4--;,details ( ! ,cry/al ,detector4 444444444444444444444444 ,a ,d\ble ,slid] ,tun+ ,coil4 44444444444444444444444444444444444444 ,a ,junior ,loose ,c\pl]4 4444444444444444444444444444444444444444 444 ,cry/al ,detectors4 4444444444444444444444444444444444444444 44444444 ,fig4 #bab ,details ( ! ,cat ,:isk] ,detector4 4444444444444444444 ,fig4 #bac4--;,ano!r ,=m ( ! ,cat-,:isk] ,detector4 4444444444444 ,fig4 #bad4--;,cat-,:isk] ,detector4 444444444444444444444444444444444 ,fig4 #bae4--;,build+ up a ,fix$ ,cond5s]4 44444444444444444444444444 ,fig4 #baf4--;,a ,fix$ ,cond5s] enclos$ 9 a ,brass ,case made f a ,piece ( ,tub+ fitt$ ) ,wood5 ,ends4 44444444444444444444444444 ,fig4 #bag4--;,a ,telephone ,head ,set4 44444444444444444444444444444444444 ,fig4 #bah4--;,a ,circuit %[+ h[ to connect a ,d\ble-,slid] ,tun+ ,coil4 4444444444444444444444444444444444444444 444444444444444444444 ,fig4 #bai4--;,circuit %[+ h[ to connect a ,loose ,c\pl]4 444444444 ,fig4 #bbj4--;,a ,diagram %[+ h[ to connect "s ( ! ,in/rum5ts describ$ 9 ?is ,*apt]4 4444444444444444444444444444444444444444 ,fig4 #bba4--;,a ,wireless ,sp>k ,coil4 4444444444444444444444444444444444 ,fig4 #bbb4--,small ,sp>k ,gaps4 444444444444444444444444444444444444444 ,fig4 #bbc4--;,diagram %[+ h[ to connect a ,simple ,transmitt]4 4444 ,fig4 #bbd4--;,a ,te/-,tube ,leyd5 ,j>4 444444444444444444444444444444444 ,fig4 #bbe4--;,eight ,te/-,tube ,leyd5 ,j>s m\nt$ 9 a ,wood5 ,rack4 444 ,fig4 #bbf4--;,a ,helix & ,clip4 444444444444444444444444444444444444444 ,fig4 #bbg4--;,an ,oscillation ,trans=m]4 44444444444444444444444444444 ,,an ,,oscillation ,,helix4 4444444444444444444444444444444444444444 44444 ,,an ,,oscillation ,,cond5s]4 4444444444444444444444444444444444444444 4 ,fig #bbh4--;,circuit %[+ h[ to connect a ,helix & a ,cond5s]4 44 ,fig #bbi4--;,circuit %[+ h[ to connect an ,oscillation ,trans=m] & a ,cond5s]4 4444444444444444444444444444444444444444 4444444444 ,fig #bcj4--;,an ,a]ial ,swit*4 4444444444444444444444444444444444444444 ,fig #bca4--;,a ,complete ,wir+ ,diagram = bo? ! ,transmitt] & ! ,receptor4 4444444444444444444444444444444444444444 44444444444444444 ,fig4 #bcb4--,! ,cont95tal ,alphabet4 4444444444444444444444444444444 ,fig4 #bcc4--;,a ,coh]] & a ,decoh]]4 444444444444444444444444444444 ,fig4 #bcd4--;,details ( ! ,coh]]4 444444444444444444444444444444444 ,fig4 #bce4--,! ,relay4 4444444444444444444444444444444444444444 444444 ,fig4 #bcf4--,! ,complete ,coh]] ,outfit4 4444444444444444444444444444 ,fig4 #bcg4--;,a ,simple ,arrangem5t %[+ ! ,inductive ,action betwe5 two ,coils4 4444444444444444444444444444444444444444 4444444444444444 ,fig4 #bch4--;,a ,simple ,wireless ,telephone4 ,spee* direct$ into ! ,transmitt] c be he>d 9 ! ,receiv]1 al?\gh !re is no direct electrical connection betwe5 ! two4 444444444444444444444 ,fig4 #bci4--;,a ,d\ble-,contact ,/rap-,key4 ,! ,dott$ ,l9es %[ h[ ! ,b9d+-,po/s are connect$4 44444444444444444444444444444444444444 ,fig4 #bdj4--,! ,circuit ( ! ,wireless ,telephone4 ,:5 ! ,key is up1 ! ,receiv] is ready = ,action4 ,:5 ! ,key is press$1 ! ,transmitt] & ,batt]y are ?r[n into ! ,circuit4 44444444444444 ,fig4 #bda4--;,a ,complete ,wireless ,telephone & ,telegraph ,/ation = ,amateurs4 #a4 ,! ,telephone ,coil4 #b4 ,! ,telephone ,transmitt]4 #c4 ,d\ble-,contact ,/rap-,key4 #d4 ,! ,batt]y4 #e4 ,sp>k ,coil4 #f4 ,key4 #g4 ,sp>k-,gap4 #h4 ,a]ial ,swit*4 #i4 ,loose ,c\pl]4 #aj4 ,detector1 #aa4 ,fix$ ,cond5s]4 #ab4 ,code ,*>t4 #ac4 ,amateur ,lic5se4 #ad4 ,a]ial4 #ae4 ,telephone ,receiv]s4 4444444444444444444444444444444444444444 44 ,fig4 #bdb4--;,a ,simple ,electric ,motor :i* may be made 9 ,fifte5 ,m9utes4 4444444444444444444444444444444444444444 444444444444444444 ,fig4 #bdc4--;,details ( ! ,armature ( ! ,simplex ,motor4 44444444444 ,fig4 #bdd4--,! ,armature4 4444444444444444444444444444444444444444 444 ,fig4 #bde4--,! ,field4 4444444444444444444444444444444444444444 444444 ,fig4 #bdf4--,! ,field & ,commutator4 4444444444444444444444444444444 ,fig4 #bdg4--,! ,be>+s4 4444444444444444444444444444444444444444 444 ,fig4 #bdh4--,! ,complete ,motor4 4444444444444444444444444444444444444 ,fig4 #bdi4--;,details ( ! ,motor4 44444444444444444444444444444444444 ,fig4 #bej4--;,complete ,motor4 4444444444444444444444444444444444444444 4 ,fig4 #bea--;,a ,telephone ,magneto4 4444444444444444444444444444444444444 ,fig4 #beb4--,! ,pr9ciple ( ! ,alt]nator & ! ,direct-,curr5t ,dynamo4 4444444444444444444444444444444444444444 4444444444444444444 ,fig4 #bec4--;,details ( ! ,armature1 ,commutator1 & ,bru%es4 4444444 ,fig4 #bed4--,! ,complete ,g5]ator4 444444444444444444444444444444444 ,fig4 #bee4--;,details ( ! ,field ,ca/+4 444444444444444444444444444 ,fig4 #bef4--;,details ( ! ,armature ,ca/+4 444444444444444444444444 ,fig4 #beg4--;,details ( ! ,commutator4 444444444444444444444444444444 ,fig4 #beh4--;,diagram %[+ h[ to connect ! ,armature ,w9d+ to ! ,commutator4 4444444444444444444444444444444444444444 444444444444444 ,fig4 #bei4--;,details ( ! ,wood5 ,base4 44444444444444444444444444444 ,fig4 #bfj4--,! ,pulley & ,be>+s4 44444444444444444444444444444444 ,fig4 #bfa4--,! ,bru%es4 4444444444444444444444444444444444444444 4444 ,,! ,,junior ,,dynamo ,,m\nt$ ,,on ,a ,,long ,,wood5 ,,base ,,& ,,belt$ ,,to ,a ,,groov$ ,,:eel ,,fitt$ ,,) ,a ,,crank ,,s ,,t ,,! ,,dynamo ,,c ,,be ,,run ,,at ,,high ,,spe$ ,,by ,,h& ,,p[]4 ,,! ,,illu/ration ,,also ,,%[s ,a ,,small ,,inc&esc5t ,,lamp ,,connect$ ,,to ,,! ,,dynamo ,,s ,,t ,,:5 ,,! ,,crank ,,is ,,turn$ ,,! ,,lamp ,,w ,,light4 444444444444444444444444444444444444444 ,fig4 #bfb4--;,complete ,dynamo4 4444444444444444444444444444444444444444 ,fig4 #bfc4--;,complete ,electric ,railway op]at$ by ,dry ,cells4 ,note h[ ! ,wires f ! ,batt]y are connect$ to ! ,rails by means ( ! ,wood5 ,conductors illu/rat$ 9 ,figure #bgg4 444444444444444444 ,fig4 #bfd4--;,details ( ! ,floor ( ! ,c>4 444444444444444444444444 ,fig4 #bfe4--;,details ( ! ,be>+ :i* supports ! ,:eel & ,axle4 ,fig4 #bff4--,! ,:eels & ,axle4 444444444444444444444444444444444444 ,fig4 #bfg4--,! ,motor4 4444444444444444444444444444444444444444 444444 ,fig4 #bfh4--,! ,complete ,truck ( ! ,c> )\t ! ,body4 444444444 ,fig4 #bfi4--,patt]n = ! ,sides & ,ends ( ! ,c>4 44444444444444 ,fig4 #bgj4--,! ,ro( ( ! ,c>4 444444444444444444444444444444444444 ,fig4 #bga4--,! ,complet$ ,c>4 44444444444444444444444444444444444444 ,fig4 #bgb4-;,details ( a ,wood5 ,tie4 44444444444444444444444444444444 ,fig4 #bgc4-;,arrangem5t ( ,track4 44444444444444444444444444444444444 ,fig4 #bgd4--,?ree ,diff]5t ,patt]ns = lay+ out ! ,track4 444444 ,fig4 #bge4--;,details ( ! ,base ( ! ,cross-ov]4 444444444444444444 ,fig4 #bgf4--,! ,complet$ ,cross-ov]4 4444444444444444444444444444444 ,fig4 #bgg4--;,a ,connector = jo9+ ! ,ends ( ! ,rails4 4444444444 ,fig4 #bgh4--;,a ,bump] = prev5t+ ! ,c> f leav+ ! ,rails4 4 ,fig4 #bgi4--;,a ,design = a ,railway ,bridge4 44444444444444444444444444 ,fig4 #bhj4--;,a ,design = a ,railway ,/ation4 4444444444444444444444444 ,fig4 #bha4--,m9iature ,c>bon ,batt]y ,lamp4 44444444444444444444444444 ,fig4 #bhb4--,m9iature ,tung/5 ,batt]y ,lamp4 444444444444444444444444 ,fig4 #bhc4--,lamps fitt$ respectively ) ,m9iature1 ,c&elabra1 & ,ediswan ,bases4 4444444444444444444444444444444444444444 444444444444 ,fig4 #bhd4--,m9iature ,flat-,base ,porcela9 ,receptacle4 444444444444444 ,fig4 #bhe4--,wea!r-pro( & ,p9-,sockets4 44444444444444444444444444 ,fig4 #bhf4--,types ( ,batt]y ,swit*es suitable = ,m9iature ,light+4 ,fig4 #bhg4--;,h[ ,lamps are ,connect$ 9 ,multiple4 44444444444444444444 ,fig4 #bhh4--;,h[ ,lamps are ,connect$ 9 ,s]ies4 4444444444444444444444 ,fig4 #bhi4--,?ree-way ,wir+ ,diagram4 ,! ,light may be turn$ (f or on f ei!r ,swit*4 4444444444444444444444444444444444444444 4444 ,fig4 #bij4--;,a ,lamp ,bracket = ,m9iature ,light+4 444444444444444444 ,fig4 #bia4--;,a ,home-made ,bracket4 444444444444444444444444444444444444 ,fig4 #bib4--;,a ,hang+ ,lamp4 4444444444444444444444444444444444444444 4 ,fig4 #bic4--;,h[ ! ,reflector is made4 444444444444444444444444444444 ,fig4 #bid4--;,a ,?ree-,cell ,dry ,batt]y = use 9 ,h&-,lant]ns1 etc4 4 ,fig4 #bie4--;,an ,electric ,h&-,lant]n4 4444444444444444444444444444444 ,fig4 #bif4--;,an ,electric ,ruby ,lant]n4 4444444444444444444444444444444 ,fig4 #big4--,! ,electric ,ruby ,lamp ) ,glass & ,%ield ,remov$4 444 ,fig4 #bih4--;,an ,electric ,night-,light = tell+ ! ,"t dur+ ! ,night4 4444444444444444444444444444444444444444 44444444444444444444 ,fig4 #bii4--;,a ,wat*-,light4 4444444444444444444444444444444444444444 44 ,fig4 #cjj4--;,a ,pea ,lamp atta*$ to a ,flexible ,wire & a ,plug4 4444 ,fig4 #cja4--;,f\r ,/eps 9 ,c>v+ a ,skull ,sc>f-,p94 #a4 ,! ,bone4 #b4 ,hole drill$ 9 ,base4 #c4 ,r\gh$ out4 #d4 ,f9i%$4 4444444444444444 ,fig4 #cjb4--,! ,complet$ ,p9 ready to be connect$ to a ,batt]y by remov+ ! ,lamp f a ,fla%light & screw+ ! ,plug into its ,place4 4444444444444444444444444444444444444444 44444444444444444444 ,fig4 #cjc4--;,h[ ! ,copp] ,wires 7,c7 & ! ,silv] ,wires 7,i7 are twi/$ toge!r 9 ,pairs4 4444444444444444444444444444444444444444 ,fig4 #cjd4--,wood5 ,r+4 4444444444444444444444444444444444444444 4444 ,fig4 #cje4--;,complete ,!rmopile4 ,an ,alcohol ,lamp %\ld be light$ & plac$ s t ! ,flame heats ! ,inside ,ends ( ! ,wires 9 ! ,c5t] ( ! ,wood5 ,r+4 4444444444444444444444444444444444444444 ,fig4 #cjf4--;,a ,reflectoscope4 4444444444444444444444444444444444444444 ,fig4 #cjg4--;,h[ ! ,l5s is ,arrang$ & ,m\nt$4 4444444444444444444 ,fig4 #cjh4--;,a ,view ( ! ,reflectoscope f ! ,re>1 %[+ ! ,door1 etc4 4444444444444444444444444444444444444444 4444444444444444 ,fig4 #cji4--;,a ,view ( ! ,reflectoscope ) ! ,cov] remov$1 %[+ ! ,arrangem5t ( ! ,lamps1 etc4 444444444444444444444444 ,fig4 #caj4--;,a ,socket = hold+ ! ,lamp4 44444444444444444444444444 ,fig4 #caa4--,! ,t9 ,reflector4 44444444444444444444444444444444444444 ,fig #cab4--,top ,view ( ,lamp ,bank1 %[+ h[ ! ,circuit is arrang$4 ,a & ,b are ! ,po/s to :i* %\ld be connect$ any ,device x#8s desirable to op]ate4 4444444444444444444444444444444444444444 44444 ,fig4 #cac4--;,a ,glass ,j> arrang$ to s]ve z an ,electro-,plat+ ,tank4 ,fig4 #cad4--;,a ,rheo/at4 4444444444444444444444444444444444444444 44444 ,fig4 #cae4--;,a ,pole-,*ang+ ,swit* or ,curr5t ,rev]s]4 ,! ,connect+ ,/rip is pivot$ s t ! ,h&le w op]ate bo? ! ,lev]s1 ,a & ,b4 4444444444444444444444444444444444444444 44444444444444444444 ,,complete ,,receiv+ ,,set1 ,,consi/+ ,,( ,,d\ble ,,slid] ,,tun+ ,,coil1 ,,detector ,,& ,,fix$ ,,cond5s]4 4444444444444444444444444444444444444 ,,complete ,,receiv+ ,,set1 ,,consi/+ ,,( ,a ,,loose ,,c\pl] ,,9 ,,place ,,( ,,! ,,tun+ ,,coil1 ,,detector ,,& ,,fix$ ,,cond5s]4 44444444444444444444 ,fig4 #caf4 ,a ,complete ,wireless ,receiv+ ,outfit4 4444444444444444444 ,fig4 #cag4--;,illu/rat+ ! ,pr9ciple ( ! ,tesla ,coil4 ,a ,leyd5 ,j> dis*>ges ?r\gh ! ,prim>y ,coil & a ,high-,frequ5cy ,sp>k is produc$ at ! ,second>y4 4444444444444444444444444444444444444444 ,fig4 #cah4--;,details ( ! ,wood5 ,r+s us$ z ! ,prim>y ,heads4 44 ,fig4 #cai4--;,details ( ! ,cross ,b>s :i* support ! ,prim>y ,w9d+4 4444444444444444444444444444444444444444 444444444444444444 ,fig4 #cbj4--,! ,second>y ,head4 4444444444444444444444444444444444444 ,a ,,complete ,,coh]] ,,outfit ,,z ,,describ$ ,,on ,,page #bgd4 444444444444444 ,,! ,,tesla ,,high ,,frequ5cy ,,coil4 444444444444444444444444444444444444 ,fig4 #cba4--;,end ,view ( ! ,complete ,tesla ,coil4 44444444444444444444 ,fig4 #cbb4--,! ,complete ,tesla ,coil4 44444444444444444444444444444444 ,fig #cbc4--,%[+ h[ a ,glass-,plate ,cond5s] is built up ( ,alt]nate ,%eets ( ,t9foil & ,glass4 4444444444444444444444444444 ,fig4 #cbd4--;,a ,diagram %[+ ! ,prop] ,me?od ( ,connect+ a ,tesla ,coil4 4444444444444444444444444444444444444444 444444444444444444444 ,,*apt] ,i ,,magnets ,,& ,,magnetism ,ov] two ?\s& ye>s ago1 9 f>-away ,asia ,m9or1 a %eph]d gu>d+ 8 flocks on ! slope ( ,m\nt ,ida sudd5ly f\nd ! iron-%od end ( 8 /aff adh]+ to a /one4 ,^u look+ fur!r ar\nd ab\t him he f\nd _m o!r pieces ( ?is peculi> h>d black m9]al1 ! small] bits ( :i* t5d$ to cl+ to ! nails & /uds 9 ! soles ( 8 s&als4 ,?is m9]al1 :i* 0 an ore ( iron1 consi/+ ( iron & oxyg51 0 f\nd 9 a di/rict kn[n z ,magnesia1 & 9 ?is way soon became widely kn[n z ! ,magnes/one1 or magnet4 ,?is is ! /ory ( ! discov]y ( ! magnet4 ,x exi/s 9 leg5ds 9 v>i\s =ms4 ,z m masses ( ?is magnetic ore 7 discov]$ 9 v>i\s p>ts ( ! _w1 ! /ories ( its attractive p[] became greatly exagg]at$1 especially dur+ ! ,middle ,ages4 ,9 fact1 magnetic m\nta9s :i* w\ld pull ! iron nails out ( %ips1 or1 lat]1 move ! compass ne$le f> a/ray1 did n lose _! place among ! t]rors ( ! sea until ne>ly ! eighte5? c5tury4 ,= _m hundr$s ( ye>s ! magnet-/one 0 ( little use to mank9d save z a curiosity :i* possess$ ! p[] ( attract+ small pieces ( iron & /eel & o!r magnets l itself4 ,!n "s "o1 no "o kn[s :o1 discov]$ t if a magnet-/one 7 hung by a ?read 9 a suitable mann] x w\ld always t5d to po9t ,nor? & ,s\?2 & s ! ,magnes-/one became also call$ ! lode/one1 or lead+-/one4 ,^! simple bits ( lode/one susp5d$ by a ?read 7 ! =]unn]s ( ! mod]n compass & 7 ( great value to ! anci5t navigators1 = !y enabl$ !m to /e] %ips 9 cl\dy wea!r :5 ! sun 0 obscur$ & on nights :5 ! pole-/> c\ld n be se54 ,! fir/ real compasses 7 call$ gnomons1 & consi/$ ( a /eel ne$le :i* _h be5 rubb$ ^u a lode/one until x acquir$ its magnetic prop]ties4 ,!n x 0 ?ru/ ?r\gh a re$ or %ort piece ( wood :i* support$ x on ! surface ( a vessel ( wat]4 ,if ! ne$le 0 left 9 ?is receptacle1 naturally x w\ld move aga9/ ! side & n po9t a true position4 ,!re=e x 0 giv5 a circul> movem5t 9 ! wat]1 & z soon z x came to re/1 ! po9t on ! horizon :i* ! nor? end designat$ 0 c>efully not$ & ! %ip's c\rse laid accord+ly4 ,! mod]n m>9]s' compass is q a diff]5t arrangem5t4 ,x consi/s ( ?ree p>ts1 ! b[l1 ! c>d1 & ! ne$le4 ,! b[l1 :i* conta9s ! c>d & ne$le1 is usually a hemisph]ical brass receptacle1 susp5d$ 9 a pair ( brass r+s1 call$ gimbals1 9 su* a mann] t ! b[l w rema9 horizontal no matt] h[ viol5tly ! %ip may pit* & roll4 ,! c>d1 :i* is circul>1 is divid$ into #cb equal p>ts call$ ! po9ts ( ! compass4 ,! ne$les1 ( :i* !re are g5]ally f two to f\r1 are fa/5$ to ! bottom ( ! c>d4 ,illu/ration3 ,fig4 #a4--,! ,c>d ( a ,m>9]'s ,compass1 ,%[+ ! ,po9ts4 ,9 ! c5t] ( ! c>d is a conical socket pois$ on an upright p9 fix$ 9 ! bottom ( ! b[l1 s t ! c>d hang+ on ! p9 turns freely ar\nd its c5t]4 ,on %ipbo>d1 ! compass is s plac$ t a black m>k1 call$ ! lubb]'s l9e1 is fix$ 9 a position p>allel to ! keel4 ,! po9t on ! compass-c>d :i* is directly aga9/ ?is l9e indicates ! direction ( ! %ip's head4 ,exp]im5ts ) ,magnetism ,! ph5om5a ( magnetism & its laws =m a v important bran* ( ! /udy ( electricity1 = !y play an important "p 9 ! con/ruction ( almo/ all electrical app>atus4 ,dynamos1 motors1 telegraphs1 telephones1 wireless app>atus1 voltmet]s1 ammet]s1 & s on ?r\gh a practically endless li/1 dep5d ^u magnetism = _! op]ation4 99,artificial ,magnets99 are ^? made f /eel by ! application ( a lode/one or "s o!r magnetiz+ =ce4 ,! pr9cipal =ms are ! ,b> & ,horse%oe1 s call$ f _! %ape4 ,! process ( mak+ su* a magnet is call$ ,magnetization4 ,illu/ration3 ,fig4 #b4--;,a ,b> ,magnet ,small horse%oe & b> magnets c be pur*as$ at toy-/ores4 ,!y c be us$ to p]=m v int]e/+ & in/ructive exp]im5ts4 ,illu/ration3 ,fig4 #c4--;,a ,horse%oe ,magnet ,/roke a l>ge d>n+-ne$le f end to end1 always 9 ! same direction1 ) "o end ( a b> magnet4 ,!n dip ! ne$le 9 "s iron fil+s & x w be f\nd t ! fil+s w cl+ to ! ne$le4 ,! ne$le has become a magnet4 ,dip ! b> magnet 9 "s iron fil+s & x w be notic$ t ! fil+s cl+ to ! magnet 9 irregul> tufts ne> ! ends1 ) few if any ne> ! middle4 ,illu/ration3 ,fig4 #d4--;,a ,magnetiz$ ,ne$le & a ,b> ,magnet :i* h be5 dipp$ 9 ,iron ,fil+s4 ,?is exp]im5t %[s t ! attractive p[] ( a magnet exi/s 9 two opposite places4 ,^! are call$ ! poles4 ,!re exi/s betwe5 magnets & bits ( iron & /eel a peculi> unse5 =ce :i* c ex]t itself across space4 ,! p[] ) :i* a magnet attracts or repels ano!r magnet or attracts bits ( iron & /eel is call$ 99,magnetic ,=ce499 ,! =ce ex]t$ by a magnet ^u a bit ( iron is n ! same at all di/ances4 ,! =ce is /rong] :5 ! magnet is ne> ! iron & weak] :5 x is f>!r away4 ,illu/ration3 ,fig4 #e4--,! ,lift+ ,p[] ( a ,b> ,magnet4 ,x mu/ be br\ght clos] to ! nails ?an ! tacks because !y are heavi]4 ,place "s small c>pet-tacks on a piece ( pap] & hold a magnet above !m4 ,gradually l[] ! magnet until ! tacks jump up to meet x4 ,!n try "s nails 9 place ( ! tacks4 ,! nails are heavi] ?an ! tacks1 & x w require a great] =ce to lift !m4 ,! magnet w h to be br\ght mu* clos] to ! nails ?an to ! tacks be=e !y are lift$1 %[+ t ! =ce ex]t$ by ! magnet is /ronge/ ne>e/ to x4 ,magnetize a ne$le & lay x on a piece ( cork float+ 9 a glass vessel ( wat]4 ,x w !n be se5 t ! ne$le always comes to re/ ly+ ne>ly 9 a nor? & s\? l9e1 ) ! same end always t[>d ! nor?4 ,illu/ration3 ,fig4 #f4--;,a ,simple ,compass4 ,! pole ( ! magnet :i* t5ds to turn t[>ds ! nor? is call$ ! nor?-seek+ pole & ! opposite "o is call$ ! s\?-seek+ pole4 ,! "n is usually abbreviat$ to simply ! nor? & s\? poles4 ,! nor? pole ( a magnet is (t5 indicat$ by a /raight l9e or a lett] ,n /amp$ into ! metal4 ,a magnetiz$ ne$le float+ on a cork 9 a bas9 ( wat] is a simple =m ( ,illu/ration3 ,fig4 #g4--,sev]al ,diff]5t ,me?ods ( ,mak+ a ,simple ,compass4 99,compass499 ,figure #g %[s sev]al o!r diff]5t ways ( mak+ compasses4 ,! fir/ me?od is to susp5d a magnetiz$ ne$le f a f9e silk fib] or ?read4 ,! second me?od illu/rates a v s5sitive compass made f pap]4 ,two magnetiz$ ne$les are /uck ?r\gh ! sides ) _! nor? poles bo? at ! same end4 ,! pap] support is m\nt$ ^u a ?ird ne$le /uck ?r\gh a cork4 ,a compass :i* m ne>ly approa*es ! famili> type kn[n z a pocket compass may be made f a small piece ( wat*-spr+ or clock-spr+4 ,! c5t] ( ! ne$le is anneal$ or s(t5$ by hold+ x 9 ! flame ( an alcohol lamp & !n all[+ x to cool4 ,lay ! ne$le on a piece ( s(t metal su* z copp] or brass1 & d5t x 9 ! c5t] ) a pun*4 ,balance ! ne$le on ! end ( a p9 /uck ?r\gh ! bottom ( a pill-box4 99,magnetic ,sub/ances99 are ^? :i* are attract$ by a magnet4 ,exp]im5t ) a numb] ( diff]5t mat]ials1 su* z pap]1 wood1 brass1 iron1 copp]1 z9c1 rubb]1 /eel1 *alk1 etc4 ,x w be f\nd t only iron & /eel are capable ( be+ attract$ by y\r magnet4 ,ord9>y magnets attract b v few sub/ances4 ,iron1 /eel1 cobalt1 & nickel are ab\t ! only ones wor?y ( m5tion4 99,attraction ?r\gh ,bodies499 ,a magnet w attract a nail or a tack ?r\gh a piece ( pap]1 j z if no?+ int]v5$4 ,illu/ration3 ,fig4 #h4--,! ,attraction ( an ,iron ,nail ?r\gh ,glass4 ,x w also attract ?r\gh glass1 wood1 brass1 & all o!r sub/ances4 ,?r\gh an iron plate1 h[ev]1 ! attraction is r$uc$ or entirely *eck$ because ! iron takes up ! magnetic effect itself & prev5ts ! =ce f pass+ ?r\gh & rea*+ ! nail4 ,a numb] ( c>pet-tacks may be support$ f a magnet 9 ! =m ( a *a94 ,ea* individual tack 9 ! s]ies becomes a tempor>y magnet by induction4 ,if ! tack 9 contact ) ! magnet be tak5 9 ! h& & ! magnet sudd5ly )drawn1 ! tacks w at once lose _! magnetism & fall ap>t4 ,illu/ration3 ,fig4 #i4--;,a ,magnetic ,*a94 ,x w fur!rmore be f\nd t a c]ta9 magnet w support a c]ta9 numb] ( tacks 9 ! =m ( a *a91 b t if a second magnet is plac$ b5ea? ! *a91 s t its s\? pole is "u ! nor? pole ( ! orig9al magnet1 ! *a9 may be l5g!n$ by ! addition ( sev]al o!r tacks4 ,! reason = ?is is t ! magnetism 9 ! tacks is increas$ by induction4 99,magnets w ,attract or ,repel99 ea* o!r1 dep5d+ ^u :i* poles are ne>e/4 ,magnetize a sew+-ne$le & hang x f a ?read4 ,br+ ! nor? pole ( a b> magnet ne> ! l[] end ( ! ne$le4 ,if ! l[] end ( ! ne$le happ5s to be a s\? pole x w be attract$ by ! nor? pole ( ! b> magnet4 ,if1 on ! o!r h&1 x is a nor? pole1 x w be repell$ & y _c t\* x ) ! nor? pole ( ! b> magnet unless y cat* x & hold x4 ,?is fact gives rise to ! g5]al law ( magnetism3 ,l poles repel ea* o!r & unlike poles attract ea* o!r4 ,illu/ration3 ,fig4 #aj4--;,an ,exp]im5t ,illu/rat+ t ,l ,poles ,repel ,ea* ,o!r & ,unlike ,poles ,attract4 ,ano!r int]e/+ way ( illu/rat+ ?is same law is by mak+ a small boat f cig>-box wood & lay+ a b> magnet on x4 ,place ! nor? pole ( ! b> magnet 9 ! b[ ( ! boat4 ,float ! boat 9 a bas9 ( wat]4 ,br+ ! s\? pole ( a second magnet ne> ! /]n ( ! boat & x w sail away to ! opposite side ( ! bas94 ,pres5t ! nor? pole ( ! magnet & x w sail back aga94 ,illu/ration3 ,fig4 #aa4--;,a ,magnetic ,boat4 ,if ! s\? pole ( ! magnet is pres5t$ to ! b[ ( ! boat ! little %ip w foll[ ! magnet all ar\nd ! bas94 ,! repulsion ( simil> poles may be also illu/rat$ by a numb] ( magnetiz$ sew+-ne$les fix$ 9 small corks s t !y w float 9 a bas9 ( wat] ) _! po9ts d[n4 ,illu/ration3 ,fig4 #ab4--,repulsion betwe5 ,simil> ,poles1 ,%[n by ,float+ ,ne$les4 ,! ne$les w !n arrange !mselves 9 diff]5t symmetrical gr\ps1 accord+ to _! numb]4 ,a b> magnet ?ru/ among !m w attract or repel !m dep5d+ ^u its pol>ity4 ,! upp] ends ( ! ne$les %\ld all h ! same pol>ity1 t is1 all be ei!r nor? or s\? poles4 ,magnetism fl[s along c]ta9 l9es call$ 99,l9es ( ,magnetic ,=ce499 ,^! l9es always =m clos$ pa?s or circuits4 ,! region 9 ! neighborhood ( a magnet ?r\gh :i* ^! l9es are pass+ is call$ ! field ( =ce1 & ! pa? ?r\gh :i* !y fl[ is call$ ! 99,magnetic ,circuit499 ,! pa?s ( ! l9es ( =ce c be easily demon/rat$ by plac+ a piece ( pap] ov] a b> magnet & !n spr9kl+ iron fil+s ov] ! pap]1 :i* %\ld be j>r$ slightly 9 ord] t ! fil+s may be drawn into ! magnetic pa?s4 ,illu/ration3 ,fig4 #ac4--;,a ,magnetic ,phantom1 ,%[+ ! ,field ( ,=ce ab\t a ,magnet4 ,! fil+s w arrange !mselves 9 curv$ l9es1 div]g+ f "o pole ( ! magnet & meet+ aga9 at ! opposite pole4 ,! l9es ( =ce are consid]$ z ext5d+ outw>d f ! nor? pole ( ! magnet1 curv+ ar\nd ?r\gh ! air to ! s\? pole & complet+ ! circuit back ?r\gh ! magnet4 ,illu/ration3 ,fig4 #ad4--,magnetic ,phantom %[+ ! ,l9es ( ,=ce ab\t a ,horse%oe ,magnet4 ,figure #ad %[s ! l9es ( =ce ab\t a horse%oe magnet4 ,x w be notic$ t ! l9es cross directly betwe5 ! nor? & s\? poles4 ,! diff]5ce betwe5 ! magnetic fields produc$ by l & unlike poles is %[n 9 ,figure #ae4 ,illu/ration3 ,fig4 #ae4--,l9es ( ,=ce betwe5 ,l & ,unlike ,poles4 ,a /udy ( ?is illu/ration w greatly assi/ ! m9d 9 conceiv+ h[ attraction & repulsion ( magnetic poles take place4 ,x w be notic$ ! l9es ( =ce betwe5 two nor? poles resi/ ea* o!r & meet abruptly at ! c5t]4 ,! l9es betwe5 a nor? & a s\? pole pass 9 regul> curves4 99,! ,e>? is a ,great ,magnet499 ,! direction assum$ by a compass ne$le is call$ ! magnetic m]idian4 ,! action ( ! e>? on a compass ne$le is exactly ! same z t ( a p]man5t magnet4 ,! fact t a magnetiz$ ne$le places itself 9 ! magnetic m]idian is because ! e>? is a great magnet ) l9es ( =ce pass+ 9 a nor? & s\? direction4 ,! compass ne$le does n g5]ally po9t exactly t[>d ! true ,nor?4 ,?is is because ! magnetic pole ( ! e>? t[>d :i* ! ne$le po9ts is n situat$ at ! same place z ! geographical pole4 99,magnetic ,dip499 ,if a sew+-ne$le is balanc$ s z to be p]fectly horizontal :5 susp5d$ f a silk ?read & is !n magnetiz$1 x w be f\nd t x has lo/ its balance & t ! nor? end po9ts slightly d[nw>d4 ,illu/ration3 ,fig4 #af4--;,a ,simple ,dipp+ ,ne$le4 ,?is is due to ! fact t ! e>? is r\nd & t ! magnetic pole :i* is situat$ 9 ! f> ,nor? is !re=e n on a horizontal l9e ) ! compass1 b bel[ su* a l9e4 ,a magnetic ne$le m\nt$ s z to move freely 9 a v]tical plane1 & provid$ ) a scale = measur+ ! incl9ation1 is call$ a 99,dipp+ ,ne$le499 ,a dipp+ ne$le may be easily made by ?ru/+ a knitt+-ne$le ?r\gh a cork be=e x has be5 magnetiz$4 ,a second ne$le is ?ru/ ?r\gh at "r angles to ! fir/ & ! arrangem5t c>efully balanc$1 s t x w rema9 horizontal :5 re/+ on ! edge ( two glasses4 ,!n magnetize ! fir/ ne$le by /rok+ x ) a b> magnet4 ,:5 x is aga9 re/$ on ! glasses x w be f\nd t ! ne$le no long] balances1 b dips d[nw>d4 99,p]man5t ,magnets99 h a numb] ( useful applications 9 ! con/ruction ( sci5tific in/rum5ts1 voltmet]s1 ammet]s1 telephone receiv]s1 magnetos & a numb] ( o!r devices4 ,9 ord] to secure a v p[]ful magnet = "s purposes a numb] ( /eel b>s are magnetiz$ sep>ately1 & !n rivet$ toge!r4 ,a magnet made 9 ?is way is call$ a comp\nd magnet1 & may h ei!r a b> or a horse-%oe %ape4 ,magnets are usually provid$ ) a s(t piece ( iron call$ an armature or keep]4 ,! keep] is laid across ! poles ( ! magnet :5 ! latt] is n 9 use & pres]ves its magnetism4 ,a bl[ or a fall w di/urb ! magnetic arrangem5t ( ! molecules ( a magnet & greatly weak5 x4 ,! mo/ p[]ful magnet becomes absolutely demagnetiz$ at a r$ heat1 & rema9s s aft] cool+4 ,!re=e if y wi% to pres]ve ! /r5g? ( a magnetic appliance or ! effici5cy ( any electrical in/rum5t provid$ ) a magnet1 d n all[ x to receive r\gh usage4 ,,*apt] ,,ii ,,/atic ,,electricity ,if y take a glass rod & rub x ) a piece ( flannel or silk1 x w be f\nd to h acquir$ a prop]ty :i* x did n =m]ly possess3 namely1 ! p[] ( attract+ to itself su* light bodies z du/ or bits ( ?read & pap]4 ,hold su* a rod ov] "s small bits ( pap] & wat* !m jump up to meet x1 j z if ! glass rod 7 a magnet attract+ small pieces ( iron in/ead ( pap]4 ,! ag5cy at "w to produce ?is my/]i\s p[] is call$ electricity1 f ! ,greek ^w ,elektron1 :i* means amb]4 ,amb] 0 ! fir/ sub/ance f\nd to possess ?is prop]ty4 ,illu/ration3 ,fig4 #ag4--;,an ,electrifi$ ,glass ,rod w ,attract ,small ,bits ( ,pap]4 ,! use ( amb] beg9s ) ! dawn ( civilization4 ,amb] beads h be5 f\nd 9 ! royal tombs at ,myc5ae & at v>i\s places ?r\gh\t ,s>d9ia1 dat+ f at lea/ two ?\s& ye>s be=e our era4 ,amb] 0 us$ by ! anci5t _w z a jewel & = decoration4 ,! anci5t ,syrian woman us$ di/affs made ( amb] = sp9n+4 ,z ! sp9dle :irl$ ar\nd x (t5 rubb$ aga9/ ! sp9n]'s g>m5ts & ?us became electrifi$1 z amb] always does :5 x is rubb$4 ,!n on ne>+ ! gr\nd x drew to itself ! du/ or bits ( *aff or leaves ly+ !re1 or sometimes p]haps attract$ ! fr+e ( ! clo?+4 ,! sp9n] easily saw ?is1 because ! bits ( *aff :i* 7 ?us attract$ w\ld become entangl$ 9 h] ?read unless %e 7 c>eful4 ,! amb] sp9dle 01 !re=e1 call$ ! h>paga or clut*]1 = x seem$ to seize su* light bodies z if x _h invisible talons1 :i* n only grasp$ b held on4 ,?is 0 probably ! fir/ intellig5t obs]vation ( an electrical effect4 ,9 ! eighte5? c5tury1 :5 ,b5jam9 ,frankl9 p]=m$ 8 fam\s kite exp]im5t1 electricity 0 believ$ to be a sort ( fi]y atmosph]ic dis*>ge :i* c\ld be captur$ 9 small quantities & /or$ 9 receptacles su* z ,leyd5 j>s4 ,frankl9 0 ! fir/ to prove t ! lightn+ dis*>ges tak+ place 9 ! heav5s are electrical4 ,! /ory ( 8 exp]im5t is v int]e/+4 ,he secur$ two light /rips ( c$> wood1 plac$ cross-wise & cov]$ ) a silk h&k]*ief = a kite4 ,to ! top ( ! upright /ick ( ! kite 0 fa/5$ a %>p wire ab\t a foot long4 ,! tw9e 0 ( ! usual k9d1 b 0 provid$ ) a %ort piece ( silk ribbon & a key4 ,! purpose ( ! ribbon 0 possible protection aga9/ ! lightn+ runn+ ?r\gh 8 body1 silk be+ a non-conductor1 z w be expla9$ a little f>!r on4 ,! key 0 secur$ to ! junction ( ! silk ribbon & ! tw9e1 to s]ve z a conv5i5t conductor f :i* to draw ! sp>ks--if !y came4 ,he did n h to wait long = a ?und]/orm1 & z he saw x ga!r+ he w5t out ) 8 son1 !n a "y man tw5ty-two ye>s ( age4 ,! great cl\ds roll$ up f ! horizon1 & ! gu/s ( w9d grew fitful & /rong4 ,! kite felt a swi%+ bla/ & began to rise /eadily1 swoop+ ?is way & t z ! breeze caught x4 ,! ?und] mutt]$ ne>] & ne>] & ! ra9 began to patt] on ! grass z ! kite flew high]4 ,! ra9 soon began to fall heavily1 compell+ ,frankl9 & 8 son to take refuge "u a ne>-by %$4 ,! heavy kite1 wet ) wat]1 0 sail+ sluggi%ly :5 sudd5ly a huge l[-ly+ black cl\d travel+ ov]head %ot =? a =k$ flame & ! fla% ( ?und] %ook ! v e>?4 ,! kite mov$ upw>d1 so>+ /raight into ! black mass1 f :i* ! fla%es began to come rapidly4 ,frankl9 wat*$ ! silk ribbon & ! key4 ,!re 0 n a sign4 ,_h he fail$8 ,sudd5ly ! loose fib]s ( ! tw9e erect$ !mselves4 ,! mom5t _h come4 ,)\t a tremor he advanc$ 8 knuckle to ! key4 ,& betwe5 8 knuckle & ! key pass$ a sp>k6 !n ano!r & ano!r4 ,!y 7 ! same k9d ( little sp>ks t he _h made hundr$s ( times ) a glass tube4 ,& !n z ! /orm abat$ & ! cl\ds swept (f t[>ds ! m\nta9s & ! kite flew lazily 9 ! blue1 ! face ( ,frankl9 gleam$ 9 ! glad sun%9e4 ,! great discov]y 0 complete1 8 "n immortal4 ,! cause ( lightn+ is ! accumulation ( ! electric *>ges 9 ! cl\ds1 ! electricity resid+ on ! surface ( ! p>ticles ( wat] 9 ! cl\d4 ,^! *>ges gr[ /rong] z ! p>ticles ( wat] jo9 toge!r & become l>g]4 ,z ! c\ntless multitude ( drops gr[s l>g] & l>g] ! pot5tial is increas$1 & ! cl\d soon becomes heavily *>g$4 ,?r\gh ! effects ( a ph5om5on call$ induction1 & :i* we h already /umbl$ aga9/ 9 ! exp]im5t ) ! tacks & ! magnetic *a91 ! =ce ex]t$ by ! *>ge gr[s /rong] because ( a *>ge ( ! opposite k9d on a neighbor+ cl\d or "s object on ! e>? b5ea?4 ,^! *>ges cont9ually /rive to bur/ across ! int]v5+ air4 ,z soon z ! *>ge gr[s /rong en\gh a vivid fla% ( lightn+1 :i* may be f "o to t5 miles long1 takes place4 ,! heat$ air 9 ! pa? ( ! lightn+ exp&s ) great =ce2 b imm$iately o!r air ru%es 9 to fill ! p>tial vacuum1 ?us produc+ ! t]rify+ s\nds call$ ?und]4 ,9 ! eighte5? c5tury1 electricity 0 believ$ to be a sort ( fi]y atmosph]ic dis*>ge1 z has be5 said4 ,lat] x 0 discov]$ t x seem$ to fl[ l wat] ?r\gh c]ta9 m$iums1 & s 0 ?\ght to be a fluid4 ,mod]n sci5ti/s believe x to be simply a vibratory motion1 ei!r betwe5 adjac5t p>ticles or 9 ! e!r surr\nd+ ^? p>ticles4 ,x 0 e>ly discov]$ t electricity w\ld travel ?r\gh "s m$iums b n ?r\gh o!rs4 ,^! 7 t]m$ respectively conductors & non-conductors or insulators4 ,metals su* z silv]1 copp]1 gold1 & o!r sub/ances l *>coal1 wat]1 etc41 are good conductors4 ,glass1 silk1 wool1 oils1 wax1 etc41 are non-conductors or insulators1 :ile _m o!r sub/ances1 l wood1 m>ble1 pap]1 cotton1 etc41 are p>tial conductors4 ,!re seems to be two k9ds ( electricity1 "o call$ /atic & ! o!r curr5t electricity4 ,! =m] is usually produc$ by friction :ile ! latt] is g5]at$ by batt]ies or dynamos4 ,a v simple & well-kn[n me?od ( g5]at+ /atic electricity is by %uffl+ or slid+ ! feet ov] ! c>pet4 ,! body w !n become *>g$1 & if ! knuckles are pres5t$ to "s metallic object1 su* z a gas-jet or radiator1 a /++ little sp>k w jump out to meet x4 ,illu/ration3 ,f ! au?or's ,wireless ,telegraphy & ,telephony by p]mission4 99,a ,d\ble ,lightn+ ,dis*>ge f a ,cl\d to ! ,e>?499 ,! electricity is produc$ by ! friction ( ! feet slid+ ov] ! c>pet & causes ! body to become electrifi$4 ,w>m a piece ( writ+-pap]1 !n lay x on a wood5 table & rub x briskly ) ! h&4 ,x soon w become /uck to ! table & w n slide along z x did at fir/4 ,if "o corn] is rais$ slightly x w t5d to jump "r back4 ,if ! pap] is lift$ (f ! table x w t5d to cl+ to ! h&s & ! clo?+4 ,if held ne> ! face x w produce a tickl+ s5sation4 ,all ^! ?+s happ5 because ! pap] is electrifi$4 ,x is drawn to ! o!r objects because !y are neutral1 t is1 d n possess an electrical *>ge4 ,illu/ration3 ,fig4 #ai4--;,a ,piece ( ,dry ,writ+-,pap] may be ,electrifi$ by ,rubb+4 ,all exp]im5ts ) /atic electricity p]=m bett] 9 ! w9t] "t1 :5 x is cool & cle>1 ?an 9 ! summ]4 ,! reason is t ! air 9 w9t] is dri] ?an 9 summ]4 ,summ] air conta9s consid]able moi/ure & wat] vapor4 ,wat] vapor is a p>tial conductor ( electricity1 & ! surr\nd+ air w !re=e conduct ! /atic electricity away f y\r app>atus almo/ z fa/ z x c be produc$ 9 ! summ] "t4 ,illu/ration3 ,fig4 #bj4--;,a ,surprise = ! ,cat4 ,"s day dur+ ! w9t] "t1 :5 x is cool & cle>1 & ! cat is ne> a fire or a /ove1 /roke ! cat rapidly ) ! h&4 ,! fur w /& up t[>ds ! h& & a fa9t crackl+ noise w be he>d4 ,! crackl+ is caus$ by small sp>ks pass+ betwe5 ! cat & ! h&4 ,if ! exp]im5t is p]=m$ 9 a d>k room1 ! sp>ks may be pla9ly se54 ,if y pres5t y\r knuckle to ! cat's nose a sp>k w jump to y\r knuckle & some:at surprise ! cat4 ,if ! day is brisk & cool1 s t ev]y?+ outside is froz5 & dry1 try comb+ ! hair ) a rubb] comb4 ,y\r hair w /& up all ov] y\r head in/ead ( ly+ d[n flat1 & ! fa9t crackl+ noise1 %[+ t sp>k+ is tak+ place z ! comb passes ?r\gh ! hair1 w be pla9ly he>d4 ,! electricity is produc$ by ! friction betwe5 ! hair & ! comb4 ,electricity may be produc$ by friction betwe5 a numb] ( sub/ances4 ,a h>d rubb] rod1 a glass rod1 a rubb] comb or a /ick ( seal+-wax may be v easily electrifi$ by rubb+ !m briskly ) a piece ( dry1 w>m flannel4 99,electroscopes99 are devices = detect+ ! pres5ce ( /atic electricity4 ,illu/ration3 ,fig4 #ba4--;,a ,pap] ,electroscope4 ,a v simple =m ( electroscope may be made 9 mu* ! same mann] z ! pap] compass describ$ 9 ! la/ *apt]4 ,x may be cut out ( writ+-pap] & m\nt$ on a p9 /uck ?r\gh a cork4 ,if an electrifi$ rod is held ne> ! electroscope x may be made to :irl ar\nd 9 ! same mann] z a compass ne$le :5 a b> magnet is br\ght to x4 99,! ,pi?-,ball ,electroscope99 is a v simple device1 9 :i* a ball ( cork or eld] pi? is hung by a f9e silk ?read f an insulat$ support4 ,a suitable electroscope may be made f a glass bottle hav+ a piece ( wire ?ru/ into ! cork to support ! pi? ball4 ,:5 ! electrifi$ rod is pres5t$ to ! pi? ball1 x w fly out t[>ds ! rod4 ,illu/ration3 ,fig4 #bb4--;,a ,pi?-,ball ,electroscope4 ,if ! pi? ball is p]mitt$ to t\* ! glass rod1 ! latt] w transf] "s ( its electricity & *>ge ! ball4 ,almo/ imm$iately ! pi? ball w fly away f ! glass rod1 & no matt] h[ ne> ! rod is br\ght1 x w refuse to be t\*$ aga94 ,?is action is mu* ! same z t ( ! magnetiz$ ne$le susp5d$ f a ?read :5 ! simil> pole ( ! magnet is pres5t$ to x4 ,:5 ! rod is fir/ pres5t$ to ! pi? ball1 ! latt] is neutral & does n possess an electrical *>ge4 ,:5 ! rod has t\*$ ! ball1 h[ev]1 "s ( ! electricity f ! rod passes to ! ball1 & aft] ?is !y w repel ea* o!r4 ,! reason is t ! rod & ! ball are simil>ly *>g$ & simil>ly *>g$ bodies w repel ea* o!r4 ,illu/ration3 ,fig4 #bc4--;,a ,d\ble ,pi?-,ball ,electroscope4 ,if y are a good obs]v] y might h notic$ :5 exp]im5t+ ) an electrifi$ rod & ! small bits ( pap]1 t "s ( ! little pap]s 7 fir/ attract$ & flew upw>ds to ! rod1 b hav+ once t\*$ x1 7 quickly repell$4 ,! repulsion betwe5 two simil>ly electrifi$ bodies may be %[n by a d\ble electroscope4 ,a d\ble electroscope is made by hang+ two pi? balls on two silk ?reads f ! same support4 ,electrify a glass rod & t\* x to ! pi? balls4 ,!y w imm$iately fly ap>t because !y are electrifi$ ) ! same k9d ( electricity4 99,! ,gold-leaf ,electroscope99 is "o ( ! mo/ s5sitive means :i* c be employ$ to detect small am\nts ( /atic electricity4 ,illu/ration3 ,fig4 #bd4--;,a ,gold-,leaf ,electroscope4 ,x is a v simple in/rum5t & is easily made 9 a %ort "t4 ,a c\ple ( n>r[ /rips ( ! ?9ne/ tissue pap]1 or1 bett] /ill1 two /rips ( gold leaf1 are hung f a support 9 a wide-m\!d glass bottle :i* s]ves at once to insulate & protect ! /rips f draughts ( air4 ,! m\? ( ! j> is clos$ by a plug ( p>aff9 wax1 ?r\gh ! c5t] ( :i* passes a small glass tube4 ,a /iff copp] wire passes ?r\gh ! tube4 ,! l[] end ( ! wire is b5t at "r angles to furni% support = ! /rips ( gold leaf4 ,a r\nd %eet metal disk ab\t ! size ( a qu>t] is sold]$ to ! upp] end ( ! rod4 ,if an electrifi$ /ick ( seal+-wax or a glass rod is pres5t$ to ! disk ( ! electroscope1 ! /rips w repel ea* o!r v /rongly4 ,if ! in/rum5t is s5sitive1 ! /rips %\ld beg9 to div]ge "s "t be=e ! rod rea*es ! disk4 ,x is possible to make an electroscope s s5sitive t *ips =m$ by %>p5+ a p5cil w cause ! /rips to div]ge4 99,!re are two k9ds ( /atic electricity499 ,rub a glass rod ) a piece ( silk & !n susp5d x 9 a wire /irrup z %[n 9 ,figure #be4 ,excite a second rod also ) a piece ( silk & br+ x ne> "o end ( ! susp5d$ "o4 ,! susp5d$ rod is repell$ & w sw+ away f ! "o held 9 ! h&4 ,illu/ration3 ,fig4 #be4--,me?od ( ,susp5d+ an ,electrifi$ ,rod 9 a ,wire ,/irrup4 ,n[ rub a /ick ( seal+-wax ) a piece ( flannel until ! seal+-wax is electrifi$4 ,!n br+ ! /ick ( seal+-wax ne> ! end ( ! susp5d$ rod4 ,! rod w be attract$ to ! seal+-wax4 ,if y exp]im5t fur!r y w f9d t two /icks ( seal+-wax w repel ea* o!r4 ,illu/ration3 ,fig4 #bf4--,simil>ly ,electrifi$ ,bodies ,repel ,ea* ,o!r4 ,dissimil>ly ,electrifi$ ,ones ,attract ,ea* ,o!r4 ,?is exp]im5t indicates t !re are two k9ds ( electrification3 "o develop$ by rubb+ glass ) silk & ! o!r develop$ by rubb+ seal+-wax ) flannel4 ,9 ! fir/ in/ance1 ! glass rod is said to be positively electrifi$1 & 9 ! latt] case ! seal+-wax is negatively electrifi$4 ,! same law t applies to magnetism also holds true 9 ! case ( /atic electricity1 & simil>ly electrifi$ bodies w repel ea* o!r & dissimil> ones attract4 99,! ,electrophorus99 is an in/rum5t devis$ by ,volta 9 #agge = ! purpose ( obta9+ /atic electricity4 ,illu/ration3 ,fig4 #bg4--,! ,electrophor\s ,x is easily con/ruct$ & w furni% a s\rce ( electricity = q a numb] ( int]e/+ exp]im5ts4 ,an electrophorus consi/s ( two p>ts1 a r\nd cake ( res9\s mat]ial ca/ 9 a metal di% or pan1 & a r\nd metal disk :i* is provid$ ) an insulat+ h&le4 ,to make an electrophorus1 fir/ procure an old cake or pie t91 & fill x ) bits ( res9 or seal+-wax4 ,place ! pan 9 a w>m spot ^u ! /ove :]e ! res9 w melt1 tak+ c>e n to ov]heat or x w spatt] & possibly take fire4 ,z ! res9 melts1 add m until ! pan is ne>ly full4 ,:5 all is melt$1 remove f ! fire & set x away :]e x may cool & h>d5 9 ! pan )\t be+ di/urb$4 ,cut a circul> disk out ( %eet t91 z9c1 or copp]1 mak+ ! diamet] ab\t two in*es less ?an t ( ! pie pan4 ,sold] a small cyl9d] ( t9 or %eet brass to ! c5t] ( ! disk to aid 9 support+ ! h&le4 ,! latt] is a piece ( glass tub+ ab\t ?ree-qu>t]s ( an in* 9 diamet] & f\r or five in*es long1 plac$ 9 ! c5t] ( ! cyl9d] & secur$ ) molt5 seal+-wax4 ,9 ord] to use ! electrophorus ! res9\s cake mu/ fir/ be beat5 or briskly rubb$ ) a piece ( w>m wool5 clo? or flannel4 ,!n place ! disk on ! cake hold+ ! insulat+ h&le ) ! "r h&4 ,t\* ! cov] or ! disk mom5t>ily ) ! =ef+] ( ! left h&4 ,aft] ! f+] is remov$1 raise ! disk f ! cake by pick+ x up ) ! glass insulat+ h&le4 ,! disk w n[ be f\nd heavily *>g$ ) positive electricity1 & if ! knuckles are pres5t$ to ! edge1 a sp>k w jump out to meet !m4 ,illu/ration3 ,fig4 #bh4--;,an ,electric ,frog-,pond4 ,! cov] may !n be replac$1 t\*$1 & once m remov$4 ,x w yield any numb] ( sp>ks1 ! res9\s cake only ne$+ to be re*>g$ by rubb+ once 9 a long :ile4 99,an ,electric ,frog-,pond99 may be exp]im5t$ ) by cutt+ out "s small tissue-pap] frogs4 ,moi/5 !m a little & lay !m on ! cov] ( ! electrophorus4 ,t\* ! electrophorus ) ! f+] & !n raise x ) ! insulat+ h&le4 ,if ! frogs are n too wet !y w jump f ! cov] ^u ! table z soon z ! cov] is rais$4 ,,*apt] ,,iii ,,/atic ,,electric ,,ma*9es ,a ,cyl9d] ,electric ,ma*9e ,! electrophorus describ$ 9 ! la/ *apt] is capable ( furni%+ suffici5t electricity = _m int]e/+ exp]im5ts1 b = ! purpose ( procur+ l>g] supplies ( electricity1 a /atic electric ma*9e is necess>y4 ,an electric ma*9e is compos$ ( two p>ts1 "o = produc+ ! electricity by ! friction ( two surfaces rubb+ aga9/ ea* o!r1 & ! o!r an arrangem5t = collect+ ! electricity ?us =m$4 ,! e>lie/ =m ( electric ma*9e consi/$ ( a ball ( sulphur fix$ ^u a sp9dle :i* c\ld be rotat$ by means ( a crank4 ,:5 ! dry h&s 7 press$ aga9/ ! sulphur by a p]son /&+ on a cake ( res91 :i* insulat$ him1 sp>ks c\ld be drawn f 8 body4 ,lat] a lea!r cu%ion 0 sub/itut$ = ! h&s1 & a glass cyl9d] = ! ball ( sulphur1 s t ! frictional electric ma*9e n[ consi/s ( a cyl9d] or a disk ( glass m\nt$ ^u a horizontal axis capable ( be+ turn$ by a h&le4 ,a lea!r cu%ion1 /uff$ ) horsehair & cov]$ ) a p[d]$ amalgam ( z9c or t91 presses aga9/ "o side ( ! cyl9d]4 ,a prime conductor 9 ! %ape ( an elongat$ cyl9d] pres5ts a r[ ( f9e metal spikes1 l ! tee? ( a rake1 to ! opposite side4 ,a flap ( silk atta*$ to ! lea!r cu%ion passes ov] ! cyl9d] & cov]s ! upp] half4 ,illu/ration3 ,fig4 #bi4--;,front ,view ( a ,cyl9d] ,electric ,ma*9e4 ,:5 ! h&le ( ! ma*9e is turn$1 ! friction produc$ betwe5 ! lea!r cu%ion & ! glass g5]ates a supply ( positive electricity on ! glass1 :i* is collect$1 z ! cyl9d] revolves1 by ! r[ ( %>p po9ts1 & transf]r$ to ! prime conductor4 ,! fir/ ?+ requir$ 9 ! con/ruction ( an electric ma*9e is a l>ge glass bottle hav+ a capacity ( f two to f\r qu>ts4 ,! insulat+ p[] ( glass v>ies consid]ably4 ,common gre5 glass 7n :ite glass color$ gre5 by copp]1 b glass su* z ! telegraph insulators are made f7 g5]ally insulates ! be/4 ,"s sorts ( :ite glass1 ! ,bohemian especially1 are good insulators1 b ?is quality w n usually be f\nd 9 ord9>y bottles4 ,illu/ration3 ,fig4 #cj4--,me?od ( ,f9d+ ! ,c5t] ( a ,circle4 ,select a smoo? bottle :i* has no lett]+ emboss$ ^u x1 & /& x ^u a piece ( :ite pap]4 ,trace on ! pap] a l9e ar\nd ! circumf]5ce ( ! bottle s t ! circle ?us =m$ is ( ! same size z ! bottom ( ! bottle4 ,lay a c>p5t]'s squ>e on ! circle s t ! po9t ,c j t\*es ! circumf]5ce4 ,draw a l9e f ,a to ,b :]e ! sides ( ! squ>e cut ! circumf]5ce4 ,! po9t 9 ! middle ( ?is l9e is ! c5t] ( ! circle4 ,place ! pap] on ! bottom ( ! bottle s t ! circle co9cides ) ! circumf]5ce1 & m>k ! c5t] ( ! bottle4 ,! bottle mu/ n[ be drill$4 ,?is is accompli%$ ) a small ?ree-corn]$ file1 ! end ( :i* has be5 brok5 (f s z to =m a ragg$ cutt+ edge4 ,! file is set 9 a brace & us$ l an ord9>y drill4 ,dur+ ! bor+ process ! drill mu/ be frequ5tly lubricat$ ) a mixture ( gum camphor & turp5t9e4 ,! drill+1 :i* w require almo/ an h\r be=e ! glass is pi]c$1 if ! bottle is a ?ick "o1 %\ld be p]=m$ sl[ly & c>efully1 s z to avoid all dang] ( crack+ ! glass4 ,! hole1 :5 f9i%$1 %\ld be f "o-qu>t] to ?ree-eigh?s ( an in* 9 diamet]4 ,aft] ! hole has be5 bor$1 fit a wood5 plug into ! neck ( ! bottle & cem5t x !re ) a mixture compos$ ( "o-half a p\nd ( res91 five ounces ( beeswax1 "o-qu>t] ( an ounce ( pla/] ( ,p>is1 & ?ree-qu>t]s ( an ounce ( r$ o*]1 melt$ toge!r ov] a mod]ately w>m /ove4 ,dip ! plug 9 ! molt5 cem5t & =ce x into ! neck ( ! bottle4 ,:5 ! cem5t dries x w be impossible to remove x4 ,! sizes ( bottles v>y1 s t x is q impossible to give dim5sions :i* mu/ be closely foll[$ 9 con/ruct+ ! ma*9e4 ,^? 9 ! text are approximate4 ,! draw+s h be5 made to scale s z to %[ ! proportions ! p>ts be> to ea* o!r4 ,a heavy wood5 base w be requir$ to m\nt ! ma*9e on4 ,two uprights are m\nt$ on ! base to support ! axis ( ! bottle4 ,?r\gh "o ( ^! bore a hole ( ! same diamet] z ! wood5 plug fitt$ 9 ! neck ( ! bottle4 ,! end ( ! wood5 plug project+ ?r\gh ! upright is not*$ & fitt$ ) a crank s t ! bottle may be revolv$4 ,! h&le ( ! crank is an ord9>y spool hav+ "o flange cut (f & m\nt$ ) a screw & a wa%]4 ,illu/ration3 ,fig4 #ca4--,! ,rubb]4 ,! ma*9e is n[ ready = ! rubb] & prime conductor4 ,! rubb] is a piece ( wood "o in* squ>e & f six to eight in*es long4 ,a piece ( undress$ lea!r is tack$ on z %[n 9 ! illu/ration & /uff$ ) horsehair4 ,! wood is %ellack$ & cov]$ ) t9-foil previ\s to tack+ on ! lea!r4 ,a /rip ( wood1 two in*es wide & "o-half an in* ?ick1 is fa/5$ to ! back ( ! rubb]4 ,! /rip %\ld be j long en\gh s t :5 ! l[] end re/s on ! base ! rubb] is level ) ! axis ( ! bottle4 ,! l[] end may be fa/5$ to ! base by means ( a small brass h+e4 ,two rubb] b&s /ret* f hooks betwe5 ! rubb] & ! base s z to pull ! =m] tightly aga9/ ! bottle4 ,! illu/ration %[s a me?od ( m\nt+ ! rubb] on a foot-piece held to ! base ) a ?umb-nut s t x may be slid back & =? & ! pressure v>i$ at w4 ,! prime conductor is =m$ f a piece ( curta9-pole two in*es 9 diamet] & eight in*es long4 ,! ends are r\nd$ ) a rasp & !n smoo!d ) s&pap]4 ,! :ole surface is !n %ellack$ & cov]$ ) a lay] ( t9foil4 ,! heads ( a numb] ( dressmak]'s p9s are cut (f1 & ! p9s =c$ into ! side ( ! prime conductor ) a pair ( p9c]s4 ,!y %\ld =m a r[ l ! tee? ( a rake ab\t ?ree-eigh?s ( an in* ap>t4 ,a hole is bor$ 9 ! c5t] ( ! "u side ( ! prime conductor to receive a glass rod "o-half in* 9 diamet]4 ,a second hole ( ! same size is bor$ 9 ! base 9 su* a position t :5 ! glass rod is 9 place1 ! tee? on ! prime conductor are on a level ) ! axis ( ! bottle1 & _! po9ts ab\t #c-cb ( an in* away f ! glass4 ,! glass rod mu/ be us$ 9 ord] to insulate ! prime conductor & prev5t ! escape ( ! electricity4 ,x is secur$ ) "s ( ! cem5t describ$ on page #cc4 ,a piece ( wat]-gauge glass may be us$ 9 place ( a glass rod4 ,illu/ration3 ,fig4 #cb4--,! ,prime ,conductor or ,collector4 ,a /rip ( oil$ silk1 or 9 its place a /rip ( silk :i* has be5 %ellack$1 eight or n9e in*es wide1 & long en\gh to rea* half-way ar\nd ! bottle1 is tack$ to ! rubb] s t ! silk cov]s ! upp] half ( ! cyl9d] & comes ov] to )9 "o-qu>t] ( an in* ( ! /eel po9ts4 ,! ma*9e is n[ complete1 & :5 ! h&le is turn$ rapidly1 y w be able to draw sp>ks f ! prime conductor4 ,! sp>ks w probably be v %ort1 ab\t "o-half ( an in* long4 ,^! c be increas$1 h[ev]1 to ?ree in*es1 if ! glass is ( ! "r quality1 by treat+ ! rubb] ) amalgam4 ,! amalgam is =m$ by melt+ "o ounce ( t9 & add+ to x "o ounce ( z9c 9 small bits4 ,z soon z ! z9c has also melt$ add to ! mixture two ounces ( m]cury :i* has be5 previ\sly w>m$4 ,be c>eful n to inhale any ( ! vapor dur+ ?is op]ation4 ,p\r ! mixture into a vessel ( cold wat]1 :i* w r$uce ! metal to small gra9s4 ,p\r (f ! wat] & gr9d ! amalgam to a p[d] by p\nd+ ! gra9s ) a hamm]4 ,! lea!r rubb] %\ld be ?9ly sme>$ ) l>d & ! p[d]$ amalgam rubb$ on x4 ,9 ord] to obta9 ! greate/ effect f an electric ma*9e1 x mu/ be c>efully fre$ f du/ & p>ticles ( amalgam adh]+ to ! glass1 & ! insulat+ column rubb$ ) a w>m wool5 clo?4 ,! be/ results are obta9$ by plac+ ! ma*9e ne> a /ove or radiator :]e x is w>m4 ,illu/ration3 ,fig4 #cc4--,! ,complete ,cyl9d] ,electric ,ma*9e4 ,a ,wim%ur/ ,ma*9e ,! ,wim%ur/ ,ma*9e consi/s ( two v>ni%$ glass plates revolv+ 9 opposite directions4 ,on ! outside ( ea* ( ^! plates are cem5t$ a numb] ( t9foil sectors1 arrang$ radially4 ,two conductors at "r angles to ea* o!r ext5d obliquely across ! plates1 "o at ! back & ! o!r at ! front4 ,^! conductors ea* t]m9ate 9 bru%es ( t9sel :i* electrically excite ! sectors z ! plates revolve4 ,! electricity is collect$ by a set ( collectors arrang$ 9 a some:at simil> mann] to ! collector on ! cyl9d] electric ma*9e4 99,! ,glass ,plates99 are ea* eighte5 in*es 9 diamet]4 ,pur*ase two panes ( cle> glass tw5ty in*es squ>e f a glass deal]4 ,! :ite glass is f> pref]able to ! gre5 glass & w make ! be/ electric ma*9e4 ,! plates %\ld be ( ! ?ickness kn[n z s+le light & %\ld be p]fectly free f wavy places1 bubbles1 or o!r imp]fections4 ,illu/ration3 ,fig4 #cd4--,pap] ,patt]n = lay+ out ! ,plates4 ,! "w is fir/ laid out on a piece ( /iff pap] tw5ty in*es squ>e z a patt]n4 ,describe a circle f\r in*es 9 diamet]4 ,us+ ! same c5t]1 draw o!r circles1 mak+ !m respectively eight1 sixte51 & eighte5 in*es 9 diamet]4 ,!n m>k sixte5 radial l9es1 f ! c5t]1 mak+ !m equal di/ances ap>t1 z %[n 9 ,figure #cd4 ,illu/ration3 ,fig4 #ce4--,plate ) ,sectors 9 ,position1 & a ,patt]n = ! ,sectors4 ,lay "o ( ! glass panes ov] ! patt]n & cut out a glass circle eighte5 in*es 9 diamet]1 or p]haps y may be able to h a glazi] d ! cutt+ = y & s save consid]able tr\ble & possible breakage4 ,two su* plates %\ld be made4 ,! ,sectors are cut f heavy flat t9foil accord+ to ! patt]n %[n 9 ,figure #ce4 ,!y %\ld be made "o in* & "o-half wide at ! wide end & ?ree-qu>t]s ( an in* at ! o!r end4 ,!y are ea* f\r in*es long4 ,?irty-two su* sectors are requir$4 ,! easie/ way to make !m is to cut out a patt]n f heavy c>dbo>d to s]ve z a guide4 ,clean & dry bo? ( ! glass plates v c>efully & !n give !m ea* two ?9 coats ( :ite %ellac4 ,aft] !y h be5 dri$1 lay "o ( ! plates on ! pap] patt]n s t ! outside ( ! plate w co9cide ) ! l>ge/ circle on ! pap]4 ,!n place a weight 9 ! c5t] ( ! plate s t x w n move1 & /ick sixte5 ( ! t9foil sectors on ! plate ) ?ick %ellac4 ,! sectors are arrang$ symmetrically on ! plate1 us+ ! eight-in* & sixte5-in* circles & ! radial l9es z guides4 ,bo? plates %\ld be treat$ 9 ?is mann]4 ,ea* sector %\ld be c>efully press$ d[n on ! glass1 s t x w /ick smoo?ly )\t air-bubbles or creases4 ,:5 all ! sectors are 9 place ! plates w appe> l t %[n 9 ,figure #ce4 99,! ,bosses99 w h to be turn$ out at a wood-work+ mill or at "s place :]e !y h a turn+-la!4 ,! bosses are f\r in*es 9 diamet] at ! l>ge end & "o in* & "o-half at ! o!r4 ,a groove is turn$ ne> ! small end ( ea* to accommodate a r\nd lea!r belt4 ,a hole %\ld be made 9 ea* boss ab\t half-way ?r\gh f ! small end4 ,^! holes %\ld be bu%$ ) a piece ( brass tub+ hav+ an inside diamet] ( "o-half in*4 ,! tub+ %\ld g into ! hole v snugly & be a driv5 fit4 ,illu/ration3 ,fig4 #cf4--;,a ,side ,view ( "o ( ! ,bosses1 %[+ ! ,brass ,bu%+ us$4 ,! bosses %\ld bo? be giv5 a coat ( %ellac1 & aft] ?is is dry1 fa/5$ to ! glass plates on ! same side to :i* ! t9foil sectors are atta*$4 ,! be/ plan is to lay ! disks on ! pap] patt]n & adju/ !m until ! out] edge co9cides ) ! l>ge/ circle4 ,!n apply "s bi*romate glue to ! flat surface ( "o ( ! bosses & place ! latt] 9 ! c5t] ( ! plate 9 l9e ) ! smalle/ circle4 ,place a weight on ! boss to hold x d[n firmly aga9/ ! plate & leave x ov] night1 or = t5 or twelve h\rs1 until ?or\ghly dry4 ,! glue is prep>$ by plac+ "s high-grade glue 9 a t9 cup & cov]+ x ) cold wat]4 ,all[ x to /& until ! glue absorbs all ! wat] x w & becomes s(t4 ,!n p\r ! wat] (f & add en\gh glacial acetic acid to cov] ! glue4 ,heat ! mixture until x is r$uc$ to a liquid1 /irr+ x until x is p]fectly smoo?4 ,add a teaspoonful ( p[d]$ bi*romate ( pota% to ! glue4 ,! glue mu/ n[ be kept 9 ! d>k1 = sunlight w set ! glue s t x becomes insoluble4 ,! ,frame ( ! ma*9e is compos$ ( two /rips tw5ty-five in*es long1 ?ree in*es wide1 & an in* & "o-half 9 ?ickness1 & two cross-pieces ( ! same ?ickness & wid? fifte5 in*es long4 ,illu/ration3 ,fig4 #cg4--,! ,frame4 ,not*es are cut at bo? sides ( ! base to admit ! feet ( ! uprights4 99,! ,uprights99 are sev5te5 in*es long1 ?ree in*es wide1 & "o & "o-half in*es ?ick4 ,illu/ration3 ,fig4 #ch4--,! ,upright4 ,! not* at ! foot is cut ! same wid? z ! ?ickness ( ! long memb]s ( ! frame & is arrang$ s t :5 fitt$ 9 place1 ! foot ( ! upright w re/ on ! table 9 l9e ) ! bottom ( ! cross-pieces4 99,! ,driv+-,:eels99 are turn$ out ( wood on a la!4 ,!y are sev5 in*es 9 diamet] & sev5-eigh?s ( an in* ?ick4 ,a groove %\ld be turn$ 9 ! edge to c>ry a small r\nd lea!r belt4 ,! :eels are m\nt$ on a wood5 axle made f a r\nd curta9-pole4 ,!y are glu$ to ! axle & arrang$ s t ! grooves w fall directly und]nea? ! pulleys turn$ 9 ! bosses4 ,illu/ration3 ,fig4 #ci4--,! ,driv+-,:eels & ,axle4 ,! ends ( ! axle pass ?r\gh ! uprights1 five in*es above ! bottom4 ,! front end ( ! axle is fitt$ ) a crank & a h&le4 ,illu/ration3 ,fig4 #dj--,! ,boss & ,axle4 ,= sake ( cle>ness1 ! ,plate is n %[n4 ,! plates are m\nt$ on %ort iron axles pass+ ?r\gh ! top ( ! upright into ! brass bu%+s4 ,"o end ( ea* ( ! axles is fil$ flat :]e x passes ?r\gh ! wood upright s t x may be firmly held by a set-screw & prev5t$ f revolv+4 ,fa/5 a small fib] wa%] to ! c5t] ( "o glass disk s t x w sep>ate ! plates & prev5t !m f t\*+ :5 revolv+4 ,! collectors1 quadrant rods1 etc41 are m\nt$ on glass rods "o in* 9 diamet]4 ,! bottoms ( ! rods fit 9 holes 7,h ,h7 bor$ 9 ! cross-pieces ( ! base1 ,figure #cg4 ,! upp] ends are ea* fitt$ ) a brass ball two in*es 9 diamet]4 ,! balls are m\nt$ on ! rods by sold]+ a piece ( brass tub+ to ! ball & slipp+ x ov] ! rod4 ,! rods %\ld be ( ! prop] l5g? to br+ ! c5t] ( ! balls on a l9e ) ! c5t] ( ! plates4 ,illu/ration3 ,fig4 #da--,%[+ h[ ! ,ball1 ,comb1 etc41 are m\nt$ on ! ,glass ,rod4 ,make two =ks z %[n 9 ,figure #db out ( brass rod1 ?ree-sixte5?s ( an in* 9 diamet] & sold] brass balls at ! ends4 ,! =ks are elev5 in*es long4 ,a numb] ( small holes mu/ be bor$ 9 ! prongs & p9s made by cutt+ ord9>y dressmak]s' p9s 9 half & sold]+ !m 9 place4 ,^! p9s1 m\nt$ on ! =ks1 =m ! combs or collectors4 ,bore a horizontal hole ?r\gh ea* ( ! brass rods on ! top ( ! glass rods & pass ! %anks ( ! =ks ?r\gh & sold] !m 9 place4 ,"o ( ! %anks may be provid$ ) a dis*>ge ball at ! end z %[n by ,d ,b 9 ,figure #dd4 ,! o!r is provid$ ) a h>d rubb] h&le made f a piece ( rod4 ,bore a ?ree-eigh?s hole directly 9 ! top ( ea* brass ball to receive ! quadrant rods =m+ ! sp>k-gap4 ,illu/ration3 ,fig4 #db4--;,a ,comb or ,collector4 ,! quadrant rods ext5d ov] ! top ( ! plates & are ?ree-eigh?s ( an in* 9 diamet]4 ,!y are loose 9 ! tops ( ! balls s t !y may be mov$ ab\t or remov$ entirely4 ,a small brass ball ?ree-qu>t]s ( an in* 9 diamet] %\ld be sold]$ to ! top ( "o ( ! quadrant rods & a simil> ball two in*es 9 diamet] to ! o!r4 ,illu/ration3 ,fig4 #dc4--,%[+ h[ ! ,t9sel ,bru%es are arrang$ on ! ,neutraliz] ,rods4 ,two l>ge brass balls1 two in*es 9 diamet]1 are fitt$ ov] ! ends ( ! axles1 :i* project ?r\gh ! uprights4 ,bore a "o-qu>t]-in* hole ?r\gh ea* ball at "r angles to ! axle & slip a "o-qu>t]-in* brass rod ?r\gh & sold] x fa/4 ,illu/ration3 ,fig4 #dd4--,! ,complete ,wim%ur/ ,electric ,ma*9e4 ,b ,b ,b ,b1 ,bru%es4 ,c ,c1 ,combs4 ,d ,b1 ,dis*>ge ,ball4 ,i ,i1 ,glass ,rods4 ,h1 ,h&le4 ,q ,q1 ,quadrant ,rods4 ,s ,s ,s ,s ,s1 ,sectors4 ,s ,g1 ,sp>k-,gap4 ,p ,p1 ,driv+-,:eels4 ,= ! sake ( cle>ness1 sev]al ( ! sectors are n %[n4 ,! ends ( ! rods %\ld be tipp$ ) a bun* ( t9sel or f9e copp] wires & be curv$ s t ! bru%es s =m$ w j t\* ! sectors on ! disks :5 ! latt] are revolv$4 ,^! are ! neutraliz]s & are arrang$ 9 ! approximate positions %[n 9 ,figure #dd4 ,! driv+-:eels are connect$ to ! bosses by means ( small r\nd lea!r belts4 ,! belt at ! re> ( ! ma*9e is cross$ 9 ord] to make ! plates revolve 9 opposite directions4 ,if ! ma*9e has be5 prop]ly built x is n[ ready = op]ation4 ,x may be necess>y to *>ge ! ma*9e ! fir/ "t t x is us$ by t\*+ sev]al ( ! sectors ) ! *>g$ cov] ( an electrophorus4 ,!n if ! h&le is turn$ ! accumulat$ electricity %\ld dis*>ge across ! sp>k-gap at ! top ( ! ma*9e 9 ! =m ( bright blue sp>ks4 ,exp]im5ts ) an ,electric ,ma*9e ,_m int]e/+ exp]im5ts c be p]=m$ ) an electric ma*9e4 ,! numb] is almo/ unlimit$4 ,a few ( ! mo/ in/ructive ones are describ$ bel[4 ,o!rs c be f\nd 9 almo/ any text book on physics4 99,! ,leyd5 j>99 consi/s ( a glass j> coat$ ) t9foil "p way up on bo? ! outside & inside4 ,?r\gh ! wood5 /opp] passes a brass rod or a heavy copp] wire :i* connects ) ! inn] coat+ ( t9foil by means ( a small brass *a94 ,! upp] & outside end ( ! rod usually t]m9ates 9 a brass ball or knob4 ,x is a v simple matt] to make a good ,leyd5 j>4 ,illu/ration3 ,fig4 #de4--,! ,leyd5 ,j>4 ,! j> mu/ be ?or\ghly clean$ & dri$ be=e coat+4 ,! inside is !n giv5 a ?or\gh bru%+ ov] ) %ellac or v>ni%4 ,be=e x is dry1 c>efully ins]t ! t9-foil & press x smoo?ly aga9/ ! glass4 ,! outside ( ! j> is treat$ & coat$ 9 ! same mann]4 ,! inside & outside ( ! bottom are also coat$ by cutt+ ! t9foil 9 circul> pieces & %ellack+ !m on4 ,9 ord] to *>ge ! ,leyd5 j>1 grasp x 9 ! h& ne> ! bottom & hold ! knob aga9/ ! prime conductor :ile turn+ ! h&le ( ! ma*9e4 ,illu/ration3 ,fig4 #df4--;,a ,wood5 ,mort> = ,ignit+ ,gunp[d]4 99,ignit+ gunp[d]499 ,bore a hole "o-half in* 9 diamet] & "o in* deep 9 a block ( h>dwood4 ,pass two small brass wires ?r\gh holes 9 ! sides1 lett+ ! ends ( ! wires be ab\t "o-eigh? ( an in* ap>t4 ,p\r a little gunp[d] 9 loosely ov] ! wires4 ,tie a piece ( ?or\ghly moi/5$ cotton tw9e1 ?ree in*es long1 to "o ( ! wires & atta* x to ! outside coat+ ( a *>g$ ,leyd5 j>4 ,connect ! knob ( ! j> to ! o!r wire4 ,! gunp[d] w imm$iately explode4 ,keep ! face & h&s away f ! gunp[d] :5 p]=m+ ?is exp]im5t4 ,illu/ration3 ,fig4 #dg4--;,an ,electric ,umbrella4 99,electric ,umbrella499 ,! repulsion ( simil>ly electrifi$ bodies :i* 0 illu/rat$ by ! action ( ! pi? ball electroscope may be bett] illu/rat$ by pa/+ "s n>r[ /ream]s ( tissue pap] ab\t "o-eigh? ( an in* wide & f\r in*es long to a small cork cov]$ ) t9foil4 ,! cork is m\nt$ on ! upp] end ( a /iff copp] wire support$ 9 a bottle4 ,:5 ! wire is connect$ to ! prime conductor & ! ma*9e set 9 motion1 ! /rips w spread out l an umbrella4 99,lightn+ ,bo>d499 ,a pane ( glass is ?or\ghly clean$ & !n giv5 a coat ( %ellac or v>ni%4 ,be=e ! v>ni% is dry1 press on a piece ( t9foil l>ge en\gh to cov] "o side ( ! glass & rub x d[n smoo?ly4 ,illu/ration3 ,fig4 #dh4--;,a ,lightn+ ,bo>d4 ,aft] ! %ellac or v>ni% is dry1 cut ! t9foil up into innum]able little squ>es ) a %>p knife & rul]1 leav+ two solid /rips ( t9foil at ! ends ( ! glass pane4 ,! pane is m\nt$ by cem5t+ x 9 a slot 9 ! cork ( a bottle4 ,connect "o ( ! t9foil /rips to ! prime conductor & ! o!r to ! e>? or ! body4 ,:5 ! ma*9e is turn$1 innum]able little sp>ks w pass betwe5 ! t9foil squ>es & give an appe>ance v simil> to t ( lightn+4 ,illu/ration3 ,fig4 #di4--;,an ,electric ,dance4 99,! ,electrical ,dance499 ,a numb] ( little balls ( cork or pi? are enclos$ 9 a cyl9d] ( glass ab\t two & "o-half or ?ree in*es high =m$ by cutt+ (f ! top ( a lamp *imney4 ,! top & bottom ( ! cyl9d] are clos$ by two circul> pieces ( %eet brass or copp]4 ,! top disk is connect$ to ! prime conductor :ile ! bottom "o is connect$ to ! rubb]4 ,:5 ! ma*9e is set 9 motion1 ! little balls w dance up & d[n4 ,bits ( fea!r or pap] cut to repres5t figures ( m5 & wom5 may be us$ z well z pi? or cork balls4 99,! ,electric ,:irl499 ,! :irl consi/s ( an ,s %ap$ piece ( brass wire1 po9t$ at bo? ends & support$ on a ne$le by a little conical depression made 9 ! c5t] ) a pun*4 ,illu/ration3 ,fig4 #ej4--;,an ,electric ,:irl4 ,! ne$le is /uck 9 a cork 9 ! top ( a bottle & connect$ ) ! prime conductor ( ! electric ma*9e4 ,:5 ! latt] is set 9 motion1 ! :irl w comm5ce to revolve at a high rate ( spe$4 99,li*t5b]g's ,figures99 c be produc$ by *>g+ a ,leyd5 j> by connect+ ! knob or inside coat+ ) ! prime conductor & hold+ ! outside coat+ 9 ! h&4 ,!n trace a small circle on ! electrophorus b$ ) ! knob4 ,*>ge a second ,leyd5 j> by connect+ ! outside coat+ ) ! prime conductor4 ,! inside coat+ %\ld be connect$ to ! rubb] by means ( a wire fa/5$ to ! knob4 ,! same result may be obta9$ by connect+ ! outside coat+ ) ! prime conductor & t\*+ ! knob ) ! h&4 ,!n trace a cross on ! electrophorus b$ ) ! knob1 mak+ ! cross inside ( ! circle4 ,illu/ration3 ,fig4 #ea4--,li*t5b]g's ,figures4 ,%ake a mixture ( r$ lead & sulphur ?r\gh a musl9 bag f a height ( sev]al in*es ov] ! electrophorus4 ,! r$ lead w accumulate ar\nd ! cross & ! sulphur ar\nd ! circle4 ,,*apt] ,,iv ,,cells ,,& ,,batt]ies ,9 ord] t ! "y exp]im5t] may obta9 electricity = driv+ 8 v>i\s electrical devices x is necess>y to resort to batt]ies1 a small dynamo1 or ! h\se-light+ curr5t4 ,all h\ses are n suppli$ ) electric curr5t4 ,fur!rmore1 _m boys h no s\rce ( p[] f :i* to drive a small dynamo4 ,batt]ies mu/ !re=e be resort$ to 9 ! majority ( cases4 ,a numb] ( diff]5t cells & batt]ies are describ$ 9 ?is *apt]4 ,all ( !m are practical1 b aft] buy+ z9c1 *emicals1 etc41 = any l5g? ( "t1 figure out :at y\r batt]ies co/ y to make4 ,! real value is n _! co/ 9 doll>s & c5ts b 9 :at y h le>n$ 9 mak+ !m4 ,if y h a cont9u\s use = electrical curr5t = runn+ small electrical devices x is *eap] to buy dry cells1 or :at is bett]1 a /orage batt]y1 & h x re*>g$ :5 necess>y4 ,build y\r own batt]ies fir/4 ,!n aft] y h le>n$ h[ !y are made & some?+ ab\t _! prop] c>e buy !m f "s reliable electrical h\se4 ,batt]ies are always int]e/+ to ! av]age exp]im5t]1 & :5 prop]ly made are "o ( ! mo/ useful pieces ( app>atus ar\nd ! home1 laboratory1 or %op t x is possible to con/ruct4 ,_m hundr$s ( ?\s&s ( exp]im5ts h be5 c>ri$ out by capable m5 9 an ef=t to discov] or devise a p]fect batt]y1 & ! li/ ( su* cells is v great4 ,only ! mo/ common =ms1 :i* are simple & inexp5sive to con/ruct b w at ! same "t r5d] fair s]vice1 h be5 *os5 = description4 ,cells are usually consid]$ "o elem5t or j> ( a batt]y4 ,a cell means only "o1 :ile a batt]y is a gr\p ( cells4 ,x is n a prop] use ( ! ^w to say batt]y :5 only "o cell is impli$4 ,?is is a v common error4 99,! ,voltaic cell99 is call$ aft] its inv5tor1 ,volta1 a pr(essor 9 ! ,univ]sity ( ,pavia1 & dates back to ab\t ! ye> #aghf4 ,illu/ration3 ,fig4 #eb4--,! ,voltaic ,cell4 ,a simple voltaic cell is easily made by plac+ "s wat] mix$ ) a little sulphuric acid 9 a glass tumbl] & imm]s+ !re9 two clean /rips1 "o ( z9c & ! o!r ( copp]4 ,! /rips mu/ be kept sep>ate f ea* o!r4 ,! sulphuric acid mu/ be dilut$ by mix+ x ) ab\t t5 times its volume ( wat]4 ,9 mix+ acid ) wat] always rememb] nev] to p\r wat] into acid b to p]=m ! op]ation ! o!r way & p\r ! acid into ! wat]4 ,a copp] wire is fa/5$ ) a screw or by sold]+ to ! top ( ea* ( ! /rips1 & c>e mu/ be ex]cis$ to keep ! wires ap>t4 ,z has be5 said1 ! z9c & copp] mu/ nev] be all[$ to t\* ea* o!r 9 ! solution1 b mu/ be kept at opposite sides ( ! j>4 ,! sulphuric acid solution attacks ! z9c1 caus+ x sl[ly to wa/e away & disappe>4 ,?is action is call$ oxidation1 & 9 reality is a v sl[ process ( burn+4 ,! consumption ( ! z9c furni%es ! electric en]gy1 :i* 9 ! case ( ?is cell w be f\nd to be suffici5t to r+ a bell or buzz]1 or run a v small toy motor4 ,z soon z ! plates are imm]s$ 9 ! acid solution1 bubbles w beg9 to rise f ! z9c4 ,^! bubbles conta9 a gas call$ hydrog5 & !y indicate t a *emical action is tak+ place4 ,! z9c is be+ dissolv$ & ! hydrog5 gas is be+ set free f ! acid4 ,x w be notic$ t no bubbles arise f ! copp] plate & t !re is little if any *emical action !re4 ,9 o!r words1 x seems t ! *emical action at "o plate is /rong] ?an t at ! o!r4 ,a cell might be lik5$ to a furnace 9 :i* ! z9c is ! fuel :i* is burn$ to furni% ! en]gy4 ,we "k t if ! z9c is burn$ or oxidiz$ 9 ! op5 air x w give out en]gy 9 ! =m ( heat4 ,:5 x is burn$ or oxidiz$ sl[ly 9 acid 9 ! pres5ce ( ano!r metal x gives out its en]gy 9 ! =m ( electricity4 ,! acid might be lik5$ to ! fire1 & ! copp] to a h& :i* dips into ! cell to pick up ! curr5t & takes no "p *emically4 ,if a wire is connect$ to ea* ( ! plates & ! free ends ( ! wires t\*$ to ! tip ( ! tongue x w produce a peculi> salty ta/e 9 ! m\? indicat+ ! pres5ce ( a curr5t ( electricity4 ,if ! wires are connect$ to an electric bell1 ! bell w r+1 or1 in/ead1 ! curr5t may be us$ to run a small motor4 ,if ! cell is made ( two z9c plates or two copp] plates1 ! bell w n r+1 because no electricity w be produc$4 ,9 ord] to produce a curr5t1 ! electrodes mu/ be made ( two diff]5t mat]ials ^u :i* ! acid acts diff]5tly4 ,curr5t may be obta9$ f a cell made ) a z9c & c>bon plate or f "o ) z9c & iron4 ,!re=e1 9 ord] to make a batt]y x is necess>y to h a metal :i* may be consum$1 a *emical to consume or oxidize x1 & an inactive elem5t :i* is m]ely pres5t to collect ! electricity4 ,:5 ! wires connect$ to ! two plates are jo9$ toge!r1 a curr5t ( electricity w fl[ f ! copp] plate ?r\gh ! wire to ! z9c4 ,! copp] is kn[n z ! positive pole & ! z9c z ! negative4 ,a simple voltaic cell may be easily made by cutt+ out a /rip ( z9c & a /rip ( copp]1 ea* #c #a_/b in*es long1 & "o in* wide4 ,a small hole bor$ ?r\gh ! upp] end ( ! /rips w p]mit !m to be m\nt$ on a wood5 /rip ) a screw z %[n 9 ,figure #ec4 ,! connect+ wires are plac$ "u ! heads ( ! screws4 ,c>e %\ld be ex]cis$ to arrange ! screws us$ = m\nt+ ! electrodes to ! wood5 /rip s t !y d n come exactly opposite1 & !re is no dang] ( ! po9ts t\*+ & =m+ a %ort circuit4 ,illu/ration3 ,fig4 #ec4--,! ,elem5ts ( ,simple ,voltaic ,cell4 ,illu/ration3 ,fig4 #ed4--;,a ,home-,made ,voltaic ,cell4 ,an ord9>y tumbl] or jelly glass w make a good batt]y j>4 ,! excit+ liquid %\ld be compos$ ( ,"o "p ( sulphuric acid ,t5 p>ts ( wat] ,"o ( ! disadvantages ( ! voltaic cell is t x becomes pol>iz$1 t is1 small bubbles ( hydrog5 :i* are lib]at$ by ! *emical action collect on ! copp] plate & cause ! /r5g? ( ! batt]y to fall (f rapidly4 ,!re are a great numb] ( elem5ts1 z ! z9c & copp] are call$1 & an ev5 great] numb] ( diff]5t solutions or excitants :i* c be employ$ 9 place ( sulphuric acid to make a cell1 =m+ an almo/ endless numb] ( possible comb9ations4 99,leclan*e ,cell499 ,"o ( ! mo/ common =ms ( cell employ$ = bell-r++1 telephones1 etc41 is call$ ! ,leclan*e cell1 aft] its inv5tor1 & consi/s ( two elem5ts1 "o ( z9c & ! o!r ( c>bon1 imm]s$ 9 a solution ( sal ammoniac or ammonium *loride4 ,?is cell has an ,e4 ,m4 ,f4 ( #a4d volts1 :i* is ab\t half z mu* aga9 z ! voltaic cell4 ,illu/ration3 ,fig4 #ee4--;,c>bon-,cyl9d] ,cell1 & ,cyl9d]4 ,! mo/ common =m ( ,leclan*e cell is illu/rat$ 9 ,figure #ee4 ,?is type is usually kn[n z a c>bon cyl9d] cell because ! positive elem5t is a holl[ c>bon cyl9d]4 ,! z9c is 9 ! =m ( a rod pass+ ?r\gh a porcela9 bu%+ set 9 ! c5t] ( ! c>bon cyl9d]4 ,a batt]y ( su* cells c only be us$ successfully = op5 circuit "w4 ,! op5 circuit is us$ = bells1 burgl> al>ms1 telephone circuits1 etc41 or :]ev] ! circuit is su* t x is op5 mo/ ( ! "t & curr5t is only drawn occasionally & !n only = %ort p]iods4 ,if ! curr5t is drawn = any appreciable l5g? ( "t hydrog5 gas w collect on ! c>bon cyl9d] & ! cell w become pol>iz$4 ,:5 pol>iz$ x w n deliv] mu* curr5t4 ,_m me?ods h be5 devis$ = ov]com+ ?is difficulty1 b ev5 ! be/ ( !m are only p>tially successful4 ,! usual me?od is to employ a *emical depol>iz+ ag5t4 ,figure #ef %[s a ,leclan*e cell provid$ ) a depol>iz]4 ,! c>bon is 9 ! =m ( a plate plac$ 9 a por\s cup made ( e>!nw>e & fill$ ) manganese dioxide4 ,*emi/s class manganese dioxide z an oxidiz+ ag5t1 :i* means t x w furni% oxyg5 ) comp>ative ease4 ,oxyg5 & hydrog5 h a /rong *emical aff9ity or attraction = ea* o!r4 ,illu/ration3 ,fig4 #ef4--;,a ,leclan*e ,cell1 %[+ ! ,por\s ,cup4 ,if ! c>bon plate is pack$ 9 manganese dioxide any hydrog5 :i* t5ds to collect on ! c>bon & pol>ize ! cell is imm$iately seiz$ by ! oxyg5 ( ! manganese dioxide & unit$ ) x to =m wat]4 ,?is =m ( ,leclan*e cell is call$ ! disk type4 ,x is capable ( deliv]+ a /rong] curr5t = a long] p]iod ( "t ?an ! c>bon cyl9d] batt]y4 ,! z9c is usually made 9 ! =m ( a cyl9d]1 & fits ar\nd ! outside ( ! por\s cup4 99,dry ,cells99 are us$ ext5sively n[adays = all op5 circuit "w on acc\nt ( _! conv5i5ce & high effici5cy4 ,! dry cell is n1 z its "n implies1 dry1 b ! excit+ ag5t or electrolyte1 in/ead ( be+ a liquid1 is a wet pa/e :i* _c spill or run ov]4 ,! top ( ! cell is p\r$ full ( molt5 pit*1 ?us effectively seal+ x & mak+ x possible to place ! cell 9 any position4 ,dry cells c be pur*as$ f almo/ any electrical h\se or g>age = tw5ty-five c5ts ea*4 ,x w !re=e h>dly pay ! "y exp]im5t] to make 8 own dry cells4 ,= ! sake ( ^? :o may c>e to d s1 h[ev]1 directions = build+ a simple b effici5t dry cell ( ! type us$ = door-bells & ignition "w1 w be f\nd bel[4 ,illu/ration3 ,fig4 #eg4--;,a ,dry ,cell4 ,! pr9ciple ( a dry cell is ! same z t ( a ,leclan*e cell ( ! disk type4 ,! excit+ solution is ammonium *loride1 ! electrodes or elem5ts are z9c & c>bon1 & ! c>bon is surr\nd$ by manganese dioxide z a depol>iz+ ag5t4 ,obta9 "s %eet z9c f a plumb+ %op or a h>dw>e /ore & cut out z _m rectangles1 #h x #f in*es1 z x is desir$ to make cells4 ,also cut out an equal numb] ( circles #b #c_/h in*es 9 diamet]4 ,roll ! %eets up into cyl9d]s #b #c_/h in*es 9 diamet] inside & #f in*es long4 ,! edges are lapp$ & sold]$4 ,fit "o ( ! r\nd circles 9 "o end ( ea* ( ! cyl9d]s & sold] !m securely into place1 tak+ c>e to close up all seams or jo9ts :i* might p]mit ! electrolyte to escape or evaporate4 ,secure "s old c>bon rods or plates by break+ op5 "s old dry cells4 ,! c>bons w be 9 ! =m ( a flat plate1 a r\nd rod1 or a />-%ap$ corrugat$ rod1 dep5d+ ^u ! manufacture ( ! cell4 ,any ( ^! types ( c>bons w s]ve ! purpose well1 provid$ t !y are fitt$ ) a ?umb-screw or a small bolt & nut at ! top s z to make wire connections ) ! c>bon4 ,make a wood5 plung] ( ! same %ape z ! c>bon :i* y may select1 b make x slightly l>g]4 ,smoo? x ) s&pap] & give x a coat ( %ellac to prev5t x f absorb+ moi/ure4 ,?is wood5 plung] is tempor>ily ins]t$ 9 ! c5t] ( "o ( ! z9c cups & support$ s t x w be ab\t "o-half in* above ! bottom4 ,! electrolyte is prep>$ by mix+ toge!r ! foll[+ +r$i5ts 9 ! proportions %[n3 ,sal ,ammoniac4 #a "p ,z9c ,*loride4 #a "p ,pla/] ( ,p>is4 #c p>ts ,fl\r4 #c_/d "p ,wat]4 #b p>ts ,illu/ration3 ,fig4 #eh4--,! ,diff]5t ,op]ations involv$ 9 ,mak+ a ,dry ,cell4 ,! above pa/e is !n firmly pack$ into ! z9c %ell ar\nd ! wood5 plung]1 leav+ a space ( ab\t #c_/d ( an in* at ! top4 ,! pa/e c be p\r$ 9 v readily :5 fir/ mix$ b sets & h>d5s aft] /&+ a %ort :ile4 ,aft] x has set1 )draw ! wood5 plung]1 ?us leav+ a space inside ( ! dry cell a little l>g] ?an ! c>bon4 ,! c>bon is n[ ins]t$ 9 ?is hole & ! surr\nd+ space is fill$ ) a mixture compos$ (3 ,sal ,ammoniac4 #a "p ,z9c ,*loride4 #a "p ,manganese ,dioxide4 #a "p ,granulat$ ,c>bon4 #a "p ,fl\r4 #a "p ,pla/] ( ,p>is4 #c p>ts ,wat]4 #b p>ts ,! granul> c>bon may be _h by cru%+ up "s old batt]y c>bons4 ,! p>ts giv5 9 bo? ( ! above =mulas are proportion$ s t !y may be measur$ by bulk & n by weight4 ,an old teaspoon or a small cup w make a good measure4 ,ea* "o ( ! z9c %ells %\ld be fill$ 9 ?is mann]4 ,aft] !y h all be5 fill$1 clean (f ! top edge ( ! z9c & p\r ! rema9+ space 9 ! cell full ( molt5 t> or pit* s z to seal x ov]4 ,sold] a small b9d+-po/ to ! top edge ( ! z9c to facilitate connection4 ,!n wrap ! cells 9 sev]al ?icknesses ( heavy pap] to prev5t !m f %ort circuit+1 & !y are ready = use4 ,a small hole bor$ ?r\gh ! seal+ mat]ial aft] x is dry w provide a v5t = ! escape ( gases4 99,re*>g+ dry cells99 is a subject t int]e/s mo/ exp]im5t]s4 ,dry cells v (t5 become useless be=e ! z9c %ell is us$ up or ! *emicals are exhau/$1 due to ! fact t ! wat] inside ( ! cell dries up & ! resi/ance !re=e becomes s great t x is practically impossible = ! curr5t to pass4 ,! life ( su* cells may be p>tially r5ew$ by drill+ sev]al holes 9 ! cell & p]mitt+ x to soak 9 a /rong solution ( sal ammoniac until "s ( ! liquid is absorb$4 ,! holes %\ld !n be plugg$ up ) "s seal+ wax 9 ord] to prev5t evaporation4 ,an old dry cell may be easily turn$ into a wet cell by drill+ ! z9c full ( holes & !n sett+ x 9 a j> conta9+ a sal ammoniac solution4 ,! batt]y %\ld be all[$ to rema9 9 ! solution4 99,wet batt]ies99 are v mu* easi] to make ?an dry batt]ies & are capable ( deliv]+ m curr5t4 ,!y h ! disadvantage1 h[ev]1 ( wa/+ away m rapidly1 :5 n 9 s]vice1 ?an dry cells4 ,! ,leclan*e cell is ! type g5]ally fir/ attempt$ by mo/ exp]im5t]s4 99,c>bon plates99 = mak+ su* a batt]y are mo/ easily & *eaply obta9$ f old dry cells4 ,ab\t ! only way t a dry cell c be brok5 op5 is ) a cold-*isel & a hamm]4 ,c>e mu/ be tak51 h[ev]1 9 ord] n to break ! c>bon4 ,ord9>y jelly-glasses make good j>s = small cells4 ,fruit-j>s may be us$ = l>g] batt]ies by cutt+ ! tops (f s t ! op5+ is l>g]4 ,! c>bon plate conta9$ 9 a dry cell is usually too long = a j> ( ?is sort & mu/ be brok5 (f be=e x c be us$4 ,! l[] end is ! "o :i* %\ld be brok5 because ! top c>ries a b9d+-po/1 ) :i* connections c be made4 ,a small hole is bor$ 9 ! c>bon rod at a di/ance f ! bottom equal to ! height ( ! j> :i* is to be us$4 ,illu/ration3 ,fig4 #ei4--;,a ,z9c-,c>bon ,elem5t1 made f ,heavy plates4 ,consid]able c>e mu/ be us$ 9 bor+ c>bon because x is v brittle & easily cracks4 ,only v light pressure %\ld be us$ on ! drill4 ,! c>bon is fa/5$ to a /rip ( wood1 ab\t an in* & "o-qu>t] wide1 "o-half an in* ?ick1 & a little long] ?an ! top ( ! glass j> is wide4 ,illu/ration3 ,fig4 #fj4--;,a ,me?od ( mak+ a ,cell ,elem5t f ,c>bon ,rods4 ,a piece ( heavy %eet z9c is fa/5$ on ! o!r side opposite ! c>bon1 ) a screw4 ,x is a good idea to pa9t ! screws & ! surr\nd+ portions ( bo? ! z9c & ! c>bon ) hot p>aff9 wax s t ! solution w n creep & attack ! screws4 ,x is also a good plan fir/ to soak ! wood5 /rip 9 "s hot p>aff9 until x is ?or\ghly impregnat$4 ,ammonium *loride1 or1 z x is m commonly call$1 sal ammoniac1 %\ld be add$ to a j> ( wat] until x w dissolve no m4 ,! z9c & c>bon elem5ts may !n be plac$ 9 ! solution4 ,"o ( ! great disadvantages ( ! voltaic cell is t ! z9c is attack$ by ! acid :5 ! batt]y is n 9 use & _c be all[$ to rema9 9 ! solution )\t quickly wa/+ away4 ,?is is true 9 ! case ( ! ,leclan*e cell only to a v small ext5t4 ,! voltaic cell is m p[]ful ?an ! ,leclan*e cell1 b ! elem5ts mu/ be c>efully lift$ out & r9s$ ) wat] e "t t y are ?r\gh us+ ! cell4 ,by us+ sev]al c>bon plates in/ead ( "o1 ! cell may be made m p[]ful4 ,! illu/rations %[ sev]al ways ( accompli%+ ?is4 ,! simple/ me?od is to place a c>bon plate on ea* side ( ! wood5 /rip & use a z9c 9 ! =m ( a rod :i* passes ?r\gh a hole betwe5 ! two4 ,c>e mu/ always be us$ to keep any screws :i* are us$ to hold ! c>bons or z9cs 9 position 9 ! cells f t\*+ ea* o!r4 ,illu/ration3 ,fig4 #fa4 ,an ,elem5t made f two ,c>bon ,plates & a ,z9c ,rod4 ,9 ,figure #fb an arrangem5t ( us+ f\r c>bons is %[n4 ,! draw+ is self-explanatory4 ,9 any ( ! cells us+ m ?an "o c>bon elem5t1 ! c>bons %\ld all be connect$4 ,9 discuss+ ! voltaic cell we m5tion$ ! fact t x becomes pol>iz$1 & expla9$ ?is ph5om5on z be+ caus$ by hydrog5 bubbles collect+ on ! copp] or positive pole4 ,! same ?+ happ5s 9 ! case ( c>bon or any o!r mat]ial :i* is us$ z a positive4 99,pol>ization99 is ! bugbe> ( batt]ies4 ,x c be elim9at$ to a c]ta9 ext5t1 h[ev]1 by ! use ( a depol>iz] plac$ 9 ! solution4 ,!re are sev]al su* sub/ances1 ! mo/ common be+ sodium bi*romate & potassium bi*romate4 ,^! are us$ 9 batt]y prep>ations on ! m>ket call$ ,electric ,s&1 ,electropoian ,fluid1 etc4 ,illu/ration3 ,fig4 #fb4 ,a ,me?od ( ,m\nt+ f\r ,c>bon ,plates4 ,:5 "o ( ^! is add$ to a sulphuric acid solution1 us+ z9c & c>bon z ! batt]y elem5ts1 x =ms a v p[]ful cell1 hav+ ,e4 ,m4 ,f4 ( two volts4 ,a batt]y solution ( ?is k9d may be prep>$ by add+ f\r ounces ( bi*romate ( pota% to a solution compos$ ( f\r ounces ( sulphuric acid mix$ ) sixte5 ounces ( wat]4 ,! batt]y w give a m p[]ful curr5t = a long] "t :5 ?is solution is us$ in/ead ( ! pla9 sulphuric acid & wat] or sal ammoniac4 ,illu/ration3 ,fig4 #fc4--;,a ,batt]y ,elem5t arrang$ = ?ree ,cells4 ,x might be well at ?is "t to caution ! exp]im5t] aga9/ ! c>eless h&l+ ( sulphuric acid4 ,x is n dang]\s if h&l$ prop]ly1 b if spill$ or spatt]$ ar\nd c>elessly x is capable ( do+ consid]able damage to mo/ ?+s ) :i* x comes 9 contact4 ,d n attempt to use x 9 any place b a %op or cell>4 ,! smalle/ drop com+ 9 contact ) any organic matt] su* z woodwork1 clo?+1 c>pets1 etc41 w n only discolor any ( ! latt]1 b eat a hole 9 x4 ,! be/ ?+ to use to c\nt]act ! effects ( ! acid :i* has be5 spill$ or spatt]$ is wat] 9 suffici5t quantity to dr5* ?+s & dilute ! acid en\gh to r5d] x h>mless4 ,a little /rong ammonia w neutralize ! acid & sometimes re/ore ! color to clo?+ :i* has be5 burn$ by acid4 ,illu/ration3 ,fig4 #fd4--;,a ,plunge ,batt]y1 ) ,w9dlass4 ,all acid batt]ies ( ?is sort h ! "o objection t x is impossible to leave ! elem5ts 9 ! solution )\t wa/+ ! z9c4 ,! usual way to arrange ! batt]y cells s t ! elem5ts may be remov$ f ! solution mo/ easily is to fa/5 ! elem5ts to a *a9 or cord pass+ ov] a w9dlass fitt$ ) a crank s t :5 ! crank is turn$ ! elem5ts may be rais$ or l[]$ z desir$4 ,a plunge batt]y ( ?is sort is illu/rat$ 9 ,figure #fd4 ,! con/ruction is s pla9ly %[n by ! draw+ t x is h>dly necess>y to ent] into ! details4 ,! crank is arrang$ ) a d[el-p9 :i* passes ?r\gh into a hole 9 ! frame1 s t :5 ! elem5ts are lift$ out ( ! solution ! p9 may be ins]t$ 9 ! hole & ! w9dlass prev5t$ f unw9d+4 ,illu/ration3 ,fig4 #fe4--;,a ,plunge ,batt]y adapt$ to a ,set ( ,elem5ts1 z %[n 9 ,figure #fc4 ,!y may be lift$ out & plac$ on ! ,arms to dra94 ,a some:at easi] me?od ( accompli%+ ! same result is t %[n by ,figure #fe4 ,9 ?is1 ! elem5ts are simply rais$ up out ( ! j>s & laid across ! two arms to dra94 99,! ,edison-,lal&e99 cell employs a block ( press$ copp] oxide z ! positive elem5t1 :ile two z9c plates =m ! negative4 ,! excit+ liquid is a /rong solution ( cau/ic soda4 ,illu/ration3 ,fig4 #ff4--;,an ,edison-,lal&e ,cell4 ,! copp] oxide acts bo? z ! positive elem5t & z a depol>iz]1 = ! oxyg5 ( ! oxide imm$iately comb9es ) any hydrog5 t5d+ to =m on ! plate4 ,?is type ( cell has "s advantages b also _m disadvantages1 *ief among :i* is ! fact t ! ,e4 ,m4 ,f4 is v l[4 ,x is us$ pr9cipally = railway signal "w1 slot-ma*9es1 etc4 99,a ,tomato-,c ,batt]y99 us+ cau/ic soda z ! excit+ liquid is a simple =m ( home-made batt]y ^: only disadvantage is ! l[ voltage t x deliv]s4 ,illu/ration3 ,fig4 #fg4--;,a ,tomato-,c ,cell2 ,sectional ,view4 ,illu/ration3 ,fig4 #fh4--,! ,tomato-,c ,cell ,complete4 ,! cell is liable to pol>ization1 b ! l>ge surface ( its positive elem5ts protects x to "s ext5t4 ,! positive elem5t & ! out] vessel is a tomato c4 ,)9 x is a por\s cup made out ( blott+ pap] or unglaz$ e>!nw>e su* z a fl[] pot4 ,! space betwe5 ! c & ! por\s cup is fill$ ) f9e scrap-iron su* z bor+s & turn+s4 ,a z9c plate is plac$ 9 ! por\s cup4 ,! cell is fill$ ) a t5-p]-c5t solution ( cau/ic soda4 ,! foll[+ table gives ! names1 elem5ts1 fluids1 voltage1 etc41 ( ! mo/ useful batt]ies1 all ( :i* may be easily con/ruct$ by ! exp]im5t]4 ,second>y or ,/orage ,batt]ies ,! /orage batt]y is a v conv5i5t means ( tak+ en]gy at "o "t or place & us+ x at "s o!r "t or place4 ,small /orage batt]ies are us$ 9 automobiles to supply curr5t = ! headlights & sp>k-coils4 ,_m automobiles are n[ equipp$ ) electric />t]s1 consi/+ ( a dynamo-motor & a /orage batt]y4 ,?r[+ a swit* w cause ! curr5t f ! /orage batt]y to drive ! motor & crank ! eng9e4 ,aft] ! eng9e is />t$1 ! motor acts z a dynamo & g5]ates a curr5t = re*>g+ ! /orage batt]y4 ,/orage batt]ies are also us$ to drive electric vehicles & c>s4 ,_m c5tral light+ & p[] /ations employ /orage batt]ies to supply ! extra curr5t dem&$ dur+ ru% h\rs4 ,9 ! middle ( ! day1 :5 ! load is light1 ! surplus curr5t ( ! dynamos is us$ to re*>ge ! /orage batt]ies4 ,:at is really effect$ 9 ! /orage batt]y is ! electrical /orage ( en]gy1 n ! /orage ( electricity4 ,prop]ly speak+1 ! en]gy is put into ! =m ( *emical en]gy1 & !re is really no m electricity 9 ! cell :5 x is *>g$ ?an aft] x is dis*>g$4 ,illu/ration3 ,fig4 #fi4--,two ,me?ods ( ,connect+ ,cells s z to obta9 ,diff]5t ,voltage & ,amp]age ,values4 ,/orage batt]ies are made up ( plates ( lead 7! electrodes7 or an alloy ( lead ca/ into a grid or framework4 ,! framework may be "o ( a l>ge numb] ( patt]ns1 b usually consi/s ( a set ( b>s cross+ "o ano!r at "r angles1 leav+ a space betwe54 ,! spaces are fill$ ) a pa/e ( lead oxide4 ,!y are !n =m$ by plac+ 9 a tank ( acid solution & connect$ to a s\rce ( electric curr5t4 ,illu/ration3 ,fig4 #gj4--,small ,/orage ,cells4 ,! plate connect$ to ! positive wire gradually turns d>k-br[n 9 color1 due to ! *anges 9 ! pa/e1 :i* gradually turns into lead p]oxide4 ,! pa/e 9 ! negative plate becomes gray 9 color & *anges into a =m ( metallic lead call$ spongy lead4 ,! positive & negative plates are plac$ 9 a bundle aft] ! =m+ process has be5 complet$4 ,!y are kept ap>t by /rips ( wood or rubb] call$ sep>ators4 ,! negative plates ( "o cell are all connect$ 9 p>allel at "o end ( ! cell4 ,! positive plates are connect$ at ! o!r end4 ,! liquid surr\nd+ ! plates is dilut$ sulphuric acid4 ,:5 ! batt]y has be5 exhau/$1 x is *>g$ by connect+ a dynamo ) ! t]m9als ( ! batt]y & s5d+ a curr5t ?r\gh x4 ,?is curr5t rev]ses ! *emical action1 :i* goes on dur+ ! dis*>ge ( ! batt]y4 99,a ,/orage ,batt]y99 furni%es ! mo/ conv5i5t s\rce ( curr5t = p]=m+ all sorts ( electrical exp]im5ts4 ,x is capable ( giv+ m curr5t = a long] p]iod ?an dry cells & is n exp5sive1 = x m]ely requires re*>g+ & does n h to be ?r[n away ea* "t ! curr5t is us$ up4 ,! /orage cell describ$ bel[ is made 9 a v simple mann] & w well repay any "t or exp5se sp5t 9 its con/ruction4 ,illu/ration3 ,fig4 #ga4--;,h[ to make ! ,plates = a ,/orage ,cell4 ,! plates are cut out ( a l>ge %eet ( lead1 "o-qu>t] ( an in* ?ick4 ,!y may be made any conv5i5t size to fit ! j>s :i* ! exp]im5t] may h at h&4 ,we w assume t !y are to be made two & sev5-eigh?s in*es wide & ?ree & "o-half in*es long4 ,!y w !n fit ! rectangul> glass /orage cell :i* is already on ! m>ket & c be procur$ f deal]s 9 electrical supplies4 ,a long t]m9al or lug is left project+ f ! plate z %[n 9 ,figure #ga4 ,any numb] ( plates may be plac$ 9 a s+le cell1 dep5d+ ( c\rse ^u ! size ( ! glass j>4 ,we w suppose t ?ree w j fit ! j> nicely4 ,an odd numb] ( plates %\ld always be us$1 s t a positive plate may come betwe5 two negatives4 ,ea* cell w give two volts reg>dless ( ! numb] ( plates4 ,increas+ ! numb] ( plates1 h[ev]1 w give ! cell a great] amp]age capacity & make ! *>ge la/ long]4 ,?ree cells 7six volts7 w =m a conv5i5t set = runn+ small fan-motors1 m9iature lights1 etc4 ,cut out n9e plates & pile !m up 9 sets ( ?ree ) a piece ( ?9 wood 7cig>-box wood7 betwe5 ea* pair ( plates4 ,clamp !m toge!r 9 a vise & bore full ( "o-qu>t]-in* holes4 ,! plates are n[ ready = pa/+4 ,!y are plac$ on a smoo? slab ( /one or glass & pa/$ ) a /iff mixture ( r$ lead & sulphuric acid 7two p>ts wat] to "o "p acid74 ,! pa/e mu/ be press$ c>efully into ! recesses ( ! plates ) a flat /ick4 ,!y are !n laid aside to dry & h>d54 ,illu/ration3 ,fig4 #gb4--,! ,wood ,sep>ator4 ,aft] !y h ?or\ghly dri$ !y %\ld be assembl$ z 9 ,figure #gc ) "o positive plate betwe5 two negative ones4 ,! wood5 sep>ators are easily cut out ( wood ) a saw & p5knife4 ,! ?9 wood us$ 9 ! con/ruction ( pea* baskets is ! be/ = ! purpose4 ,! sep>ators %\ld be made ! same size z ! lead batt]y plates4 ,ea* gr\p ( plates is !n plac$ 9 a j> conta9+ a mixture ( sulphuric acid & wat] 7#d p>ts wat] to "o "p acid74 ,9 mix+ ! acid be v c>eful to p\r ! acid into ! wat]1 /irr+ ! mixture sl[ly at ! same "t1 & n ! wat] into ! acid4 ,illu/ration3 ,fig4 #gc4--,! ,complete ,elem5t = a ,/orage ,cell4 ,! plates are n[ ready = =m+4 ,! b9d+-po/s on ! lugs ( ! plates may be secur$ f ! c>bons ( "s old dry cells4 ,! simple/ me?od ( =m+ ! plates is to use f\r gravity cells & =m "o /orage cell at a "t4 ,illu/ration3 ,fig4 #gd4--;,a ,batt]y ( ,home-,made ,/orage ,cells4 ,connect ! positive pole 7copp]7 ( ! gravity batt]y to ! positive pole 7c5t]-plate7 ( ! /orage cell & ! negative 7z9c7 ( ! gravity batt]y to ! negative 7outside plates7 ( ! /orage cell4 ,all[ ! curr5t to fl[ ?r\gh ! /orage batt]y = sev]al days or until ! positive plate turns to a d>k *ocolate-br[n color & ! negatives to a gray-slate4 ,illu/ration3 ,fig4 #ge4--;,gravity ,cells4 ,^! consi/ ( z9c & copp] elem5ts1 imm]s$ 9 a z9c-copp] sulphate solution4 ,!y _c be easily made1 & are be/ pur*as$4 ,! illu/ration also %[s ! />-%ap$ copp] & cr[foot z9c elem5t us$ 9 a gravity cell4 ,aft] ! cells h once be5 =m$ all t !y require is occasional re*>g+ f gravity cells or f a dynamo1 by connect+ ! positive pole ( ! *>g+ curr5t to ! positive plates ( ! /orage cells & ! negative pole to ! negative plates4 ,:5 ! cells are fully *>g$1 bubbles ( gas w rise freely f ! plates4 ,if a dynamo is us$ x mu/ be %unt w\nd & n a s]ies ma*9e4 ,re*>g+ w only require ab\t "o-qu>t] ( ! "t consum$ 9 =m+4 ,x is a v good plan to connect twelve gravity cells 9 s]ies & use !m to re*>ge ! /orage batt]y4 ,! gravity cells c always be kept connect$ to ! /orage cells :5 ! latt] are n 9 use & ?us rema9 fully *>g$ & ready to supply _! maximum curr5t4 ,aft] ! cells h be5 9 use = "s "t1 x is a good plan to lift out ! plates & remove all s$im5t :i* has settl$ to ! bottom ( ! j>s4 ,a set ( ?ree su* /orage cells w h an ,e4 ,m4 ,f4 ( ov] six volts4 ,any numb] may be connect$ up 9 s]ies 9 ord] to obta9 a high] voltage4 ,/orage batt]ies are usually rat$ 9 amp]e h\rs4 ,an amp]e h\r is ! am\nt ( curr5t repres5t$ by "o amp]e fl[+ = "o h\r4 ,a t5-amp]e-h\r /orage batt]y w deliv]3 ,"o amp]e = t5 h\rs ,two amp]es = five h\rs ,five amp]es = two h\rs ,t5 amp]es = "o h\r ,9 o!r words1 ! result obta9$ by multiply+ ! numb] ( amp]es by ! "t 9 h\rs is ! amp]e h\r capacity4 ,a dynamo mu/ h an ,e4 ,m4 ,f4 ( ab\t t5 volts 9 ord] to *>ge a ?ree-cell /orage batt]y4 ,,*apt] ,v ,,electro-,,magnetism ,,& ,,magnetic ,,induction ,connect two copp] wires to a voltaic cell & /ret* a portion ( ! wire ov] a compass ne$le1 hold+ x p>allel to x & z ne> z possible )\t t\*+4 ,!n br+ ! free ends ( ! wires toge!r & obs]ve t ! ne$le is deflect$ & aft] a few movem5ts back & =? comes to re/ at an angle ) ! wire4 ,illu/ration3 ,fig4 #gf4--;,a ,curr5t ( ,electricity fl[+ ?r\gh a ,wire w deflect a ,compass ,ne$le4 ,next =m a rectangul> loop ( wire & place ! ne$le )9 x z 9 ,figure #gg4 ,a great] deflection w n[ be obta9$4 ,if a loop ( sev]al turns is =m$1 ! deflection w be /ill great]4 ,^! exp]im5ts 7 fir/ p]=m$ by ,o]/$1 9 #ahai1 & %[ t ! region ar\nd a wire c>ry+ a curr5t ( electricity has magnetic prop]ties4 ,illu/ration3 ,fig4 #gg4--;,if a ,loop ( ,wire is =m$ ab\t a ,compass ,ne$le1 ! ,deflection w be great]4 ,ano!r int]e/+ exp]im5t %[+ ! magnetic effect ( a curr5t ( electricity :5 pass+ ?r\gh a wire may be p]=m$ by connect+ a heavy copp] wire to two or ?ree bi*romate-(-pota% cells4 ,dip ! wire into a pile ( f9e iron fil+s & a ?ick clu/] ( !m w adh]e to ! wire z 9 ,figure #gh4 ,z soon z ! circuit is brok5 s t ! curr5t ( electricity ceases fl[+1 ! fil+s w fall (f1 %[+ t ! magnetic effect ceases ) ! curr5t4 ,illu/ration3 ,fig4 #gh4--;,iron ,fil+s clu/]$ on a ,wire c>ry+ a ,curr5t ( ,electricity4 ,^! ?ree simple exp]im5ts h %[n t if a curr5t ( electricity is pass$ ?r\gh a copp] wire1 ! wire w deflect a compass ne$le1 attract to itself iron fil+s1 etc41 z long z ! curr5t cont9ues to fl[4 ,z soon z ! curr5t is %ut (f1 ! magnetic effect is de/roy$4 ,! region 9 ! neighborhood ( a wire c>ry+ a curr5t is a field ( =ce ?r\gh :i* l9es ( magnetism are fl[+ 9 exactly ! same way t !y d 9 ! neighborhood ( a b> or horse%oe magnet4 ,illu/ration3 ,fig4 #gi4--,magnetic ,phantom =m$ ab\t a ,wire c>ry+ a ,curr5t ( ,electricity4 ,?is is readily %[n by pun*+ a small hole 9 a piece ( c>dbo>d1 & pass+ a wire c>ry+ a /rong curr5t ( electricity ?r\gh ! hole4 ,if a few iron fil+s are sift$ on ! c>dbo>d & ! latt] j>r$ slightly ) a p5cil z !y fall1 !y w arrange !mselves 9 circles ) ! wire at ! c5t]1 =m+ a magnetic phantom & %[+ ! pa?s ( ! l9es ( magnetic =ce4 ,illu/ration3 ,fig4 #hj4--,magnetic ,phantom =m$ ab\t sev]al ,turns ( wire4 ,by =m+ ! wire into a coil z 9 ,figure #hj ! magnetic field g5]at$ is mu* /rong] & m pla9ly se51 = !n ! comb9$ effect ( ! wires is secur$4 ,illu/ration3 ,fig4 #ha4--,pap] ,tube wrapp$ ) ,wire = ,exp]im5tal ,purposes4 ,roll up a small pap] tube ab\t #a_/b in* 9 diamet] & f\r in*es long4 ,w9d neatly on ! tube ?ree lay]s ( ,no4 #ah insulat$ copp] wire4 ,pass an electric curr5t ?r\gh x f two or ?ree cells ( a batt]y1 & te/ its magnetic prop]ties by br++ x ne> a compass ne$le4 ,x w be f\nd t ! coil possesses v m>k$ magnetic prop]ties1 & w readily cause ! ne$le to sw+ ab\t1 ev5 ?\gh x is held q a di/ance away4 ,if an iron b> is plac$ inside ( ! pap] tube1 ! magnetic effect w be greatly increas$4 ,illu/ration3 ,fig4 #hb4--,%[+ h[ ! ,l9es ( ,=ce ,leak at ! sides ( ! coil1 f a ,coil ( ,wire1 & h[ !y are conc5trat$ by an ,iron ,core4 ,! pres5ce ( ! iron b> inside ( ! coil ( wire greatly increases ! numb] ( l9es ( =ce runn+ ?r\gh ! coil4 ,illu/ration3 ,fig4 #hc4--,! ,pr9ciple ( an ,electro-,magnet4 ,:5 a b> is n us$1 _m ( ! l9es ( =ce leak out at ! sides ( ! coil1 & b few ext5d f end to end4 ,! effect ( ! iron core is n only to dim9i% ! leakage ( ! l9es ( =ce1 b also to add _m m to ^? previ\sly exi/+4 ,h5ce ! magnetic /r5g? ( a coil is greatly increas$ by ! iron core4 ,a coil ( wire wrapp$ ar\nd an iron core =ms an electro-magnet4 ,illu/ration3 ,fig4 #hd4--;if y wrap "s insulat$ ,wire ar\nd an ,ord9>y ,nail & connect x to a ,batt]y1 x w become an ,electro-,magnet4 ,if y wrap "s insulat$ wire ar\nd an ord9>y nail & connect x to "o or two cells ( a batt]y x w become an electro-magnet & pick up bits ( iron & /eel4 ,if y w9d ! wire ar\nd a small pap] tube into :i* a nail w slide easily1 ! coil w draw ! nail 9 :5 ! curr5t is turn$ ,on4 ,a holl[ coil ( ?is sort is call$ a sol5oid4 ,electro-magnets & sol5oids play a "p 9 ! con/ruction ( almo/ all electrical ma*9]y4 ,!y =m ! ess5tial p>ts ( dynamos1 motors1 telephone receiv]s1 telegraph relays & s\nd]s1 & a ho/ ( o!r devices4 ,! =m usually giv5 to an electro-magnet dep5ds ^u ! use to :i* x is to be put4 ,! horse%oe is ! mo/ common4 ,?is consi/s ( two electro-magnets m\nt$ on a yoke & connect$ s t ! two free poles are ,nor? & ,s\?4 ,illu/ration3 ,fig4 #he4--;,if y w9d ! ,wire ar\nd a small ,pap] ,tube into :i* a ,nail w slide easily1 ! ,coil w draw ! ,nail 9 :5 ! ,curr5t is turn$ on4 ,electro-magnets are made on a huge scale = lift+ l>ge ca/+s & heavy pieces ( iron4 ,su* magnets are us$ 9 ! great /eel mills & 9 factories :]e nails1 bolts1 etc41 are manufactur$4 ,mon/] electro-magnets c be se5 9 wond]ful p]fection at ! great /eel mill at ,g>y1 ,indiana4 ,%ips br+ ! ore d[n ! lakes to ,g>y1 :]e great /eel jaws lift x out ( ! hold ( ! boat & c>ry x to ! furnaces4 ,aft] be+ melt$1 great ma*9es p\r x out4 ,x is divid$ into huge +ots1 & ^!1 :ile hot1 are c>ri$ to ! fir/ "p ( ! roll+ mill4 ,! +ot is squeez$ by a ma*9e1 made long] & n>r[]1 !n squeez$ aga9 & made /ill long] & n>r[]4 ,x is />t$ on its j\rney along ! roll]s ( ! mill1 squeez$ & press$ "h & !re1 z x travels hundr$s ( y>ds--no h& ev] t\*+ x4 ,x f9ally arrives1 a r$-hot /eel rail1 ! "r %ape & ! "r l5g?4 ,dur+ ?is "t ! /eel has made a long j\rney & *ang$ f a %apeless +ot to a f9i%$ rail1 h&l$ entirely by ma*9]y guid$ & controll$ by "o or two op]ators1 press+ lev]s & swit*es4 ,:5 almo/ f9i%$1 ! rail slides d[n an incl9e be=e a man :o grasps ! rail ) huge p9*]s1 & /&+ at "o end1 runs 8 eye along x4 ,z he looks along ! rail he sees ! defects1 moves ! left or ! "r h&1 & ano!r man at ! lev]s ( ! /raight5+ ma*9e1 /raight5s ! rail z direct$4 ,& soon !re are t5 rails1 p]fectly /raight1 side by side1 ) m com+ d[n ! incl9e to meet ! glance ( ! man's eye4 ,!y are /ill too hot = any man's t\* & s a man sitt+ 9 a t[] t\*es an electric swit*1 & along ! ov]head rails !re comes glid+ a mon/] electro-magnet4 ,! magnet moves along1 drops d[n ^u ! t5 rails1 ly+ side by side & weigh+ ?\s&s ( p\nds4 ,! man 9 ! t[] presses ano!r swit*1 ?us turn+ on ! curr5t1 & electricity glues ! rails to ! magnet4 ,illu/ration3 ,by p]mission1 f ,sol5oids by ,c4 ,r4 ,und]hill4 ,lift+-,magnets ( ! type kn[n z ,plate1 ,billet1 & ,+ot ,magnets4 ,! t5 rails are lift$ at once1 z easily z y w\ld lift a ne$le ) y\r horse%oe magnet2 !y are c>ri$ to a flat-c>1 & :5 l[]$ 9 position1 ! curr5t is turn$ (f1 releas+ ! rails1 & ! magnet travels back = ano!r load4 ,induction ,9 #ahca1 ,mi*ael ,f>aday1 a fam\s ,engli% *emi/ & physici/1 discov]$ t if a magnet be sudd5ly plung$ into a holl[ coil ( wire1 a mom5t>y curr5t ( electricity is g5]at$ 9 ! coil4 ,z long z ! magnet rema9s motionless1 x induces no curr5t 9 ! coil1 b :5 x is mov$ back & =?1 x sets up ! curr5ts4 ,! s\rce ( electrical en]gy is ! me*anical "w done 9 mov+ ! magnet4 ,illu/ration3 ,fig4 #hf4--,%[+ h[ a ,curr5t ( ,electricity may be induc$ by a ,b> ,magnet & a ,coil4 ,! m$ium :i* *anges ! me*anical en]gy into electricity is ! magnetic field :i* we h already se5 exi/s 9 ! neighborhood ( a magnet4 ,a curr5t ( electricity produc$ 9 a coil 9 su* a mann] is said to be an induc$ curr5t & ! ph5om5on is t kn[n z magnetic induction4 ,magnetic induction is met 9 ! dynamo1 induction coil1 telephone1 trans=m]1 "s =ms ( motors1 & a numb] ( o!r electrical devices4 ,illu/ration3 ,fig4 #hg4--;,a ,horse%oe ,magnet & a ,coil arrang$ to produce ,electric ,curr5ts by ,induction4 ,a simple exp]im5t 9 :i* electricity is produc$ by magnetic induction may be p]=m$ by w9d+ a numb] ( turns ( f9e insulat$ wire ar\nd ! armature or keep] ( a horse%oe magnet1 leav+ ! ends ( ! iron free to come 9 contact ) ! poles ( ! p]man5t magnet4 ,connect ! ends ( ! coil to a s5sitive galvanomet]1 ! ends ( ! armature be+ 9 contact ) ! poles ( ! horse%oe magnet z %[n 9 ,figure #hg4 ,keep+ ! magnet fix$1 sudd5ly pull (f ! armature4 ,! galvanomet] w %[ a mom5t>y curr5t4 ,sudd5ly br+ ! armature up to ! poles ( ! magnet2 ano!r mom5t>y curr5t 9 ! rev]se direction w fl[ ?r\gh ! circuit4 ,! fact t x is a rev]se curr5t is %[n by ! actions ( ! galvanomet] = x w be notic$ t ! ne$le sw+s 9 ! opposite direction ?is "t4 ,x w also be notic$ t no curr5t is produc$ :5 ! coil & magnet are /ation>y4 ,curr5t is only g5]at$ :5 ! coil & magnet are approa*+ "o ano!r or mov+ ap>t sudd5ly4 ,?is is because x is only !n t ! magnetic field is *ang+4 ,! field is /ronge/ ne>e/ ! magnet1 & !re=e if ei!r ! magnet or ! coil ( wire is mov$1 ! /r5g? ( t "p ( ! field :i* int]sects ! coil is *ang$4 ,induc$ curr5ts c only be g5]at$ by a *ang+ magnetic field4 ,see *apt] on ,measur+ ,in/rum5ts4 ,,*apt] ,,vi ,,electrical ,,units ,! ,amp]e ,!re are c]ta9 t]ms us$ 9 ! electrical field to di/+ui% v>i\s prop]ties & qualities ( ! electrical curr5t ) :i* x is well = ! "y exp]im5t] to acqua9t himself4 ,"o ( ! fir/ units usually requir$1 9 ord] to make intellig5t comp>isons1 is a unit ( measure4 ,! qu>t is ! unit ( measure commonly appli$ to liquids & is bas$ ^u ! am\nt ( space occupi$ by a c]ta9 volume4 ,! p\nd is a unit ( weight :i* det]m9es a c]ta9 am\nt ( any sub/ance by comp>+ ! =ce :i* gravity ex]ts 9 pull+ x to ! e>? ) ! same effect ( gravity on ano!r /&>d weight4 ,electric curr5t is invisible & weightless1 & = ^! & o!r reasons _c be measur$ by ! qu>t or weigh$ by ! p\nd4 ,! only way t x c be measur$ is by means ( "s ( ! effects :i* x produces4 ,ei!r ! *emical1 electro-magnetic1 or ! heat+ effects may be made ! basis ( a sy/em ( measurem5t4 ,! fir/ me?od us$ to measure electric curr5t 0 ! *emical "o4 ,if a curr5t is pass$ ?r\gh a solution ( a *emical call$ copp] sulphate 7blue vitriol7 by means ( two copp] plates1 copp] w be deposit$ on "o plate & dissolv$ f ! o!r4 ,if ! curr5t is furni%$ by a batt]y ! copp] w be deposit$ on ! plate connect$ ) ! z9c ( ! batt]y4 ,if ! curr5t is all[$ to fl[ = a %ort "t & ! two copp] plates are !n tak5 out & weigh$ x w be f\nd t "o plate is consid]ably heavi] ?an ! o!r4 ,! copp] has be5 tak5 f "o plate & deposit$ on ! o!r by ! electric curr5ts4 ,! am\nt ( electric curr5t :i* w deposit #a4agg grammes ( copp] 9 an h\r is call$ an amp]e4 ,! amp]e is ! unit ( electrical curr5t measurem5t1 & implies quantity or am\nt4 ,! *emical me?od ( measur+ curr5t 0 at "o "t put to practical s]vice 9 ! di/ribution ( electric curr5t = light+ & p[]4 ,_m ye>s ago ! h\se met]s1 us$ to measure ! curr5t1 consi/$ ( a j> conta9+ two copp] plates4 ,! curr5t us$ 9 ! h\se w\ld cause copp] to deposit on "o plate1 & by weigh+ ! plate ! p[] company c\ld det]m9e ! am\nt ( curr5t us$1 & !reby ! am\nt ( ! bill4 ,! met]s n[adays make use ( ! magnetic effects ( ! curr5t in/ead ( ! *emical1 z describ$ lat] on4 ,! ,volt ,= purposes ( explanation ! electric curr5t may be lik5$ to a /ream ( wat] fl[+ ?r\gh a pipe4 ,if y hold y\r ?umb ov] ! end ( a wat]-pipe ?r\gh :i* wat] is fl[+ x w pu% y\r ?umb away because ( ! pressure :i* ! wat] ex]ts4 ,electric curr5ts also ex]t a pressure1 only x is n call$ pressure 9 electrical p>lance1 b1 spok5 ( z electromotive =ce or pot5tial4 ,! pressure ( ! wat] enables x to pass ?r\gh small op5+s & to ov]come ! resi/ance (f]$ by ! pipe4 ,wires & o!r electrical conductors d n (f] a p]fectly free pa? to an electric curr5t1 b also possess a resi/ance4 ,x is ! pot5tial ( ! electro-motive =ce :i* ov]comes ! resi/ance & pu%es ! curr5t ?r\gh ! wire4 ,advantage has be5 tak5 ( ! fact to fix a unit ( electrical pressure call$ ! volt4 ,! pressure ( ! wat] 9 a wat]-pipe is measur$ 9 p\nds1 b ! pressure ( an electric curr5t 9 a wire is measur$ by volts4 ,! volt is ! unit ( electrical =ce :i* w cause a curr5t ( "o amp]e to fl[ ?r\gh a resi/ance ( "o ohm4 ,! ,ohm ,! ohm is ! unit ( electrical resi/ance4 ,! /&>d ohm is ! resi/ance (f]$ by a column ( pure m]cury hav+ a section ( "o squ>e millimet] & a l5g? ( #ajf4bh c5timet]s at a temp]ature ( #j c5tigrade4 ,! pressure :i* w =ce suffici5t curr5t ?r\gh su* a column ( m]cury to deposit #a4agg grammes ( copp] 9 "o h\r is a volt1 & 9 do+ s has pass$ a curr5t ( "o amp]e ?r\gh a resi/ance ( "o ohm4 ,! units ohm1 amp]e1 & volt1 7 nam$ 9 honor ( ! ?ree great electricians3 ,ohm1 ,ampre1 & ,volta4 ,^! ?ree units be> a v close relation to ea* o!r :i* is expla9$ by ,ohm's ,law4 ,ohm's ,law is a simple /atem5t ( facts :i* x is well = ! "y electrician ?or\ghly to und]/&1 = x might almo/ be said to be ! basis ( design ( almo/ all electrical in/rum5ts4 ,x is simply ?is3 ,! /r5g? ( a curr5t equals ! voltage divid$ by ! resi/ance4 ,x may be express$ 9 symbols by3 ,c ,e_/,r4 ,:]e ,c is ! curr5t 9 amp]es1 ,e is ! pot5tial 9 volts1 & ,r ! resi/ance 9 ohms4 ,by way ( a simple example1 we w suppose t a small telegraph s\nd] is connect$ to a batt]y & t ! voltage ( ! batt]y is t5 volts4 ,we w fur!r suppose t ! resi/ance ( ! s\nd] connect+ wires & ! batt]y itself is five ohms4 ,kn[+ ^! two facts1 x is v easy to f9d out h[ _m amp]es are fl[+ ?r\gh ! s\nd] by sub/itut+ ^! values 9 ! equation z foll[s3 ,c ,e_/,r ,e #aj volts & ,r #e ohms !re=e ,c #aj_/e or #b amp]es ,9 ord] to indicate fractions or v l>ge values ( ! amp]e1 volt1 & ohm1 x is cu/om>y to use ! foll[+ t]ms3 ,milli-volt #a_/ajjj ( a volt ,mill-amp]e #a_/ajjj ( an amp]e ,kilo-volt #ajjj volts ,meg-ohm #a1jjj1jjj ohms ,! ,watt ,x is no d\bt p]fectly pla9 t ! wat] 9 a c]ta9 size ( pipe at a pressure ( #ajj lbs4 is m p[]ful ?an a /ream ( wat] 9 ! same size ( pipe at #be lbs4 pressure4 ,likewise a curr5t ( electricity repres5ts m p[] at #ajj volts pot5tial ?an ! same curr5t w\ld at #be volts4 ,! unit ( electrical p[] is call$ ! watt4 ,a watt is repres5t$ by a curr5t ( "o amp]e fl[+ ?r\gh a wire at a pot5tial ( "o volt4 ,! numb] ( watts is f\nd by multiply+ ! voltage by ! amp]age4 ,9 ! case ( ! s\nd] & batt]y us$ z an example to expla9 ,ohm's ,law1 & :]e ! voltage 0 #aj & ! amp]age f\nd to be #b1 ! numb] ( watts is #aj x #b1 or #bj watts4 ,sev5 hundr$ & =ty-six watts repres5t "o electrical horse-p[]4 ,"o ?\s& watts are call$ a kilo-watt4 ,! ,c\lomb ,s f>1 none ( ! units h tak5 into consid]ation ! elem5t ( "t4 ,if wat] %\ld be p]mitt$ to run out ( a pipe into a tank until t5 gallons _h pass$ x w\ld n be possible to tell at :at rate ! wat] 0 fl[+ by kn[+ t t5 gallons _h pass$ unless x 7 also kn[n h[ long ! wat] _h be5 fl[+4 ,t5 gallons p] m9ute or t5 gallons p] h\r w\ld indicate ! rate ( fl[4 ,"o amp]e fl[+ = "o second is ! electrical unit ( fl[4 ,?is unit is call$ ! c\lomb4 ,"o amp]e fl[+ = "o h\r is call$ an amp]e h\r4 ,! numb] ( amp]e h\rs is f\nd by multiply+ ! curr5t 9 amp]es by ! "t 9 h\rs4 ,a batt]y may be said to h a capacity ( #aj amp]e h\rs4 ,?is means t x w deliv] "o amp]e = #aj h\rs 7#a amp]e x #aj h\rs #aj amp]e h\rs7 or #b amp]es = #e h\rs 7#b amp]es x #e h\rs #aj amp]e h\rs74 ,! same elem5t ( "t ent]s into consid]ation 9 connection ) ! watt4 ,"o watt fl[+ = "o h\r is a watt h\r & "o kil[att fl[+ = "o h\r is a kilo-watt h\r4 ,! ,diff]5ce betwe5 ,alt]nat+ & ,direct ,curr5ts ,!re are two di/9ct k9ds ( electric curr5t suppli$ = light+ & p[]1 "o kn[n z direct curr5t & ! o!r z alt]nat+4 ,a direct curr5t is "o :i* passes 9 "o direction only4 ,x may be repres5t$ by a /raight l9e1 z ,a 9 ,figure #hh4 ,an alt]nat+ curr5t is "o :i* rev]ses its direction & passes fir/ "o way & !n ! o!r4 ,x may be repres5t$ by a curv$ l9e1 %[n 9 ,figure #hh4 ,x />ts at z]o1 & gradually gr[s /rong] & /rong]4 ,!n x comm5ces to die away until no curr5t is fl[+4 ,at ?is po9t x rev]ses & comm5ces to fl[ 9 ! opposite direction1 ris+ gradually & !n dy+ away aga94 ,?is is repeat$ a def9ite numb] ( times p] second2 :5 ! curr5t rises f z]o1 rev]ses & returns to z]o1 x is said to pass ?r\gh a cycle4 ,illu/ration3 ,fig4 #hh4--;,graphic ,repres5tation ( a ,direct & an ,alt]nat+ ,curr5t4 ,! "p ( ! curv$ l9e f a to b 9 ,figure #hh repres5ts ! fir/ "p ( ! curr5t1 :5 x is ris+4 ,f b to c repres5ts its fall4 ,! po9t at :i* ! curv$ l9e crosses ! /raight l9e is z]o4 ,at c ! curr5t crosses ! l9e & comm5ces to fl[ 9 ! opposite direction until x rea*es d1 at :i* po9t x dies away & aga9 crosses ! l9e to fl[ 9 its orig9al direction & repeat ! cycle4 ,9 electrical p>lance1 t "p ( ! curr5t f a to c or f c to e is kn[n z an alt]nation4 ,f a to e is call$ a cycle4 ,! reason :y alt]nat+ curr5t is (t5 us$ 9 place ( direct curr5t is t x c be s5t ov] ! wires = long di/ances m economically ?an direct curr5t4 ,?is is m fully expla9$ f>!r on 9 ! *apt] deal+ ) a /ep-d[n trans=m]4 ,! numb] ( cycles tak+ place 9 "o second is kn[n z ! frequ5cy ( ! curr5t4 ,! usual frequ5cy ( comm]cial alt]nat+ curr5ts is #fj cycles p] second or #gbjj alt]nations p] m9ute4 ,,*apt] ,,vii ,,electrical ,,appurt5ances ,wires ,electric curr5ts are usually l$ f place to place1 at w1 by means ( conductors call$ wires4 ,!re are a great _m k9ds ( wires1 ea* adapt$ to "s special purpose4 ,wires are usually cov]$ ) a mat]ial call$ an insulator1 9 ord] to prev5t ! loss ( electric curr5t due to ! wires com+ into contact ) o!r bodies or circuits4 ,insulators are sub/ances :i* d n conduct electricity4 ,wires :i* are insulat$ by heavy braids ( cotton fib] & !n impregnat$ ) "s comp\nd1 su* z creosote1 are call$ wea!r-pro( wires1 & are be/ adapt$ to outside s]vice1 :]e !y mu/ be expos$ to ! action ( ! elem5ts4 ,! wires us$ = int]ior wir+ 9 build+s1 etc41 are usually insulat$ ) rubb]1 ov] :i* is plac$ a cotton braid to protect ! rubb]4 ,rubb] _c well be us$ z an insulator = all wires1 al?\gh its insulat+ value is v great1 ow+ to ! fact t x det]iorates "u _m conditions4 ,rubb]-cov]$ & wea!r-pro( wires are made 9 a v>iety ( insulations4 ,"s may h only "o insulat+ lay]1 :ile o!rs h a great _m4 ,diff]5t sub/ances are us$ z insulators to adapt ! wire to "s special purpose4 ,copp] is usually ! only metal us$ to =m ! wire or conductor itself4 ,! reason = ?is is t copp] is a bett] conductor ?an any o!r metal except ^? kn[n z preci\s metals1 su* z gold & silv]1 ! co/ ( :i* prohibits _! use = su* purposes4 ,! wire may be solid1 or made up ( a numb] ( small conductors s t x is flexible4 ,! v>i\s comb9ations ( insulat+ lay]s1 toge!r ) ei!r a solid or a /r&$ conductor1 h made possible a v>iety ( curr5t-c>ri]s1 kn[n z3 ,!at] or ,/age ,cable ,elevator ,cable ,fixture ,wire ,telephone ,wire ,m9+ ,cable ,fe$] ,cable ,brew]y ,cord ,heat] ,cord1 etc4 dep5d+ ^u ! special use = :i* !y 7 design$4 ,! wires :i* ! "y exp]im5t] is likely to use 9 8 "w ! mo/ are kn[n z magnet wires1 & are us$ = mak+ electro-magnets1 coils1 & v>i\s w9d+s4 ,magnet wires may be insulat$ ) ei!r silk1 cotton1 or enamel4 ,silk-cov]$ & cotton-cov]$ wires may be obta9$ ) ei!r a s+le or d\ble cov]+4 ,wires ) a s+le cov]+ ( silk or enamel are us$ :5 x is desirable to save space1 = ! cov]+ ( ^! two classes ( magnet wires is ?9n] ?an ei!r ! cotton or d\ble-silk-cov]$ wire1 & consequ5tly !y require less room = w9d+4 ,! size ( ! wire is indicat$ by its diamet]1 & 9 ! ,unit$ ,/ates is measur$ by ! ,br[n & ,%>pe gauge1 (t5 indicat$ by ! t]m1 ,b4 ,s4 ,! prec$+ table %[s ! v>i\s sizes ( wire ( ! ,br[n & ,%>pe gauge1 & also sev]al ( _! *>act]i/ics1 su* z weight1 resi/ance1 etc4 ,insulators ,! cov]+ plac$ ov] wires is n ! only precaution tak5 to insulate !m1 b 9 ! case ( p]man5t wir+ !y are usually m\nt$ on glass or porcela9 supports4 ,illu/ration3 ,fig4 #hi4--,/aples & ,wood5 ,cleat us$ = runn+ ,l[ ,voltage ,wires4 ,wires us$ = batt]ies1 bells1 telephones1 etc41 op]at$ by batt]ies & :]e ! voltage is n ov] #bj volts1 may be run "u insulat$ /aples or wood5 cleats inside ( a build+4 ,if outside & expos$ to ! wea!r1 !y %\ld be m\nt$ on suitable glass or porcela9 knobs4 ,illu/ration3 ,fig4 #ij4--,porcela9 ,insulators to support ,electric ,light ,wires4 ,electric-light wires = inside use are commonly support$ by insulators made ( porcela9 & kn[n z cleats1 knobs1 & tubes accord+ to ! %ape4 ,telegraph1 telephone1 & p[] l9es are usually support$ by glass knobs or l>ge porcela9 insulators :i* screw on to wood5 p9s4 ,illu/ration3 ,fig4 #ia4--;,glass ,insulator ,b9d+-,po/s & ,p9 us$ to support ,telegraph & ,telephone wires4 ,b9d+-,po/s ,b9d+-po/s are ! mo/ conv5i5t device to make quick connections betwe5 wires & o!r p>ts ( electrical app>atus4 ,b9d+-po/s may be ei!r made or pur*as$4 ,^? :i* are pur*as$ are ( c\rse ! be/1 & w add greatly to ! appe>ance ( any in/rum5t ^u :i* !y are m\nt$4 ,sev]al ( ! be/-kn[n types ( manufactur$ po/s are %[n 9 ,figure #ib4 ,illu/ration3 ,fig4 #ib4--,types ( ,b9d+-,po/s4 ,figure #ic %[s diff]5t ways ( mak+ simple b9d+-po/s & connectors f screws1 wa%]s1 screw-eyes1 & /rips ( metal4 ,! draw+s are self-explanatory & %\ld ne$ no comm5t4 ,illu/ration3 ,fig4 #ic4--;,home-made ,b9d+-,po/s4 ,! screws & nuts obta9able f old dry cells are v conv5i5t to use = b9d+-po/s & o!r simil> purposes4 ,swit*es & ,cut-,outs ,swit*es & cut-outs are us$ 9 electrical "w = turn+ ! curr5t on & (f4 ,if ! exp]im5t] *ooses to make !m himself1 c>e %\ld be tak51 to con/ruct !m 9 a /rong & durable fa%ion1 = !y usually are subject$ to consid]able use1 ) consequ5t we> & te>4 ,illu/ration3 ,fig4 #id4--;,b9d+-,po/ remov$ f ! ,c>bon ( a ,dry ,cell4 ,sev]al v simple home-made swit*es are illu/rat$ 9 ,figure #ie4 ,illu/ration3 ,fig4 #ie4--,simple ,swit*es4 ,a1 ,s+le-,po9t ,swit*4 ,b1 ,two-,po9t ,swit*4 ,c1 ,?ree-,po9t ,swit*4 ,d1 ,five-,po9t ,swit*4 ,e1 ,lev] ) ,end ,roll$ up to =m ,h&le4 ,f1 ,lev] ) ,h&le made f "p ( a ,spool4 ,! fir/ "o %[n 7,a7 has "o contact1 =m$ by driv+ a brass-head$ tack ?r\gh a small /rip ( copp] or brass4 ,! movable arm is a /rip ( copp] or brass1 roll$ up to =m a h&le at "o end4 ,! o!r end is pivot$ ) a brass screw4 ,! brass screw passes ?r\gh a small /rip ( copp] or brass hav+ a b9d+-po/ m\nt$ on ! end4 ,a small copp] wa%] %\ld be plac$ betwe5 ! movable arm & ! copp] /rip to make ! swit* "w m easily4 ,a some:at simil> swit* is %[n by ,b 9 ! same illu/ration1 only 9 ?is case a h&le made f half ( a spool is us$1 in/ead ( roll+ up ! end ( ! arm4 ,! o!r illu/rations %[ h[ ! same me?od ( con/ruction may be appli$ to make swit*es hav+ m ?an "o po9t or contact4 ,no dim5sions h be5 giv5 = con/ruct+ ^! swit*es1 because x is d\btless easi] = ! "y exp]im5t] to use mat]ials :i* he may h at h&1 & con/ruct a swit* ( 8 own proportions4 ,only "o sugge/ion is necess>y1 & t is to bevel ! "u edges ( ! arm ) a file1 s t x w slip ov] ! head ( ! brass tack m easily4 ,! swit*es %[n 9 ,figure #if are capable ( c>ry+ heavi] curr5ts ?an ^? j describ$1 & m ne>ly approa* ! type us$ on light+ & p[] swit*bo>ds4 ,! base may be made ( wood1 b pref]ably %\ld be made ( "s insulat+ sub/ance su* z fib] or slate4 ,illu/ration3 ,fig4 #if4--,knife ,swit*es4 ,! patt]ns = ! metal p>ts are %[n 9 ,figure #ig4 ,^! are cut f heavy %eet-brass or %eet-copp]1 & !n b5t into %ape ) a pair ( flat-nos$ pli]s4 ,! h&le ( ! s+le-pole swit* is driv5 on ov] ! metal tongue4 ,! d\ble-pole swit* is almo/ a duplicate ( ! s+le-pole type1 b has two sets ( lev]s & contacts1 actuat$ by ! h&le1 9 place ( "o4 ,illu/ration3 ,fig4 #ig4--,metal ,p>ts = ! ,knife ,swit*es4 ,! ends ( ! blades to :i* ! h&le is connect$ are turn$ ov] at "r angles & a h>d-wood cross-b> fa/5$ betwe5 ! ends4 ,! h&le is fa/5$ to ! c5t] ( ! cross-b>4 ,aft] ! swit* is assembl$1 b5d ! v>i\s p>ts until !y l9e up t is1 are 9 prop] position 9 respect to ea* o!r1 s t ! blades w drop into ! contacts )\t br++ pressure to be> on ei!r "o side or ! o!r ( ! h&le 9 ord] to =ce ! blades into l9e4 ,fuses ,fuses are us$ to prev5t electrical in/rum5ts & wires f damage due to too mu* curr5t fl[+ ?r\gh4 ,:5 an electric curr5t passes ?r\gh a resi/ance x produces heat4 ,a fuse is usually a %ort piece ( lead or "s alloy :i* melts at a l[ temp]ature1 & :i* is ins]t$ 9 ! circuit s t ! curr5t mu/ fl[ ?r\gh x4 ,if too mu* curr5t fl[s ?r\gh ! fuse x w become hot & melt1 because ( its l[ melt+-po9t1 ?us int]rupt+ ! circuit & %utt+ ! curr5t (f until ! cause :i* occasion$ ! surplus curr5t to fl[ c be asc]ta9$4 ,fuses are rat$ accord+ to ! am\nt ( curr5t :i* is requir$ to bl[ !m out1 & !re=e are call$ #a1 #c1 #e1 or #aj amp]e fuses1 z ! case may be4 ,illu/ration3 ,fig4 #ih4--,simple ,fuses4 ,a1 ,fuse-,block ) pla9 ,wire ,fuse4 ,d1 ,fuse-,block ) ,mica ,fuse 9 position4 ,:5 a fuse burns out 9 a trolley c> or 9 a light or p[] circuit1 x is because a great] am\nt ( curr5t is try+ to pass ?an ! circuit c safely c>ry4 ,if a fuse 7 n plac$ 9 su* a circuit s z to %ut ! curr5t (f be=e ! dang] po9t is rea*$1 any electrical device might become burn$ out1 or 9 extreme cases1 ! wires become s hot z to cause a s]i\s fire4 ,figure #ih %[s sev]al simple =ms ( fuses :i* ! exp]im5t] may easily make to protect ! batt]ies1 etc41 f %ort circuits4 ,! simple/ possible fuse consi/s m]ely ( a small piece ( lead wire or a /rip ( ?ick t9foil held betwe5 two b9d+-po/s m\nt$ ^u a wood5 block4 ,! same =m ( fuse may be made f a /rip ( mica ab\t two & "o-half in*es long & "o-half an in* wide4 ,a /rip ( ?9 %eet-copp] is b5t ar\nd ! ends ( ! mica /rip4 ,a piece ( fuse wire is /ret*$ betwe5 ! two copp] contacts & fa/5$ to ea* ) a drop ( sold]4 ,fuse wire ( any desir$ amp]e-c>ry+ capacity c be obta9$ f mo/ electrical supply h\ses4 ,su* a fuse is held 9 a m\nt+ z %[n by ,d4 ,! contacts are made f %eet-copp] or brass4 ,!y %\ld spr+ toge!r v tightly1 s z to make p]fect contact ) ! copp] ends on ! mica /rip4 ,lightn+-,arre/]s ,lightn+-arre/]s are us$ to protect all wires :i* run into a build+ f outdoors1 especially telegraph or telephone wires1 s t /atic electricity due to lightn+ w n damage ! in/rum5ts4 ,lightn+-arre/]s may be con/ruct$ 9 _m ways & ( diff]5t mat]ials1 b !re are only two types = :i* ! av]age exp]im5t] w h any use4 ,illu/ration3 ,fig4 #ii4--,lightn+-,arre/] & ,gr\nd-,wire ,swit*4 ,! arre/] %[n 9 ,figure #ii is ! type kn[n z lightn+-arre/] & gr\nd-wire swit*4 ,x is us$ pr9cipally on telegraph l9es4 ,x consi/s ( ?ree pieces ( %eet-brass ab\t "o-sixte5? ( an in* ?ick1 & %ap$ z %[n by ,a1 ,b1 & ,c 9 ,figure #ajj4 ,! metal pieces are m\nt$ on a wood5 block ) a n>r[ space ( ab\t "o-?irty-second ( an in* sep>at+ !m4 ,illu/ration3 ,fig4 #ajj4--;,home-made ,lightn+-,arre/]4 ,! two outside pieces are ea* fitt$ ) two b9d+-po/s1 & ! c5t] triangul>-%ap$ piece is fitt$ ) "o po/4 ,a hole ab\t "o-eigh? ( an in* 9 diamet] is bor$ betwe5 ea* ( ! metal pieces4 ,make a tap]$ metal p9 :i* c be plac$ tightly 9 ! holes1 & w make contact betwe5 ! metal pieces4 ,! two outside l9e wires ( ! telegraph circuit are connect$ to ! outside metal pieces ,c & ,b4 ,a is connect$ to ! e>? or gr\nd4 ,9 case ( a lightn+ /orm1 if ! wires become *>g$1 ! small space betwe5 ! metal plates w p]mit ! *>ge to jump across & pass h>mlessly into ! gr\nd4 ,if complete protection is desir$1 x is m]ely necess>y to ins]t ! plug 9 "o ( ! holes1 & ?us gr\nd ei!r wire or %ort-circuit bo? ( !m4 ,illu/ration3 ,fig4 #aja4--,lightn+-,arre/] = ,telephone ,wires4 ,! lightn+-arre/] %[n 9 ,figure #aja is design$ = s]vice on telephone wires4 ,x is an ord9>y fuse provid$ ) an arre/] 9 ! %ape ( two c>bon blocks ab\t "o in* squ>e4 ,! blocks re/ on a copp] /rip1 & are held 9 place by a spr+-/rip connect$ to ,b4 ,! c>bon blocks are sep>at$ by a piece ( ?9 %eet-mica1 ( ! same size z ! blocks4 ,! po/1 ,b1 is connect$ to "o ( ! telephone-l9e wires ne> ! po9t :]e x ent]s ! build+ f outdoors4 ,! po/1 ,a1 is connect$ to ! in/rum5t2 ,c is connect$ to ! gr\nd4 ,an arre/] ( ?is k9d %\ld be connect$ to ea* "o ( ! telephone wires4 ,if ! l9e wires %\ld happ5 to come into contact ) a p[] wire1 !re is dang] ( damage to ! in/rum5ts1 b if an arre/] is connect$ 9 ! circuit su* an occurr5ce w\ld be prev5t$ by ! bl[+ out ( ! fuse4 ,if ! l9es become *>g$ by lightn+1 ! *>ge c easily pass ov] ! edge ( ! mica betwe5 ! two blocks & into ! gr\nd4 ,,*apt] ,,viii ,,electrical ,,measur+ ,,in/rum5ts ,an in/rum5t design$ to measure electromotive =ce 7electrical pressure7 is call$ a voltmet]4 ,an in/rum5t design$ to measure volume ( curr5t is call$ an ammet]4 ,!re are _m =ms ( reliable met]s = measur+ curr5t & voltage1 b all are m or less exp5sive & out ( ! rea* ( an ord9>y boy4 ,"s met]s are m c>efully made ?an a wat*1 & are provid$ ) f9e hair-spr+s & jewel$ be>+s1 b all dep5d ^u ! same pr9ciple = _! action1 namely1 ! mutual effects produc$ betwe5 a magnetic ne$le & a coil ( insulat$ wire c>ry+ a curr5t ( electricity4 ,! little met]s describ$ 9 ?is *apt] are simple & inexp5sive b q s5sitive4 ,unlike a met] mak+ use ( a hair-spr+1 !y w /& consid]able r\gh h&l+1 b ( c\rse %\ld n be subject$ to su* treatm5t unnecess>ily4 ,two types ( met]s are describ$4 ,bo? op]ate on exactly ! same pr9ciple1 b "o is m elaborate ?an ! o!r4 ,a ,simple ,voltmet] & ,ammet] ,a base-bo>d five in*es long1 two & "o-half in*es wide & "o-half in* ?ick is cut out ( h>d wood4 ,9 its c5t]1 cut a slot ?ree-eigh?s ( an in* wide & "o & "o-half in*es long1 ) ! slot runn+ l5g?wise ! bo>d4 ,along ea* side ( ! slot glue two small wood5 blocks "o & "o-half in*es long1 "o-qu>t] ( an in* ?ick1 & "o-half ( an in* high4 ,illu/ration3 ,fig4 #ajb4--;,a1 ,base1 %[+ ,slot4 ,b & ,c1 ,sides & ,top ( ! ,bobb94 ,d1 ,base & ,bobb9 9 ,position4 ,:5 !y are firmly 9 position1 glue a /rip ( wood1 two & "o-half in*es long1 ?ree-qu>t]s ( an in* wide & "o-eigh? in* ?ick to ! top z %[n by ,d 9 ,figure #ajb4 ,us+ ^! z a support1 w9d a horizontal coil compos$ ( #bjj feet ( ,no4 #cf ,b4 ,s4 gauge silk-cov]$ wire4 ,a ne$le is next made f a piece ( wat*-spr+4 ,x %\ld be ab\t "o & "o-qu>t] in*es long1 & "o-eigh? ( an in* wide4 ,/raight5 x out by b5d+1 & !n heat ! c5t] 9 a small alcohol flame until ! c5t] is r$-hot1 tak+ c>e to keep ! ends z cool z possible4 ,! spr+ is m\nt$ on a small /eel %aft made by break+ up an ord9>y sew+-ne$le4 ,make ! piece "o-half ( an in* long4 ,x mu/ h v %>p po9ts at bo? ends4 ,! ends may be po9t$ by gr9d+4 ,illu/ration3 ,fig4 #ajc4--;,arrangem5t ( ! ,ne$le & ,po9t]4 ,bore a small hole j l>ge en\gh to receive ! ne$le ?r\gh ! c5t] ( ! spr+4 ,ins]t ! ne$le 9 ! hole & fa/5 x 9 ! c5t] by two small circul> pieces ( wood :i* fit tightly on ! ne$le4 ,a little glue or seal+-wax w s]ve to help make ev]y?+ firm4 ,! po9t] is a piece ( broom-/raw1 ab\t ?ree in*es long4 ,bore a small hole 9 ! top ( "o ( ! wood5 clamps & ins]t ! po9t] 9 ! hole1 fa/5+ x ) a little glue4 ,! po9t] %\ld be p]fectly /raight1 & 9 a position at "r angles to ! spr+4 ,bore a small hole 9 ! bottom ( "o ( ! wood5 clamps & glue a small wire nail 9 ! hole4 ,! purpose ( ! nail is to s]ve z a c\nt]weight & keep ! po9t] 9 a v]tical position4 ,! spr+ %\ld be magnetiz$ by w9d+ t5 or twelve turns ( magnet wire ar\nd "o end & connect+ x ) a batt]y = a mom5t4 ,illu/ration3 ,fig4 #ajd4--;,a1 ,be>+s4 ,b1 ,h[ ! ,ne$le is m\nt$4 ,! ne$le is m\nt$ 9 two small pieces ( ?9 %eet-brass1 "o in* long & "o-half in* wide4 ,b5d ea* /rip at "r angles 9 ! middle1 & at "o-qu>t] ( an in* f "o end make a small d5t by means ( a po9t$ nail & a hamm]4 ,! /rips are n[ slipp$ d[n 9 ! c5t] ( ! slot 9 ! coil ) ! d5ts inside ( ! coil & exactly opposite "o ano!r4 ,aft] ! exact position is f\nd1 !y may be fa/5$ into position by two v small screws4 ,! %>p-po9t$ sew+-ne$le1 toge!r ) ! magnetiz$ spr+1 po9t]1 & c\nt]weight1 %\ld slip d[n into ! d5ts made 9 ! /rips & sw+ freely !re4 ,x may require a little fil+ & b5d+1 b ! "w %\ld be done pati5tly1 because ! prop] work+ ( ! met] w dep5d ^u hav+ ! ne$le sw+ freely & easily 9 its place4 ,fa/5 an upright bo>d1 f\r in*es wide & "o-qu>t] ( an in* ?ick1 to ! base-bo>d1 back ( ! bobb94 ,atta* a piece ( ?ick c>dbo>d to ! upright by means ( small blocks1 9 su* a position t ! po9t] sw+s v close to x b does n t\* x4 ,! met] is n[ complete1 except = m>k+ or calibrat+ ! scale4 ,! me?od ( accompli%+ ?is w be describ$ f>!r on4 ,illu/ration3 ,fig4 #aje4--,! ,complet$ ,met]4 ,if ! met] is w\nd ) ,no4 #cf ,b4 ,s4 gauge wire x is a voltmet] = measur+ voltage4 ,if x is w\nd ) ,no4 #af ,b4 ,s4 gauge wire x w con/itute an ammet] = measur+ amp]es4 ,a ,portable ,voltmet] & ,ammet] ,! bobb9 ^u :i* ! wire is w\nd is illu/rat$ 9 ,figure #ajf4 ,! wood is ! ,spani% c$>1 ( :i* cig> boxes are made4 ,x %\ld be "o-eigh? ( an in* ?ick1 & c be easily work$ ) a pocket-knife4 ,9 lay+ out ! "w1 scrat* ! l9es on ! wood ) ! po9t ( a d>n+-ne$le4 ,p5cil l9es are too ?ick to p]mit ( accuracy 9 small "w4 ,! bobb9 :5 f9i%$ mu/ be p]fectly true & squ>e4 ,! dim5sions are be/ und]/ood f ! illu/rations4 ,9 putt+ ! bobb9 toge!r1 d n use any nails4 ,use /rong glue only4 ,two bobb9s are requir$1 "o = ! ammet] & "o = ! voltmet]4 ,aft] complet+ ! bobb9s1 s&pap] !m & coat !m ) %ellac4 ,illu/ration3 ,fig4 #ajf4--;,details ( ! ,bobb94 ,! bobb9 = ! ammet] is w\nd ) ,no4 #ad ,b4 ,s4 d\ble-cotton-cov]$ magnet wire4 ,! voltmet] requires ,no4 #dj ,b4 ,s4 silk-cov]$ wire4 ,9 bo? cases ! wire %\ld be w\nd c>efully 9 smoo?1 ev5 lay]s4 ,a small hole is bor$ 9 ! flange ?r\gh :i* to pass ! end ( ! wire :5 />t+ ! fir/ lay]4 ,aft] f9i%+ ! w9d+1 ab\t six in*es ( wire %\ld be left at bo? ends to make connection ) ! t]m9als4 ,! :ole w9d+ is !n giv5 a coat ( %ellac4 ,a /rip ( passe-p>t\t tape1 "o-half ( an in* wide w\nd ov] ! wire ar\nd ! bobb9 w n only protect ! wire f injury1 b also give ! bobb9 a v neat appe>ance4 ,! armature is a piece ( s(t /eel "o in* long1 "o-eigh? ( an in* ?ick & ?ree-eigh?s wide4 ,a "o-eigh?-in* hole is bor$ "o-sixte5? ( an in* above ! c5t] = ! reception ( ! %aft4 ,! c5t] ( gravity is ?us ?r[n bel[ ! c5t] ( ! mass ( ! armature1 & ! po9t] w always return to z]o if ! in/rum5t is level4 ,! %aft is a piece ( "o-eigh?-in* ,bessem] /eel rod1 sev5-sixte5?s ( an in* long4 ,! ends are fil$ to a %>p knife-edge on ! "u side1 z indicat$ 9 ! figure4 ,illu/ration3 ,fig4 #ajg4--,! ,bobb9 p>tly cut away s z to %[ ! ,be>+4 ,details ( ! ,armature & ,%aft4 ,a "o-sixte5?-in* hole is bor$ 9 ! top ( ! armature to receive ! l[] end ( ! po9t]1 :i* is a piece ( ,no4 #af alum9um wire1 f\r & "o-half in*es long4 ,aft] ! holes h be5 bor$1 ! armature is temp]$ s t x w reta9 its magnetism4 ,x is heat$ to a bright r$ heat & dropp$ into a bas9 ( /rong salt wat]4 ,! armature is !n magnetiz$ by rubb+ "o end aga9/ ! pole ( a /rong magnet4 ,! be>+s are =m$ by two /rips ( ?9 %eet-brass1 ?ree-sixte5?s ( an in* wide1 & "o & "o-qu>t] in*es long1 b5t & glu$ to ! sides ( ! bobb94 ,9 ! illu/ration1 "p ( ! bobb9 is repres5t$ z cut away4 ,! c5t] ( ! be>+ is b5t out s t ! end ( ! %aft w n come 9 contact ) ! sides ( ! bobb94 ,! top ( ! c5t] is not*$ ) a file to =m a socket = ! knife-edges ( ! %aft4 ,illu/ration3 ,fig4 #ajh4--;,complet$ ,voltmet]4 ,! bobb9 is glu$ to ! c5t] ( a wood5 base1 sev5 in*es long1 f\r in*es wide & ?ree-qu>t]s ( an in* ?ick4 ,! t]m9als ( ! coil lead d[n ?r\gh two small holes 9 ! base & !nce to two l>ge b9d+-po/s4 ,! wires are inlaid on ! "u side ( ! base1 i4e41 !y pass f ! holes to ! b9d+-po/s ?r\gh two grooves4 ,?is precaution avoids ! possibility ( _! becom+ %ort-circuit$ or brok54 ,! case is =m$ ( two sides1 a back & top ( "o-half-in* wood4 ,x is six in*es high1 f\r in*es wide1 & two in*es deep4 ,a glass front slides 9 two %all[ grooves cut 9 ! wood5 sides1 "o-eigh? ( an in* f ! front4 ,! case is held d[n to ! base by f\r r\nd-head$ brass screws1 :i* pass ?r\gh ! base into ! sides4 ,x is !n easily removable 9 case x ev] becomes necess>y to repair or adju/ ! in/rum5t4 ,! met] & case1 z illu/rat$ 9 ,figure #ajh1 are int5d$ = portable use & are s con/ruct$ t !y w /& up4 ,a small brass screw1 long en\gh to pass all ! way ?r\gh ! base1 s]ves to level ! in/rum5t4 ,if a little brass /rip is plac$ 9 ! slot 9 ! screw-head & sold]$ s z to =m :at is kn[n z a w+$ screw1 ! adju/m5t may be made ) ! f+]s & )\t ! aid ( a screw-driv]4 ,:]e ! in/rum5t is int5d$ = m\nt+ ^u a swit*-bo>d1 x c be giv5 a mu* bett] appe>ance by fitt+ ) a small] base1 simil> 9 size & %ape to ! top4 ,! b9d+-po/s are !n m\nt$ 9 ! c5t] ( ! sides4 ,to calibrate ! met]s prop]ly1 !y are comp>$ ) "s /&>d4 ,! scale is =m$ by a piece ( :ite c>dbo>d glu$ by two small blocks on ! inside ( ! case4 ,! v>i\s values are m>k$ ) a p5 & ink4 ,! glass front1 !re=e1 _c be put 9 place until !y are locat$4 ,! z]o value on ! met]s w normally be 9 ! c5t] ( ! scale4 ,:5 a curr5t is pass$ ?r\gh ! bobb91 ! armature t5ds to sw+ ar\nd at "r angles to ! turns ( wire4 ,b s9ce ! armature is pivot$ above ! c5t] ( ! mass1 :5 x sw+s1 ! c5t] ( gravity is displac$ & ex]ts a pull 9 opposition to t ( ! bobb91 & ! am\nt ( sw+ indicat$ by ! po9t] w be great] z ! curr5t is /rong]4 ,! po9t] w sw+ ei!r to ! "r or ! left1 dep5d+ ^u ! direction 9 :i* ! curr5t passes ?r\gh ! bobb94 ,! po9t] ( ! in/rum5t illu/rat$ 9 ,figure #ajh is at z]o :5 at ! extreme left ( ! scale4 ,! po9t] is b5t to ! left1 s t ! curr5t w be regi/]$ :5 pass+ ?r\gh ! met] only 9 "o direction1 b ! scale w h a great] range ( values4 ,x w also be necess>y to cut a small groove 9 ! base ( ! in/rum5t 9 ?is case s t ! armature w h pl5ty ( room 9 :i* to sw+4 ,illu/ration3 ,fig4 #aji4--;,circuits = ,calibrat+ ! ,ammet] & ,voltmet]4 ,:5 calibrat+ ! ammet]1 x is plac$ 9 s]ies ) ! /&>d met]1 a set ( /rong batt]ies1 & a rheo/at4 ,! rheo/at is adju/$ s t v>i\s curr5t read+s are obta9$4 ,! correspond+ positions ( ! po9t] on ! met] be+ calibrat$ are !n locat$ = ea* value4 ,! voltmet]s mu/ be plac$ 9 p>allel1 or %unt ) ea* o!r1 & 9 s]ies ) sev]al batt]y cells4 ,a swit* is arrang$ s t ! voltage ( a v>y+ numb] ( cells may be pass$ ?r\gh ! met]s4 ,to secure fractional values ( a volt1 ! rheo/at is plac$ 9 %unt ) ! fir/ cell ( ! batt]y4 ,!n1 by adju/+ bo? ! swit* & ! rheo/at1 any voltage )9 ! maximum range ( ! batt]y may be secur$4 ,?is means ( regulat+ voltage is a common "o1 & ( mu* use 9 wireless telegraph circuits1 z w be expla9$ lat]4 ,:5 us+ ! met]s1 x is always necess>y t ! ammet] %all be 9 s]ies & ! voltmet] 9 p>allel or 9 %unt ) ! circuit4 ,galvanoscopes & ,galvanomet]s ,9 ! fir/ "p ( ,*apt] ,v x 0 expla9$ t sev]al turns ( wire surr\nd+ a compass-ne$le w\ld cause ! ne$le to move & %[ a deflection if a curr5t ( electricity 7 s5t ?r\gh ! coil4 ,su* an in/rum5t is call$ a galvanoscope & may be us$ = detect+ v feeble curr5ts4 ,a galvanoscope becomes a galvanomet] by provid+ x ) a scale s t ! deflection may be measur$4 ,a galvanomet] is really1 9 pr9ciple1 an ammet] ! scale ( :i* has n be5 calibrat$ to read 9 amp]es4 ,illu/ration3 ,fig4 #aaj4--,simple ,compass ,galvanoscope4 ,a v simple galvanoscope may be made by w9d+ fifty turns ( ,no4 #cf ,b4 ,s4 gauge s+le-silk-cov]$ wire ar\nd an ord9>y pocket compass4 ,! compass may be set 9 a block ( wood1 & ! wood provid$ ) b9d+-po/s s t connections are easily made4 ,ano!r v>iety ( ! same in/rum5t is %[n 9 ,figure #aaa4 ,illu/ration3 ,fig4 #aaa4--;,galvanoscope4 ,w9d ab\t tw5ty-five turns ( ,no4 #cj ,b4 ,s4 gauge cotton-cov]$ wire ar\nd ! l[] end ( a glass tumbl]4 ,leave ab\t six in*es ( ea* end free = t]m9als1 & !n1 aft] slipp+ ! coil f ! glass1 tie ! wire ) ?read 9 sev]al places s t x w n unw9d4 ,press two sides ( ! coil toge!r s z to flatt5 x1 & !n atta* x to a block ( wood ) "s hot seal+-wax4 ,make a little wood5 bridge z %[n 9 ,figure #aaa1 & m\nt a compass-ne$le on x 9 ! c5t]4 ,! compass-ne$le may be made out ( a piece ( spr+-/eel 9 ! mann] already describ$ 9 ,*apt] ,i4 ,m\nt two b9d+-po/s to ! corn]s ( ! block1 & connect ! ends ( ! wire coil to !m4 ,turn ! block s t ! ne$le po9ts ,nor? & ,s\? & p>allel to ! coil ( wire4 ,if a batt]y is connect$ to ! b9d+-po/s1 ! ne$le w fly ar\nd to a position at "r angles to t :i* x fir/ occupi$4 ,an a/atic galvanoscope is "o hav+ two ne$les ) _! poles 9 opposite directions4 ,! ^w a/atic means hav+ no directive magnetic t5d5cy4 ,if ! ne$les ( an a/atic pair are sep>at$ & pivot$ sep>ately1 !y w ea* po9t to ,nor? & ,s\? 9 ! ord9>y mann]4 ,b :5 connect$ toge!r ) ! poles arrang$ 9 opposite directions !y neutralize ea* o!r4 ,an a/atic ne$le requires b v little curr5t 9 ord] to turn x ei!r "o way or ! o!r1 & = ?is reason an a/atic galvanoscope is usually v s5sitive4 ,a simple in/rum5t ( ?is sort may be made by w9d+ ab\t fifty turns ( ,no4 #cj-cf ,b4 ,s4 gauge s+le-silk or cotton-insulat$ wire into a coil ar\nd a glass tumbl]4 ,aft] remov+ ! coil f ! glass1 %ape x into ! =m ( an ellipse & fa/5 x to a small base-bo>d4 ,sep>ate ! /r&s ( wire at ! top ( ! coil s t !y are divid$ into two gr\ps4 ,illu/ration3 ,fig4 #aab4--;,a/atic ,galvanoscope4 ,make a bridge or /&>d 9 ! %ape ( an inv]t$ ,u out ( ?9 wood5 /rips & fa/5 x to ! block4 ,! ne$les are ord9>y sew+-ne$les :i* h be5 magnetiz$ & %ov$ ?r\gh a small c>ri]-b>1 made f a /rip ( c>dbo>d1 ) _! poles opposite "o ano!r1 z %[n 9 ! illu/ration4 ,illu/ration3 ,fig4 #aac4--;,a/atic ,ne$les4 ,!y may be held 9 place 9 ! c>dbo>d /rip by a small drop ( seal+-wax4 ,a small hole is pun*$ 9 ! top ( ! c>ri]1 ?r\gh :i* to pass ! end ( a ?read4 ,! upp] end ( ! ?read passes ?r\gh a hole 9 ! bridge & is ti$ to a small screw-eye 9 ! c5t] ( ! upp] side ( ! bridge4 ,! c>ri]-b> is pass$ ?r\gh ! space :]e ! coil is split at ! top4 ,! l[] ne$le %\ld hang 9 ! c5t] ( ! coil4 ,! upp] ne$le %\ld be above & outside ! coil4 ,! t]m9als ( ! coil are connect$ to two b9d+-po/s m\nt$ on ! base-block4 ,ow+ to ! fact t ?is galvanoscope is fitt$ ) an a/atic ne$le1 ! in/rum5t does n h to be turn$ s t ! coil may face ,nor? & ,s\?4 ,! slighte/ curr5t ( electricity pass+ into ! coil w in/antly affect ! ne$les4 ,an a/atic galvanomet] = ! detection ( exce$+ly weak curr5ts & = use 9 connection ) a ,:eat/one bridge = measur+ resi/ance1 z describ$ f>!r on1 w =m a valuable addition to ! laboratory ( ! boy electrician4 ,make two small bobb9s simil> to ^? already describ$ 9 connection ) ! volt & ammet]1 b twice z long1 z %[n 9 ,figure #aad4 ,w9d ea* ( ! bobb9s 9 ! same direction ) ,no4 #cf silk-cov]$ or cotton-cov]$ wire1 leav+ ab\t six in*es free at ! ends = connection to ! b9d+-po/s4 ,fa/5 ea* ( ! bobb9s to ! base-bo>d ) glue4 ,d n nail or screw !m 9 position1 because ! pres5ce ( nails or screws may impair ! s5sitiv5ess ( ! in/rum5t4 ,9 m\nt+ ! bobb9s1 leave ab\t "o-sixte5? ( an in* ( space betwe5 ! inside flanges1 ?r\gh :i* ! ne$le may pass4 ,connect ! coils w\nd on ! bobb9s s t ! end ( ! outside lay] ( ! fir/ coil is connect$ to ! inside lay] ( ! o!r coil4 ,?is arrangem5t is s t ! curr5t w travel ?r\gh ! w9d+s 9 ! same cont9u\s direction1 exactly ! same z ?\gh ! bobb9 7 "o cont9u\s spool4 ,illu/ration3 ,fig4 #aad4--;,bobb9 = ,a/atic ,galvanomet]4 ,magnetize two small sew+-ne$les & m\nt !m 9 a pap] /irrup made f good1 /rong pap]1 z %[n 9 ,figure #aad4 ,take c>e t ! poles are rev]s$ s t ! nor? pole ( "o magnet w be on ! same side ( ! /irrup z ! s\? pole ( ! o!r4 ,!y may be fa/5$ securely by a drop ( %ellac or melt$ seal+-wax4 ,cut out a c>dbo>d disk & divide x into degrees z 9 ,figure #aae4 ,glue ! disk to ! top ( ! bobb9s4 ,a small slot %\ld be cut 9 ! disk s t x w pass ! l[] ne$le4 ,a wood5 po/ %\ld be glu$ to ! back ( ! base4 ,to ! top ( ?is po/ is fa/5$ an arm f :i* are susp5d$ ! magnetic ne$les4 ,a f9e fib] = susp5d+ ! ne$le may be secur$ by unravel+ a piece ( embroid]y silk4 ,illu/ration3 ,fig4 #aae4--;,complet$ ,a/atic ,galvanomet]4 ,! upp] end ( ! fib] is ti$ to a small hook 9 ! end ( ! arm4 ,! wire hook may be twi/$ s t ! ne$les may be br\ght to z]o on ! scale4 ,z]o %\ld lie on a l9e p>allel to ! two coils4 ,! fib] us$ = susp5d+ ! ne$les %\ld be z f9e z possible4 ,! f9] ! fib] is1 ! m s5sitive w ! in/rum5t be4 ,! l[] ne$le %\ld sw+ inside ( ! two coils1 & ! upp] ne$le above ! disk4 ,h[ to ,make a ,:eat/one ,bridge ,! amateur exp]im5t] w f9d _m occasions :5 x is desirable to "k ! resi/ance ( "s ( 8 electrical app>atus4 ,telephone receiv]s1 telegraph relays1 etc41 are all grad$ accord+ to _! resi/ance 9 ohms4 ,! measurem5t ( resi/ance 9 any electrical in/rum5t or circuit is usually accompli%$ by comp>+ its resi/ance ) t ( "s kn[n circuit1 su* z a coil ( wire :i* has be5 previ\sly te/$4 ,! simple/ me?od ( measur+ resi/ance is by means ( a device kn[n z ! ,:eat/one bridge4 ,?is in/rum5t is v simple b at ! same "t is rem>kably s5sitive if prop]ly made4 ,a ,:eat/one bridge is %[n 9 ,figure #aaf4 ,! base is a piece ( well-season$ h>d wood1 ?irty in*es long1 six in*es wide1 & ?ree-qu>t]s ( an in* ?ick4 ,secure a long /rip ( ,no4 #ah ,b4 ,s4 gauge %eet-copp]1 "o in* wide1 & cut x into ?ree pieces1 mak+ two ( ! pieces ?ree in*es long1 & ! o!r piece tw5ty-?ree & "o-half in*es long4 ,m\nt ! copp] /rips on ! base1 z %[n1 be+ v c>eful to make ! di/ance betwe5 ! inside edges ( ! end-pieces j tw5ty-five in*es4 ,! /rips %\ld be fa/5$ to ! base ) small r\nd-head$ brass screws4 ,m\nt two b9d+-po/s on ea* ( ! %ort /rips 9 ! positions %[n 9 ! illu/ration1 & ?ree on ! long /rip4 ,^! b9d+-po/s %\ld pass ?r\gh ! base & make firm contact ) ! /rips4 ,illu/ration3 ,fig4 #aaf4--,:eat/one ,bridge4 ,!n make a pap] scale tw5ty-five in*es long1 & divide x into "o hundr$ equal divisions "o-qu>t] ( an in* long4 ,m>k e fif? division ) a slightly long] l9e1 & e t5? division ) a d\ble-l5g? l9e4 ,/>t at "o end & numb] e t5 divisions1 !n />t at ! o!r end & numb] !m back1 s t ! scale reads #j1 #aj1 #bj1 #cj1 #dj1 #ej1 #fj1 #gj1 #hj1 #ij1 #ajj1 f "r to left at ! top & #j1 #aj1 #bj1 #cj1 #dj1 #ej1 #fj1 #gj1 #hj1 #ij1 #ajj1 f left to "r at ! bottom4 ,sold] a piece ( ,no4 #cj ,b4 ,s4 gauge ,g]man-silv] wire to "o ( ! %ort copp] /rips opposite ! end ( ! scale1 & !n /ret* x tightly across ! scale & sold] x to ! /rip at ! o!r end4 ,make a knife-contact by flatt5+ a piece ( heavy copp] wire z %[n 9 ,figure #aag4 ,sold] a piece ( flexible wire1 su* z lamp cord1 at ! o!r end4 ,x is well to fit ! contact ) a small wood5 h&le1 made by bor+ out a piece ( d[el4 ,! in/rum5t is n[ practically complete4 ,illu/ration3 ,fig4 #aag4--,knife-,contact4 ,9 ord] to use ! ,:eat/one bridge1 x is necess>y to h a set ( resi/ances ( kn[n value4 ,! resi/ance ( any unkn[n circuit or piece ( app>atus is f\nd by comp>+ x ) "o ( ! kn[n coils4 ,x is j l go+ to a /ore & buy+ a p\nd ( sug>4 ,! groc] weighs out ! sug> by balanc+ x on ! scales ) an iron weight ( kn[n value1 & tak+ x = grant$ t ! weight is correct1 we w\ld say t we h "o1 five1 or t5 p\nds ( sug>1 z ! case may be4 ,! ,:eat/one bridge might be call$ a pair ( electrical scales = weigh+ resi/ance by comp>+ an unkn[n coil ) "o :i* we "k has a c]ta9 value4 ,! next /ep is to make up "s /&>d resi/ance coils4 ,secure "s ,no4 #cb ,b4 ,s4 gauge s+le-cotton-cov]$ wire f an electrical deal] & cut into ! foll[+ l5g?s1 lay+ x /raight on ! floor b us+ c>e n to pull or /ret* x4 #a_/b ohm coil--#c feet #a_/b in* #a ohm coil--#f feet #a #a_/d in*es #b ohm coil--#ab feet #b #a_/b in*es #e ohm coil--#cj feet #f #a_/d in*es #aj ohm coil--#fa feet #bj ohm coil--#abb feet #cj ohm coil--#ahc feet #ej ohm coil--#cje feet ,^! l5g?s ( wire are !n wrapp$ on ! spools 9 ! foll[+ mann]4 ,illu/ration3 ,fig4 #aah4--,resi/ance-,coil4 ,a %[s h[ ! ,wire is d\bl$ & w\nd on ! ,spool4 ,b is ! complet$ ,coil4 ,?is me?od ( w9d+ is kn[n z ! non-inductive me?od1 because ! w9d+s d n g5]ate a magnetic field1 :i* might affect ! galvanomet] ne$le us$ 9 connection ) ! ,:eat/one bridge z describ$ lat] on4 ,ea* l5g? ( wire %\ld be d\bl$ exactly 9 ! middle1 !n wrapp$ on ! spools l a s+le wire1 ! two ends be+ left free = sold]+ to ! t]m9als z %[n 9 ,figure #aah1 ,b4 ,! spools may be ! ord9>y reels ^u :i* cotton & sew+-silk are wrapp$4 ,! t]m9als ( ! spools are pieces ( /\t copp] wire1 ,no4 #ab or ,no4 #ad ,b4 ,s4 gauge4 ,two pieces ( wire ab\t ?ree in*es long are driv5 into holes bor$ 9 ! ends ( ea* spool4 ,a small drop ( sold] is us$ p]man5tly to secure ! ends ( ! coil to ea* ( ! heavy wire t]m9als4 ,! spools are !n dipp$ into a pan ( molt5 p>aff9 & boil$ until ! air bubbles cease to rise4 ,! spools %\ld be m>k$ #a1 #b1 #aj1 #bj1 #cj1 & #ej1 accord+ to ! am\nt ( wire ea* "o conta9s z indicat$ 9 ! table above4 ,h[ to ,use a ,:eat/one ,bridge = ,measur+ ,resi/ance ,! in/rum5t is connect$ z 9 ,figure #aaf4 ,! unkn[n resi/ance or device to be measur$ is connect$ across ! gap at ,b4 ,"o ( ! /&>d kn[n coils is connect$ across ! gap at ,a4 ,a s5sitive galvanomet] or a telephone receiv] & two cells ( batt]y are also connect$ z %[n4 ,if a telephone receiv] is us$1 place x to ! e>4 ,if a galvanomet] is us$ in/ead1 wat* ! ne$le c>efully4 ,!n move ! %>p edge ( ! knife-contact ov] ! scale along ! ,g]man-silv] slide wire until a po9t is rea*$ :5 !re is no deflection ( ! ne$le or no s\nd 9 ! telephone receiv]4 ,if ?is po9t lies v f> on "o side or ! o!r ( ! c5t] division on ! scale1 sub/itute ! next high] or l[] kn[n resi/ance spool until ! po9t falls z ne> z possible to ! c5t] ( ! scale4 ,:5 ?is po9t is f\nd1 note ! read+ on ! scale c>efully4 ,n[ comes ! h>de/ "p4 ,almo/ all my read]s h no d\bt progress$ f> en\gh 9 ari?metic to be able to c>ry on ! foll[+ simple calculation 9 proportion :i* mu/ be made 9 ord] to f9d out ! resi/ance ( ! unkn[n coil4 ,! unkn[n resi/ance1 connect$ to ,b1 be>s ! same ratio to ! kn[n coil1 at ,a1 t ! numb] ( divisions betwe5 ! knife-contact & ! "r-h& end ( ! scale 7l[] r[ ( figures7 be>s to ! numb] ( divisions betwe5 ! knife-edge & ! left-h& end ( ! scale 7upp] r[ ( figures74 ,we w suppose t a #e-ohm coil 0 us$ at ,a 9 a te/1 & ! ne$le ( ! galvanomet] /opp$ sw++ :5 ! knife-contact re/$ on ! #fj? division f ! left-h& end1 or on ! #dj? f ! "r4 ,!n1 9 ord] to f9d ! value ( ! unkn[n resi/ance at ,b1 x is simply necess>y to multiply ! /&>d resi/ance at ,a by ! numb] ( left-h& divisions & divide ! product by ! numb] ( "r-h& divisions4 ,! answ] w be ! resi/ance ( ,b 9 ohms4 ,! calculation 9 ?is case w\ld be z foll[s3 #e ,x #dj #bjj #bjj_/fj #c4cc ohms #c4cc ohms is ! resi/ance ( ,b4 ,?is explanation may seem v long & complex1 b if y w /udy x c>efully y w f9d x to be v simple4 ,:5 once y ma/] x1 y w be enabl$ to make _m measurem5ts ( resi/ance :i* w add greatly to ! int]e/ & value ( y\r exp]im5ts4 ,,*apt] ,,ix ,,bells1 ,,al>ms1 ,,& ,,annunciators ,an electric bell may be b\ght almo/ any:]e = tw5ty-five c5ts1 & f ! /&po9t ( economy x does n pay to build "o4 ,a bell is n a h>d ?+ to con/ruct1 & ! "t & money sp5t w be amply repaid by ! m intimate k ( ?is useful piece ( app>atus :i* w be ga9$ by con/ruct+ x4 ,! base is f\r in*es wide & five & "o-half in*es long4 ,! magnets consi/ ( two ma*9e bolts1 w\nd ) ,no4 #bb cotton-cov]$ magnet wire4 ,fib] ends are fitt$ on ! bolts to hold ! wire 9 place4 ,! wire is w\nd on ea* ( ! magnets sep>ately4 ,cov] ! cores ) two or ?ree lay]s ( pap] be=e w9d+ on ! wire4 ,! ends ( ! wire are l$ ?r\gh holes 9 ! core ends4 ,! ends ( ! bolts are pass$ ?r\gh ! yoke1 & ! nuts appli$ to hold !m 9 place4 ,! magnets are clamp$ d[n to ! bell-base by means ( a h>d-wood /rip hav+ a screw pass$ ?r\gh x betwe5 ! magnets into ! base4 ,illu/ration3 ,fig4 #aai4--;,details ( ! ,magnet ,spools1 & ,yoke = an ,electric ,bell4 ,! armature ( ! bell is %[n 9 ,figure #abj4 ,x is made ( a piece ( iron hav+ a /eel spr+ rivet$ to x1 z illu/rat$4 ,! armature is fa/5$ to a small block m\nt$ on ! l[] left-h& corn] ( ! base4 ,illu/ration3 ,fig4 #abj4--;,details ( ! ,armature1 & ,contact ,screw4 ,a second block ) a contact-po9t made f an ord9>y brass screw by fil+ ! end into ! %ape %[n 9 ! illu/ration1 is m\nt$ on ! base s t x is opposite ! end ( ! contact-spr+ fa/5$ to ! armature4 ,! gong may be secur$ f an old bell or al>m clock4 ,x is m\nt$ on ! upp] "p ( ! base 9 su* a position t ! hamm] w /rike x on its l[] edge4 ,! in/rum5t is connect$ z %[n 9 ,figure #aba4 ,"o t]m9al ( ! magnets is connect$ to ! contact-screw4 ,! o!r end is connect$ to ! b9d+-po/4 ,a second b9d+-po/ is connect$ to ! armature4 ,illu/ration3 ,fig4 #aba4--,! ,complet$ ,bell4 ,! armature spr+ %\ld be b5t s t ! armature is pu%$ ov] aga9/ ! contact4 ,if a batt]y is connect$ to ! bell1 ! electromagnets w pull ! armature & cause ! hamm] to /rike ! gong4 ,z soon z ! armature has mov$ a %ort di/ance1 ! spr+ w move away f ! contact & break ! circuit4 ,! magnets cease pull+ z soon z ! curr5t is cut (f & ! armature spr+ !n causes ! armature to move back & t\* ! contact4 ,z soon z ! contact is made1 ! armature is drawn 9 aga9 & ! process is repeat$4 ,illu/ration3 ,fig4 #abb4--;,diagram %[+ h[ to connect a ,bell1 ,batt]y1 & ,pu%-,button4 ,a little exp]im5t+ ) ! bell w soon enable "o to f9d its be/ adju/m5t4 ,figure #abb %[s h[ to connect a bell to a batt]y & a pu%-button4 ,a pu%-button is simply a small swit* :i* closes ! circuit :5 press$4 ,d n make ! armature spr+ too weak1 or ! hamm] w move v sl[ly & ) v little life4 ,ea* "t t ! armature moves t[>d ! magnets1 x %\ld b>ely t\* ! iron cores be=e ! ball /rikes ! bell4 ,aft] y get ! bell 9 good work+ ord]1 x is well to make a small box to s]ve z a cov] = ! work+ p>ts ( ! in/rum5t1 leav+ only ! gong expos$4 ,illu/ration3 ,fig4 #abc4--,two ,simple ,pu%-,buttons4 ,illu/ration3 ,fig4 #abd4--;,diagram %[+ h[ to arrange a ,bell ,sy/em ( ,return ,signals4 ,x is sometimes desirable to arrange two bells & two pu%-buttons1 s t a return signal c be s5t4 ,9 t case ! circuit %[n 9 ,figure #abd may be employ$4 ,x is !n possible = ! p]son answ]+ ! bell to indicate t he has he>d ! call by pu%+ ! second button4 ,= in/ance1 "o pu%-button & bell might be locat$ on ! top floor ( a h\se & ! o!r bell & button 9 ! basem5t4 ,a p]son 9 ! basem5t wi%+ to call ano!r on ! top floor w\ld pu% ! button4 ,! p]son answ]+ c\ld return ! signal by pu%+ ! button on ! top floor & cause ! bell 9 ! basem5t to r+4 ,a ,burgl> ,al>m ,a simple me?od ( mak+ an effici5t burgl> al>m is %[n 9 ,figure #abe4 ,! base is a piece ( wood ab\t five by six in*es1 & half an in* ?ick4 ,a small brass /rip1 ,a1 is fa/5$ to ! base by means ( two r\nd-head$ wood screws & ! ends turn$ up at "r angles4 ,! lev]1 ,b1 is also a /rip ( brass4 ,"o end is b5t out1 s z to cle> ! /rip & ! screws t are "u x4 ,! lev] is pivot$ 9 ! middle ) a screw & a wa%]4 ,a small hole1 ,d1 is bor$ 9 ! l[] end ?r\gh :i* a spr+ & a /r+ are pass$4 ,! o!r end ( ! spr+ is fa/5$ "u a screw & wa%]1 ,c4 ,illu/ration3 ,fig4 #abe4--;,burgl>-,al>m ,trap4 ,9 ord] to set ! al>m1 fir/ fa/5 ! base 9 any conv5i5t place4 ,c>ry ! /r+ across ! room & fa/5 x4 ,adju/ ! /r+ s t ! lev] is half-way betwe5 ! two ends ( ! /rip1 ,a4 ,if ! /r+ is di/urb$1 x w pull ! lev] ov] aga9/ ! /rip1 ,a4 ,if ! /r+ is cut1 ! spr+ w pull ! lev] ov] to ! opposite side4 ,9 ei!r case1 if ! al>m is prop]ly connect$ to a bell & batt]y1 ! circuit w be clos$ if ! /r+ is di/urb$1 & ! bell w r+4 ,"o wire lead+ f ! bell & ! batt]y %\ld be connect$ to ,a1 & ! o!r to ! screw & wa%]1 ,c4 ,! al>m may be arrang$ across a w9d[ or doorway & a black ?read sub/itut$ = ! /r+4 ,any "o ent]+ 9 ! d>k & unaw>e ( ! exi/5ce ( ! al>m is liable to break ! ?read & r+ ! bell4 ,an ,electric ,al>m ,x is (t5 desirable to arrange an electrical al>m clock s t a bell w r+ cont9u\sly until %ut (f4 ,illu/ration3 ,fig4 #abf4--;,an ,e>ly-,ris]'s ,electric ,al>m ,atta*m5t = a ,clock4 ,figure #abf %[s an electrical al>m atta*m5t4 ,x consi/s ( a wood5 box1 l>ge en\gh to receive an ord9>y dry cell4 ,a bell is fa/5$ on ! outside ( ! box4 ,connect "o t]m9al ( ! batt]y to "o t]m9al ( ! bell4 ,connect ! o!r bell & batt]y t]m9als1 ea* to a %ort piece ( brass *a91 ab\t f\r in*es long4 ,! ends ( ! *a9 are !n fa/5$ to a small piece ( %eet fib] or h>d rubb]1 s t !y are insulat$ f ea* o!r4 ,! opposite end ( ! fib] is fa/5$ to a piece ( wire spr+ hav+ a g>t] or susp5d] clip sold]$ to ! end4 ,illu/ration3 ,fig4 #abg4--;,details ( ! ,*a9 ,electrodes1 etc4 ,! op]ation ( ?is electrical atta*m5t is v simple4 ,w9d up ! al>m key ( an ord9>y al>m clock & place ! clip on ! key4 ,place ! clock 9 su* a position t ! two *a9s d n t\* ea* o!r4 ,set ! clock4 ,:5 ! me*anical al>m goes (f1 ! key w revolve & twi/ ! two *a9s1 ?us clos+ ! electric circuit & caus+ ! bell to r+4 ,! bell w r+ until ! clamp is remov$4 ,! outfit c be atta*$ to any ord9>y al>m clock4 ,an ,annunciator ,annunciators are (t5 plac$ 9 bell & burgl> al>m-circuits to indicate :]e ! button r++ ! bell 0 pu%$1 9 case !re are sev]al4 ,! sep>ate indicators us$ on an annunciator are call$ drops4 ,illu/ration3 ,fig4 #abh4--;,an ,annunciator ,drop4 ,a drop may be made f an electromagnet & "s brass /rips1 etc4 ,! frame is cut f heavy %eet-brass & %ap$ z %[n 9 ,figures #abh & #abi4 ,! drop b> is a /rip ( metal :i* is pivot$ on ! frame at its l[] end & has ! upp] end turn$ up to receive a num]al or lett]4 ,! armature is made f a /rip ( %eet-iron4 ,x is pivot$ on ! frame at its upp] end4 ,! /rip is b5t at "r angles s z to fall 9 front ( ! magnet4 ,! l[] "p ( ! armature is b5t into a hook4 ,! hook fits into a slot cut 9 ! drop b>4 ,a f9e wire spr+ is plac$ betwe5 ! frame & ! upp] end ( ! armature s z to pull ! armature away f ! core :5 ! curr5t is n pass+ ?r\gh ! magnet4 ,! electromagnet %\ld be w\nd ) ,no4 #be ,b4 ,s4 cotton-cov]$ magnet wire4 ,:5 a curr5t is s5t ?r\gh ! magnet1 x w draw ! armature 94 ,?is action releases ! hook f ! edge ( ! slot 9 ! drop b> & p]mits ! b> to drop & br+ ! numb] or lett] d[n into view4 ,illu/ration3 ,fig #abi4--;,details ( ! ,drop-,frame & ,armature4 ,a numb] ( drops may be arrang$ on a bo>d & plac$ 9 diff]5t circuits s z to indicate :i* circuit is clos$ at any "t4 ,x is a good plan to arrange a b> to act z a /op1 s t ! num]al w n drop d[n too f>4 ,ea* "t t any "o ( ! drops falls1 x mu/ be reset by pu%+ ! b> back into position4 ,,*apt] ,x ,,electric ,,telegraphs ,exp]im5ts 9 telegraphy 7 c>ri$ out z f> back z ! ye> #agec1 :5 x 0 propos$ to transmit messages by repres5t+ ! lett]s ( ! alphabet by comb9ations ( sp>ks produc$ by a /atic ma*9e2 b ^! 7 ( little practical value & no?+ ( any importance 0 accompli%$ until aft] ! discov]y ( galvanic curr5t4 ,_m ( ^! old exp]im5ts 7 v crude & appe> some:at ridicul\s :5 comp>$ ) ! me?ods ( n[adays4 ,! e>lie/ proposal = an electric telegraph appe>$ 9 ! ,scots' ,magaz9e = ,febru>y1 #agec1 & %[s sev]al k9ds ( propos$ telegraphs act+ by ! attractive p[] ( electricity1 convey$ by a s]ies ( p>allel wires1 "o wire correspond+ to ea* lett] ( ! alphabet & support$ by glass rods at e tw5ty y>ds4 ,words 7 to be spell$ by ! action ( ! electricity 9 attract+ pap] lett]s1 or by /rik+ bells correspond+ to lett]s4 ,! mod]n telegraph consi/s ess5tially ( f\r ?+s1 namely3 ,a batt]y :i* produces an electric curr5t4 ,a wire :i* conducts ! electric curr5t f "o po9t to ano!r4 ,a transmitt] = %utt+ ! curr5t (f & on4 ,an electro-magnetic receiv+ app>atus1 :i* gives out 9 s\nds1 ! signals made by ! pulsations ( ! curr5t f a di/ant po9t4 ,! batt]y may be almo/ any =m ( batt]y4 ,gravity cells are pref]r$1 h[ev]1 = telegraph "w4 ,heavy galvaniz$ iron wire is usually employ$ z ! l9e4 ,x is necess>y to use non-conductors :]ev] ! wire is fa/5$4 ,glass insulators plac$ on a wood5 p9 or bracket1 :i* is fa/5$ to ! pole or build+ on :i* ! wire is to be support$1 are us$ = outside "w4 ,inside ( build+s1 rubb] tubes are us$ :]e ! wires pass ?r\gh walls1 etc4 ,! op]ation ( a telegraph is n1 z _m p suppose1 a complicat$ or difficult matt] to und]/&1 b is q simple4 ,! key is a contrivance = controll+ ! passage ( ! electric curr5t 9 mu* ! same mann] z an ord9>y swit*4 ,x consi/s ( a /eel lev]1 swung on trunnion-screws m\nt$ 9 a frame1 & provid$ ) a rubb] knob :i* ! op]ator grasps lightly ) ! ?umb & =ef+]4 ,on press+ ! lev] d[nw>d1 a plat9um po9t fa/5$ on ! "u side ( ! lev] is br\ght into contact ) ano!r po9t set into a rubb] bu%+ 9 ! base ( ! key1 s t !re is no electrical connection betwe5 ! two po9ts unless ! key is press$ d[n or clos$1 z x is (t5 t]m$4 ,! key is usually fa/5$ to ! op]at+ b5* by two rods call$ legs4 ,! lev] is provid$ ) screws :i* p]mit ! /roke ( ! key to be v closely adju/$4 ,illu/ration3 ,fig4 #acj4--;,a ,typical ,telegraph ,key1 %[+ ! ,v>i\s ,p>ts4 ,! l9e wire & batt]y are connect$ to ! key1 s t no curr5t c fl[ until ! key is press$ & ! contacts br\ght toge!r4 ,a s\nd] consi/s ( two electromagnets m\nt$ on a base "u a movable flat piece ( iron :i* is attract$ by ! magnetism ( ! electromagnets :5 a curr5t fl[s ?r\gh !m & is )drawn by a spr+ :5 no magnetism excites ! w9d+s4 ,?is piece ( iron1 :i* is call$ ! armature1 is m\nt$ ^u a /rip ( brass or alum9um call$ ! lev]4 ,! lev] /rikes aga9/ a brass anvil & produces ! clicks1 :i* =m ! dots & da%es ( ! telegraph alphabet4 ,illu/ration3 ,fig4 #aca4--;,a ,typical ,telegraph ,s\nd]1 %[+ ! ,v>i\s ,p>ts4 ,e "t t ! key is press$1 an electric curr5t is s5t out into ! l9e4 ,! curr5t fl[s ?r\gh ! magnets ( ! s\nd] & causes ! armature to be drawn d[nw>d4 ,! lev] /rikes ! anvil & produces a click4 ,:5 ! key lev] is releas$1 ! curr5t is %ut up & ! lev] flies up & clicks aga9/ ! top ( ! anvil4 ,! p]iod ( "t betwe5 ! fir/ click & ! second click may be v>i$ at w accord+ to ! l5g? ( "t t ! key is held d[n4 ,a %ort p]iod is call$ a dot & a long p]iod a da%4 ,comb9ations ( dots1 da%es1 & spaces arrang$ accord+ to ! ,morse ,alphabet1 make intelligible signals4 ,h[ ,to ,make a ,simple ,key & ,s\nd] ,! little telegraph in/rum5ts %[n 9 ,figures #acb & #acc are n practical = long l9es b may be us$ = tick+ messages f "o room to ano!r1 & c be made ! s\rce ( mu* in/ruction & pleasure4 ,illu/ration3 ,fig4 #acb4--;,a ,simple ,home-made ,telegraph ,key4 ,! key is a /rip ( brass fa/5$ to a wood5 base 9 ! mann] %[n 9 ,figure #acb4 ,x is fitt$ ) a knob ( "s sort on ! front end1 s t x is conv5i5tly gripp$ ) ! f+]s4 ,! little bridge is made f heavy %eet-brass & prev5ts ! lev] f mov+ too f> away f ! contact on ! upw>d /roke4 ,connections are made to ! key lev] at ! back end & ! contact 9 front by ! b9d+-po/s1 ,a & ,b4 ,! po/1 ,c1 connects ) ! bridge4 ,! s\nd] consi/s ( two small electromagnets m\nt$ 9 a v]tical position on a wood5 base4 ,! magnets are connect$ at ! bottom by a /rip ( heavy %eet-iron :i* acts z a yoke4 ,illu/ration3 ,fig4 #acc4--;,a ,simple ,home-made ,telegraph ,s\nd]4 ,! armature is made out ( %eet-iron1 roll$ up 9 ! mann] %[n 9 ! illu/ration4 ,"o end ( ! armature is fa/5$ to a wood5 block 9 su* a position t ! armature comes directly ov] ! magnets & ab\t "o-eigh? ( an in* above !m4 ,! opposite end ( ! armature moves up & d[n = ab\t an eigh? ( an in* betwe5 two screws1 ea* fa/5$ 9 a wood5 block m\nt$ on an upright bo>d 9 ! back ( ! magnets4 ,! purpose ( ! screws is to make ! click ( ! s\nd] l\d] & cle>] ?an x w\ld be if ! armature only /ruck ! wood4 ,a rubb] b& or a small wire spr+ pass+ ov] a screw & connect$ at ! o!r end to ! armature w draw ! latt] away f ! magnets :5 ! curr5t is n pass+4 ,! t]m9als ( ! magnets are connect$ to b9d+-po/s m\nt$ on ! base4 ,illu/ration3 ,fig4 #acd4--;,a ,diagram %[+ h[ to connect two ,simple ,telegraph ,/ations4 ,! key & s\nd] %\ld be plac$ 9 s]ies ) "o or two cells ( a batt]y4 ,press+ ! key w !n cause ! armature ( ! s\nd] to be drawn d[n & make a click4 ,:5 ! key is releas$1 ! armature w be drawn up by ! spr+ or rubb] b& & make a second click4 ,h>dly a boy int]e/$ 9 me*anics & electricity has n at "s "t or o!r wi%$ = a telegraph in/rum5t ) :i* to put up a l9e ) 8 *um4 ,a practical work+ set ( su* in/rum5ts c be v easily con/ruct$1 & ) little exp5se1 by foll[+ ! sket*es & in/ructions giv5 "h4 ,! magnets = ! s\nd] may ei!r be con/ruct$ by ! int5d+ telegraph op]ator or secur$ f "s old electrical in/rum5t su* z a magneto-bell4 ,9 ! latt] case1 ! h>de/ "p ( ! "w w be avoid$4 ,if !y are to be home-made1 ! foll[+ sugge/ions may prove ( value 9 c>ry+ out _! con/ruction4 ,illu/ration3 ,fig4 #ace4--;,a ,complete ,telegraph ,set1 consi/+ ( a ,keybo>d & a ,s\nd]4 ,! cores are made f "o-qu>t]-in* /ove-bolts ) ! heads cut (f4 ,! magnet heads are cut out ( h>d-wood fib]1 "o-eigh? ( an in* ?ick & "o in* 9 diamet]4 ,!y %\ld fit tightly & be held 9 place ) glue4 ,!y are sep>at$ s z to =m a w9d+ space betwe5 ( sev5-eigh?s ( an in*4 ,! magnets %\ld be w\nd full ( ,no4 #be ,b4 ,s4 gauge cotton-cov]$ wire4 ,illu/ration3 ,fig4 #acf4--;,details ( ! ,telegraph ,set %[n 9 ,figure #ace4 ,! yoke is made ( en\gh /rips ( %eet-iron1 "o-half in* wide & two in*es long1 to =m a pile "o-qu>t] ( an in* ?ick4 ,two "o-qu>t]-in* holes are bor$ 9 ! opposite ends ( ! yoke1 "o & "o-half in*es ap>t4 ,! l[] ends ( ! magnet cores are pass$ ?r\gh ^! holes4 ,! ends %\ld project "o-half ( an in* beyond ! yoke4 ,!y are pass$ ?r\gh two holes 9 a base-bo>d ?ree-qu>t]s ( an in* ?ick4 ,! holes are c\nt]sunk f ! l[] side1 s t a nut c be screw$ on ! l[] end ( ea* & ! magnets held tightly 9 an upright position4 ,! rema9+ p>ts ( ! in/rum5t are v easily made1 & are s cle>ly %[n by ! draw+ t x is h>dly necess>y to say m ?an a few words 9 explanation4 ,! lev] or tongue1 ! anvil1 ! /&>d1 & ! lev] ( ! key are all cut out ( h>d-wood accord+ to ! patt]n %[n 9 ! illu/ration4 ,! armature is a piece ( s(t iron fa/5$ to ! lev] ) a small brass screw4 ,tacks are plac$ "u ! heads ( ! adju/+ screws on ! s\nd] s t x w click m l\dly4 ,! rubb] b& acts z a spr+ to c\nt]act ! weight ( ! armature & lev] & draw x up z soon z ! curr5t is cut (f4 ,! movem5t ( ! lev] %\ld be s adju/$ t x is only suffici5t to make an audible click4 ,use c>e to avoid friction betwe5 ! lev] & ! /&>d1 s t ! =m] w move ) p]fect fre$om4 ,all ! screws us$ 9 ! "w %\ld be r\nd-head$ brass wood screws ) ! po9ts fil$ flat4 ,bore a small hole be=e screw+ !m into place s z to avoid splitt+ ! wood4 ,! con/ruction ( ! key is ev5 m simple ?an t ( ! s\nd]4 ,x %\ld move up & d[n )\t any side motion4 ,! circuit-clos] %\ld be kept clos$ :5 ! in/rum5ts are n 9 use1 & :5 y are receiv+ a message4 ,z soon z y are ?r\gh receiv+ & wi% to transmit1 y %\ld op5 y\r circuit-clos] & y\r fri5d close 84 ,! t5sion ( ! spr+ "u ! lev] ( ! key mu/ be adju/$ to suit ! ne$s ( ea* individual op]ator4 ,illu/ration3 ,fig4 #acg4--;,a ,diagram %[+ h[ to connect two ,complete ,telegraph ,sets1 us+ "o ,l9e ,wire & a ,gr\nd4 ,! ,two-,po9t ,swit*es ?r[ ! ,batt]ies out ( ,circuit :5 ! ,l9e is n 9 use4 ,! diagram = connect+ ! in/rum5ts is self-explanatory4 ,9 cities or t[ns :]e a gr\nd is available by connect+ to ! gas or wat] pipes1 "o l9e wire may be easily disp5s$ )4 ,or1 if desirable1 a gr\nd may be =m$ by bury+ a l>ge plate ( z9c 7?ree or f\r feet squ>e7 9 a moi/ spot & lead+ ! wire to x4 ,h[ ,to ,build a ,telegraph ,relay ,9 work+ a telegraph ov] a long l9e or :]e !re are a l>ge numb] ( in/rum5ts on "o circuit1 ! curr5ts are (t5 n /rong en\gh to "w ! s\nd] directly4 ,9 su* a case a relay is us$4 ,! relay is built on ! same pr9ciple z a s\nd]1 b ! p>ts are made mu* light]1 s t ! in/rum5t is m s5sitive4 ,! armature ( a relay is s small & its movem5t s little t its click+ is sc>cely audible4 ,x is !re=e fitt$ ) a second set ( contacts & connect$ to a batt]y & a s\nd]1 :i* is to set 9 op]ation e "t ! contacts close4 ,! pr9ciple ( a relay is t a weak curr5t ( insuffici5t /r5g? to d ! "w itself may set a /rong local curr5t to d its "w = x4 ,!re are _m =ms ( relays1 & :ile t :i* is describ$ bel[ is n ( ! type commonly us$ on telegraph l9es1 x has ! advantage ( be+ f> m s5sitive ?an any in/rum5t ( ! regul> l9e relay type t ! av]age exp]im5t] c\ld build4 ,illu/ration3 ,fig4 #ach4--;,details ( ! ,relay ,p>ts4 ,make ! magnets f "o-qu>t]-in* /ove-bolts1 & cut !m (f s t !y w =m a core ab\t two & "o-qu>t] in*es long4 ,fit ea* ( ! cores ) two fib] heads to hold ! wire 9 place4 ,insulate ! legs ) pap] & w9d ea* ) ab\t fifty lay]s ( ,no4 #cj ,b4 ,s4 gauge s+le-cotton-cov]$ magnet wire4 ,! w9d+ space betwe5 ! magnet's heads %\ld be "o & "o-eigh? in*es4 ,! upp] ends ( ! magnet cores %\ld be all[$ to project ab\t "o-qu>t] ( an in* beyond ! fib] head4 ,! end ( ! core is fil$ flat1 z %[n 9 ! illu/ration4 ,! magnets are m\nt$ ^u an iron yoke1 ?ree-sixte5?s ( an in* ?ick4 ,! holes 9 ! yoke %\ld be spac$ s t !re is a di/ance ( "o & "o-half in*es betwe5 ! c5t]s ( ! magnet cores4 ,! armature ( ! relay is m\nt$ on a small /eel %aft ) %>p po9ts at ea* end4 ,! exact %ape ( ! armature may be be/ und]/ood f ! illu/rations4 ,! l[] end ( ! %aft re/s 9 a small cone-%ap$ depression made by driv+ a c5t] pun* into ! yoke half-way betwe5 ! two magnets4 ,! top be>+ is a /rip ( brass project+ f a wood5 support4 ,! end ( ! %aft re/s 9 a depression simil> to t 9 ! yoke4 ,! contact lev] is made ( brass & =c$ on ! %aft bel[ ! armature4 ,x sw+s betwe5 a small brass clip fa/5$ to "o side ( ! support & a little screw held 9 a simil> clip on ! opposite side4 ,! contact clip is made ( spr+ brass ab\t ,no4 #bb gauge 9 ?ickness4 ,x may be adju/$ by a screw pass+ ?r\gh ! support4 ,! armature may be controll$ 9 its movem5t s t ! latt] w be v slight by adju/+ ! screws4 ,!re %\ld n be any friction 9 ! be>+s & ! armature %\ld move ) p]fect fre$om4 ,! armature %\ld approa* ! ends ( ! magnet cores until a space ab\t ! ?ickness ( heavy pap] sep>ates !m & %\ld n t\* !m4 ,illu/ration3 ,fig4 #aci4--,! ,complet$ ,relay4 ,! spr+ is made ( f9e brass wire4 ,x is fa/5$ to ! armature %aft1 & ! screw m\nt$ on ! wood5 support ) a piece ( silk ?read4 ,! ?read is pass$ ar\nd ! %aft once or twice s t ! t5sion ( ! spr+ w cause ! armature to move away f ! pole pieces j z soon z ! curr5t fl[+ ?r\gh ! magnets ceases4 ,illu/ration3 ,fig4 #adj4--;,a ,diagram %[+ h[ to connect a ,relay1 ,s\nd]1 & ,key4 ,clos+ ! ,key w op]ate ! ,relay4 ,! ,relay w !n op]ate ! ,s\nd] 9 turn4 ,! t5sion ( ! spr+ may be adju/$ by turn+ ! screw ) a screw-driv]4 ,if ! armature t5ds to /ick to ! magnet poles fa/5 a small piece ( pap] to ! poles ) "s %ellac4 ,! t]m9als ( ! magnets are connect$ to two b9d+-po/s m>k$ ,a & ,b4 ,! b9d+-po/s m>k$ ,c & ,d are connect$ respectively to ! contact clip & ! brass be>+ on ! top ( ! wood5 support4 ,! diagram 9 ,figure #adj %[s h[ ! relay is connect$ to a telegraph l9e4 ,h[ ,to ,le>n ,to ,telegraph ,! in/rum5ts s f> describ$ h be5 practical work+ telegraph in/rum5ts1 b !y lack ! f9e po9ts ( comm]cial app>atus & x is n possible to become z effici5t an op]ator ) _! aid z ) a real key & s\nd]4 ,if ! "y exp]im5t] desires to become a pr(ici5t telegraph op]ator1 ! fir/ ?+ to d is to pur*ase a ,le>n]'s telegraph key & s\nd]4 ,connect a dry cell to ! b9d+-po/s on ! back ( ! in/rum5t4 ,screw ! set d[n on a table ab\t eighte5 in*es f ! front edge1 s t !re is pl5ty ( room = ! arm to re/4 ,see t none ( ! v>i\s adju/m5t screws ab\t ! in/rum5t are loose & t ! armature ( ! s\nd] moves freely up & d[n ?r\gh a di/ance ( ab\t "o-sixte5? ( an in*4 ,! spr+ :i* draws ! lev] upw>ds away f ! magnets %\ld be set only at suffici5t t5sion to raise ! lev] :5 no curr5t is pass+4 ,if too tight1 ! spr+ w n all[ ! armature to respond to ! curr5t fl[+ ?r\gh ! magnets4 ,! key is provid$ ) sev]al adju/m5t-screws to regulate ! t5sion & ! play ( ! lev] to suit ! h& ( ! op]ator4 ,a little practice w enable ! /ud5t to judge be/ = himself j h[ ! key %\ld be set4 ,! next /ep is to memorize ! alphabet1 s t ea* "* c in/antly be call$ to m9d at w4 ,! punctuation m>ks are n us$ v frequ5tly1 & ! p]iod is ! only "o :i* ! /ud5t ne$ le>n at fir/4 ,! ,morse alphabet consi/s ( dots1 da%es1 & spaces4 ,comb9ations ( ^! signals spell lett]s & words4 ,_m ( ! *>act]s are ! rev]se ( o!rs4 ,= example1 ,a is ! rev]se ( ,n4 ,b & ,f1 ,d & ,u1 ,c & ,r1 ,q & ,x1 ,z & 1 are ! o!r rev]se lett]s1 s if ! =mation ( "o ( ea* ( ^! lett]s is memoriz$ ! rev]se is easily ma/]$4 ,x is important t ! beg9n] %\ld le>n h[ prop]ly to grasp ! key1 = habits are easily =m$ & a poor position w limit ! s5d+ spe$ ( ! op]ator4 ,place ! fir/ or index f+] on ! top ( ! key-h&le1 ) ! ?umb "u ! edge2 & ! second f+] on ! opposite side4 ,! f+]s %\ld be curv$ s z to =m a qu>t]-section ( a circle4 ,br+ ! ?ird & f\r? f+]s d[n s t !y are almo/ clos$ on ! palm ( ! h&4 ,re/ ! arm on ! table 9 front ( ! key & all[ ! wri/ to be p]fectly limb]4 ,illu/ration3 ,fig4 #ada4--;,h[ to hold a ,telegraph ,key4 ,! grasp on ! key %\ld be firm b n rigid4 ,avoid us+ too mu* /r5g? or a light hesitat+ t\*4 ,endeavor to acquire a positive1 firm up & d[n motion ( ! key4 ,avoid all side pressure1 & d n all[ ! f+]s to leave ! key :5 mak+ ! signals4 ,! movem5t is made pr9cipally ) ! wri/1 ) ! f+]s & h& p]fectly ela/ic4 ,a dot is made by a s+le in/antane\s1 d[nw>d /roke ( ! key4 ,a da% is made by hold+ ! key d[n = ! same p]iod ( "t t x takes to make ?ree dots4 ,a long da% is made by hold+ ! key d[n = ! same "t t x takes to make five dots4 ,a space 9 ! lett]s1 su* z1 = in/ance1 ! space betwe5 ! fir/ & la/ two dots 9 ! lett] ,r %\ld occupy ! "t ( "o dot4 ,! space betwe5 ea* lett] %\ld occupy ! "t requir$ = two dots1 & ! space betwe5 words %\ld occupy ! "t requir$ = ?ree dots4 ,comm5ce ! use ( ! key by mak+ dots 9 succession1 fir/ at ! rate ( two e second1 & increas+ ! spe$ until t5 c be made4 ,practice %\ld be cont9u$ until ?ree hundr$ & sixty dots a m9ute c be made ) p]fect regul>ity4 ,!n beg9 mak+ da%es at ! rate ( two e ?ree seconds1 & cont9ue until "o hundr$ & tw5ty a m9ute c be made ) p]fect regul>ity4 ,practise ! long da%es at ! rate ( "o a second1 & increase until n9ety c be made 9 a m9ute4 ,illu/ration3 ,fig4 #adb4--,! ,morse ,telegraphic ,code4 ,:5 ?is has be5 accompli%$1 practise ! foll[+ lett]s until !y c be p]fectly made4 ,ea* r[ ( lett]s is an ex]cise :i* %\ld be practis$ sep>ately until ma/]$4 ,dot ,lett]s ,e ,i ,s ,h ,p #f ,dot & ,space ,lett]s ,o ,c ,r ,y ,z ,da% ,lett]s ,t ,l ,m #e ,o ,dots & ,da%es ,a ,u ,v #d ,da%es & ,dots ,n ,d ,b #h ,mix$ ,dots & ,da%es ,f ,g ,j ,k ,q ,w ,x #a #b #c #g #i ,p]iod ,aft] y c write ^! diff]5t lett]s1 practise mak+ words4 ,select a li/ ( commonly us$ words4 ,:5 words seem easy to write1 practise s5d+ pages f a book4 ,sy/ematic & cont9ual practice w enable ! /ud5t to make surpris+ progress 9 ma/]+ ! art ( s5d+4 ,read+ & receiv+ messages mu/ be practis$ ) a companion /ud5t4 ,place two in/rum5ts 9 sep>ate rooms or 9 sep>ate h\ses s t ! op]ators w be entirely dep5d5t ^u ! in/rum5ts = _! communication ) ea* o!r4 ,/>t by transmitt+ & receiv+ simple messages4 ,!n use pages f a book1 & increase ! spe$ until x is possible to s5d & receive at lea/ #ae words a m9ute )\t wat*+ ! s\nd] b m]ely dep5d+ ^u ! clicks to det]m9e ! duration ( ! dots & da%es4 ,figure #adj %[s h[ to arrange a regul> telegraph l9e = two /ations4 ,gravity batt]ies %\ld be us$ = regul> telegraph "w4 ,x is necess>y t ! key %\ld be kept clos$ by hav+ its circuit-clos] %ut :5 messages are n be+ s5t4 ,if "o ( ! keys is left op5 ! circuit is brok51 & x is n possible = a p]son at ! o!r end ( ! l9e to s5d a message4 ,e telegraph (fice has a "n or call usually consi/+ ( two lett]s2 ?us = ,new ,york ! call might be ,n4 ,y4 & = ,*icago1 ,c4 ,h4 ,if ,new ,york %\ld desire to call ,*icago1 he w\ld repeat ! call lett]s1 ,c ,h41 until answ]$4 ,*icago w\ld answ] by s5d+ ,i1 sev]al times & sign+1 ,c ,h4 ,:5 s answ]$1 ,new ,york w\ld proce$ ) ! message4 ,,*apt] ,,xi ,,microphones ,,& ,,telephones ,9 #ahgh1 ,david ,edw>d ,hughes discov]$ t ! imp]fect contact =m$ betwe5 two pieces ( "s su* sub/ance z c>bon or *>coal is v s5sitive to ! slighte/ *anges 9 pressure1 & :5 includ$ 9 an electric circuit ) a batt]y & a telephone receiv]1 w transmit s\nds4 ,su* an in/rum5t is call$ a microphone4 ,x has v>i\s =ms b 9 mo/ ( !m "o piece ( c>bon or *>coal is held loosely betwe5 two o!r pieces 9 su* a mann] z to be easily affect$ by ! slighte/ vibrations convey$ to x ?r\gh ! air or any o!r m$ium4 ,illu/ration3 ,fig4 #adc4--;,a ,microphone connect$ to a ,telephone ,receiv]1 & a ,batt]y4 ,figure #adc illu/rates a simple =m ( in/rum5t embody+ ?is pr9ciple4 ,a small p5cil ( c>bon is support$ loosely betwe5 two blocks ( ! same sub/ance glu$ to a ?9 wood5 s\nd+-bo>d ( p9e4 ,! s\nd+-bo>d is m\nt$ 9 an upright position on a wood5 base4 ,! c>bon p5cil re/s loosely 9 two small ind5tations 9 ! c>bon blocks4 ,! blocks are connect$1 by means ( a v f9e wire or a /rip ( t9foil1 ) "o or two cells ( batt]y & a telephone receiv]4 ,any vibration or s\nds 9 range ( ! microphone w cause ! s\nd+-bo>d to vibrate4 ,?is w affect ! pressure ( ! contact betwe5 ! c>bon p5cil & ! two blocks4 ,:5 ! pressure betwe5 ! two is increas$ ! resi/ance 9 ! pa? ( ! electric curr5t is decreas$ & m curr5t imm$iately fl[s ?r\gh ! circuit4 ,on ! o!r h&1 :5 ! pressure is decreas$1 ! resi/ance is increas$ & less curr5t fl[s ?r\gh ! telephone receiv]4 ,! am\nt ( curr5t fl[+ 9 ! circuit ?us keeps /ep ) ! *anges 9 ! resi/ance1 & accord+ly produces s\nds 9 ! telephone receiv]4 ,! vibrations emitt$ f ! receiv] are usually mu* great] ?an ^? ( ! orig9al s\nds1 & s ! microphone may be us$ to magnify weak s\nds su* z ! tick+ ( clock-:eels or ! footfalls ( insects4 ,if a wat* is laid on ! base ( ! microphone1 ! tick+ ( ! escapem5t :eel c be he>d ) />tl+ l\dness4 ,! s\nds caus$ by a fly walk+ on a microphone may be made to s\nd z l\d z ! tramp ( a horse4 ,illu/ration3 ,fig4 #add4--;,a ,v ,s5sitive ,=m ( ,microphone1 ) :i* ! ,foot/eps ( a ,fly c be he>d4 ,! electrical /e?oscopes us$ by physicians to li/5 to ! action ( ! he>t are 9 pr9ciple only a microphone & telephone receiv] connect$ to a batt]y4 ,! draw+ 9 ,figure #add illu/rates a v s5sitive microphone t is q easy to make4 ,) ?is in/rum5t x is possible to he> ! tramp+ ( a fly's feet or ! noise ( its w+s4 ,! base ^u :i* ! app>atus is m\nt$ s]ves z ! s\nd+-bo>d & is made 9 ! =m ( a holl[ wood5 box4 ,x c be made f an ord9>y cig>-box by remov+ ! pap] & tak+ ! box ap>t4 ,! piece =m+ ! top ( ! box mu/ be plan$ d[n until x is only ?ree ?irty-seconds ( an in* ?ick4 ,! box %\ld measure ab\t five in*es squ>e & ?ree-qu>t]s ( an in* ?ick :5 f9i%$4 ,d n use any nails or small brads :atsoev] 9 its con/ruction1 b fa/5 x toge!r ) glue4 ,if y use any nails y w decrease ! s5sitiv5ess ( ! in/rum5t q appreciably4 ,! bottom ( ! box %\ld be left op54 ,! result is a s\nd+-bo>d ( ! same pr9ciples z t ( ! banjo head4 ,small feet1 "o-qu>t] ( an in* squ>e1 are glu$ to ! f\r "u corn]s s z to raise ! bottom cle> ( ! table1 or :atev] ! microphone may be plac$ ^u4 ,! bottom ( ea* "o ( ! small feet is cu%ion$ ) a lay] ( felt s t no j>s w be transmitt$ to ! in/rum5t by any object ^u :i* x is re/+4 ,! c>bon p5cil us$ on ?is type ( in/rum5t is pivot$ 9 ! c5t] & re/s at "o end ^u a c>bon block4 ,! c>bon block is made ab\t "o in* long1 "o-qu>t] ( an in* ?ick1 & "o-half ( an in* wide4 ,a small hole is drill$ ne> ea* end to receive a screw :i* fa/5s ! block to ! s\nd+-bo>d4 ,a f9e wire is l$ f "o ( ^! screws to a b9d+-po/ m\nt$ at ! side ( ! box4 ,ano!r wire leads f a second b9d+-po/ to a /&>d :i* is also fa/5$ to ! s\nd+-bo>d ) a small screw4 ,! /&>d is made f a %eet ( ?9 brass & is b5t into ! %ape %[n 9 ! illu/ration4 ,! p5cil is a piece ( "o-qu>t]-in* c>bon rod1 two & ?ree-qu>t] in*es long4 ,a small hole is drill$ "o & five-eigh?s ( an in* f "o end ) a sew+-ne$le1 & a piece ( f9e brass wire1 po9t$ at bo? ends1 pu%$ 94 ,! wire %\ld be a tight fit 9 ! hole4 ,x %\ld be ab\t "o-half ( an in* long1 & may be made f an ord9>y p94 ,! slide-b> is us$ to regulate ! pressure ( ! p5cil ^u ! c>bon block & is simply a piece ( s(t copp] wire ab\t "o-eigh? ( an in* 9 diamet]4 ,x is b5t into ! %ape %[n 9 ! illu/ration s t x w slide ov] ! c>bon p5cil4 ,! sides ( ! /&>d %\ld press j tightly en\gh aga9/ ! ends ( ! pivot :i* passes ?r\gh ! c>bon p5cil to hold x 9 position )\t slipp+1 & at ! same "t all[ x to sw+ freely up & d[n4 ,! two b9d+-po/s %\ld be connect$ 9 s]ies ) two dry cells & a pair ( good telephone receiv]s4 ,place ! receiv]s aga9/ ! e>s4 ,move ! slide-b> g5tly back & =? until ! voice ( any "o talk+ 9 ano!r "p ( ! room c be he>d di/9ctly 9 ! telephone receiv]s4 ,9 ord] to he> fa9t :isp]s1 move ! slide-b> away f ! c>bon block4 ,9 ord] to he> a fly walk x is necess>y to h ! c>bons v dry & clean4 ,! in/rum5t mu/ be v c>efully adju/$4 ,cov] ! microphone ) a l>ge glass globe & place a fly inside ( ! globe4 ,:5ev] ! fly walks on any "p ( ! microphone y w be able to he> ea* foot/ep 9 ! telephone receiv]s4 ,:5 he flies ab\t inside ( ! globe1 8 w+s w cause a l\d ro>+ & buzz+ noise to be he>d 9 ! receiv]s4 ,telephones ,n _m ye>s ago1 :5 ! telephone made its fir/ appe>ance1 x 0 ! wond] ( ! times j z wireless telegraphy is to-day4 ,/>t+ z an exce$+ly simple & inexp5sive app>atus1 x has gradually develop$ into a wond]ful & complex sy/em1 s t at ! pres5t "t1 in/ead ( exp]i5c+ difficulty 9 telephon+ ov] di/ances ( fifty or "o hundr$ miles1 z at fir/1 x is possible to c>ry on a conv]sation ov] a l9e two ?\s& miles long z easily z x is face to face4 ,l ! telegraph1 ! pr9ciple ( ! telephone is t ( a curr5t ( electricity fl[+ ov] a l9e wire into a pair ( electro-magnets1 b ) _m important diff]5ces4 ,:5 comp>$ ) telegraph app>atus1 ! telephone is f\nd to be exce$+ly s5sitive4 ,a telegraph relay requires p]haps ab\t "o-hundr$? ( an amp]e to "w x prop]ly4 ,a telegraph s\nd] w require ab\t "o-t5? ( an amp]e1 b a telephone receiv] w r5d] spee* audible ) less ?an a million? ( an amp]e1 & !re=e may almo/ be said to be a hundr$ ?\s& times m s5sitive ?an a s\nd]4 ,ano!r diff]5ce betwe5 ! telephone & ! telegraph lies 9 ! fact t ! curr5ts fl[+ ov] a telegraph l9e d n usually v>y at a rate great] ?an tw5ty or ?irty times a second1 :]eas telephone curr5ts *ange _! int5sity hundr$s ( times a second4 ,! telephone is an in/rum5t = ! transmission ( spee* to a di/ance by means ( electricity1 :]e9 ! speak] talks to an ela/ic plate ( ?9 %eet-iron :i* vibrates & s5ds out a pulsat+ curr5t ( electricity4 ,! transmission ( ! vibrations dep5ds ^u well-kn[n pr9ciples ( electricity1 & does n consi/ ( ! actual transmission ( s\nds1 b ( electrical impulses :i* keep p]fect accord or /ep ) ! s\nd waves produc$ by ! voice 9 ! transmitt]4 ,^! electrical curr5ts pass ?r\gh a pair ( small electro-magnets act+ ^u a plate or diaphragm1 :i* 9 turn agitates ! air 9 a mann] simil> to ! orig9al voice speak+ into ! transmitt] & ?us emits s\nds4 ,t "p ( ! app>atus :i* takes up ! s\nds & *anges !m into electric curr5ts composes ! transmitt]4 ,:5 words are spok5 into ! m\?piece !y /rike a diaphragm1 on ! back ( :i* is fa/5$ a small cup-%ap$ piece ( c>bon4 ,a second cup is m\nt$ 9 a rigid position directly back ( ! fir/4 ,! space betwe5 !m is fill$ ) small poli%$ granules ( c>bon4 ,:5 ^! granules are 9 a p]fectly loose /ate & are undi/urb$1 _! resi/ance to an electric curr5t is v great & !y all[ almo/ none to fl[4 ,:5 slightly compress$ _! resi/ance is greatly l[]$ & !y p]mit ! curr5t to pass4 ,! vibrations ( ! diaphragm cause ! c>bon cup m\nt$ on its back to move & ex]t a v>y+ pressure ^u ! granules ) a correspond+ v>iation 9 _! resi/ance & ! am\nt ( curr5t :i* w pass ?r\gh4 ,illu/ration3 ,fig4 #ade4--;,a ,telephone ,sy/em1 consi/+ ( a ,receiv]1 ,transmitt]1 & a ,batt]y connect$ 9 ,s]ies4 ,words spok5 into ! ,transmitt] are reproduc$ by ! ,receiv]4 ,! receiv]1 or t "p ( ! app>atus :i* trans=ms ! pulsat+ curr5t back into s\nd waves consi/s ( a ?9 iron disk1 plac$ v ne> b n q t\*+ ! end ( a small /eel b>1 p]man5tly magnetiz$1 & ab\t :i* is w\nd a coil ( f9e insulat$ wire4 ,! transmitt] & ! receiv] are connect$ toge!r 9 s]ies ) a batt]y z 9 ,figure #ade4 ,:5 words are spok5 into ! transmitt] ! little c>bon granules are imm$iately ?r[n into motion1 & be+ alt]nately compress$ & releas$ cause correspond+ *anges 9 ! curr5t fl[+ ?r\gh ! receiv] f ! batt]y4 ,! magnetism ( ! receiv] *anges ) ea* *ange 9 ! electric curr5t1 & ?us by alt]nately attract+ & repell+ ! diaphragm causes x to vibrate & emit s\nds4 ,su* is ! pr9ciple ( ! telephone4 ,! telephones 9 actual s]vice to-day are complicat$ ) bells1 magnetos1 induction coils1 cond5s]s1 relays1 & v>i\s o!r app>atus1 :i* fact r5d]s !m m effici5t4 ,! bells & magnetos are = ! purpose ( call+ ! c5tral op]ator or ! p]son at ! o!r end ( ! l9e & draw+ att5tion to ! fact t "s "o wi%es to get into communication ) him4 ,! old] /yles ( telephones us$ :at is kn[n z a pol>iz$ bell & a h& magneto = ?is purpose4 ,a pol>iz$ bell is a v s5sitive piece ( app>atus :i* w op]ate ) v little curr5t4 ,a magneto is a small h& dynamo :i* :5 turn$ ) a crank w g5]ate a curr5t caus+ ! bell at ! o!r end ( ! l9e to r+4 ,:5 ! telephone receiv] is rais$ (f its hook 9 ord] to place x to ! e> ! bell & magneto are automatically disconnect$ f ! l9e & ! receiv] & ! transmitt] are connect$ 9 _! place4 ,! curr5t necess>y to supply ! telephone & receiv] is suppli$ by two or ?ree dry cells plac$ inside ( ea* telephone4 ,! late/ types ( in/rum5ts employ :at is kn[n z ! c5tral en]gy sy/em1 :]e9 ! curr5t is suppli$ by a l>ge /orage batt]y locat$ at ! c5tral (fice & s]v+ z a curr5t supply to all ! telephones connect$ to t sy/em4 ,x w\ld be impossible to ent] into ! hi/ory ( ! telephone f> en\gh to expla9 ! details ( "s ( ! v>i\s sy/ems 9 e-day use 9 su* a book z ?is because ( ! imm5se am\nt ( mat]ial x w\ld be necess>y to pres5t4 ,su* a "w w\ld occupy a volume ( its own4 ,additional in=mation may be readily f\nd 9 any ref]5ce libr>y4 ,h[ev]1 ! boy electrician :o wi%es to make a telephone = communicat+ betwe5 ! h\se & b>n1 or ) 8 *um d[n ! /reet1 w f9d ! necess>y in=mation 9 ! foll[+ pages4 ,if ?is "w is c>ri$ out c>efully & a home-made telephone sy/em built & in/all$ x w n only prove a v int]e/+ und]tak+ b w also s]ve to dispel all my/]y :i* may surr\nd ?is device 9 ! m9d ( ! "y exp]im5t]4 ,h[ to ,build a ,telephone ,telephone receiv]s are useful = _m purposes 9 electrical "w o!r ?an to receive spee*4 ,!y are us$ 9 connection ) wireless in/rum5ts1 9 place ( a galvanomet] 9 measur+ electrical circuits1 & = te/+ 9 v>i\s ways4 ,telephone receiv]s are ( two types4 ,"o ( !m is long & cumb]some1 & is v simil> to ! orig9al ,bell telephone receiv]4 ,! o!r is small & flat1 & is call$ a wat*-case receiv]4 ,a wat*-case receiv] is %[n 9 ,figure #adf4 ,x consi/s ( a ,u-%ap$ p]man5t magnet s m\nt$ z to ex]t a pol>iz+ influ5ce ^u a pair ( little electro-magnets1 be=e ! poles ( :i* is plac$ an iron diaphragm4 ,= conv5i5ce1 ^! p>ts are assembl$ 9 a small cyl9drical cas+1 usually ( h>d rubb]4 ,! p]man5t magnet ex]ts a cont9ual pull ^u ! diaphragm1 t5d+ to draw x 94 ,:5 ! telephone curr5ts pass ?r\gh ! little magnets1 !y w ei!r /r5g!n ! p]man5t magnet & assi/ x 9 attract+ ! diaphragm1 or detract f its /r5g? & all[ ! diaphragm to rec$e1 dep5d+ ^u :i* direction ! curr5t fl[s4 ,illu/ration3 ,fig4 #adf4--;,a ,wat*-,case ,telephone ,receiv]4 ,wat*-case receiv]s are usually employ$ = wireless telegraph "w because !y are v light 9 weight & c easily be atta*$ to a head-b& 9 ord] to hold !m to ! e>s & leave ! h&s free4 ,wat*-case receiv]s c be pur*as$ = =ty-five to sev5ty-five c5ts at almo/ any electrical supply h\se4 ,!y are v useful to ! amateur exp]im5t] 9 _m ways4 ,a telephone receiv] capable ( giv+ fair results on a %ort telephone l9e c be v easily made1 b ( c\rse w n prove z effici5t z "o :i* is pur*as$ ready-made f a reliable electrical manufactur]4 ,! fir/ practical telephone receiv] 0 inv5t$ by ,alex&] ,graham ,bell & 0 made some:at along ! same l9es z t %[n 9 ,figure #adg4 ,su* a receiv] may be made f a piece ( curta9-pole1 ?ree & ?ree-qu>t] in*es long & ab\t "o & "o-eigh? in*es 9 diamet]4 ,a hole1 ?ree-eigh?s ( an in* 9 diamet]1 is bor$ along ! axis ?r\gh\t its entire l5g?1 to receive ! p]man5t magnet4 ,! %ell ( ! receiv] is a cup-%ap$ piece ( h>d wood1 two & "o-half in*es 9 diamet] & "o in* deep4 ,x w h to be turn$ on a la!4 ,its exact %ape & dim5sions are be/ und]/ood f ! dim5sions %[n 9 ! cross section 9 ,figure #adg4 ,! %ell is firmly atta*$ to "o end ( ! piece ( curta9-pole by glu+4 ,! p]man5t magnet is a piece ( h>d /eel1 ?ree-eigh?s ( an in* 9 diamet] & f\r & five-eigh?s ( an in* 9 l5g?4 ,! /eel w h to be temp]$ or h>d5$ be=e x w make a suitable magnet1 & ! be/ way to accompli% ?is is to h a blacksmi? d x = y by heat+ ! rod & !n plung+ x into wat] :5 j at ! "r temp]ature4 ,illu/ration3 ,fig4 #adg4--;,a ,simple ,=m ( ,telephone ,receiv]4 ,"o end ( ! b> is fitt$ ) two ?ick fib] wa%]s ab\t sev5-eigh?s ( an in* 9 diamet] & spac$ "o-qu>t] ( an in* ap>t4 ,! bobb9 s =m$ is w\nd full ( ,no4 #cf ,b4 ,s4 gauge s+le-silk-cov]$ magnet wire4 ,! ends ( ! wire are pass$ ?r\gh two small holes 9 ! fib] wa%]s & !n connect$ to a pair ( heavi] wires4 ,! wires are run ?r\gh two holes 9 ! curta9-pole1 pass+ l5g?wise f end to end1 p>allel to ! hole bor$ to receive ! b> magnet4 ,?is b> magnet is !n pu%$ ?r\gh ! hole until ! end ( ! rod on :i* ! spool is fix$ is j bel[ ! level ( ! edges ( ! %ell4 ,! two wires are connect$ to b9d+-po/s1 ,a & ,b1 m\nt$ on ! end ( ! receiv]4 ,a hook is also provid$ s t ! receiv] may be hung up4 ,! diaphragm is a circul> piece ( ?9 %eet-iron1 two & "o-half in*es 9 diamet]4 ,x is plac$ ov] ! %ell1 & ! b> magnet adju/$ until ! end almo/ t\*es ! diaphragm4 ,! magnet %\ld fit into ! hole v tightly1 s t x w h to be driv5 9 ord] to be mov$ back & =?4 ,! diaphragm is held 9 place by a h>d-wood cap1 two & ?ree-qu>t] in*es 9 diamet] & hav+ a hole ?ree-qu>t]s ( an in* 9 diamet] 9 ! c5t]4 ,! cap is held to ! %ell by means ( f\r small brass screws4 ,! receiv] is n[ complet$ & %\ld give a l\d click ea* "t t a batt]y is connect$ or disconnect$ f ! two po/s1 ,a & ,b4 ,! orig9al ,bell telephone app>atus 0 made up simply ( two receiv]s )\t any batt]y or transmitt]4 ,9 su* a case ! curr5t is g5]at$ by induction4 ,! receiv] is us$ to speak ?r\gh z well z to he> ?r\gh4 ,?is me?od ( telephon+ is unsatisfactory ov] any appreciable di/ances4 ,! "t utiliz$ 9 mak+ a transmitt] w be well sp5t4 ,a simple =m ( transmitt] is %[n 9 ,figure #adh4 ,! wood5 back1 ,b1 is ?ree & "o-half in*es squ>e & ?ree-qu>t]s ( an in* ?ick4 ,! front face ( ! block is holl[$ out 9 ! c5t] z %[n 9 ! cross-section view4 ,! face-plate1 ,a1 is two & "o-half in*es squ>e & "o-half an in* ?ick4 ,a hole1 sev5-eigh?s ( an in* 9 diamet]1 is bor$ ?r\gh ! c5t]4 ,"o side is !n holl[$ out to a diamet] ( "o & ?ree-qu>t] in*es1 s z to give space = ! diaphragm to vibrate z %[n 9 ! cross-sectional draw+4 ,! c>bon buttons are "o in* 9 diamet] & ?ree-sixte5?s ( an in* ?ick4 ,a small hole is bor$ 9 ! c5t] ( ea* to receive a brass ma*9e screw4 ,! hole is c\nt]sunk1 s z to br+ ! head ( ! screw d[n z close to ! surface ( ! c>bon z is possible4 ,!n1 us+ a %>p knife or a ?ree-corn]$ file1 score ! surface ( ! c>bon until x is cov]$ ) criss-cross l9es4 ,! diaphragm is a piece ( ?9 %eet-iron cut 9 ! =m ( a circle two & "o-half in*es 9 diamet]4 ,a small hole is bor$ ?r\gh ! c5t] ( ?is4 ,"o ( ! c>bon buttons is fa/5$ to ! c5t] ( ! diaphragm ) a small screw & a nut4 ,cut out a /rip ( flannel or ?9 felt1 n9e-sixte5?s ( an in* wide & ?ree & "o-half in*es long4 ,ar\nd ! edge ( ! c>bon button m\nt$ on ! diaphragm1 b9d ?is /rip ) silk ?read 9 su* a mann] t ! /rip =ms a cyl9d] clos$ at "o end ) ! button4 ,fill ! cyl9d] ) poli%$ c>bon telephone transmitt] granules to a dep? ( ab\t "o-eigh? ( an in*4 ,^! granules w h to be pur*as$ f an electrical supply h\se4 ,!y are f9ely poli%$ small c>bon balls1 mu* l bird%ot 9 appe>ance4 ,slip a long ma*9e-screw ?r\gh ! hole 9 ! second c>bon button & clamp x 9 place ) a nut4 ,!n place ! c>bon button 9 ! cyl9d] s t x closes up ! end4 ,! space betwe5 ! two buttons %\ld be ab\t ?ree-sixte5?s ( an in*4 ,b9d ! flannel or felt ar\nd ! button ) a piece ( silk ?read s t x _c slip out ( place4 ,! arrangem5t ( ! p>ts %\ld n[ be ! same z t %[n by ! cross-sectional draw+ 9 ! upp] "r-h& corn] ( ,figure #adh4 ,! complete transmitt] is assembl$ z %[n 9 ! l[] "p ( ,figure #adh4 ,a small t9 funnel is fitt$ into ! hole 9 ! face-plate1 ,a1 to act z a m\?piece4 ,a screw passes ?r\gh ! back1 ,b1 & connects to ! diaphragm4 ,! screw is m>k$ ,e 9 ! illu/ration4 ,a b9d+-po/ is ?read$ on ! screw s t a wire may be easily connect$4 ,! screw pass+ ?r\gh ! back c>bon button also passes ?r\gh a hole 9 ! wood5 back1 & is clamp$ firmly 9 position ) a brass nut s t ! button is held v rigidly & _c move4 ,! front button1 be+ atta*$ to ! diaphragm1 is free to move back & =? ) ea* vibration ( ! latt]4 ,illu/ration3 ,fig4 #adh4--;,a ,home-made ,telephone ,transmitt]4 ,! c>bon granules %\ld fill ! space betwe5 ! buttons ?ree-qu>t]s full4 ,!y %\ld lie loosely toge!r1 & n be pack$ 94 ,:5 connect$ to a batt]y & a telephone receiv] ! curr5t passes f ! po/1 ,d1 to ! back button1 ?r\gh ! mass ( c>bon granules into ! front button & out at ! po/1 ,e4 ,:5 ! voice is direct$ into ! m\?piece1 ! s\nd waves /rike ! diaphragm & cause x to vibrate4 ,! front button atta*$ to x !n also vibrates & con/antly *anges ! pressure on ! c>bon granules4 ,ea* *ange 9 pressure is accompani$ by an imm$iate *ange 9 resi/ance & consequ5tly ! am\nt ( curr5t fl[+4 ,figure #adi %[s a complete telephone ready = m\nt+ on ! wall4 ,x consi/s ( a receiv]1 telephone transmitt]1 bell1 hook1 & pu%-button4 ,! bell is m\nt$ on a flat base-bo>d4 ,! transmitt] is simil> to t j describ$1 b is built into ! front ( a box-l cab9et4 ,! box is fitt$ ) a pu%-button at ! l[] "r-h& corn]4 ,a simple me?od ( mak+ a suitable pu%-button is %[n 9 ! upp] left-h& "p ( ! illu/ration4 ,x consi/s ( two small brass /rips arrang$ s t pu%+ a small wood5 plug project+ ?r\gh ! side ( ! cab9et w br+ ! two /rips toge!r & make an electrical connection4 ,! hook consi/s ( a /rip ( brass1 pivot$ at "o end ) a r\nd-head$ brass wood screw & provid$ ) a small spr+1 s t :5 ! receiv] is tak5 (f ( ! hook x w fly up & make contact ) a screw1 m>k$ ,c 9 ! illu/ration4 ,:5 ! receiv] is on ! hook1 its weight w draw ! latt] d[n aga9/ ! screw1 ,d4 ,! hook is m\nt$ on ! base-bo>d ( ! telephone1 & projects ?r\gh a slot cut 9 ! side ( ! cab9et4 ,f\r b9d+-po/s are m\nt$ on ! l[] "p ( ! base-bo>d4 ,! two m>k$ ,b & ,b are = ! batt]y4 ,illu/ration3 ,fig4 #adi4--;,a ,complete ,telephone ,in/rum5t4 ,two ,in/rum5ts su* z ?is are necess>y to =m a simple ,telephone ,sy/em4 ,t m>k$ ,l is = ! l9e1 & ,g is = ! gr\nd connection or ! return wire4 ,illu/ration3 ,fig4 #aej4--;,diagram ( ,connection = ! ,telephone ,in/rum5t %[n 9 ,fig4 #adi4 ,! diagram ( ! connections is %[n 9 ,figure #aej4 ,! l9e-wire com+ f ! telephone at ! o!r /ation ent]s ?r\gh ! b9d+-po/ m>k$ ,l1 & !n connects to ! hook4 ,! l[] contact on ! hook is connect$ to "o t]m9al ( ! bell4 ,! o!r t]m9al ( ! bell leads to ! b9d+-po/ m>k$ ,g1 :i* is connect$ to ! gr\nd1 or to ! second l9e-wire1 :]e two are us$4 ,! po/1 ,g1 & "o po/1 ,b1 are connect$ toge!r4 ,! o!r po/ m>k$ ,b connects to "o t]m9al ( ! transmitt]4 ,! o!r t]m9al ( ! transmitt] is connect$ to ! telephone receiv]4 ,! o!r po/ ( ! telephone receiv] leads to ! upp] contact on ! hook m>k$ ,c4 ,! pu%-button is connect$ directly across ! t]m9als ( ! transmitt] & ! receiv] s t :5 ! button is pu%$ x %ort-circuits ! transmitt] & ! receiv]4 ,:5 ! receiv] is on ! hook & ! latt] is d[n s t x makes contact ) ,d any curr5t com+ ov] ! l9e-wire w pass ?r\gh ! bell & d[n ?r\gh ! gr\nd or ! return-wire to ! o!r /ation1 ?us complet+ ! circuit4 ,if ! curr5t is /rong en\gh x w r+ ! b$4 ,:5 ! receiv] is lift$ (f ! hook1 ! spr+ w cause ! hook to rise & make contact ) ! screw m>k$ ,c4 ,?is w connect ! receiv]1 transmitt]1 & ! batt]y to ! l9e s t x is possible to talk4 ,if1 h[ev]1 x is desir$ to r+ ! bell on ! in/rum5t at ! o!r end ( ! l9e1 all t x is necess>y to d is to press ! pu%-button4 ,?is w %ort-circuit ! receiv] & ! transmitt] & r+ ! bell4 ,! batt]y curr5t is fl[+ ov] ! l9e all ! "t :5 ! receiv] is up1 b ! transmitt] & ! receiv] (f] s mu* resi/ance to its fl[ t n en\gh curr5t c pass to r+ ! bell until ! resi/ance is cut out by %ort-circuit+ !m ) ! pu%-button4 ,! in/rum5ts at bo? ends ( ! l9e %\ld be simil>4 ,9 connect+ !m toge!r c>e %\ld be tak5 to see t ! batt]ies at ea* end ( ! l9e are arrang$ s t !y are 9 s]ies & d n oppose ea* o!r4 ,"o side ( ! l9e may be a wire1 b ! return may be ! gr\nd1 z already expla9$ 9 ! *apt] on telegraph app>atus4 ,a transmitt] ( ! desk-/& type may be made accord+ to ! s*eme %[n 9 ,figure #aea4 ,x consi/s simply ( a transmitt] m\nt$ ^u an upright1 & provid$ ) a base s t x may /& on a desk or a table4 ,illu/ration3 ,fig4 #aea4--;,a ,desk-,/& ,type ( ,telephone4 ,x is also fitt$ ) a hook & a pu%-button1 s t x is a complete telephone in/rum5t ) ! exception ( ! bell & ! batt]y4 ,! batt]y & ! bell may be locat$ 9 ano!r place & connect$ to ! desk-/& by means ( a flexible wire or electrical cord4 ,figure #aeb %[s :at is kn[n z a telephone induction coil4 ,induction coils are us$ 9 telephone sy/ems :5ev] x is necess>y to "w ov] a long di/ance4 ,su* a sy/em is m complicat$1 & requires consid]able c>e 9 mak+ ! connections1 b is f> sup]ior to ! sy/em j describ$4 ,illu/ration3 ,fig4 #aeb4--;,a ,telephone ,induction ,coil4 ,an induction coil consi/s ( two fib] or h>d-wood heads1 ab\t "o in* squ>e & "o-qu>t] ( an in* ?ick1 m\nt$ on ! ends ( an iron core compos$ ( a bundle ( small iron wires ab\t two & "o-half in*es long4 ,! core %\ld be ab\t five-sixte5?s ( an in* 9 diamet]4 ,! core is cov]$ ) a lay] ( pap] & !n w\nd ) ?ree lay]s ( ,no4 #bb ,b4 ,s4 s+le-cotton-cov]$ wire4 ,^! ?ree lay]s ( wire =m ! prim>y4 ,! prim>y is cov]$ ) a lay] ( pap] & !n ! second>y is w\nd on4 ,! second>y consi/s ( twelve lay]s ( ,no4 #cf ,b4 ,s4 s+le-silk-cov]$ magnet wire4 ,x is advisable to place a lay] ( pap] betwe5 lay]s ( ! second>y w9d+1 & to give ea* "o a coat+ ( %ellac4 ,! two second>y t]m9als ( ! coil are l$ out ?r\gh holes 9 ! fib] head & kept sep>ate f ! prim>y t]m9als4 ,illu/ration3 ,fig4 #aec4--;,diagram ( ,connection = a ,telephone ,sy/em employ+ an ,induction ,coil at ea* ,/ation4 ,! wir+ diagram ( a telephone sy/em us+ an induction coil at ea* /ation is %[n 9 ,figure #aec4 ,! spee* s5t ov] a l9e us+ an induction coil sy/em is mu* cle>] & m easily und]/ood ?an t on a l9e n us+ su* a device4 ,9 build+ telephone in/rum5ts or connect+ !m up1 c>e & accuracy w g a long way t[>ds success4 ,telephony involves "s v delicate & s5sitive vibratory me*anical & electrical actions1 & su* in/rum5ts mu/ be v c>efully made4 ,a transmitt] is really a microphone built especially to receive ! s\nds ( ! human voice1 & op]ates on ! same pr9ciple4 ,,*apt] ,,xii ,,induction ,,coils ,a ,m$ical ,coil or %ock+ coil1 z x is prop]ly t]m$1 is no?+ m or less ?an a small induction coil1 & consi/s ( a core1 a prim>y w9d+1 a second>y w9d+1 & an int]rupt]4 ,! pr9ciple ( an induction coil & t ( magnetic induction h already be5 expla9$ 9 ,*apt] ,v4 ,x might be well = ! read]s to turn back to pages #hi-ia & r]ead !m4 ,! human body possesses consid]able resi/ance1 & ! voltage ( "o or two ord9>y cells ( batt]y is n suffici5t to ov]come t resi/ance & pass en\gh curr5t ?r\gh ! body to be felt1 unless "u exceptional conditions4 ,! simple/ means employable = rais+ ! voltage ( a batt]y high en\gh to produce a %ock is ! m$ical coil4 ,! fir/ /ep 9 mak+ su* a coil is to roll up a pap] tube1 five-sixte5?s ( an in* 9 diamet] inside1 & two & "o-half in*es long4 ,! out] end ( ! pap] is c>efully glu$1 s t x w n unroll4 ,! tube is fill$ ) pieces ( iron wire two & "o-half in*es long :i* h be5 /raight5$ by roll+ betwe5 two bo>ds4 ,! size ( ! iron wire may v>y f ,no4 #bj to ,no4 #bd ,b4 ,s4 gauge4 ,en\gh %\ld be slipp$ into ! tube to pack x tightly & admit no m4 ,a squ>e block1 #a x #a x #e-af in*es1 is cut out ( fib] or a close-gra9$ h>d wood & a hole ?ree-eigh?s ( an in* 9 diamet] bor$ ?r\gh ! c5t]4 ,"o end ( ! tube conta9+ ! core is sme>$ ) glue & slipp$ into ! block4 ,! end ( ! tube is all[$ to project ?r\gh ab\t "o-sixte5? ( an in*4 ,a second block1 9 ! =m ( a circle ?ree-qu>t]s ( an in* 9 diamet]1 "o-qu>t] ( an in* ?ick1 & hav+ a ?ree-eigh?s ( an in* hole ?r\gh ! c5t]1 is glu$ on ! opposite end4 ,illu/ration3 ,fig4 #aed4--;,details ( ,v>i\s ,p>ts ( a ,m$ical ,coil4 ,aft] ! glue has dri$1 f\r small holes are drill$ 9 ! squ>e head 9 ! approximate positions %[n by ,figure #aed4 ,f\r lay]s ( ,no4 #bb ,b4 ,s4 gauge magnet wire 7x may be ei!r silk or cotton1 d\ble or s+le cov]$7 is w\nd smoo?ly & c>efully ov] ! core4 ,! t]m9als are l$ out ( ! holes a & b4 ,! prim>y is cov]$ ) two or ?ree lay]s ( pap]1 & !n en\gh second>y w\nd on to br+ ! total diamet] ( ! coil to ab\t elev5-sixte5?s ( an in*4 ,! second>y wire mu/ be mu* f9] ?an ! prim>y4 ,x is possible to use any size f ,no4 #cb to ,no4 #cf ,b4 ,s4 gauge & obta9 good results4 ,! insulation may be ei!r s+le silk or s+le cotton4 ,illu/ration3 ,fig4 #aee4--;,details ( ,int]rupt] = ,m$ical ,coil4 ,! second>y t]m9als are l$ out ?r\gh ! holes c & d4 ,x is p]haps a wise plan to re-en=ce ^! leads ) a heavi] piece ( wire1 because o!rwise !y are easily brok54 ,! int]rupt] is a simple arrangem5t capable ( be+ made 9 sev]al diff]5t ways4 ,! draw+ %[s an arrangem5t :i* c be improv$ ^u by any exp]im5t]s :o are famili> ) a m$ical coil4 ,i h %[n ! simple/ arrangem5t1 s t all my read]s w be able to build x1 & ^? :o want to improve x c d s4 ,if a small piece ( silv] is sold]$ to ! spr+ & to ! contact-po9t x w give bett] results4 ,! silv] is easily secur$ by cutt+ up a t5-c5t piece4 ,"o t]m9al ( ! prim>y is connect$ to ! int]rupt] spr+ & ! o!r to a b9d+-po/4 ,! contact-po/ is also connect$ to a b9d+-po/4 ,if a batt]y is connect$ to ! two b9d+-po/s1 ! curr5t w fl[ f "o po/ ?r\gh ! coil to ! int]rupt] spr+1 ?r\gh ! spr+ to ! contact po/1 & !nce back to ! batt]y1 mak+ a complete circuit4 ,z soon z ! curr5t fl[s1 h[ev]1 x produces magnetism :i* draws ! spr+ away f ! contact & breaks ! circuit1 cutt+ (f ! magnetic pull4 ,! spr+ flies back to ! contact b is drawn =w>d aga9 imm$iately & repeats ! op]ation cont9u\sly at a high rate ( spe$4 ,illu/ration3 ,fig4 #aef4--;,complet$ ,m$ical ,coil4 ,! second>y t]m9als are l$ out to two b9d+-po/s to :i* are connect$ two electrodes or h&les by means ( flexible wires4 ,! electrode may be made ( two ord9>y flat /rips ( %eet-metal or a piece ( tub+4 ,9 ! latt] case1 ! wires may be connect$ by w$g+ !m 9 ) a cork4 ,if ! h&les are grasp$ :ile ! batt]y is connect$ to ! prim>y po/s & ! int]rupt] is 9 op]ation a p[]ful %ock w be felt4 ,! %ock may be regulat$ f a weak curr5t t c h>dly be felt to a v p[]ful "o by provid+ ! coil ) a piece ( iron tub+ ( ab\t sev5-eigh?s ( an in* inn] diamet] & two in*es long :i* w slip on & oh ! coil4 ,:5 ! tube is all ! way on1 ! %ock is v mild1 & :5 all ! way (f1 ! %ock is v /rong4 ,( c\rse any int]m$iate /r5g? may be secur$ at /ages betwe5 ! two extremes4 ,! curr5t f m$ical coils is (t5 prescrib$ by physicians = rheumatism & n]v\s disord]s1 b mu/ be prop]ly appli$4 ,! coil j describ$ is h>mless4 ,x w give a /rong %ock1 b ! only result is to make ! p]son receiv+ x drop ! h&les & n be anxi\s to try x aga94 ,sp>k-,coils ,a sp>k-coil is "o ( ! mo/ int]e/+ pieces ( app>atus an exp]im5t] c possess4 ,! exp]im5ts t may be p]=m$ ) its aid are v>i$ & _m4 ,! purpose ( a sp>k-coil is to g5]ate enorm\sly high voltages :i* are able to s5d sp>ks across an air space t ord9>y curr5ts ( l[ voltage c\ld n possibly pi]ce4 ,! sp>k-coil is ! same 9 pr9ciple z ! small induction coils us$ z m$ical or %ock+ coils1 b is made on a l>g] scale & is provid$ ) a cond5s] connect$ across ! t]m9als ( ! int]rupt]4 ,illu/ration3 ,fig4 #aeg4--;,diagram %[+ ,ess5tial ,p>ts ( ,induction ,coil4 ,x consi/s ( a c5tral iron core surr\nd$ by a coil ( heavy wire call$ ! prim>y1 & by a second outside w9d+ ( wire kn[n z ! second>y4 ,! prim>y is connect$ to a few cells ( batt]y 9 s]ies ) an int]rupt]4 ,! int]rupt] makes & breaks ! circuit1 i4 e41 %uts ! curr5t on & (f repeat$ly4 ,e "t t ! curr5t is made or brok51 a high voltage is induc$ 9 ! second>y4 ,by means ( ! cond5s] connect$ across ! int]rupt] t]m9als1 ! curr5t at make is caus$ to take a consid]able fraction ( "t to gr[1 :ile at break1 ! cessation is in/antane\s4 ,! curr5ts induc$ 9 ! second>y at break are s p[]ful t !y leap across ! space 9 a brilliant torr5t ( sp>ks4 ,build+ a ,sp>k-,coil ,p]haps m attempts are made by exp]im5t]s to con/ruct a sp>k-coil ?an any o!r piece ( app>atus1 & ! results are usually poor4 ,a sp>k-coil is n h>d to con/ruct1 b x requires c>eful "w & pati5ce4 ,x is n a job to be f9i%$ 9 a day1 b "t mu/ be lib]ally exp5d$ 9 its con/ruction4 ,satisfactory results are easily obta9$ by any "o ( ord9>y me*anical ability if pati5ce & c>e are us$4 ,p>ts = sp>k-coils are = sale by _m electrical h\ses1 & x is possible to pur*ase a set ( su* ma*9e-made p>ts = less ?an ! sep>ate mat]ials usually co/4 ,= ! b5efit ( ^? :o might wi% to build a l>g] coil ?an ! "o describ$ 9 ! foll[+ text1 a table %[+ ! dim5sions ( two o!r sizes w be f\nd4 ,illu/ration3 ,fig4 #aeh4--;,empty ,pap] ,tube1 & ,tube fill$ ) ,core ,wire prep>atory to w9d+ on ! ,prim>y4 99,! core99 is made ( v s(t iron wire ab\t ,no4 #bj or #bb ,b4 ,s4 gauge1 cut to exact l5g?4 ,ea* piece %\ld be six in*es long4 ,iron wire may be pur*as$ f electrical supply h\ses already cut to v>i\s l5g?s = tw5ty c5ts a p\nd4 ,9 view ( ! am\nt ( labor requir$ c>efully to cut ea* piece to l5g? & !n /raight5 x out s t x w =m a neat bundle1 x is *eap] to pur*ase ! wire already cut4 ,su* wire has be5 anneal$1 i4e41 s(t5$ by br++ to a r$ heat & !n cool+ sl[ly4 ,9 case ! wire is pur*as$ at a plumb+ %op or a h>dw>e /ore x mu/ be anneal$ be=e x c be us$4 ,?is is accompli%$ by ty+ ! wire 9 a compact bundle & plac+ x 9 a wood fire :]e x w gr[ r$-hot4 ,:5 ?is /age is rea*$1 cov] ! wire ) a%es & all[ ! fire to die away4 ,illu/ration3 ,fig4 #aei4--;,illu/rat+ ! ,v>i\s ,/eps 9 w9d+ on ! ,prim>y & fa/5+ ! ,ends ( ! ,wire4 ,cut a piece ( t\gh wrapp+ pap] into /rips six in*es long & ab\t five in*es wide4 ,wrap x ar\nd a /ick or metal rod "o-half ( an in* 9 diamet]1 s z to =m a tube six in*es long & hav+ a diamet] ( "o-half ( an in*4 ,glue ! inside & outside edges ( ! pap] s t ! tube _c unroll & !n slip x (f ! /ick4 ,illu/ration3 ,fig4 #afj4--;,complete ,prim>y ,w9d+ & ,core4 ,fill ! tube ) ! six-in* wires until x is pack$ tightly & no m c be slipp$ 94 99,! prim>y99 consi/s ( two lay]s ( ,no4 #ah ,b4 ,s4 gauge cotton-cov]$ wire w\nd ov] ! core = a di/ance ( five in*es4 ,"o-half p\nd ( wire is m ?an en\gh = "o prim>y4 ,! wire mu/ be w\nd on v smoo?ly & c>efully4 ,9 ord] to fa/5 ! inside end s t x w n become loose1 place a %ort piece ( tape l5g?wise ( ! core & w9d on two or ?ree turns ov] x4 ,!n d\ble ! end back & complete ! w9d+4 ,aft] ! fir/ lay] is f9i%$1 give x a coat ( %ellac & w9d on ! second lay]4 ,! end ( ! wire is w\nd ) a piece ( tape & fa/5$ by slipp+ ?r\gh a loop ( tape emb$d$ "u ! la/ few turns4 ,! illu/rations w expla9 m cle>ly j h[ ?is is accompli%$4 ,! second lay] is !n giv5 a coat ( %ellac & all[$ to dry4 ,aft] x is dry1 wrap ab\t fifte5 lay]s ( pap] :i* h be5 soak$ 9 p>aff9 ar\nd ! prim>y4 ,?is op]ation %\ld be p]=m$ 9 a w>m place1 ov] a fire or light$ lamp :]e ! p>aff9 may be kept s(t1 s t ! pap] w g on tightly4 ,illu/ration3 ,fig4 #afa4--,! ,prim>y cov]$ ) ,insulat+ ,lay] ( ,pap] ready = ! ,second>y4 ,! coil is n[ ready to receive ! second>y w9d+4 ,! core & prim>y :i* h be5 describ$ are suit-able = a second>y giv+ sp>ks f "o-half to ?ree-f\r?s ( an in* long4 99,! second>y99 w9d+ consi/s ( sev]al ?\s& turns ( v f9e wire w\nd on 9 smoo? ev5 lay]s ) pap] betwe5 ea* two lay]s4 ,! foll[+ table %[s ! size & am\nt ( wire requir$4 ,9 addition1 ab\t two p\nds ( p>aff9 & a pad ( l95 pap] or typewrit] pap] w be requir$4 ,! wire may be ei!r enamel1 cotton1 or silk insulat$4 ,s+le silk-cov]$ wire is pref]r$4 ,,size ,,( ,,coil ,,size ,,( ,,wire ,,am\nt #a_/b in* #cf ,b4 ,s4 #aj ounces #a in* #cd ,b4 ,s4 #a lb4 #a_/b in* #cd ,b4 ,s4 #b lbs4 ,! means = support+ & turn+ ! coil 9 ord] to w9d on ! second>y may be left some:at to ! +5uity ( ! "y exp]im5t]4 ,! foll[+ sugge/ion1 h[ev]1 is "o :i* exp]i5ce has prov$ to be well wor? foll[+ out1 & may be appli$ to o!r ?+s ?an ! con/ruction ( an induction coil4 ,x seems to be ! nature ( mo/ boys1 = "s reason or o!r1 to be unwill+ to sp5d "t & labor on any?+ :i* w aid !m 9 _! "w4 ,!y are always 9 su* a hurry & s anxi\s to see some?+ complet$ t !y direct all _! en]gy to t end r ?an sp5d "p ( _! "t 9 con/ruct+ "s little device :i* w\ld really light5 ! o!r "w & g a long way t[>ds insur+ its successful completion4 ,i h frequ5tly giv5 in/ructions = build+ an induction coil & plac$ p>ticul> /ress ^u w9d+ ! second>y1 only to h su* sugge/ions ignor$ 9 ! anxi\s endeavor ( boys to f9i% ! coil z soon z possible4 ,9 e su* in/ance ! coil has be5 a failure4 ,illu/ration3 ,fig4 #afb4--,simple ,w9d+ ,device = w9d+ ! ,second>y4 ,! illu/ration %[s a simple =m ( w9d]1 ) :i* ! op]ation ( w9d+ ! second>y is a v sl[ "o1 b1 on ! o!r h&1 x is possible to d v accurate1 c>eful w9d+ ) ! aid ( su* a device4 ,! p>ts may all be made f wood4 ,! *ucks fit tightly ov] ! ends ( ! core s t :5 ! h&le is turn$1 ! coil w revolve also4 ,! spr+ s]ves to keep ! *ucks snugly aga9/ ! coil ends1 s t !y w n slip4 ,f "o-half to five-eigh?s ( a p\nd ( wire w be requir$ to w9d ! coil4 ,a l>ge numb] ( /rips ( ?9 p>aff9$ or wax$ pap] mu/ be cut five in*es wide4 ,! inside t]m9al1 or beg9n+ end ( ! wire is ti$ ar\nd ! insulat+ tube ne> ! left-h& end4 ,! spool ( wire mu/ be plac$ 9 a position :]e x w revolve freely )\t /ra9 on ! wire4 ,no4 #cf is v f9e & easily brok51 s use ! utmo/ c>e to gu>d aga9/ ?is mi%ap4 ,illu/ration3 ,fig4 #afc4--;,complet$ ,second>y ,w9d+4 ,w9d on a smoo?1 ev5 lay] ( wire1 p]mitt+ ea* turn to t\* ! o!r1 b none to lap ov]4 ,c>ry ! w9d+ to )9 "o-half in* ( ! ends ( ! insulat+ tube & !n w9d on two lay]s ( ! wax$ pap]4 ,! pap] mu/ be put on smoo?ly & ev5ly1 s z to af=d a firm f\ndation = ! next lay]4 ,! wire is wrapp$ ar\nd ) ! pap]1 s t ! next lay] />ts "o-half in* f ! edge4 ,a second lay] is !n w\nd on v c>efully1 /opp+ :5 x comes "o-half in* f ! edge4 ,two m lay]s ( pap] are put on1 & ! process repeat$1 alt]nately w9d+ on pap] & wire until ! /at$ quantity ( ! latt] has be5 us$ up4 ,! lay]s ( wire may occasionally be giv5 a coat+ ( %ellac4 ,?is is a good insulator1 & w s]ve to hold !m toge!r & prev5t ! wire f becom+ loose4 ,9 w9d+ ! coil1 rememb] t if at any po9t y all[ ! w9d+ to become irregul> or unev51 ! irregul>ity w be mu* exagg]at$ on ! succe$+ lay]s4 ,= ?is reason1 d n all[ any to occur4 ,if ! wire t5ds to g on unev5ly1 wrap an extra lay] ( ?ick pap] ar\nd und]nea? s z to (f] a smoo? f\ndation1 & y w f9d ! difficulty rem$i$4 ,illu/ration3 ,fig4 #afd4--;,int]rupt] ,p>ts4 ,an effici5t vibrator = a coil _c be easily made1 & x is be/ to buy "o :i* is already fitt$ ) plat9um po9ts4 ,! int]rupt] w play a v important "p 9 ! successful work+ ( ! coil1 & its arrangem5t & con/ruction are important4 ,int]rupt]s l t %[n 9 ! illu/ration & us$ = automobile w be f\nd ! be/4 ,! cond5s] may be home-made4 ,x consi/s ( alt]nate %eets ( t9foil & p>aff9$ pap]1 arrang$ 9 a pile z %[n 9 ! illu/ration4 ,! foll[+ table gives ! prop] sizes = cond5s]s = ?ree diff]5t coils4 ,,t9foil ,,size ,,( ,,sp>k-,,coil ,,no4 ,,%eets ,,size ,,( ,,%eets #a_/b in* #ej #b x #b #a in* #ajj #g x #e #a #a_/b in* #ajj #h x #f ,! pap] mu/ be ab\t "o-half in* l>g] all ! way ar\nd1 s z to leave a good m>g94 ,! alt]nate %eets ( t9foil1 t is1 all on "o side & all on ! o!r1 are connect$4 ,! cond5s] is connect$ directly across ! t]m9als ( ! int]rupt]4 ,illu/ration3 ,fig4 #afe4--;,cond5s]4 ,!re are v>i\s me?ods ( m\nt+ a coil1 ! mo/ common be+ to place x 9 a box ) ! int]rupt] at "o end4 ,p]haps1 h[ev]1 "o ( ! neate/ & also ! simple/ me?ods is to m\nt x 9 ! mann] %[n 9 ! illu/ration4 ,! end-pieces are cut out ( wood4 ,no specific dim5sions c be giv51 because ! diamet] ( ! coils w v>y some:at accord+ to :o w9ds !m & h[ tightly !y are made4 ,! coil is enclos$ 9 a tube made by roll+ up a /rip ( c>dbo>d & !n giv+ x a coat ( %ellac4 ,! tube may be cov]$ by a /rip ( black clo?1 s z to improve its appe>ance4 ,illu/ration3 ,fig4 #aff4--;,complet$ ,coil4 ,! vibrator is m\nt$ on ! end4 ,! core projects ?r\gh a hole 9 ! wood ne> ! end ( ! vibrator spr+ s t ! latt] w be drawn 9 by ! magnetism ( ! core :5 ! curr5t fl[s4 ,! cond5s] may be plac$ 9 ! holl[ box :i* =ms ! base ( ! coil4 ,! second>y t]m9als ( ! coil are m\nt$ on a small /rip ( wood bridg+ ! two coil ends4 ,"o t]m9al ( ! prim>y is connect$ to a b9d+-po/ m\nt$ on ! base1 & ! o!r l$ to ! vibrator spr+4 ,! vibrator yoke is connect$ to a second b9d+-po/ on ! base4 ,"o t]m9al ( ! cond5s] is connect$ to ! spr+1 & ! o!r to ! yoke4 ,f\r cells ( dry batt]y %\ld be suffici5t to run ! coil & cause x to give a good "o-half-in* sp>k if built accord+ to ! directions "h giv54 ,! vibrator or int]rupt] w require adju/+ & a position ( ! adju/+ screw w soon be f\nd :]e ! coil works be/4 ,exp]im5ts ) a ,sp>k-,coil 99,electrical ,h&s499 ,_m extraord9>y & int]e/+ exp]im5ts may be p]=m$ ) ! aid ( a sp>k-coil4 ,! foll[+ exp]im5t nev] fails to amuse a p>ty ( fri5ds1 & is my/ify+ & weird to ! ord9>y p]son1 unacqua9t$ ) ! secret ( its op]ation4 ,figure #afg %[s ! arrangem5t ( ! app>atus4 ,! prim>y ( an ord9>y "o-in* sp>k induction coil is connect$ 9 s]ies ) a twelve-volt batt]y & telephone transmitt]4 ,a small swit* is includ$ 9 ! circuit to break ! curr5t & prev5t ne$less wa/e ( ! batt]y :5 ! app>atus is n 9 imm$iate use4 ,! second>y t]m9als ( ! induction coil are l$ by means ( an insulat$ wire to ! adjo9+ room :]e !y t]m9ate 9 a pair ( scissors1 or "s o!r small metallic object :i* may be clasp$ 9 ! h&4 ,ea* ( two p]sons1 we>+ dry %oes or rubb]-sol$ slipp]s1 grasps ! t]m9al ( "o wire 9 "o h&4 ,! o!r h& is plac$ flat aga9/ ! e> ( a ?ird p]son1 ) a piece ( dry l95 pap] int]v5+ betwe5 ! h&s & ! head4 ,if a f\r? p]son1 9 ! room :]e ! induction coil is locat$1 !n closes ! small swit* & speaks into ! telephone transmitt]1 ! p]son aga9/ ^: e>s ! h&s are be+ held w he> ! spee* v di/9ctly4 ,! tick+ ( a wat* held aga9/ ! m\?piece ( ! transmitt] w be he>d ) />tl+ cle>ness4 ,illu/ration3 ,fig4 #afg4--;,diagram %[+ h[ to connect ! ,app>atus = ! ,electric ,h&s ,exp]im5t4 ,! pr9ciple gov]n+ ! op]ation ( ! app>atus is v simple4 ,almo/ e exp]im5t] is famili> ) ! ord9>y electrical cond5s]1 :i* consi/s ( alt]nate %eets ( p>aff9$ pap] & t9foil4 ,:5 ?is is connect$ to a s\rce ( electricity ( high pot5tial1 b n en\gh s z to puncture ! pap] dielectric1 ! alt]nate %eets ( t9foil w become oppositely *>g$ & attract ea* o!r4 ,if ! circuit is !n brok5 ! %eets w lose _! *>ge & also _! attraction = "o ano!r4 ,if ! t9foil %eets & pap] are n press$ tightly toge!r1 !re w be a slight movem5t ( ! t9foil & pap] :i* w correspond 9 frequ5cy to any fluctuations ( ! *>g+ curr5t :i* may take place4 ,! head ( ! ?ird p]son & ! h&s held aga9/ 8 head act l ?ree t9foil %eets ( a cond5s]1 sep>at$ by two %eets ( pap]4 ,! words spok5 9 ! transmitt] cause ! curr5t to fluctuate & ! induction coil raises ! pot5tial ( ! curr5t suffici5tly to *>ge ! cond5s] & cause a slight vibration ( ! pap] dielectric4 ,! vibrations correspond 9 /r5g? & spe$ to ^? ( ! voice1 & s ! words spok5 9 ! transmitt] are audible to ! p]son ov] ^: e>s ! pap] is press$4 ,ev]y?+ ab\t ! app>atus mu/ be z dry z possible1 to insure its successful op]ation4 ,! p hold+ ! wires 9 _! h&s %\ld /& on a c>pet$ floor4 ,always be v c>eful to tight5 ! adju/+ screw & block ! int]rupt] on ! coil1 s t by no means c x possibly comm5ce to op]ate1 or ! p]son li/5+1 in/ead ( he>+ ?+s w become ! victim ( a r pa9ful1 practical joke4 ,geissl] ,tubes ,! mo/ beautiful & surpris+ effects may be obta9$ by light+ ,geissl] tubes ) a coil4 ,! tubes are made 9 intricate & v>i$ patt]ns ( special glass1 conta9+ fluoresc5t m9]als & salts1 & are fill$ ) diff]5t r>efi$ gases4 ,:5 ! tubes are connect$ to ! second>y ( a sp>k-coil by means ( a wire fa/5$ to ! little r+s at ! end1 & ! coil is set 9 op]ation1 !y light up 9 ! mo/ wond]ful way imag9able4 ,! r>efi$ gases & m9]als 9 ! glass ?r[ out beautiful iridesc5t colors1 light+ up a d>k room ) a weird flick]+ light4 ,e tube is usually ( a diff]5t patt]n & has a comb9ation ( diff]5t colors4 ,! mo/ beautiful tubes are ^? provid$ ) a d\ble wall conta9+ a fluoresc5t liquid1 :i* height5s ! color effects :5 ! tube is light$4 ,illu/ration3 ,fig4 #afh4--;,geissl] ,tubes4 ,eight to t5 tubes may be light$ at once on an ord9>y coil by connect+ !m 9 s]ies4 ,gho/ ,light ,if y grasp ! bulb ( an old inc&esc5t electric lamp 9 "o h& & t\* ! base to "o side ( ! second>y :5 ! coil is 9 op]ation ! bulb w emit a peculi> gre5i% light 9 ! d>k4 ,punctur+ ,pap] ,if y place a piece ( heavy pap] or c>dbo>d betwe5 two %>p wires connect$ to ! second>y ( a sp>k-coil & />t ! coil work+1 ! pap] w be pi]c$4 ,a ,practical ,joke ,?is action ( ! coil may be made ! basis ( an amus+ joke4 ,(f] a fri5d :o may smoke cig>ettes "s cig>ette pap] :i* has be5 prep>$ 9 ! foll[+ way4 ,illu/ration3 ,fig4 #afi4--,! ,bulb w emit a ,peculi> ,gre5i% ,light4 ,place sev]al %eets ( ! pap] on a piece ( %eet-metal :i* is connect$ to "o side ( ! second>y4 ,by means ( an insulat$ h&le s t y w n get a %ock1 move ! o!r wire all ov] ! surface ( ! cig>ette pap]4 ,! pap] w be pi]c$ ) num]\s f9e holes :i* are s f9e t !y c h>dly be se54 ,if y\r fri5d uses any ( ! pap] 9 mak+ a cig>ette & tries to light x he w wa/e a box ( mat*es )\t be+ able to get "o good puff1 because ! little invisible holes 9 ! pap] w spoil ! draft4 ,p]haps he may quit smok+ altoge!r4 ,an ,electric ,g>bage-c ,illu/ration3 ,fig4 #agj4--;,an ,electrifi$ ,g>bage-c4 ,if !re are any dogs 9 y\r neighborhood t h a habit ( extract+ ?+s f y\r a%-b>rel or g>bage-c1 place ! latt] on a piece ( dry wood4 ,lead a well insulat$ wire f "o second>y t]m9al ( y\r coil to ! c4 ,gr\nd ! o!r second>y t]m9al4 ,if y see a dog ) 8 nose 9 ! c press y\r key & />t ! coil work+4 ,x w n hurt ! dog1 b he w get ! surprise ( 8 life4 ,he w g = home z fa/ z he c travel & w n t\* t p>ticul> c aga91 ev5 if x %\ld conta9 "s ( ! *oice/ can9e delicacies4 ,photograph+ an ,electric ,dis*>ge ,! foll[+ exp]im5t mu/ be conduct$ 9 a d>k room ) ! aid ( a ruby photographic lamp1 z o!rwise ! plates us$ w\ld become light/ruck & spoil$4 ,illu/ration3 ,fig4 #aga4--;,jacob's ,ladd]4 ,plac$ an ord9>y photographic plate on a piece ( %eet-metal ) ! coat$ side ( ! plate upw>ds4 ,connect "o ( ! second>y t]m9als ( ! sp>k-coil to ! piece ( %eet-metal4 ,!n sift a ?9 film ( dry />* p[d]1 sulphur1 or talcum ?r\gh a piece ( f9e gauze on ! plate4 ,lead a %>p-po9t$ wire f ! o!r second>y t]m9al ( ! coil to ! c5t] ( ! plate & !n pu% ! key j long en\gh to make "o sp>k4 ,wipe ! p[d] (f ! plate & develop x 9 ! usual mann] ( films & plates4 ,if y _c d develop+ y\rself1 place ! plate back 9 its box & s5d x to "s fri5d1 or to a photograph]4 ,! result w be a negative %[+ a peculi> electric dis*>ge1 some:at l sea-moss 9 appe>ance4 ,no two su* photographs w be alike & ! greate/ v>iety ( new designs1 etc41 imag9able may be produc$ 9 ?is mann]4 ,jacob's ,ladd] ,take two pieces ( b>e copp] wire ab\t eight in*es long & b5d !m at "r angles4 ,place !m 9 ! second>y t]m9als ( a sp>k-coil z 9 ,figure #aga4 ,b5d !m s t ! v]tical portions are ab\t "o-half ( an in* ap>t at ! bottom & "o in* ap>t at ! top4 ,/>t ! coil work+1 & ! sp>ks w run up ! wires f ! bottom to ! top & appe> v mu* l ! rungs 9 a ladd]4 ,x-,rays ,mo/ "y exp]im5t]s are unaw>e :at a wond]ful & int]e/+ field is op5 to ! possessor ( a small ,x-ray tube4 ,small ,x-ray tubes :i* w op]ate satisfactorily on an in* & "o-half sp>k-coil may be obta9$ f sev]al electrical supply h\ses4 ,!y usually co/ ab\t f\r doll>s & a half4 ,) su* a tube & a fluoroscope x is possible to see ! bones 9 ! human h&1 ! cont5ts ( a clos$ purse1 etc4 ,! tube is made ( glass & conta9s a v high vacuum4 ,! long end ( ! tube conta9s a plat9um electrode call$ ! ca?ode4 ,! %ort end conta9s two electrodes call$ anodes1 "o p]p5dicul> to ! tube & ! o!r diagonal4 ,! tube is usually clamp$ 9 a wood5 hold] call$ an ,x-ray tube /&4 ,! tube %\ld be s adju/$ t ! ,x-rays :i* are reflect$ f ! diagonal anode w pass (f 9 ! direction %[n by ! dott$ l9es 9 ,figure #agd4 ,! fluoroscope is a cone-%ap$ wood5 box fitt$ ) a scre5 compos$ ( a %eet ( pap] cov]$ ) cry/als ( a *emical call$ plat9um-b>ium-cyanide4 ,illu/ration3 ,fig4 #agb4--;,an ,x-,ray ,tube4 ,! opposite end ( ! box is fitt$ ) a cov]+ ( felt or velvet :i* %uts (f ! light ar\nd ! eyes & nose :5 y look into ! fluoroscope & hold x tightly aga9/ ! face4 ,a fluoroscope may be pur*as$ complete1 or ! plat9um-b>ium-cyanide scre5 pur*as$ sep>ately & m\nt$ on a box z %[n 9 ,figure #agc4 ,! two anodes ( ! tube %\ld be connect$1 & l$ to "o t]m9al ( a sp>k-coil capable ( giv+ a sp>k at lea/ "o & "o-half in*es long4 ,ano!r wire %\ld be l$ f ! ca?ode ( ! tube to ! o!r t]m9al ( ! coil4 ,illu/ration3 ,fig4 #agc4--;,fluoroscope4 ,:5 x is desir$ to inspect any object1 su* z ! h&1 x mu/ be held close to ! scre5 ( ! fluoroscope & plac$ betwe5 ! latt] & ! tube 9 ! pa? ( ! ,x-rays4 ,! ,x-rays are ?r[n =? f ! tube at an angle ( #de degrees f ! diagonal anode4 ,look into ! fluoroscope & x %\ld appe> to be fill$ ) a gre5 light4 ,if n1 ! batt]y t]m9als connect$ to ! prim>y ( ! coil %\ld be rev]s$1 s z to s5d ! curr5t ?r\gh 9 ! opposite direction4 ,! ,x-rays w cause ! *emicals on ! scre5 to light up & give =? a peculi> gre5 light4 ,if ! h& is held aga9/ ! scre51 betwe5 ! scre5 & ! tube1 ! ,x-rays w pass ?r\gh ! h& & ca/ a %ad[ on ! scre54 ,!y d n pass ?r\gh ! bones z easily z !y d ?r\gh ! fle% & s w ca/ a %ad[ ( ! bones 9 ! h& on ! scre51 & if y look closely y w be able to see ! v>i\s jo9ts1 etc4 ,! int]rupt] on ! coil %\ld be c>efully adju/$ s t ! light does n flick] too mu*4 ,illu/ration3 ,fig4 #agd4--;,h[ to connect an ,x-,ray ,tube to a ,sp>k-,coil4 ,if x is desir$ to take ,x-ray pictures1 a fluoroscope is unnecess>y4 ,turn ! tube ar\nd s t ! ,x-rays po9t d[nw>d4 ,%ut ! batt]y curr5t (f s t ! tube is n 9 op]ation until ev]y?+ else is ready4 ,place an ord9>y photographic plate1 conta9$ 9 an ord9>y plate-hold]1 directly "u ! tube ) ! gelat9 side ( ! plate upw>ds4 ,place ! h& flat on ! plate & l[] ! tube until x is only ab\t ?ree in*es above ! h&4 ,!n />t ! coil work+ s t ! tube lights up & p]mit x to run = ab\t fifte5 m9utes )\t remov+ ! h&4 ,!n turn ! curr5t (f & develop ! plate 9 a d>k room4 ,x is possible to obta9 a v good ,x-ray photograph ( ! h& 9 ?is mann]4 ,photographs %[+ ! skeleton ( a m\se1 nails 9 a bo>d1 co9s 9 a purse1 a bullet 9 a piece ( wood1 etc41 are a few ( ! o!r objects :i* make int]e/+ pictures4 ,illu/ration3 ,an ,x-,ray ,photograph ( ! h& tak5 ) ! ,outfit %[n 9 ,figure #agd4 ,! arr[s po9t to injuries to ! bone ( ! ?ird f+] ne> ! middle ,jo9t ,result+ 9 a ,/iff ,jo9t4 ,,*apt] ,,xiii ,,trans=m]s ,9 mo/ t[ns & cities :]e electricity = light & p[] is c>ri$ ov] long di/ances1 x w be notic$ t small iron boxes are fa/5$ to ! poles at frequ5t int]vals1 usually :]ev] !re is a gr\p ( h\ses or build+s suppli$ ) ! curr5t4 ,_m boys "k t ! boxes conta9 trans=m]s1 b d n q und]/& exactly :at _! purpose is1 & h[ !y are con/ruct$4 ,:5 x is desir$ to convey electrical en]gy to a di/ance1 = ! purpose ( produc+ ei!r light or p[]1 "o ( ! *ief problems to be fac$ is1 h[ to r$uce to a m9imum any possible wa/e or loss ( en]gy dur+ its transmission4 ,fur!rmore1 s9ce wires & cables ( l>ge size are v co/ly1 x is desirable t !y be z small z possible & yet /ill be able to c>ry ! curr5t )\t undue losses4 ,x has already be5 expla9$ t wires (f] resi/ance to an electrical curr5t1 & t "s ( ! en]gy is lo/ 9 pass+ ?r\gh a wire because ( ?is resi/ance4 ,small wires possess m resi/ance ?an l>ge ones1 & if small wires are to be us$1 9 ord] to save on ! co/ ( ! transmission l9e1 ! loss ( en]gy w be great]1 necessitat+ "s me?od ( p>tially r$uc+ or ov]com+ ?is fault4 ,9 ord] to expla9 cle>ly h[ ! problem is solv$1 ! electric curr5t may = ! mom5t be comp>$ to a /ream ( wat] fl[+ ?r\gh a pipe4 ,illu/ration3 ,fig4 #age4--;,comp>ison betwe5 ,electric ,curr5t & ,fl[ ( ,wat]4 ,! illu/ration %[s two pipes1 a small "o & a l>ge "o1 ea* suppos$ to be connect$ to ! same tank1 s t ! pressure 9 ea* is equal1 & x is cle>ly app>5t t m wat] w fl[ out ( ! l>ge "o ?an out ( ! small "o4 ,if t5 gallons ( wat] fl[ out ( ! l>ge pipe 9 "o m9ute1 x may be possible t ! comp>ative sizes ( ! pipes are su* t only "o gallon ( wat] w fl[ out ( ! small "o 9 ! same l5g? ( "t4 ,b 9 case x %\ld be necess>y or desirable to get t5 gallons ( wat] a m9ute out ( a small pipe su* z ,b1 :at c\ld be done to accompli% x8 ,! pressure c\ld be increas$4 ,! wat] w\ld !n be able bett] to ov]come ! resi/ance ( ! small pipe4 ,?is is exactly :at is done 9 ! di/ribution ( electric curr5ts = p[] & light+4 ,! pressure or pot5tial is increas$ to a value :]e x c ov]come ! resi/ance ( ! small wires4 ,b un=tunately x r>ely happ5s t electrical p[] c be utiliz$ at high pressure = ord9>y purposes4 ,= in/ance1 #aaj volts is usually ! maximum pressure requir$ by inc&esc5t lamps1 :]eas ! pressure on ! l9e wires issu+ f ! p[]-h\se is g5]ally #b1bjj volts or m4 ,su* a high voltage is h>d to insulate1 & w\ld kill mo/ p com+ into contact ) ! l9es1 & is o!rwise dang]\s4 ,be=e ! curr5t ent]s a h\se1 !re=e1 "s app>atus is necess>y1 :i* is capable ( r$uc+ ?is high pressure to a value :]e x may be safely employ$4 ,?is is ! duty p]=m$ by ! trans=m] enclos$ 9 ! black iron box fa/5$ on ! top ( ! electric light poles ab\t ! /reets4 ,if a trans=m] 7 to be def9$ x might be said to be a device = *ang+ ! voltage & curr5t ( an ,alt]nat+ circuit 9 pressure & am\nt4 ,! ^w1 alt]nat+1 has be5 plac$ 9 italics because x is only ^u alt]nat+ curr5ts t a trans=m] may be successfully employ$4 ,!re91 also1 lies ! reason :y alt]nat+ curr5t is suppli$ 9 "s cases in/ead ( direct curr5t4 ,x makes possible ! use ( trans=m]s = l[]+ ! voltage at ! po9t ( s]vice4 ,_m boys possess+ electrical toys & app>atus op]at+ ^u direct curr5t only1 h bemoan$ ! fact t ! light+ sy/em 9 _! t[n furni%$ alt]nat+ curr5t4 ,v (t5 9 ! case ( small cities or t[ns "o p[]-h\se furni%es ! curr5t = sev]al communities & ! en]gy has to be c>ri$ a consid]able di/ance4 ,alt]nat+ curr5t is !n usually employ$4 ,illu/ration3 ,fig4 #agf4--;,alt]nat+ ,curr5t ,sy/em = ,light & ,p[]4 ,! illu/ration %[s ! g5]al me?od ( arrang+ su* a sy/em4 ,a l>ge dynamo locat$ at ! p[]-h\se g5]ates alt]nat+ curr5t4 ,! alt]nat+ curr5t passes into a /ep-up trans=m] :i* raises ! pot5tial to #b1bjj volts 7approximately74 ,x is !n possible to use mu* small] l9e wires1 & to transmit ! en]gy ) small] loss ?an if ! curr5t 7 s5t out at ! ord9>y dynamo voltage4 ,! curr5t passes ov] ! wires at ?is high voltage1 b :]ev] connection is e/abli%$ ) a h\se or o!r build+1 ! s]vice wires :i* supply ! h\se are n connect$ directly to ! l9e wires1 b to a a /ep-d[n trans=m] :i* l[]s ! pot5tial ( ! curr5t fl[+ into ! h\se to ab\t #aaj volts4 ,9 l>g] cities :]e ! dem& = curr5t 9 a giv5 area is mu* great] ?an t 9 a small t[n1 a some:at diff]5t me?od ( di/ribut+ ! en]gy is employ$4 ,illu/ration3 ,fig4 #agg4--,motor ,g5]ator ,set = *ang+ ,alt]nat+ ,curr5t to ,direct ,curr5t4 ,! alt]nat+ curr5t g5]at$ by ! huge dynamos at ! c5tral /ation is pass$ into a set ( trans=m]s :i* 9 "s cases raise ! pot5tial z high z five or six ?\s& volts4 ,! curr5t is !n s5t out ov] cables or fe$]s to v>i\s sub /ations1 or conv]t] /ations1 locat$ 9 v>i\s p>ts ( ! city4 ,"h ! curr5t is fir/ s5t ?r\gh a set ( /ep-d[n trans=m]s :i* r$uce ! pot5tial to ! approximate value orig9ally g5]at$ by ! dynamos4 ,x !n passes into ! rot>y conv]t]s :i* *ange ! alt]nat+ curr5t into direct curr5t aft] :i* x is s5t by und]gr\nd cables direct to ! consum]s 9 ! neighborhood4 ,a trans=m] 9 its simple/ =m consi/s ( two indep5d5t coils ( wire w\nd ^u an iron r+4 ,:5 an alt]nat+ curr5t is pass$ ?r\gh "o ( ! coils1 kn[n z ! prim>y1 x produces a magnetic field :i* induces a curr5t ( electricity 9 ! o!r1 or second>y1 coil4 ,! pot5tial or voltage ( ! curr5t 9 ! second>y is 9 ne>ly ! same ratio to ! pot5tial ( ! curr5t pass$ into ! prim>y z ! numb] ( turns 9 ! second>y is to ! numb] ( turns 9 ! prim>y4 ,illu/ration3 ,fig4 #agh4--,/ep-,up ,trans=m]4 ,kn[+ ?is1 x is v easy to arrange a trans=m] to /ep ! pot5tial up or d[n z desir$4 ,! trans=m] 9 ,figure #agh repres5ts a /ep-up trans=m] hav+ t5 turns ( wire on ! prim>y & tw5ty turns on ! second>y4 ,if an alt]nat+ curr5t ( #aj volts & #b amp]es is pass$ into ! prim>y1 ! second>y w9d+ w d\ble ! pot5tial1 s9ce x has twice z _m turns z ! prim>y & ! curr5t deliv]$ by ! second>y w be approximately #bj volts & #a amp]e4 ,! action may be v easily rev]s$ & a /ep-d[n trans=m] arrang$ by plac+ tw5ty turns ( wire on ! prim>y & t5 turns on ! second>y4 ,if a curr5t ( #bj volts & #a amp]e is pass$ into ! prim>y1 ! second>y w deliv] a curr5t ( only #aj volts & #b amp]es1 s9ce x conta9s only half z _m turns4 ,a circul> r+ ( iron wire w\nd ) two coils w\ld 9 _m respects be some:at difficult to con/ruct1 & s ! iron core is usually built 9 ! =m ( a holl[ rectangle & =m$ ( %eets ( iron4 ,illu/ration3 ,fig4 #agi4--,/ep-,d[n ,trans=m]4 ,x is (t5 desirable to h at h& an alt]nat+ curr5t ( l[ voltage = exp]im5tal purposes4 ,su* a curr5t may be us$ = op]at+ induction coils1 motors1 lamps1 toy railways1 etc41 & is q z satisfactory z direct curr5t = _m purposes1 ) ! possible exception ( electro-plat+ & /orage-batt]y *>g+1 = :i* x _c be us$4 ,:5 ! supply is drawn f ! #aaj-volt light+ circuit & pass$ ?r\gh a small /ep-d[n trans=m]1 ! alt]nat+ curr5t is n only *eap] b m conv5i5t4 ,a trans=m] ( ab\t #ajj watts capacity1 capable ( deliv]+ a curr5t ( #aj volts & #aj amp]es f ! second>y w n draw m ?an approximately "o amp]e f ! #aaj-volt circuit4 ,?is curr5t is only equal to t consum$ by two ord9>y #af-;c&le-p[] lamps or "o ( #cb c&le-p[]1 mak+ x possible to op]ate ! trans=m] to its full capacity = ab\t "o c5t an h\r4 ,a fur!r advantage is ! fact t a /ep-d[n trans=m] enables ! small boy to use ! light+ curr5t = op]at+ electrical toys )\t dang] ( receiv+ a %ock4 ,illu/ration3 ,fig4 #ahj4--;,core ,dim5sions4 ,! trans=m] describ$ 9 ! foll[+ pages c be easily built by any boy at all famili> ) tools1 & %\ld make a valuable addition to 8 electrical equipm5t1 provid$ t ! directions are c>efully foll[$ & pa9s are tak5 to make ! insulation p]fect4 ,! capacity ( ! trans=m] is approximately #ajj watts4 ,! dim5sions & details ( con/ruction describ$ & illu/rat$ are ^? ( a trans=m] int5d$ = use ^u a light+ curr5t ( #aaj volts & #fj-;cycles frequ5cy4 ,! frequ5cy ( mo/ alt]nat+ curr5t sy/ems is #be1 #fj1 or #abj cycles4 ,! mo/ common frequ5cy is #fj4 ,dim5sions & p>ticul>s ( trans=m]s = #be & #abj cycles w be f\nd 9 ! =m ( a table f>!r on4 ,! frequ5cy ( y\r light circuit may be asc]ta9$ by inquir+ ( ! company supply+ ! p[]4 ,illu/ration3 ,fig4 #aha4--,! ,core1 ,assembl$ & ,tap$4 ,! fir/ "p to be consid]$ 9 ! con/ruction ( a trans=m] is ! core4 ,! core is made up ( ?9 %eet-iron /rips ( ! dim5sions %[n 9 ,figure #ahj4 ,! iron may be secur$ f almo/ any h>dw>e /ore or plumb+ %op by ord]+ /ove-pipe iron4 ,h ! iron cut into /rips #a #a_/d in*es wide & #bd in*es long4 ,!n1 us+ a pair ( t9n]'s %e>s1 cut ! long /rips into pieces #c in*es & #d #c_/d in*es long until y h en\gh to make a pile ( ea* #b #a_/b in*es high :5 !y are /ack$ up neatly & compress$4 ,! long /rips are us$ to =m ! legs ( ! core1 & ! %ort ones ! yokes4 ,illu/ration3 ,fig4 #ahb4--,trans=m] ,leg4 ,! /rips are assembl$ accord+ to ! diagram %[n 9 ,figure #ahj4 ,! alt]nate ends ov]lap & =m a holl[ rectangle #d #a_/d x #f in*es4 ,! core %\ld be press$ tightly toge!r & ! legs b\nd ) ?ree or f\r lay]s ( insulat+ tape prep>atory to w9d+ on ! prim>y4 ,aft] ! legs are b\nd1 ! yoke pieces may be pull$ out1 leav+ ! legs intact4 ,f\r fib] heads1 #b #a_/b in*es squ>e & #a_/h ( an in* ?ick1 are made z %[n 9 ,figure #ahc4 ,a squ>e hole #a #a_/d x #a #a_/d in*es is cut 9 ! c5t]4 ,two ( ^! are plac$ on ea* ( ! assembl$ legs z %[n 9 ,figure #ahd4 ,illu/ration3 ,fig4 #ahc4--;,fib] ,head4 ,! prim>y w9d+ consi/s ( "o ?\s& turns ( ,no4 #bj ,b4 ,s4 gauge s+le-cotton-cov]$ magnet wire4 ,five hundr$ turns are w\nd on ea* leg ( ! trans=m]4 ,! wire %\ld be w\nd on v smoo?ly & ev5ly ) a lay] ( %ellack$ pap] betwe5 ea* lay] ( wire4 ,! two legs %\ld be connect$ 9 s]ies4 ,! t]m9als are protect$ & insulat$ by cov]+ ) "s insulat+ tape roll$ up 9 ! =m ( a tube4 ,! second>y w9d+ consi/s ( "o hundr$ turns ( ,no4 #aj ,b4 ,s4 gauge d\ble-cotton-cov]$ wire4 ,fifty turns are w\nd on ea* leg1 ov] ! prim>y1 sev]al lay]s ( pap] be+ plac$ betwe5 ! two4 ,illu/ration3 ,fig4 #ahd4--,leg ) ,heads 9 ,position = ,w9d+4 ,a tap is br\ght out at e t5 turns4 ,! taps are made by sold]+ a n>r[ /rip ( %eet-copp] to ! wire at prop] int]vals4 ,c>e mu/ be tak5 to insulate ea* jo9t & tap ) a small /rip ( insulat+ tape s t !re is no dang] ( a %ort circuit be+ =m$ betwe5 adjac5t turns4 ,aft] ! w9d+ is complet$ ! trans=m] is ready = assembl+4 ,! yoke pieces ( ! core %\ld be slipp$ into position & ! :ole c>efully l9$ up4 ,! trans=m] itself is n[ ready = m\nt+4 ,illu/ration3 ,fig4 #ahe4--;,h[ to make a ,tap 9 ! ,prim>y by sold]+ a ,copp] ,/rip to ! ,wire4 ,! base-bo>d measures #aa x #g #c_/d x #g_/h in*es4 ,x is %[n 9 ,figure #aib4 ,! trans=m] re/s ^u two wood5 /rips1 ,a & ,b1 #d #a_/d in*es long1 #a #a_/d in*es wide1 & #c_/d ( an in* high4 ,! /rips are nail$ to ! base s t !y w come "u ! ends ( ! core outside ( ! fib] heads4 ,! trans=m] is held to ! base by two tie-rods pass+ ?r\gh a /rip1 ,c1 #f in*es long1 "o-half ( an in* ?ick & ?ree-qu>t]s ( an in* wide4 ,! /rip re/s on ! ends ( ! core4 ,! tie-rods are fa/5$ on ! "u side ( ! base by means ( a nut & wa%] on ! ends4 ,:5 ! nuts are screw$ up tightly1 ! cross-piece w pull ! trans=m] firmly d[n to ! base4 ,illu/ration3 ,fig4 #ahf4--,! ,trans=m] completely ,w\nd & ready = ,assembl+4 ,! regulat+ swit*es1 two 9 numb]1 are m\nt$ on ! l[] "p ( ! base4 ,! contact po9ts & ! arm are cut out ( %eet-brass1 "o-eigh? ( an in* ?ick4 ,x is unnecess>y to g into ! details ( _! con/ruction1 because ! dim5sions are pla9ly %[n 9 ,figure #ahh4 ,! contacts are drill$ out & c\nt]sunk s t !y may be fa/5$ to ! base ) small flat-head$ wood screws4 ,ea* swit*-arm is fitt$ ) a small rubb] knob to s]ve z a h&le4 ,! arm works on a small piece ( brass ( exactly ! same ?ickness z ! swit*-po9ts4 ,c>e mu/ be tak5 t ! po9ts & ?is wa%] are all exactly 9 l9e1 s t ! arm w make good contact ) ea* po9t4 ,!re are five po9ts to ea* swit*1 z %[n 9 ,figure #aij4 ,illu/ration3 ,fig4 #ahg4--,wood5 ,/rips = m\nt+ ! ,trans=m] on ! ,base4 ,! swit*1 ,d1 is arrang$ s t ea* /ep cuts 9 or out tw5ty turns ( ! second>y1 ! fir/ po9t be+ connect$ ) ! end ( ! w9d+4 ,! second po9t connects ) ! fir/ tap1 ! ?ird contact ) ! second tap1 ! f\r? contact ) ! ?ird tap1 & ! fif? contact ) ! f\r? tap4 ,illu/ration3 ,fig4 #ahh4--;,details ( ! ,swit* ,p>ts4 ,! swit*1 ,e1 is arrang$ s t ea* /ep cuts 9 or out five turns4 ,! contacts on ?is swit* are numb]$ 9 ! rev]se direction4 ,! fif? contact ( swit* ,d1 & ! fif? contact ( swit* ,e1 are connect$ toge!r4 ,! f\r? contact is connect$ to ! fif? tap1 ! ?ird contact to ! six? tap1 ! second contact to ! sev5?1 & ! fir/ contact to ! end ( ! w9d+4 ,?is arrangem5t makes x possible to secure any voltage f "o-half to t5 9 "o-half-volt /eps f ! second>y ( ! ma*9e4 ,ea* /ep on ! swit*1 ,d1 w give two volts1 :ile ^? on ,e w ea* give "o-half ( a volt4 ,illu/ration3 ,fig4 #ahi4--,! ,complete ,swit*4 ,two b9d+-po/s 7m>k$ ,p & ,p 9 ! draw+7 m\nt$ 9 ! upp] corn]s ( ! base are connect$ to ! t]m9als ( ! prim>y w9d+4 ,! two po/s 9 ! l[] corn]s 7m>k$ ,s & ,s 9 ! draw+7 are connect$ to ! swit* lev]s1 & are ! po/s f :i* ! second>y or l[ voltage is obta9$4 ,illu/ration3 ,fig4 #aij4--;,diagram ( ,connections4 ,! trans=m] may be connect$ to ! #aaj-,v4 alt]nat+ curr5t circuit by means ( an atta*m5t plug & cord4 ,"o end ( ! cord is plac$ 9 ea* ( ! prim>y b9d+-po/s4 ,! o!r end ( ! cord is connect$ to ! atta*m5t plug s t ! latt] may be screw$ into any conv5i5t electric-light socket4 ,illu/ration3 ,fig4 #aia4--,top ,view ( ! ,trans=m]4 ,! trans=m] mu/ n be connect$ directly to ! l9e4 ,an in/rum5t su* z ?is is n design$ = cont9u\s s]vice & is int5d$ to be disconnect$ z soon z y are ?r\gh us+ x4 ,illu/ration3 ,fig4 #aib4--,side ,view ( ! ,trans=m]4 ,x w be f\nd a great conv5i5ce 9 op]at+ _m ( ! electrical devices describ$1 :]ev] direct curr5t is n ess5tial4 ,,*apt] ,,viv ,,wireless ,,telegraphy ,probably no bran* ( electrical sci5ce ev] appeal$ m to ! imag9ation ( ! exp]im5t] ?an t com+ "u ! head+ ( wireless telegraphy4 ,:]ev] y g1 y are likely to see ! e>-m>ks ( amateur wireless telegraph /ations 9 ! a]ials & ma/s set up 9 trees & on h\se-tops4 ,x is e/imat$ t !re are ne>ly a qu>t] ( a million su* /ations 9 ! ,unit$ ,/ates4 ,!re is really no great my/]y ab\t ?is wond]ful art :i* made possible ! in/antane\s transmission ( messages ov] imm5se di/ances )\t any app>5t physical connection save t ( ! e>?1 air1 or wat]4 ,did y ev] ?r[ a /one 9 a pool ( wat]8 ,z soon z ! /one /ruck1 little waves spread out f ! spot 9 gradually enl>g+ circles until !y rea*$ ! %ore or di$ away4 ,by ?r[+ sev]al /ones 9 succession1 ) v>y+ int]vals ( "t betwe5 !m1 x w\ld be possible s to arrange a set ( signals1 t !y w\ld convey a mean+ to a second p]son /&+ on ! opposite %ore ( ! pool4 ,wireless telegraphy is bas$ ^u ! pr9ciple ( creat+ & detect+ waves 9 a great pool ( e!r4 ,mod]n sci5ti/s suppose t all space is fill$ ) an imag9>y sub/ance call$ e!r4 ,! e!r is invisible1 odorless1 & practically weightless4 ,?is e!r1 h[ev]1 be>s no relation to ! anae/hetic ( t "n :i* is us$ 9 surgical op]ations4 ,x surr\nds & p5etrates all sub/ances & all space4 ,illu/ration3 ,fig4 #aic4--,little ,waves spread out f ! ,spot4 ,x exi/s 9 a vacuum & 9 solid rocks4 ,s9ce ! e!r does n make itself app>5t to any ( our physical s5ses1 "s ( ^! /atem5ts may seem contradictory4 ,its def9ite exi/5ce _c be prov$ except by reason+1 b by accept+ & imag9+ its reality1 x is possible to und]/& & expla9 _m sci5tific puzzles4 ,a good in/ance is (f]$ by ! sun4 ,light & heat c be %[n to consi/ ( extremely rapid vibrations4 ,t fact c be prov$4 ,! sun is ov] #ij1jjj1jjj miles away f our e>? & yet light & heat come /ream+ d[n to u ?r\gh a space t is devoid ev5 ( air4 ,some?+ mu/ exi/ z a m$ium to transmit ^! vibrations2 x is ! e!r4 ,let u consid] aga9 ! pool ( wat]4 ,! waves or ripples caus$ by ?r[+ 9 ! /one are vibrations ( ! wat]4 ,! di/ance betwe5 two adjac5t ripples is call$ ! wave l5g?4 ,! di/ances betwe5 two vibrations ( light c also be measur$4 ,!y are s small1 h[ev]1 t !y may be spok5 ( only 9 ?\s&?s ( an in*4 ,! waves creat$ 9 ! e!r by wireless telegraph app>atus are ! same z ^? ( light except t _! l5g? usually v>ies f #ge to #i1jjj feet in/ead ( a fraction ( a ?\s&? ( an in*4 ,illu/ration3 ,fig4 #aid4--;,a ,simple ,transmitt]4 99,a ,simple ,transmitt]99 is illu/rat$ 9 ,figure #aid4 ,a telegraph key is connect$ 9 s]ies ) a set ( cells & ! prim>y ( an induction coil1 :i*1 x w be rememb]$1 is simply a coil consi/+ ( a few turns ( wire4 ,?is induces a high voltage 9 a second coil consi/+ ( a l>g] numb] ( turns & call$ ! second>y4 ,! t]m9als ( ! second>y are l$ to a sp>k-gap--an arrangem5t compos$ ( two poli%$ brass balls1 sep>at$ by a small air-gap4 ,"o ( ! balls1 9 turn1 is connect$ to a metal plate buri$ 9 ! e>?1 & ! o!r to a network ( wires susp5d$ high 9 ! air & insulat$ f all surr\nd+ objects4 ,:5 ! key at ! transmitt] is press$1 ! batt]y curr5t fl[s ?r\gh ! prim>y ( ! induction coil & g5]ates 9 ! second>y a curr5t ( v high voltage1 #bj1jjj volts or m1 :i* is able to jump an air-gap 9 ! %ape ( a sp>k at ! second>y t]m9als4 ,! latt] are connect$ to ! e>? & a]ial1 z expla9$ above4 ,! high pot5tial curr5ts are !re=e enabl$ to *>ge ! a]ial4 ,! *>ge 9 ! a]ial ex]ts a great t5d5cy to pass into ! gr\nd1 b is prev5t$ f do+ s by ! small air-gap betwe5 ! sp>k-balls until ! *>ge becomes s great t ! air-gap is punctur$ & ! *>ge passes across & fl[s d[n into ! gr\nd4 ,! passage ( ! *>ge is made evid5t by ! sp>k betwe5 ! two sp>k-balls4 ,! electrical *>ges fl[+ up & d[n ! a]ial di/urb ! e!r1 /rike x a bl[1 z x 74 ,! effect ( ! bl[ is to cause ! e!r to vibrate & to s5d out waves 9 all directions4 ,x may be lik5$ to ! pond ( wat] :i* is sudd5ly /ruck a bl[ by ?r[+ a /one into x1 s t ripples are imm$iately s5t out 9 wid5+ circles4 99,^! ,waves 9 ! ,e!r99 are call$ electro-magnetic or ,h]tzian waves1 aft] _! discov]]1 ,h]tz4 ,! di/ance ov] :i* !y pass is dep5d5t ^u ! p[] ( ! transmitt+ /ation4 ,! waves c be made to correspond to ! dots & da%es ( ! telegraphic code by s press+ ! key4 ,if "s means ( detect+ ! waves is employ$ we may readily see h[ x is possible to s5d wireless messages4 99,! ,action ( ! ,receiv+ ,/ation99 is j ! opposite ( t ( ! transmitt]4 ,:5 ! waves pass out ?r\gh ! e!r1 "s ( !m /rike ! a]ial ( ! receiv+ /ation & g5]ate a *>ge ( electricity 9 x :i* t5ds to pass d[n into ! e>?4 ,if ! transmitt+ & receiv+ /ations are v close toge!r & ! =m] is v p[]ful1 x is possible to make a v small gap 9 ! receiv+ a]ial across :i* ! *>ge w jump 9 ! %ape ( sp>ks4 ,?us ! action ( ! receptor simply takes place 9 a rev]s$ ord] f t ( ! transmitt]4 ,if ! /ations are any consid]able di/ance ap>t1 x is impossible = ! curr5ts induc$ 9 ! receiv+ a]ial to produce sp>ks1 & s "s m s5sitive means ( detect+ ! waves f ! transmitt] is necess>y1 pref]ably "o :i* makes itself evid5t to ! s5se ( he>+4 ,! telephone receiv] is an extremely s5sitive in/rum5t1 & x only requires a v weak curr5t to op]ate x & produce a s\nd4 ,! curr5ts or oscillations g5]at$ 9 ! a]ial1 h[ev]1 are alt]nat+ curr5ts 7see pages #ig-ii7 ( high frequ5cy1 t is1 !y fl[ 9 "o direction & !n rev]se & fl[ 9 ! o!r sev]al ?\s& times a second4 ,su* a curr5t _c be made to pass ?r\gh a telephone receiv]1 & 9 ord] to d s ! nature ( ! curr5t mu/ be *ang$ by conv]t+ x into direct curr5t fl[+ 9 "o direction only4 ,c]ta9 m9]als & cry/als possess ! rem>kable ability to d ?is1 silicon1 gal5a1 & iron pyrites are among ! be/4 ,illu/ration3 ,fig4 #aie4--;,a ,simple ,receptor4 ,! diagram 9 ,figure #aie %[s ! arrangem5t ( a simple receiv+ outfit4 ,! detector consi/s ( a s5sitive m9]al plac$ betwe5 two contacts & connect$ s t ! a]ial curr5ts mu/ pass ?r\gh x on _! way to ! gr\nd4 ,a telephone receiv] is connect$ to ! detector s t ! rectifi$ curr5ts 7curr5ts :i* h be5 *ang$ into direct curr5t7 pass into x & produce a s\nd4 ,by v>y+ ! p]iods dur+ :i* ! key is press$ at ! transmitt+ /ation1 accord+ to a pre>rang$ code1 ! s\nds 9 ! receiv] may be made to assume an intelligible mean+4 ,,h[ ,,to ,,build ,,wireless ,,in/rum5ts 99,! ,a]ial99 ,e wireless /ation is provid$ ) a sy/em ( wires elevat$ high 9 ! air1 above all surr\nd+ objects1 ! purpose ( :i* is to radiate or int]cept ! electromagnetic waves1 accord+ly z ! /ation is transmitt+ or receiv+4 ,?is sy/em ( wires is1 z already has be5 /at$1 call$ ! a]ial or ant5na4 ,! arrangem5t ( ! a]ial w greatly det]m9e ! effici5cy & range ( ! app>atus4 ,! a]ial %\ld be z long z x is reasonably possible to make x1 t is f #ej to #aej feet4 ,x w be necess>y = mo/ amateurs to put up _! a]ial 9 "s "o c]ta9 place1 reg>dless ( :at else may be 9 ! vic9ity1 b :5ev] possible ! site select$ %\ld pref]ably be su* t ! a]ial w n be 9 ! imm$iate neighborhood ( any tall objects1 su* z trees1 smoke-/acks1 telephone wires1 etc41 because su* objects w int]f]e ) ! a]ial & noticeably decrease ! range ( ! /ation1 bo? :5 transmitt+ & receiv+4 ,b>e copp] wire makes ! be/ a]ials4 ,alum9um wire is v (t5 us$ & on acc\nt ( its light weight causes v little /ra9 on ! poles or cross arms4 ,iron wire %\ld nev] be us$ = an a]ial1 ev5 if galvaniz$ or t9n$1 because x t5ds to *oke ! curr5ts :i* mu/ fl[ up & d[n ! a]ial :5 ! /ation is 9 op]ation4 ,illu/ration3 ,fig4 #aif4--,mold$ ,a]ial ,insulator ,! a]ial mu/ be v c>efully insulat$ f its supports & all surr\nd+ objects4 ,! insulation mu/ be /rong en\gh to hold ! weight ( ! a]ial & able to )/& any /ra9 caus$ by /orms4 ,special a]ial insulators made ( mold$ insulat+ mat]ial & hav+ an iron r+ imb$d$ 9 ea* end are ! be/4 ,illu/ration3 ,fig4 #aig4--;,a ,porcela9 ,cleat w make a ,good ,insulator = ,small ,a]ials4 ,ord9>y porcela9 cleats may be us$ on small a]ials :]e ! /ra9 is light4 ,"o insulator %\ld be plac$ at ea* end ( ea* wire close to ! spread] or sp>4 ,mo/ a]ials are made up ( f\r wires4 ,! wires %\ld be plac$ z f> ap>t z possible4 ,!re are sev]al diff]5t =ms ( a]ials1 ! pr9cipal ones ( :i* are %[n 9 ,figure #aii4 ,!y are kn[n z ! grid1 8,v1 inv]t$ 8,l10 & 8,t0 types4 ,mo/ amateurs support _! a]ials f a pole plac$ on ! top ( ! h\se1 9 a tree1 or erect$ 9 ! y>d4 ,_m use two supports1 s9ce su* an a]ial has _m advantages4 ,! facilities to be _h = support+ ! a]ial w l>gely det]m9e :i* =m to use4 ,illu/ration3 ,fig4 #aih4--,me?od ( ,arrang+ ! ,wires & ,insulat+ !m f ! ,cross ,arm or ,spread]4 ,! grid a]ial has no p>ticul> advantages or disadvantages4 ,! 8,v0 a]ial receives waves mu* bett] :5 !y come f a direction opposite to t 9 :i* ! free end po9ts4 ,! free end ( ! a]ial is ! "o n lead+ into ! /ation4 ,! inv]t$ 8,l0 a]ial possesses ! same *>act]i/ics z ! 8,v0 type4 ,! 8,t0 a]ial is ! be/ 8all ar\nd & is to be recomm5d$ :5ev] x is possible to put up an a]ial ( ?is sort4 ,mu* ( ! detail ( actually putt+ up an a]ial or ant5na mu/ be omitt$1 because ea* exp]im5t] w usually meet diff]5t conditions4 ,x %\ld be rememb]$1 h[ev]1 t ! success ( ! :ole und]tak+ w re/ l>gely ^u ! con/ruction ( a prop] a]ial4 ,! mo/ excell5t in/rum5ts w n give v good results if connect$ to a poor a]ial1 :ile1 on ! o!r h&1 inf]ior in/rum5ts w (t5 give fair results :5 connect$ to a good a]ial4 ,illu/ration3 ,fig4 #aii4--,v>i\s ,types ( ,a]ials4 ,! a]ial %\ld be at lea/ ?irty feet high4 ,! wire %\ld n be small] ?an ,no4 #ad ,b4 ,s4 ,! ma/s :i* support ! a]ial %\ld be ( wood & provid$ ) pulleys s t ! wires may be l[]$ any "t x may be necess>y4 ,! ma/ %\ld be ?or\ghly brac$ ) /ays or guys s z to c\nt]act ! /ra9 ( ! a]ial4 ,! a]ial %\ld n be hoi/$ up p]fectly tight1 b %\ld be all[$ to hang some:at loose1 z x w !n put less /ra9 on ! ropes & poles t support x4 ,:5 an a]ial is to be fa/5$ 9 a tree1 x is be/ to atta* x to a pole plac$ 9 ! top ( ! tree1 s t x w come well above any possible int]f]5ce f ! bran*es4 ,! wires lead+ f ! a]ial to ! in/rum5ts %\ld be v c>efully insulat$ ?r\gh\t _! l5g?4 ,?is "p ( ! a]ial is call$ ! rat-tail or lead-94 ,! illu/rations 9 ,figure #aii %[ ! prop] place to atta* ! 8lead-9 =m ( a]ial4 ,! wires %\ld gradually conv]ge4 ,illu/ration3 ,fig4 #bjj4--;,a ,gr\nd ,clamp = ,pipes4 ,x is v important t a good gr\nd connection be secur$ = wireless in/rum5ts4 ,a good gr\nd is absolutely necess>y = ! prop] work+ ( ! app>atus4 ,amateur exp]im5t]s usually use ! wat] or gas-pipes = a gr\nd1 & fa/5 ! wires by means ( a gr\nd clamp su* z %[n 9 ,figure #bjj4 ,9 ! c\ntry1 :]e su* pipes are n available1 x is necess>y to bury a %eet ( copp]1 ?ree or f\r feet squ>e1 9 a moi/ spot 9 ! e>? & connect a wire to x4 99,! ,receiv+ ,app>atus99 ,! receiv+ in/rum5ts =m ! mo/ int]e/+ "p ( a wireless /ation & usually receive fir/ att5tion f ! amateurs4 ,!y are ! e>s ( ! wireless /ation & are wondr\sly s5sitive1 yet are v simple & easy ( con/ruction4 ,! in/rum5ts necess>y = receiv+ are3 ,a ,detector1 ,a ,tun+ ,coil or a ,loose ,c\pl]1 ,a ,fix$ ,cond5s]1 ,a ,telephone ,receiv]4 ,o!r devices1 su* z a te/ buzz]1 v>iable cond5s]1 etc41 may be add$ & w improve ! outfit4 ,aft] ! a]ial has be5 prop]ly erect$1 ! fir/ in/rum5t necess>y to con/ruct w be ei!r a tun+ coil or a loose c\pl]4 ,x is a good plan to make a tun+ coil fir/1 & a loose c\pl] aft] y h _h a little exp]i5ce ) y\r app>atus4 99,a ,tun+ ,coil99 is a v simple arrangem5t mak+ x possible to receive messages f great] di/ances1 & also some:at to elim9ate any messages n desirable & to li/5 )\t confusion to ! "o want$4 ,a tun+ coil consi/s ( a s+le lay] ( wire w\nd ^u a cyl9d] & arrang$ s t connection may be _h ) any "p ( x by means ( slid+ contacts4 ,! cyl9d] ^u :i* ! wire is w\nd is a c>dbo>d tube six & ?ree-qu>t]s in*es long & two & sev5-eigh?s in*es 9 diamet] outside4 ,x %\ld be giv5 two or ?ree coats ( %ellac bo? inside & out s t x is ?or\ghly impregnat$1 & !n laid away until dry4 ,?is treatm5t w prev5t ! wire f becom+ loose aft] ! tube is w\nd1 due to %r9kage ( ! c>dbo>d4 ,illu/ration3 ,fig4 #bja4--;,details ( ! ,tun+ ,coil4 ,aft] hav+ become dry1 ! tube is w\nd ) a s+le lay] ( ,no4 #be ,b4 ,s4 gauge gre5 silk or cotton-cov]$ magnet wire4 ,! wire mu/ be w\nd on v smoo?ly & tightly1 /opp+ & />t+ "o-qu>t] ( an in* back f ea* end4 ,! ends ( ! wire are fa/5$ by weav+ back & =? ?r\gh two small holes pun*$ 9 ! c>dbo>d tube ) a p94 ,! w9d+ %\ld be giv5 a s+le coat ( cle> v>ni% or :ite %ellac & all[$ to dry4 ,! coil heads or end pieces are cut f "o-half-in* wood accord+ to ! plan & dim5sions %[n 9 ! accompany+ illu/ration4 ,! top corn]s are bevel$ & not*$ to receive ! slid]-rods4 ,a circul> piece ( wood two & five-eigh?s in*es 9 diamet] & ?ree-eigh?s ( an in* ?ick is nail$ to ! inside ( ea* ( ! coil heads to support ! ends ( ! cyl9d]4 ,! wood5 p>ts %\ld be /a9$ mahogany or "s o!r d>k color & f9i%$ ) a coat ( %ellac or v>ni%4 ,! slid]-rods are squ>e brass #c-af x #c-af in*es & sev5 & ?ree-qu>t]s in*es long4 ,a small hole is bor$ ne> ! ends ( ea*1 "o-qu>t] ( an in* f ! edge1 to receive a r\nd-head$ brass wood screw :i* holds ! rod to ! tun] end4 ,! slid]s may be made accord+ to ! plan %[n 9 ,figure #bja4 ,! slid] is made f a small piece ( brass tub+1 ?ree-sixte5?s ( an in* squ>e4 ,an #h-cb flat-head$ brass screw is sold]$ to "o face1 9 ! c5t]4 ,a small /rip ( phosphor bronze %eet or spr+ copp] sold]$ to ! bottom ( ! slid] =ms a contact = mak+ connection to ! wire on ! cyl9d]4 ,a small electrose knob screw$ to ! slid] makes a neat & effici5t h&le4 ,two slid]s are requir$1 "o = ea* rod4 ,! tun+ coil is assembl$ z %[n 9 ,figure #bjc4 ,! c>dbo>d tube is held 9 place by sev]al small brass nails driv5 ?r\gh x into ! circul> pieces on ! coil heads4 ,a slid] is plac$ on ea* ( ! slid]-rods & ! rods fa/5$ 9 ! slots 9 ! coil ends by a small r\nd-head$ brass screw1 pass+ ?r\gh ! holes bor$ ne> ! ends = t purpose4 ,illu/ration3 ,fig4 #bjb4--,side & ,end ,views ( ! ,tun+ ,coil4 ,two b9d+-po/s are m\nt$ on "o ( ! coil ends4 ,"o %\ld be connect$ to ea* ( ! slid]-rods4 ,a ?ird b9d+-po/ is plac$ bel[ 9 ! c5t] ( ! head & connect$ to "o end ( ! wire w\nd ar\nd ! cyl9d]4 ,a small1 n>r[ pa? along ! coil1 directly und]nea? ea* slid] & to :i* ! copp] /rip c make contact1 mu/ be =m$ by scrap+ ! insulation (f ! wire ) a %>p knife4 ,! slid]s %\ld make contact ) ea* "o ( ! wires z !y pass ov]1 & %\ld slide smoo?ly )\t damag+ or dis>rang+ any ( ! wires4 ,illu/ration3 ,fig4 #bjc4--;,complete ,d\ble-,slid] ,tun+ ,coil4 ,:5 scrap+ ! insulation1 be v c>eful n to loos5 ! wires or remove ! insulation f betwe5 !m1 s t !y are liable to %ort-circuit betwe5 adjac5t turns4 99,a ,loose ,c\pl]99 is a mu* m effici5t tun+ device ?an a d\ble-slid] tun]1 & soon] or lat] mo/ amateur wireless op]ators in/all "o 9 _! /ation4 ,! loose c\pl] %[n 9 ! figure giv5 on ! next page is a v simple "o & is bo? easy & inexp5sive to build4 ,its simplicity is a disadvantage 9 "o respect1 h[ev]4 ,ow+ to its con/ruction1 x is impossible to move ! slid] on ! second>y :5 ! latt] is inside ! prim>y4 ,! reason t ,i h *os5 ?is sort ( loose c\pl] to describe is to acqua9t my "y read]s ) ! me?ods ( mak+ a loose c\pl]4 ,! ,junior loose c\pl] describ$ f>!r on is a m elaborate in/rum5t ( great] effici5cy1 b mu* h>d] to build4 ,illu/ration3 ,fig4 #bjd4--;,a ,simple ,loose ,c\pl]4 ,! base ( ! loose c\pl] is ( wood & measures twelve by f\r in*es4 ,! head support+ ! prim>y is ( ! same size z ^? us$ on ! ,junior d\ble-slide tun+ coil j describ$4 ,x may be made 9 ! same mann]1 & fitt$ ) a circul> block to support ! tube4 ,! prim>y tube is ( ! same diamet] z t on ! tun+ coil b is only f\r in*es long4 ,x is fa/5$ to ! prim>y head ) glue & !n secur$ ) a numb] ( small tacks4 ,"o or two coats ( %ellac lib]ally appli$ w r5d] x non-%r9kable1 s t ! wire w n be apt to loos5 aft] ! loose c\pl] has be5 9 use a :ile4 ,! second>y is ( ! same l5g? z ! prim>y1 b ( small] diamet]1 s t x w easily slip inside4 ,x also is treat$ ) %ellac4 ,! prim>y %\ld be w\nd ) a s+le lay] ( ,no4 #bb s+le-silk-cov]$ magnet wire4 ,! second>y is w\nd ) ,no4 #bi s+le-silk4 ,! head support+ ! second>y is small] ?an t us$ = ! same purpose on ! prim>y4 ,! r\nd boss to :i* ! tube is fa/5$1 h[ev]1 is mu* ?ick]4 ,! second>y slides on a guide-rod support$ at "o end by pass+ ?r\gh ! prim>y head & at ! o!r by a brass upright4 ,! upright may also be made ( wood4 ,if ! second>y is (fset1 t is1 plac$ out ( c5t] slightly to "o side1 x w leave room s t ! second>y slid] w possibly pass inside ( ! prim>y )\t /rik+4 ,bo? ! prim>y & ! second>y mu/ be fitt$ ) slid]s to make contact ) ! v>i\s turns ( wire4 ,! me?od ( con/ruct+ a slid] has already be5 describ$4 ,! ends ( ! slid]-rods are b5t at "r angles & fa/5$ to ! coil heads by two small screws pass+ ?r\gh holes bor$ ne> ! ends4 ,a small n>r[ pa? mu/ be scrap$ 9 ! insulation "u ea* s t ! slid] w make contact ) ea* turn4 ,! second>y head may be provid$ ) a small electrose h&le to facilitate slid+ x back & =?4 ,two b9d+-po/s are m\nt$ on ea* ( ! coil heads4 ,"o po/ on ea* is connect$ to ! end ( ! coil f>!/ f ! head1 & ! o!r po/s are ea* connect$ to ! slid]-rods4 ,figure #bbj %[s h[ to connect ! loose c\pl] 9 ! receiv+ set4 ,9 ord] to tune ) a loose c\pl]1 fir/ adju/ ! slid] on ! prim>y until ! signals are ! cle>e/4 ,!n set ! second>y slid] 9 ! be/ place & move ! second>y 9 & out ( ! prim>y until ! signals are cle>e/4 99,h[ to ,build ! ,junior ,loose ,c\pl]99 ,a loose c\pl] ( ! sort j describ$ is simple & q easily con/ruct$1 b w n be f\nd to "w z well z "o 9 :i* ! second>y may be v>i$ by means ( a swit* :ile x is inside ( ! prim>y4 ,! base ( ! in/rum5t measures twelve by ?ree & five-eigh?s in*es4 ,! prim>y is compos$ ( a s+le lay] ( ,no4 #bd ,b4 ,s4 gauge s+le-silk-cov]$ wire w\nd on a c>dbo>d tube two & ?ree-qu>t] in*es 9 diamet] & ?ree & ?ree-qu>t] in*es long4 ,! w9d+ is laid on 9 a s+le lay] & %\ld comprise ab\t #aej turns4 ,aft] w9d+ on tightly1 x %\ld be giv5 a coat ( clean :ite %ellac & all[$ to dry4 ,! %ellac is = ! purpose ( fa/5+ ! wire d[n tightly to ! tube s t x w n loos5 :5 ! slid] is mov$ back & =?4 ,! prim>y is m\nt$ betwe5 two heads1 ! details ( :i* are %[n 9 ,figure #bje4 ,"o ( ! heads1 ,b1 has a flang$ hole two & ?ree-qu>t] in*es 9 diamet] cut ?r\gh ! c5t] s z to receive ! end ( ! tube & p]mit ! second>y to pass inside4 ,illu/ration3 ,fig4 #bje4--;,details ( ! ,wood5 ,p>ts4 ,! second>y w9d+ is compos$ ( a s+le lay] ( ,no4 #bh ,b4 ,s4 gauge silk-cov]$ wire & divid$ into six equal sections4 ,! second>y is support$ by two circul> wood5 pieces1 ,c & ,f1 & slides back & =? on two guide-rods4 ,! guide-rods %\ld be brass4 ,iron or /eel rods runn+ ?r\gh ! c5t] ( a loose c\pl] w s]i\sly weak5 ! signals1 & su* practice mu/ by all means be avoid$4 ,illu/ration3 ,fig4 #bjf4--,side ,view ( ! ,loose ,c\pl]4 ,illu/ration3 ,fig4 #bjg4--,top ,view ( ! ,loose ,c\pl]4 ,! second>y sections are connect$ to six contacts & a swit*-arm m\nt$ on ! end ( ! second>y s t by turn+ ! swit* ei!r "o1 two1 ?ree1 f\r1 five1 or six sections ( ! w9d+ may be connect$4 ,illu/ration3 ,fig4 #bjh4--;,end ,views ( ! ,loose ,c\pl]4 ,illu/ration3 ,fig4 #bji4--;,complete ,loose ,c\pl]4 ,! two b9d+-po/s ne> ! second>y end ( ! c\pl] are connect$ to ! t]m9als ( ! second>y w9d+ by means ( two flexible wires4 ,!y h n be5 %[n 9 sev]al ( ! illu/rations because !y w\ld be liable to confuse ! draw+4 ,! prim>y is provid$ ) a slid] mov+ back & =? ov] a n>r[ pa? scrap$ ?r\gh ! insulation s t x may make contact ) ea* wire indep5d5tly4 99,detectors99 ,detectors are v simple devices & consi/ m]ely ( an arrangem5t = hold+ a small piece ( c]ta9 m9]als & mak+ a contact aga9/ ! surface4 ,! cry/al detector %[n 9 ,figure #baj is a v effici5t =m t may be easily & quickly made4 ,:5 f9i%$1 x w make a valuable addition to almo/ any amateur exp]im5t]'s wireless equipm5t4 ,illu/ration3 ,fig4 #baj4--;,a ,cry/al ,detector4 ,! bracket is b5t out ( a piece ( /rip brass ab\t "o-eigh? ( an in* ?ick & five-eigh?s ( an in* wide1 accord+ to ! %ape %[n 9 ! illu/ration4 ,! bracket is m\nt$ on a circul> wood5 base ab\t ?ree in*es 9 diamet]4 ,! circul> wood5 blocks us$ by electricians 9 putt+ up *&eli]s1 call$ 8fixture blocks10 w make a satisfactory base4 ,an electrose knob ( ! typewrit] type may be pur*as$ f any good deal] 9 wireless supplies4 ,x %\ld be fitt$ ) a ?read$ %ank :i* w screw into a hole 9 ! upp] "p ( ! bracket4 ,! m9]al is conta9$ 9 a small brass cup m\nt$ on ! base bel[ ! end ( ! knob4 ,contact ) ! m9]al 9 ! cup is made by means ( a f9e wire spr+ sold]$ to ! end ( ! adju/+ screw4 ,mov+ ! screw up or d[n w v>y ! pressure ( ! spr+ on ! m9]al & p]mit ! mo/ s5sitive adju/m5t to be secur$4 ,! bracket is connect$ to "o ( ! b9d+-po/s & ! cup to ! o!r4 ,illu/ration3 ,fig4 #baa4--;,details ( ! ,cry/al ,detector4 ,! detector %[n 9 ,figure #bab is ( ! type (t5 t]m$ a cat-:isk]1 because ( ! long1 f9e wire re/+ on ! m9]al4 ,x consi/s ( a small clip1 =m$ by b5d+ a /rip ( %eet-brass1 :i* grips a piece ( gal5a4 ,illu/ration3 ,a ,d\ble ,slid] ,tun+ ,coil4 ,illu/ration3 ,a ,junior ,loose ,c\pl]4 ,illu/ration3 ,cry/al ,detectors4 ,gal5a may be obta9$ f any deal] 9 radio supplies4 ,a piece ( ,no4 #cj phosphor bronze wire is sold]$ to ! end ( a %ort l5g? ( brass rod support$ by a b9d+ po/4 ,! o!r end ( ! rod is fitt$ ) an electrose knob4 ,?is "p ( ! detector is call$ ! feel]4 ,illu/ration3 ,fig4 #bab ,details ( ! ,cat ,:isk] ,detector4 ,! detector is fitt$ ) b9d+ po/s & may be m\nt$ ^u any suitable small base4 ,! m9]al clip is connect$ to "o po/ & ! b9d+-po/ support+ ! feel] to ! o!r4 ,! t5sion or pressure ( ! end ( ! f9e wire ^u ! m9]al may be regulat$ by twi/+ ! electrose knob s z to twi/ ! rod4 ,! diff]5t portions ( ! cry/al may be se>*$ = ! mo/ s5sitive spot by slid+ ! rod back & =?4 ,a some:at simil> =m ( cat-:isk] detector is %[n 9 ,figure #bac4 ,x is provid$ ) a cup to hold ! m9]al 9 place ( a clip4 ,! detector %[n 9 ,figure #bad is m elaborate ?an any ( ! o!rs describ$ s f>4 ,illu/ration3 ,fig4 #bac4--;,ano!r ,=m ( ! ,cat-,:isk] ,detector4 ,illu/ration3 ,fig4 #bad4--;,cat-,:isk] ,detector4 ,! base is a wood5 block1 ?ree & "o-half by "o & ?ree-qu>t]s in*es by "o-half in*4 ,! b9d+-po/s are ( ! type commonly us$ on electrical in/rum5ts4 ,"o ( ! po/s is pivot$ s t x w sw+ f side to side4 ,a %ort piece ( brass rod fitt$ ) a rubb] or fib] knob passes ?r\gh ! wire hole 9 ! po/4 ,a piece ( ,no4 #cj ,b4 ,s4 gauge bronze wire is sold]$ to ! end ( ! rod4 ,a small brass cup conta9s ! m9]al1 :i* may be ei!r gal5a1 or silicon4 ,by twi/+ ! po/ & slid+ ! rod back & =?1 any portions ( ! m9]al surface may be select$4 99,fix$ ,cond5s]499 ,! con/ruction ( ! cond5s] is illu/rat$ 9 ,figure #bje4 ,take tw5ty-f\r %eets ( ?9 typewrit] pap]1 ?ree by f\r in*es1 & tw5ty-?ree %eets ( t9foil1 two by f\r in*es4 ,pile !m up1 us+ fir/ a %eet ( pap] !n a %eet ( t9foil1 !n pap]1 & s on1 s t e two %eets ( t9foil are sep>at$ by a %eet ( pap]4 ,ea* %eet ( t9foil mu/1 h[ev]1 project out beyond ! edge ( ! pap]4 ,connect all ! t9foil projections on "o end ( ! cond5s] toge!r & & atta* a small wire4 ,connect all ^? on ! opposite side 9 a simil> mann]4 ,!n fa/5 a c\ple ( rubb] b&s ar\nd ! cond5s] to hold x toge!r4 ,illu/ration3 ,fig4 #bae4--;,build+ up a ,fix$ ,cond5s]4 ,illu/ration3 ,fig4 #baf4--;,a ,fix$ ,cond5s] enclos$ 9 a ,brass ,case made f a ,piece ( ,tub+ fitt$ ) ,wood5 ,ends4 ,if x is desir$ to give ! cond5s] a f9i%$ appe>ance1 x may be plac$ 9 a brass tube fitt$ ) two wood5 or fib] ends4 ,! ends are provid$ ) b9d+-po/s to :i* ! t]m9als ( ! cond5s] are connect$4 99,telephone ,receiv]s99 = use ) wireless in/rum5ts mu/ be pur*as$4 ,_! con/ruction is su* t !y _c be made by ! exp]im5t]4 ,illu/ration3 ,fig4 #bag4--;,a ,telephone ,head ,set4 ,a sev5ty-five ohm1 d\ble-pole telephone receiv] w d = /ations n wi%+ to receive f>!r ?an fifty miles4 ,9 ord] to secure ! be/ results f wireless in/rum5ts1 x is necess>y to h receiv]s especially made = wireless4 ,ea* receiv] %\ld h #ajjj ohms resi/ance4 ,"s boys may f9d x necess>y to pur*ase "o receiv] at a "t4 ,two receiv]s1 a d\ble headb&1 & a d\ble cord1 =m+ a complete head set z %[n 9 ,figure #bag1 %\ld be secur$ z soon z possible4 ,illu/ration3 ,fig4 #bah4--;,a ,circuit %[+ h[ to connect a ,d\ble-,slid] ,tun+ ,coil4 99,connect+ ! ,receiv+ ,app>atus99 ,figure #bah %[s h[ to connect a d\ble-slide tun]1 a detector1 a fix$ cond5s] & a pair ( telephones to ! a]ial & gr\nd4 ,! same in/rum5ts ) a loose c\pl] 9 place ( ! d\ble-slide tun] are %[n 9 ,figure #bai4 ,! diagrams 9 ,figure #bbj are ! same circuits z ^? %[n 9 ,figures #bah & #bai1 b %[ diff]5t in/rum5ts4 ,illu/ration3 ,fig4 #bai4--;,circuit %[+ h[ to connect a ,loose ,c\pl]4 ,illu/ration3 ,fig4 #bbj4--;,a ,diagram %[+ h[ to connect "s ( ! ,in/rum5ts describ$ 9 ?is ,*apt]4 ,aft] ! in/rum5ts are connect$1 place a piece ( gal5a or silicon 9 ! cup ( ! detector & br+ ! wire d[n on x4 ,!n move ! slid]s on ! tun+ coil or loose c\pl] & adju/ ! detector until y c he> a message buzz+ 9 ! telephones4 ,x may require a little pati5ce & practice1 b if y p]si/ y w soon le>n h[ to adju/ ! app>atus s z to receive ! signals l\dly & cle>ly ) v little tr\ble4 99,! ,transmitt+ ,app>atus99 ,sp>k coils h already be5 describ$ 9 ,*apt] ,,xii4 ,!y may be us$ to transmit wireless messages simply by connect+ to a sp>k-gap & a key4 ,sp>k coils :i* are especially made = wireless telegraphy w usually s5d f>!r ?an an ord9>y sp>k coil us$ = exp]im5tal purposes4 ,illu/ration3 ,fig4 #bba4--;,a ,wireless ,sp>k ,coil4 ,a good "o-in* coil co/s f #d4ej to #e4jj & w s5d f ?ree to five miles if us$ ) a fair a]ial4 ,a sp>k coil requires consid]able curr5t = its successful op]ation & w give ! be/ results if op]at$ on /orage cells1 dry cells1 or bi*romate cells4 ,if dry cells are us$1 x is a good plan to connect !m 9 s]ies multiple z %[n 9 ,figure #fi4 ,sp>k-gaps may be made by m\nt+ two d\ble b9d+-po/s on a wood5 base z %[n 9 ,figure #bbb4 ,z9c possesses "s peculi> prop]ty :i* makes x v effici5t = a sp>k-gap1 & = ?is reason ! electrodes ( a sp>k-gap are usually z9c4 ,illu/ration3 ,fig4 #bbb4--,small ,sp>k ,gaps4 ,! figure %[s two diff]5t =ms ( electrodes4 ,9 "o1 !y are made ( z9c rods & provid$ ) 8electrose0 h&les4 ,9 ! o!r gap1 ! z9c electrodes are 9 ! %ape ( tips fitt$ on ! ends ( two %ort brass rods4 ,a "o-in* sp>k coil w give v good results by connect+ ! sp>k-gap directly across ! second>y ( ! coils4 ,! a]ial is connect$ to "o side ( ! gap & ! gr\nd to ! o!r4 ,! transmitt] may be tun$ & ! range sometimes increas$ by us+ a cond5s] & a helix4 ,a cond5s] is mo/ easily made by coat+ ! inside & outside ( a te/-tube ) t9foil s z to =m a m9iature ,leyd5 j>4 ,! end ( ! tube is clos$ ) a cork ?r\gh :i* passes a brass rod connect+ to ! inn] coat+ ( t9foil4 ,illu/ration3 ,fig4 #bbc4--;,diagram %[+ h[ to connect a ,simple ,transmitt]4 ,if su* a cond5s] is connect$ directly across ! sp>k-gap1 ! sp>k w become v :ite & crackl+4 ,sev]al tubes may be arrang$ 9 a rack z %[n 9 ,figure #bbe4 ,a helix consi/s ( a spiral ( brass ribbon set 9 a wood5 frame4 ,! two /rips compos+ ! frame are ea* n9e in*es long4 ,! spiral consi/s ( eight turns ( brass ribbon1 ?ree-eigh?s ( an in* wide1 set 9 saw-cuts made 9 ! frame4 ,a b9d+-po/ is connect$ to ! outside end ( ! ribbon4 ,figure #bbh %[s h[ to connect a helix & a cond5s] to a coil & a sp>k-gap4 ,! two clips are made by b5d+ a /rip ( %eet brass & connect+ a piece ( flexible wire to "o end4 ,illu/ration3 ,fig4 #bbd4--;,a ,te/-,tube ,leyd5 ,j>4 ,9 l>ge /ations1 ! be/ position = ! clips is f\nd by plac+ a hot-wire ammet] 9 ! a]ial circuit & !n mov+ ! clips until ! met] %[s ! highe/ read+4 ,! "y exp]im5t] w h to tune 8 set by mov+ ! helix clips ab\t until ! be/ results are obta9$ 9 s5d+4 ,illu/ration3 ,fig4 #bbe4--;,eight ,te/-,tube ,leyd5 ,j>s m\nt$ 9 a ,wood5 ,rack4 ,if ! sp>k coil is a good "o & capable ( giv+ a good hot sp>k1 x may be possible to tell :5 ! set is 9 prop] tune by plac+ a small m9iature tung/5 lamp 9 s]ies ) ! a]ial & *ang+ ! clips1 ! cond5s]1 & ! l5g? ( ! sp>k-gap until ! lamp lights ! brighte/4 ,an oscillation trans=m] is sometimes us$ to replace an ord9>y helix :5 x is desirable to tune a /ation v closely s t its messages %all n be liable to be confus$ ) ^? ( ano!r /ation :5 bo? are work+ at ! same "t4 ,illu/ration3 ,fig4 #bbf4--;,a ,helix & ,clip4 ,an oscillation trans=m] consi/s ( two helixes arrang$ s t "o acts z a prim>y & ! o!r z a second>y4 ,an oscillation helix may be made by mak+ two sets ( helix frames simil> to t 9 ,second>y ,figure #bbf4 ,illu/ration3 ,fig4 #bbg4--;,an ,oscillation ,trans=m]4 ,! prim>y %\ld be provid$ ) eight turns ( brass ribbon & ! second>y ) twelve4 ,! prim>y supports a /iff brass rod ^u :i* ! second>y is m\nt$4 ,! second>y %\ld slide up & d[n on ! rod b move v /iffly s t x w /ay :]e x is put4 ,illu/ration3 ,,an ,,oscillation ,,helix4 ,illu/ration3 ,,an ,,oscillation ,,cond5s]4 ,an ord9>y d\ble-?r[1 d\ble-pole knife swit* hav+ a porcela9 base w make a v good a]ial swit* 9 a small /ation4 ,x is us$ to connect ! a]ial & gr\nd to ei!r ! transmitt+ or receiv+ app>atus at w4 ,su* a swit* is %[n 9 ,figure #bcj4 ,illu/ration3 ,fig #bbh4--;,circuit %[+ h[ to connect a ,helix & a ,cond5s]4 ,! a]ial %\ld be connect$ to ! po/ ,a & ! gr\nd to ,b4 ,! po/s ,e & ,f lead to ! transmitt]1 & ,c & ,d to ! receptor1 or vice-v]sa accord+ to :i* is ! m conv5i5t f ! location ( ! app>atus on ! table or op]at+ b5*4 ,a suitable table %\ld be arrang$ to place ! wireless in/rum5ts ^u s t !y may be p]man5tly connect$ toge!r4 ,illu/ration3 ,fig #bbi4--;,circuit %[+ h[ to connect an ,oscillation ,trans=m] & a ,cond5s]4 ,! ,cont95tal ,code is ! "o usually employ$ 9 wireless telegraphy4 ,x diff]s slightly f ,morse z x conta9s no space lett]s4 ,x w be f\nd easy to le>n & some:at easi] to h&le ?an ,morse4 ,illu/ration3 ,fig #bcj4--;,an ,a]ial ,swit*4 ,two or ?ree mon?s' /eady practice ) a *um %\ld enable ! "y exp]im5t] to become a v fair wireless telegraph op]ator4 ,!n by li/5+ = "s ( ! high p[] wireless /ations :i* s5d out ! press news to %ips at sea dur+ ! ev5+ x %\ld be possible to become v pr(ici5t4 ,! press news is s5t m sl[ly ?an ord9>y comm]cial wireless messages1 & is !re=e easy to read & a good />t+ po9t = ! beg9n] le>n+ to read4 ,illu/ration3 ,fig #bca4--;,a ,complete ,wir+ ,diagram = bo? ! ,transmitt] & ! ,receptor4 ,illu/ration3 ,fig4 #bcb4--,! ,cont95tal ,alphabet4 99,a ,coh]] ,outfit99 99,a ,coh]] ,outfit99 is usually capable ( only receiv+ messages com+ f a di/ance ( "u "o mile4 ,9 spite ( ?is fact1 h[ev]1 x is an exce$+ly int]e/+ app>atus to con/ruct & exp]im5t )1 & = ?is reason is f\nd fully describ$ bel[4 ,a coh]] set w r+ a bell or "w a s\nd] = %ort di/ances & !re=e is ! be/ sort ( an arrangem5t = demon/rat+ ! work+s ( y\r wireless app>atus to y\r fri5ds4 ,! fir/ ?+ t y ne$ = a coh]] is a pair ( d\ble b9d+-po/s4 ,m\nt ^! ab\t an in* & ?ree-qu>t]s ap>t on a wood5 base1 six in*es long & f\r in*es wide z %[n 9 ,figure #bcc4 ,illu/ration3 ,fig4 #bcc4--;,a ,coh]] & a ,decoh]]4 ,get a piece ( glass tub+ ab\t an in* & "o-half long & ab\t "o-eigh? ( an in* inside diamet]4 ,y w also ne$ "s brass rod :i* w j slide into ! tube tightly4 ,cut (f two pieces ( ! brass rod ea* "o & ?ree-qu>t]s in*es long & slip ^! ?r\gh ! upp] holes 9 ! b9d+-po/s & into ! glass tube z %[n 9 ,figure #bcd4 ,be=e putt+ ! second rod 9 place1 h[ev]1 y mu/ put "s nickel & silv] fil+s 9 ! tube1 s t :5 ! rods are pu%$ almo/ toge!r1 ) only a di/ance ( ab\t "o-sixte5? ( an in* betwe5 !m1 ! fil+s w ab\t half fill ! space4 ,! fil+s mu/ be v c>efully prep>$1 & 9 ord] to make !m1 fir/ use a co>se-gra9$ file on ! edge ( a five-c5t piece4 ,d n use ! f9e du/ & p[d]1 b only ! fairly co>se fil+s4 ,mix a few silv] fil+s f a t5-c5t piece ) ! nickel 9 su* proportion t ! mixture is #ij nickel & #aj silv]4 ,illu/ration3 ,fig4 #bcd4--;,details ( ! ,coh]]4 ,y w h to exp]im5t consid]ably to f9d out j ! "r am\nt ( fil+s to place 9 ! tube1 & h[ f> ap>t to place ! brass rods or plugs4 ,remove ! gong f an old electric bell & m\nt ! bell on ! base z %[n 9 ,figure #bcc4 ,x %\ld be 9 su* a position t ! bell hamm] w t\* ! coh]] v lightly :5 ! bell is r++4 ,! two b9d+-po/s1 tube rods1 & fil+s con/itute ! coh]]4 ,! bell is ! decoh]]4 ,! next ?+ requir$ 9 ord] to complete ! app>atus is a relay4 ,y may use ! relay describ$ 9 ,*apt] ,x or build "o accord+ to ! plan %[n 9 ,figure #bce4 ,?is relay consi/s ( a s+le electro-magnet m\nt$ on a wood5 base1 two in*es wide & f\r in*es long4 ,! armature is a piece ( s(t iron rod "o-qu>t] ( an in* 9 diamet] & "o-eigh? ( an in* long1 rivet$ to ! end ( a ?9 piece ( spr+ brass1 ab\t ,no4 #cd ,b4 ,s4 gauge 9 ?ickness4 ,illu/ration3 ,fig4 #bce4--,! ,relay4 ,! o!r end ( ! spr+ is fitt$ to a bracket & provid$ ) a ?umbscrew to adju/ ! t5sion ( ! spr+4 ,! "u side ( ! armature & ! upp] side ( ! magnet core are ea* fitt$ ) a small silv] contact4 ,! contacts %\ld meet squ>ely :5 ! armature is drawn d[n on to ! core by a curr5t ( electricity pass+ ?r\gh ! electro-magnet4 ,by turn+ ! adju/+ screw1 ! armature c be rais$ or l[]$4 ,x %\ld be adju/$ s t x almo/ t\*es ! core & is only j f> en\gh away to slip a piece ( ?ick pap] "u4 ,! t]m9als ( ! magnet are connect$ to ! two b9d+-po/s on ! base m>k$ ,s & ,s4 ,"o ( ! b9d+-po/s1 ,p1 is connect$ to ! brass upright1 & ! o!r is connect$ to ! core ( ! magnet4 ,figure #bcf %[s h[ to connect up ! outfit4 ,x w require "s v nice adju/+ be=e y w be able to get x to work+ prop]ly4 ,illu/ration3 ,fig4 #bcf4--,! ,complete ,coh]] ,outfit4 ,if y wi% to use ! outfit = demon/ration purposes or = s5d+ messages = v %ort di/ances1 z = in/ance across a room1 y d n ne$ an a]ial b m]ely a pair ( cat*-wires4 ,! cat*-wires are two pieces ( /iff copp] wire1 ab\t two feet long1 plac$ 9 ! l[] holes 9 ! d\ble b9d+-po/s =m+ "p ( ! coh]]4 ,9 ord] to set ! app>atus = op]ation1 raise ! adju/+ screw ( ! relay until ! armature is q f> away f ! core4 ,!n pu% ! armature d[n aga9/ ! contact on ! core4 ,! decoh]] %\ld !n imm$iately op]ate & beg9 to tap ! coh]]4 ,!n turn ! ?umbscrew until ! armature is br\ght d[n to ! core 9 su* a position t x is z close z x is possible to get x )\t r++ ! bell4 ,! transmitt] %\ld consi/ ( a sp>k coil1 batt]y1 key1 & a sp>k-gap4 ,! gap %\ld be connect$ to ! second>y ( ! coil & adju/$ s t ! electrodes are only ab\t "o-eigh? ( an in* ap>t4 ,! key is plac$ 9 s]ies ) ! prim>y ( ! coil & ! batt]y1 s t press+ ! key w s5d a /ream ( sp>ks across ! gap4 ,fit ! sp>k-gap ) two cat*-wires simil> to ^? on ! coh]] & place ! transmitt] ab\t f\r or five feet away f ! coh]] outfit4 ,y are n[ likely to f9d t if y press ! key ( ! transmitt]1 ! decoh]] w r+4 ,x is possible t x w cont9ue to r+ aft] y h /opp$ press+ ! key4 ,if su* is ! case1 x w be necess>y to turn ! adju/+ screw on ! relay s z to move ! armature upw>d a %ort di/ance away f ! core4 ,if ! decoh]] w n op]ate ea* "t :5 y press ! key1 ! brass plugs 9 ! coh]] ne$ adju/+4 ,y mu/ n be disc\rag$ if y h "s difficulty 9 mak+ ! app>atus "w at fir/4 ,aft] y le>n h[ to adju/ x prop]ly1 y w f9d t y c move ! transmitt] q a di/ance away f ! coh]] & x w /ill op]ate v nicely4 ,aft] y manage t1 y c place ! app>atus 9 sep>ate rooms & f9d x possible to "w x j ! same1 because ord9>y walls w n make any diff]5ce to wireless waves4 ,be> 9 m9d t ! ne>] ! coh]] plugs are to ea* o!r1 ! m s5sitive ! coh]] w be1 b t if too close1 ! decoh]] w n be able to %ake ! fil+s prop]ly & w n /op :5 y /op press+ ! key4 ,! op]ation ( ! app>atus dep5ds ^u ! fact t :5 prop]ly adju/$ ! resi/ance ( ! fil+s betwe5 ! two brass plugs is too great to all[ suffici5t batt]y curr5t to fl[ to attract ! armature ( ! relay4 ,z soon z any wireless waves f ! transmitt] /rike ! cat*-wires ( ! coh]]1 !y cause ! fil+s to cl+ toge!r or coh]e4 ,:5 9 ?is /ate1 !y h a l[ resi/ance & p]mit ! curr5t to fl[ 9 ! relay circuit & draw d[n ! armature4 ,! armature closes ! second circuit & sets ! decoh]] into op]ation4 ,! decoh]] %akes ! fil+s & causes !m to decoh]e or fall ap>t & s makes !m ready aga9 = ! next signal4 ,a coh]] set ( ?is sort may be us$ on an a]ial & gr\nd by sub/itut+ ! coh]] = ! detector1 b o!rwise foll[+ any ( ! receiv+ circuits :i* h already be5 %[n4 ,,*apt] ,,xv ,a ,,wireless ,,telephone ,probably _m read]s ( ! ,boy ,electrician are amateur wireless op]ators & h con/ruct$ _! own app>atus ) :i* !y are able to pick up comm]cial messages or communicate ) o!r exp]im5t]s 9 ! neighborhood1 b n _m h ev] built a wireless telephone4 ,! device describ$ 9 ! foll[+ pages is easy to make & arrange1 & w s]ve = "s v int]e/+ exp]im5ts4 ,x is ( no practical value z a comm]cial wireless telephone1 because ! di/ance ov] :i* x w transmit spee* is limit$ to f #bej to #cjj feet4 ,if y h a *um :o lives across ! /reet & )9 ! di/ance nam$ above1 x is possible = y to con/ruct a simple wireless telephone :i* w enable y to rema9 9 y\r own rooms & talk to ea* o!r )\t any connect+ wires4 ,! in/rum5ts op]ate by magnetic induction4 ,x has already be5 expla9$ h[ x is possible = ! curr5t 9 ! prim>y ( an induction coil to induce a curr5t 9 ! second>y coil1 ev5 ?\gh ! two are n electrically connect$4 ,?is type ( wireless telephone really consi/s ( an induction coil 9 :i* ! two w9d+s are widely sep>at$4 ,suppose t two coils ( wire are connect$ z 9 ,figure #bcg4 ,! illu/ration %[s t "o coil1 ,a1 is connect$ 9 s]ies ) a set ( batt]ies & a telegraph key4 ,! t]m9als ( ! o!r coil1 ,b1 are connect$ to a telephone receiv]4 ,! coils are plac$ p>allel to ea* o!r & a few in*es ap>t4 ,if ! key is press$ s t ! batt]y curr5t may fl[ ?r\gh ! coil1 ,a1 x w create a magnetic field1 & l9es ( =ce w be set up 9 ! imm$iate vic9ity4 ,! l9es ( =ce w pass ?r\gh ! coil1 ,b1 & induce 9 x a curr5t ( electricity :i* w cause a s\nd l a click to be he>d 9 ! telephone receiv]4 ,illu/ration3 ,fig4 #bcg4--;,a ,simple ,arrangem5t %[+ ! ,inductive ,action betwe5 two ,coils4 ,if a telephone transmitt] is sub/itut$ = ! key & words are spok5 into x1 ! curr5t pass+ ?r\gh ! coil f ! batt]y w v>y ) ea* vibration ( ! voice & ! words w be di/9ctly repeat$ by ! receiv] connect$ to ,b4 ,?is exp]im5t may be tri$ by any boy ) ! equipm5t he probably has already ar\nd 8 %op4 ,tw5ty-five to ?irty turns ( wire w\nd ar\nd a c>dbo>d tube five or six in*es 9 diamet] w s]ve z a coil4 ,two su* coils1 an ord9>y telephone transmitt]1 a telephone receiv] & a c\ple ( dry cells are all t is requir$4 ,illu/ration3 ,fig4 #bch4--;,a ,simple ,wireless ,telephone4 ,spee* direct$ into ! ,transmitt] c be he>d 9 ! ,receiv]1 al?\gh !re is no direct electrical connection betwe5 ! two4 ,! diagram 9 ! accompany+ illu/ration %[s h[ ! app>atus is arrang$4 ,! coils may be us$ sev]al in*es ap>t & ! voice w be cle>ly he>d 9 ! receiv]4 ,su* an outfit is1 h[ev]1 only exp]im5tal1 & if x is desir$ to make a practical set1 ! coils1 etc41 mu/ be mu* l>g] 9 diamet] & conta9 a great] numb] ( turns4 ,l>g] coils are made by fir/ draw+ a circle f\r feet 9 diamet] on ! floor ( ! %op or attic4 ,!n drive a numb] ( small nails ar\nd ! circumf]5ce1 ab\t f\r in*es ap>t4 ,procure two & "o-half p\nds ( ,no4 #bj ,b4 ,s4 gauge cotton-cov]$ magnet wire & w9d x ar\nd ! circumf]5ce ( ! circle4 ,! wire %\ld =m at lea/ sixty complete turns4 ,ab\t "o foot %\ld be left at ea* end to e/abli% connections )4 ,aft] w9d+1 ! coil %\ld be ti$ ab\t e six in*es ) a small piece ( /r+ s t x w reta9 its %ape & n come ap>t4 ,! nails are !n pull$ out s t ! coil may be remov$4 ,! coil may be us$ j z x is = exp]im5tal purposes1 b if x is int5d$ = any am\nt ( h&l+ x is wise to procure a l>ge hoop su* z girls use = roll+ along ! sidewalk1 & make ! coil ! same diamet] z ! hoop s t ^u completion !y may be firmly b\nd toge!r ) "s insulat+ tape4 ,two b9d+-po/s may !n be fa/5$ to ! hoop & ! t]m9als ( ! coil connect$ to !m4 ,two su* coils are requir$ = a complete wireless telephone sy/em1 "o to be locat$ at ea* /ation4 ,x is also necess>y to make a d\ble-contact /rap-key4 ,su* a key is easily built out ( a few screws & "s %eet-brass4 ,! illu/ration %[s ! v>i\s p>ts & con/ruction s cle>ly t no detail$ explanation is necess>y4 ,illu/ration3 ,fig4 #bci4--;,a ,d\ble-,contact ,/rap-,key4 ,! ,dott$ ,l9es %[ h[ ! ,b9d+-,po/s are connect$4 ,! telephone transmitt] & ! telephone receiv] requir$ = ?is exp]im5t mu/ be v s5sitive1 & x is h>dly possible = ! "y exp]im5t] to build "o :i* w be satisfactory4 ,!y c be secur$ f a second-h& telephone or pur*as$ at an electrical supply h\se4 ,! transmitt] %\ld be ( ! long di/ance type4 ,an #hj-ohm receiv] w s]ve ! purpose1 b if y also h a wireless /ation1 use ! same #ajjj-ohm receiv]s belong+ to y\r wireless set & y w secure v good results4 ,a batt]y capable ( deliv]+ ab\t #aj volts & a good con/ant curr5t is requir$4 ,! app>atus is connect$ z %[n 9 ,figure #bdj4 ,:5 ! key is press$1 ! coil is connect$ to ! batt]y & ! telephone transmitt]4 ,if words are !n spok5 into ! transmitt] !y w v>y ! am\nt ( curr5t fl[+ & ! magnetic field :i* is set up 9 ! neighborhood ( ! coil w induce curr5ts 9 ! coil at ! o!r /ation1 provid$ t x is n too f> away1 & cause ! words to be reproduc$ 9 ! telephone receiv]4 ,:5 ! key is releas$ x w connect ) ! upp] contact & place ! telephone receiv] 9 ! circuit = receiv+1 s t y\r *um at ! o!r /ation c answ] y\r message by press+ 8 key & talk+ into 8 transmitt]4 ,illu/ration3 ,fig4 #bdj4--,! ,circuit ( ! ,wireless ,telephone4 ,:5 ! ,key is up1 ! ,receiv] is ready = ,action4 ,:5 ! ,key is press$1 ! ,transmitt] & ,batt]y are ?r[n into ! ,circuit4 ,! be/ plan is to m\nt ea* ( ! coils ^u a tripod & exp]im5t by plac+ !m close toge!r at fir/ & gradually mov+ !m ap>t until ! maximum di/ance t ! app>atus w "w is discov]$4 ,be v c>eful to keep ! two coils exactly p>allel4 ,mu* dep5ds ^u ! batt]y4 ,be c]ta9 t x is capable ( deliv]+ a good /rong curr5t4 ,d n hold ! key d[n any long] ?an is absolutely necess>y1 or ! telephone transmitt] w become hot4 ,by mak+ ! coils six feet 9 diamet] & plac+ f #bjj to #djj turns ( wire 9 ea* coil y c make a set :i* is capable ( transmitt+ spee* #cjj feet or m4 ,illu/ration3 ,fig4 #bda4--;,a ,complete ,wireless ,telephone & ,telegraph ,/ation = ,amateurs4 #a4 ,! ,telephone ,coil4 #b4 ,! ,telephone ,transmitt]4 #c4 ,d\ble-,contact ,/rap-,key4 #d4 ,! ,batt]y4 #e4 ,sp>k ,coil4 #f4 ,key4 #g4 ,sp>k-,gap4 #h4 ,a]ial ,swit*4 #i4 ,loose ,c\pl]4 #aj4 ,detector1 #aa4 ,fix$ ,cond5s]4 #ab4 ,code ,*>t4 #ac4 ,amateur ,lic5se4 #ad4 ,a]ial4 #ae4 ,telephone ,receiv]s4 ,! coil may be m\nt$ on ! wall ( y\r %op 9 a position :]e x w be p>allel to "o locat$ 9 y\r *um's h\se4 ,! success ( a wireless telephone sy/em ( ?is sort lies 9 mak+ ! coils ( l>ge diamet] & _m turns1 9 keep+ ! coils p>allel1 us+ a s5sitive transmitt] & receiv]1 & 9 employ+ a good /rong batt]y4 ,/orage cells are ! be/ = ! purpose4 ,,*apt] ,,xvi ,,electric ,,motors ,! fir/ ,am]ican pat5tee & build] ( an electric motor 0 ,?omas ,dav5port4 ,! fa!r ( ,dav5port di$ :5 8 son 0 only t5 ye>s old4 ,?is result$ 9 ! "y inv5tor be+ appr5tic$ to ! blacksmi?'s trade at ! age ( f\rte54 ,"s ye>s lat]1 aft] hav+ ?or\ghly le>n$ 8 trade1 he m>ri$ a beautiful girl ( sev5te51 nam$ ,emily ,goss1 & settl$ 9 ! t[n ( ,br&on1 ,v]mont1 z an indep5d5t work+ blacksmi?4 ,ab\t ?is "t ,joseph ,h5ry inv5t$ ! electro-magnet4 ,dav5port he>d ( ?is wond]ful galvanic magnet :i* x 0 rumor$ w\ld lift a blacksmi?'s anvil4 ,?is 0 8 undo+1 = nev] aga9 0 he to "k peace ( m9d b 0 de/9$ to always be a seek] aft] "s elusive sci5tific w-o'-!-wisp4 ,al?\gh _m times he ne$$ iron = 8 %op1 ! great] "p ( 8 money 0 sp5t 9 mak+ electro-magnets & batt]ies4 ,9 ^? days insulat$ wire c\ld n be pur*as$1 & any "o wi%+ insulat$ wire _h to buy b>e wire & insulate x himself4 ,x 0 !n suppos$ by sci5ti/s t silk 0 ! only suitable mat]ial = insulat+ wire & s ,dav5port's brave "y wife cut h] silk w$d+ g[n into n>r[ /rips & ) !m w\nd ! coils ( ! fir/ electric motor4 ,cont9u+ 8 exp]im5ts 9 spite ( almo/ insurm\ntable difficulties & mak+ _m sacrifices :i* 7 equally %>$ by 8 family1 he 0 enabl$ to make a trip to ,wa%+ton 9 #ahce = ! purpose ( tak+ out a pat5t4 ,8 err& 0 fruitless1 h[ev]1 & he 0 oblig$ to return home p5niless4 ,no?+ daunt$1 he made ! second & ?ird trip & f9ally secur$ 8 memorable pat5t1 ! fir/ ( ! long l9e ( electric-motor pat5ts t h made possible bo? ! electric locomotive t hauls its long tra9 s swiftly & sil5tly1 & ! :irr+ little fan :i* /irs up a breeze dur+ ! hot & sultry days4 ,^! are a few ( ! reasons :y a mode/ c\ntry blacksmi?1 9 turn an inv5tor & an editor1 ?r\gh p]sev]ance 9 /ruggl+ aga9/ adv]sity & pov]ty succe$$ 9 plac+ 8 "n on ! li/ :i* w be des]v$ly immortal among ! sci5ti/s & eng9e]s ( ! _w4 99,a ,simple ,electric ,motor99 c be made 9 fifte5 m9utes by foll[+ ! plan %[n 9 ,figure #bdb4 ,! armature is made by /ick+ a p9 9 ea* end ( a long cork4 ,! p9s %\ld be z ne>ly c5tral z x is possible to make !m1 s t :5 ! cork is revolv$ ^u !m x w n wabble4 ,! p9s =m ! %aft or sp9dle ( ! motor4 ,!n take ab\t t5 feet ( f9e magnet wire 7,nos4 #bh-cb ,b4 ,s4 gauge7 & w9d x on z %[n 9 ! illu/ration1 w9d+ an equal numb] ( turns on ea* side ( ! two p9s4 ,illu/ration3 ,fig4 #bdb4--;,a ,simple ,electric ,motor :i* may be made 9 ,fifte5 ,m9utes4 ,:5 ?is is f9i%$1 fa/5 ! wire securely to ! cork by b9d+ x ) ?read4 ,b5d ! two free ends 7! />t+ & ! f9i%+ end7 d[n at "r angles & p>allel to ! %aft s z to =m two commutator sections z %[n 9 ! upp] left h& corn] ( ,figure #bdb4 ,cut !m (f s t !y only project ab\t ?ree-eigh?s ( an in*4 ,b>e ! ends ( ! wire & clean !m ) a piece ( f9e em]y pap] or s&pap]4 ,! be>+s are made by driv+ two p9s into a c\ple ( corks s t ! p9s cross ea* o!r z %[n 9 ! upp] "r-h& corn] ( ,figure #bdb4 ,!y mu/ n be at too %>p an angle1 or :5 ! armature is plac$ 9 position1 ! friction ( ! %aft w be s great t x may n revolve4 ,! motor is assembl$ by plac+ ! armature 9 ! be>+s & !n m\nt+ two b> magnets on ei!r side ( ! armature4 ,! magnets may be laid on small blocks ( wood & %\ld be s close to ! armature t ! latt] j cle>s :5 x is spun ar\nd by h&4 ,! nor? pole ( "o magnet %\ld be next to ! armature & ! s\? pole ( ! o!r1 opposite4 ,connect two wires ab\t "o foot long & ,no4 #bf ,b4 ,s4 gauge 9 diamet] to a dry cell4 ,b>e ! ends ( ! wires = ab\t an in* & "o half4 ,take ! ends ( ! two wires betwe5 ! =ef+] & ?umb & b5d !m out1 s t :5 ! armature is revolv$ !y c be made j to t\* ! ends ( ! wire on ! armature1 or ! commutator sections1 z !y are m>k$ 9 ! draw+4 ,give ! armature a twi/ s z to />t x sp9n+1 & hold ! long wires 9 ! h& s t !y make contact ) ! commutator z x revolves4 ,v light pressure %\ld be us$4 ,if y press too h>d1 y w prev5t ! armature f revolv+1 :ile1 on ! o!r h&1 if y d n press h>d en\gh1 ! wires w n make good contact4 ,! armature w run 9 only "o direction1 & s try bo? ways4 ,if y />t x 9 ! "r direction & hold ! wires prop]ly1 x w cont9ue to revolve at a high rate ( spe$4 ,if c>efully made1 ?is little motor w rew>d its mak] by runn+ v nicely4 ,al?\gh x is ( ! utmo/ simplicity x demon/rates ! same fundam5tal pr9ciples :i* are employ$ 9 real electric motors4 99,! ,simplex ,motor99 is an int]e/+ little toy :i* c be made 9 a c\ple ( h\rs1 & :5 f9i%$ x w make an in/ructive model4 ,illu/ration3 ,fig4 #bdc4--;,details ( ! ,armature ( ! ,simplex ,motor4 ,z a motor itself1 x is n v effici5t1 = ! am\nt ( iron us$ 9 its con/ruction is necess>ily small4 ,! advantage ( ?is p>ticul> type ( motor & ! me?od ( mak+ x is t x demon/rates ! actual pr9ciple & ! me?od ( application t is us$ 9 l>g] ma*9es4 ,! field ( ! motor is ( ! type kn[n z ! simplex :ile ! armature is ! ,siem5s ,h or two-pole type4 ,! field & ! armature are cut f ord9>y t9-plat$ iron su* z is us$ 9 ! manufacture ( t9 cans & crack]-boxes4 ,! simple/ me?od ( secur+ good flat mat]ial is to get "s old scrap f a plumb+ %op4 ,an old cocoa t9 or bak+-p[d] c may1 h[ev]1 be cut up & flatt5$ & w !n s]ve ! purpose almo/ z well4 ,illu/ration3 ,fig4 #bdd4--,! ,armature4 99,! ,armature499 ,two /rips ( t91 ?ree-eigh?s ( an in* by "o & "o-half in*es1 are cut to =m ! armature4 ,!y are slightly long] ?an w actually be necess>y1 b are cut to l5g? aft] ! f9i% ( ! b5d+ op]ations4 ,m>k a l9e c>efully across ! c5t] ( ea* /rip4 ,!n1 tak+ c>e to keep ! %ape symmetrical s t bo? pieces are exactly alike1 b5d !m into ! %ape %[n 9 ,figure #bdc4 ,! small b5d 9 ! c5t] is mo/ easily made by b5d+ ! /rip ov] a knitt+-ne$le & !n b5d+ x back to ! requir$ ext5t4 ,illu/ration3 ,fig4 #bde4--,! ,field4 ,a piece ( knitt+-ne$le "o & "o-half in*es long is requir$ = ! %aft4 ,b9d ! two halves ( ! armature toge!r 9 ! position %[n 9 ,figure #bdi4 ,b9d !m ) a piece ( iron wire & sold] !m toge!r4 ,! wire %\ld be remov$ aft] !y are sold]$4 ,illu/ration3 ,fig4 #bdf4--,! ,field & ,commutator4 99,! ,field ,magnet99 is made by fir/ cutt+ out a /rip ( t9 "o-half by f\r & !n b5d+ x into ! %ape %[n 9 ,figure #bde4 ,! easie/ way ( do+ ?is ) accuracy is to cut out a piece ( wood z a =m1 & b5d ! t9 ov] ! =m4 ,! dim5sions %[n 9 ,figure #bde %\ld be us$ z a guide = ! =m4 ,illu/ration3 ,fig4 #bdg4--,! ,be>+s4 ,two small holes %\ld be bor$ 9 ! feet ( ! field magnet to receive ,no4 #c wood screws1 :i* fa/5 ! field to ! base4 99,! ,be>+s99 are %[n 9 detail 9 ,figure #bdg4 ,!y are easily made by cutt+ f %eet-t94 ,two small wa%]s1 s]v+ z coll>s1 %\ld be sold]$ to ! %aft z %[n 9 ,figure #bdc4 99,! ,commutator ,core99 is =m$ by cutt+ a /rip ( pap] five-sixte5?s ( an in* wide & ab\t five in*es long4 ,x %\ld be giv5 a coat ( %ellac on "o side & all[$ to get /icky4 ,! /rip is !n wrapp$ ar\nd ! %aft until its diamet] is ?ree-sixte5?s ( an in*4 99,! ,base99 is cut f any ord9>y piece ( wood & is 9 ! =m ( a block ab\t two by "o & "o-half by "o-half in*4 ,illu/ration3 ,fig4 #bdh4--,! ,complete ,motor4 99,assembl+ ! ,motor499 ,! p>ts mu/ be c>efully prep>$ = w9d+ by cov]+ ) pap]4 ,cut a /rip ( pap] "o-half in* wide & "o & "o-eigh? ( an in* long & give x a coat ( %ellac on "o side4 ,z soon z x becomes /icky1 wrap x ar\nd ! top b> ( ! field magnet4 ,! armature is insulat$ 9 exactly ! same way1 tak+ c>e t ! pap] cov]s ! entire flat portion4 ,! field & armature are n[ ready = w9d+4 ,x is necess>y to take prop] precautions to prev5t ! fir/ turn f slipp+ out ( place4 ,?is is accompli%$ by loop+ a small piece ( tape or cord ov] x4 ,! next two turns are !n tak5 ov] ! ends ( ! loop s z to emb$ !m4 ,w9d on ?ree lay]s ( wire & :5 9 ! middle ( ! f\r? lay] emb$ ! ends ( ano!r loop1 :i* may be us$ at ! end ( ! f\r? lay] to fa/5 ! end s t x w n unw9d4 ,aft] ! w9d+ is f9i%$1 give x a coat ( %ellac4 ,! w9d+ ( ! armature is some:at m difficult4 ,! wire us$ = w9d+ bo? ! armature & ! field %\ld be ,no4 #be or ,no4 #bf ,b4 ,s4 gauge d\ble-cotton-cov]$4 ,9 ord] to w9d ! armature1 cut (f ab\t five feet ( wire & d\ble x back to f9d ! c5t]4 ,!n place ! wire diagonally across ! c5t] ( ! armature s t !re is an equal l5g? on bo? sides4 ,place a piece ( pap] "u ! wire at ! cross+ po9t to insulate x4 ,!n1 us+ "o end ( ! wire1 w9d f\r lay]s on half ( ! armature4 ,tie ! end d[n ) a piece ( ?read & w9d on ! o!r half4 ,! ends ( ! wire are cut & scrap$ to =m ! commutator segm5ts4 ,figure #bdf %[s h[ ?is is done4 ,b5d ! wires z %[n s t !y w fit closely to ! pap] core4 ,b9d !m tightly into position ) "s silk ?read4 ,use c>e s t ! two wires d n t\* ea* o!r4 ,cut ! free ends ( ! wires (f close to ! core4 ,:5 f9i%$1 ! relative positions ( ! armature & ! commutator %\ld be z %[n 9 ,figure #bdh4 ,! bru%es are made by flatt5+ a piece ( wire by a few light hamm] bl[s4 ,! bru%es are fa/5$ "u a small clamp =m$ by a /rip ( t9 held d[n at ea* end ) a wood screw4 ,!y c be adju/$ to ! be/ advantage only "u actual work+ conditions :5 ! curr5t is pass+ ?r\gh ! motor4 ,"o or two dry cells %\ld be suffici5t to op]ate ! motor4 ,illu/ration3 ,fig4 #bdi4--;,details ( ! ,motor4 ,"o end ( ! field w9d+ is connect$ to "o ( ! bru%es4 ,! o!r bru% & ! o!r end ( ! field =m ! t]m9als to :i* ! batt]y is connect$4 ,! motor1 be+ ( ! two-pole armature type1 mu/ be />t$ :5 ! curr5t is turn$ on by giv+ x a twi/ ) ! f+]s4 99,a ,l>g] ,motor99 may be built 9 some:at ! same mann] z ! "o j describ$ by cutt+ armature & field out ( %eet t94 ,x w be m sub/antial if x is built up out ( lam9ations & n b5t into %ape1 z 9 ! case ( ! o!r4 ,lay out an armature disk & a field lam9ation on a %eet ( t9 9 accordance ) ! dim5sions & patt]n %[n 9 ,figure #bdi4 ,^! pieces are us$ z patt]ns = lay+ out ! re/ ( ! lam9ations4 ,illu/ration3 ,fig4 #bej4--;,complete ,motor4 ,place !m on "s ?9 %eet-iron & trace ! outl9e ) a %>p-po9t$ ne$le4 ,!n cut a suffici5t numb] ( pieces ( ea* patt]n to =m a pile ?ree-qu>t]s ( an in* ?ick4 ,f\r lam9ations = ! field %\ld be cut ) ext5sions %[n by ! dott$ l9es4 ,!y are b5t out at "r angles = m\nt+ ! motor & hold+ x upright4 ,assemble ! armature & field by pil+ ! pieces on top ( ea* o!r & tru+ !m up4 ,en\gh lam9ations %\ld be us$ to =m a pile ?ree-qu>t]s ( an in* ?ick :5 pil$ up & clamp$ tightly4 ,file (f any burrs & r\gh edges & !n b9d ! lam9ations toge!r ) "s /r+ to hold !m until w\nd4 ,wrap a c\ple ( lay]s ( pap] ar\nd ^? portions ( ! armature & field :i* are liable to come into contact ) ! iron4 ,five or six lay]s ( ,no4 #ah ,b4 ,s4 gauge d\ble-cotton-cov]$ magnet wire are suffici5t to =m ! field coil4 ,! armature is w\nd ) ?ree or f\r lay]s ( wire ( ! same size4 ,! commutator is made out ( a circul> piece ( h>d wood or fib]1 fitt$ ) segm5ts cut out ( ?9 %eet-copp]4 ,! segm5ts may be fa/5$ to ! core ) ?ick %ellac or "s melt$ seal+-wax4 ,! ends may be b\nd d[n tightly by wrapp+ ) silk ?read4 ,! bru%es are cut out ( ?9 %eet-copp] simil> to t us$ = ! commutator segm5ts4 ,! be>+s are /rips ( heavy %eet-brass b5t into ! %ape %[n4 ,!y are m\nt$ by pass+ a nail ?r\gh ! holes 9 ! ends & ?r\gh ! holes1 ,a & ,b1 9 ! field & !n rivet+ ! ends ov]4 ,assemble ! motor z %[n 9 ,figure #bee4 ,if desirable1 a small pulley may be fitt$ to ! %aft & ! motor us$ to run small me*anical toys4 ,if x is prop]ly con/ruct$1 two or ?ree dry cells w furni% suffici5t curr5t to run ! motor at high spe$4 ,,*apt] ,,xvii ,,dynamos ,!re is p]haps no o!r electrical device ent]+ into ! "y exp]im5t]'s doma9 requir+ ! c>eful workman%ip & tool facilities t ! dynamo does4 ,9 ord] to con/ruct a practical work+ dynamo x w\ld be necess>y to h at h& a la! = turn+ ! ca/+s4 ,r ?an describe a ma*9e :i* comp>atively few ( my read]s w\ld be able to build1 ,i h expla9$ bel[ h[ x is possible to s alt] an old telephone magneto t x may be made to s]ve z a small dynamo4 ,telephone magnetos1 also sometimes call$ h& g5]ators1 are us$ 9 _m telephone sy/ems to supply ! curr5t :i* r+s ! telephone bell at ! o!r end4 ,! magneto is plac$ 9 a small box on ! telephone1 only ! h&le be+ expos$4 ,9 ord] to make a call ! h&le is giv5 sev]al brisk turns be=e rais+ ! receiv]4 ,:5 ! h&le is turn$ ! mov+ p>ts ( ! g5]ator revolve & produce a curr5t ( electricity :i* goes =? ov] ! l9e & r+s ! bell at ! o!r end4 ,illu/ration3 ,fig4 #bea--;,a ,telephone ,magneto4 ,telephone magnetos are gradually be+ disc>d$ 9 all ! l>ge telephone sy/ems1 a me?od kn[n z c5tral en]gy1 9 :i* ! curr5t = r++ bells is suppli$ f ! c5tral (fice1 tak+ _! place4 ,= t reason1 !re are a great _m telephone magnetos to be f\nd 9 second-h& %ops & at electrical h\ses1 :]e !y c be pur*as$ = a fractional "p ( ! orig9al co/4 ,fifty c5ts w buy a fir/-class second-h& telephone magneto4 ,! au?or saw a pile ( telephones z l>ge z a hay/ack1 ea* telephone conta9+ a magneto1 9 ! back y>d ( a second-h& %op1 & ! own] w\ld h be5 glad to sell ! complete in/rum5ts = fifty c5ts ea*4 ,be=e expla9+ h[ to recon/ruct su* a ma*9e1 x is be/ to impress ^u ! read] t a c>eful /udy ( ! pr9ciples ( ! dynamo is well wor? ! "t sp5t4 ,almo/ any book on physics or electricity1 or ev5 ! encyclop$ia1 w be f\nd to conta9 a description ( ?is wond]ful ma*9e t supplies ! p[] = runn+ ! trolley c>s1 electric lights1 etc41 9 fact all ( ! electricity 9 use to-day ) ! exception ( t g5]at$ by batt]ies = telegraph & telephone l9es4 ,x w be rememb]$ t if a b> magnet is sudd5ly plung$ into a holl[ coil ( wire1 a mom5t>y electric curr5t w be g5]at$ 9 ! coil4 ,! curr5t is easily detect$ by means ( an in/rum5t call$ a galvanomet]4 ,! space 9 ! vic9ity ( a magnet is fill$ ) a peculi> invisible =ce call$ magnetism4 ,! magnetism fl[s along a c]ta9 pa?1 pass+ ?r\gh ! magnet itself & !n spread+ out 9 curv$ l9es4 ,if a %eet ( pap] is laid ov] a magnet & a few iron fil+s are spr9kl$ on ! pap]1 !y w foll[ ! magnetic l9es ( =ce4 ,:5 ! magnet is plung$ into ! holl[ coil1 ! l9es ( =ce fl[ ?r\gh ! turns ( wire1 or are said to cut !m4 ,:5ev] l9es ( =ce cut a coil ( wire & !y are 9 motion1 electricity is produc$4 ,x does n matt] :e!r ! coil is slipp$ ov] ! magnet or ! magnet is plung$ into ! coil1 a curr5t w be produc$ z long z !y are 9 motion4 ,z soon z ! magnet or ! coil /ops mov+ ! curr5t /ops4 ,by arrang+ a coil ( wire betwe5 ! poles ( a horse-%oe magnet s t x c be made to revolve1 ! motion c be made cont9u\s & ! curr5t ( electricity ma9ta9$4 ,figure #beb %[s su* an arrangem5t4 ,"s means ( connection ) ! coil ( wire mu/ be e/abli%$ s t ! curr5t c be l$ (f4 ,if two metal r+s are connect$ to ! ends ( ! coil1 connection c be made by little /rips ( metal call$ bru%es rubb+ aga9/ ! r+s4 ,?is s*eme is ! pr9ciple ( ! telephone magneto & ! basis ( all dynamos4 ,illu/ration3 ,fig4 #beb4--,! ,pr9ciple ( ! ,alt]nator & ! ,direct-,curr5t ,dynamo4 ,9 ! telephone magneto1 m ?an "o horse%oe magnet is usually provid$4 ,! coil ( wire revolves betwe5 ! poles ( ! magnets4 ,! coil is w\nd ar\nd an iron frame & toge!r !y are call$ ! armature4 ,! end ( ! armature %aft is fitt$ ) a small spur ge> me%+ ) a l>g] ge> be>+ a crank1 s t :5 ! crank is turn$ ! motion is multipli$ & ! armature is caus$ to revolve rapidly4 ,"o end ( ! coil or armature w9d+ is connect$ to a small brass p94 ,?is p9 connects ) a second p9 set 9 ! end ( ! %aft 9 an insulat+ bru% ( h>d rubb]4 ,! o!r t]m9al ( ! coil is connect$ to ! armature itself4 ,?us connection c be _h to ! coil by connect+ a wire to ! frame ( ! ma*9e & to ! insulat$ p94 ,illu/ration3 ,fig4 #bec4--;,details ( ! ,armature1 ,commutator1 & ,bru%es4 ,! armature ( a magneto is usually w\nd ) a v f9e silk insulat$ wire1 ab\t ,no4 #cf ,b4 ,s4 gauge 9 size4 ,?is %\ld be c>efully remov$ & w\nd ^u a spool = future use4 ,replace ! wire ) "s ord9>y cotton-cov]$ magnet wire1 ab\t ,no4 #bd or #be ,b4 ,s4 gauge1 w9d+ x on v c>efully & smoo?ly4 ,connect "o end ( ! w9d+ to ! p9 lead+ to ! insulat$ p9 by sold]+ x4 ,?is p9 is ! "o at ! end ( ! %aft opposite to t "o to :i* ! spur ge> is fa/5$4 ,connect ! o!r end ( ! wire to ! p9 at ! same end ( ! %aft z ! ge>4 ,?is p9 is gr\nd$1 t is1 connect$ to ! frame4 ,an ord9>y telephone magneto gives a v high voltage curr5t4 ,! voltage may v>y f tw5ty-five to sev]al hundr$1 dep5d+ ^u h[ fa/ ! ma*9e is run4 ,?is is due to ! fact t ! armature w9d+ is compos$ ( a v l>ge numb] ( turns ( wire4 ,! m turns t are plac$ on ! armature1 ! high] its voltage w be4 ,! curr5t or amp]age ( a l>ge telephone magneto w\nd ) a l>ge numb] ( turns ( f9e wire is v l[4 ,too l[ 9 fact to be us$ = any?+ except r++ a bell or te/+4 ,w9d+ ! armature ) few] turns ( l>ge wire r$uces ! voltage & increases ! amp]age s t ! curr5t w light a small lamp or may be us$ = o!r purposes4 ,! w9d+ does n *ange ! pr9ciple ( ! magneto1 x m]ely *anges its amp]age & voltage4 ,! magneto may be m\nt$ on a wood5 base-bo>d & screw$ to a table1 s t ! h&le may be turn$ )\t inconv5i5ce4 ,a small /rip ( copp]1 call$ a bru%1 %\ld be fa/5$ to ! base ) a screw & br\ght to be> aga9/ ! end ( ! insulat$ p94 ,! bru% %\ld be connect$ to a b9d+-po/ ) a piece ( wire4 ,a second wire lead+ to a b9d+-po/ %\ld be connect$ to ! frame ( ! magneto4 ,:5 ! h&le is turn$ rapidly1 curr5ts may be drawn f ! two b9d+-po/s4 ,! curr5t is ( ! k9d kn[n z alt]nat+1 t is to say1 x fl[s fir/ 9 "o direction1 !n rev]ses & fl[s 9 ! o!r4 ,9 ord] to make ! ma*9e give direct curr5t1 x mu/ be fitt$ ) a commutator4 ,?is is some:at difficult ) "s magnetos b ! foll[+ plan may be c>ri$ out 9 mo/ cases4 ,cut a small fib] circle or disk ab\t "o in* 9 diamet] f %eet fib] ?ree-sixte5?s ( an in* ?ick4 ,cut a small hole 9 ! c5t]1 j l>ge en\gh s t ! fib] w slip v lightly ov] ! end ( ! %aft f :i* ! insulat$ p9 projects4 ,two small commutator sections simil> to t %[n 9 ,figure #bec mu/ be cut f %eet-brass or %eet-copp]4 ,! ?ree long e>s %[n 9 ! draw+ are b5t back ar\nd ! fib] & squeez$ d[n flat ) a pair ( p9c]s s t !y grip ! fib] v tightly & w n slip4 ,"o e> on "o section %\ld be b5t ov] ! back d[n to ! hole1 :]e x w connect ) ! %aft4 ,! o!r section ( ! commutator is connect$ to ! insulat$ p9 by a drop ( sold]4 ,9 ?is mann]1 "o end ( ! w9d+ is connect$ to "o section ( ! commutator & ! o!r end to ! o!r section4 ,! commutator %\ld fit tightly on ! end ( ! %aft s t x w n twi/4 ,! divid+ l9e betwe5 ! section %\ld be p>allel to a l9e drawn to ! axis ( ! actual armature coil4 ,:5 ! iron p>ts ( ! armature are ne>e/ ! poles ( ! horse%oe magnets 9 _! revolution1 ! slot 9 ! commutator %\ld be horizontal4 ,:5 ! magnet is provid$ ) a commutator1 x may also be run z a motor by connect+ x to a batt]y4 ,9 ord] to op]ate x ei!r z a dynamo or a motor1 h[ev]1 x mu/ fir/ be fitt$ ) a pair ( bru%es4 ,!y are %[n 9 detail 9 ,figure #bec4 ,!y are made f two small /rips ( %eet-copp] b5t z %[n & m\nt$ on a small wood5 block4 ,!y mu/ be adju/$ to be> aga9/ ! commutator s t :5 ! divid+ l9e betwe5 ! two sections is horizontal1 ! upp] bru% be>s aga9/ ! upp] section & ! l[] bru% aga9/ ! l[] section4 ,! two bru%es =m ! t]m9als ( ! ma*9e4 ,!y %\ld be connect$ to b9d+-po/s4 ,illu/ration3 ,fig4 #bed4--,! ,complete ,g5]ator4 ,9 ord] to op]ate ! dynamo prop]ly & obta9 suffici5t curr5t f x to op]ate a c\ple ( small inc&esc5t lamps1 x w h to be provid$ ) a pulley m\nt$ on ! end ( ! %aft aft] ! ge> :eel has be5 remov$4 ,! dynamo may !n be driv5 at high spe$ by connect+ x to a sew+-ma*9e ) a belt1 or ! back :eel ( a bicycle f :i* ! tire has be5 remov$4 ,! complet$ dynamo is %[n 9 ,figure #bed4 ,! voltage & amp]age ( ! dynamo w dep5d ^u ! ma*9e 9 "q1 n only ^u ! size ( ! wire b also ^u ! size ( ! ma*9e1 ! spe$ at :i* x is run1 & ! /r5g? ( ! horse%oe magnets4 ,x is impossible to tell j :at ! curr5t w be until x is te/$ & tri$4 ,a #aj-,watt ,dynamo ,probably few exp]im5t]s fully und]/& h[ almo/ impossible x is to con/ruct a dynamo1 wor?y ( ! "n z su*1 )\t resort to mat]ials & me?ods employ$ 9 ! comm]cial manufacture ( su* ma*9es4 ,practical telegraph in/rum5ts1 telephones1 etc41 c be con/ruct$ out ( all sorts ( odds & ends1 b 9 ord] to make a real dynamo x is necess>y to use c]ta9 mat]ials = :i* no?+ c be sub/itut$4 ,! field magnets mu/ be s(t gray ca/-iron except 9 special in/ances4 ,! wire us$ ?r\gh\t mu/ be ( good quality & mu/ be new4 ,! necessity = good workman%ip 9 ev5 ! smalle/ detail _c be ov]e/imat$4 ,poor workman%ip always results 9 ineffici5t work+4 ,no dynamo w give its /at$ output cont9u\sly & safely unless ! mat]ials & workman%ip are up to a high /&>d4 ,s9ce ca/+s mu/ be us$ z field magnets1 a patt]n is necess>y to =m ! m\ld = ! ca/+4 ,patt]n "w is some?+ requir+ skill & k usually beyond ! av]age exp]im5t]4 ,a la! is necess>y 9 ord] to bore or tunnel ! space betwe5 ! ends ( ! field magnet into :i* ! armature fits4 ,x may be possible = sev]al boys to club toge!r & h a patt]n made by a patt]n-mak] = build+ a dynamo4 ,!n by us+ ! la! 9 "s conv5i5t %op or manual tra9+ s*ool secure a field magnet & armature = a really practical small dynamo4 ,illu/ration3 ,fig4 #bee4--;,details ( ! ,field ,ca/+4 ,= ^! reasons1 ,i h describ$ bel[ a small dynamo ( ab\t t5 watts output1 ! ca/+s = :i* c be pur*as$ f _m electrical deal]s ) all ma*9e "w done at an extremely l[ price4 ,! field magnet %[n 9 ,figure #bee is drawn to scale & repres5ts ! be/ proportions = a small ov]type dynamo ( t5 to fifte5' watts output4 ,! dim5sions are s cle>ly %[n by ! draw+s t fur!r comm5t 9 t respect is unnecess>y4 ,! armature is ( ! type kn[n z ! ,siem5's ,h4 ,x is ! simple/ type ( armature x is possible to make1 :i* is a feature ( prime importance to ! beg9n] at dynamo con/ruction1 al?\gh x is n ! mo/ effici5t =m f ! electrical /&po9t4 ,! armature 9 ?is case is also a ca/+ & !re=e a patt]n is requir$4 ,illu/ration3 ,fig4 #bef4--;,details ( ! ,armature ,ca/+4 ,! patt]ns = bo? ! field & ! armature are ( ! same size & %ape z %[n 9 ,figures #bee & #bef4 ,!y are made ( wood1 & are f9i%$ by rubb+ ) f9e s&pap] until p]fectly smoo? & !n giv5 a coat ( %ellac4 ,! p>ts are also giv5 a slight draft1 t is1 a tap] t[>d "o side1 s t ! patt]n may be )drawn f ! m\ld4 ,! patt]ns are turn$ ov] to a f\ndry1 :]e !y are c>efully pack$ 9 a box1 call$ a flask1 full ( m\ld]'s s&4 ,:5 ! patt]ns are prop]ly )drawn1 !y w leave a p]fect impression ( !mselves beh9d 9 ! s&4 ,! m\ld is !n clos$ up & p\r$ full ( molt5 iron4 ,:5 ! iron has cool$ ! ca/+s are f9i%$ except = clean+ & bor+4 ,! %aft is a piece ( /eel rod1 ?ree-sixte5?s ( an in* 9 diamet]1 & f\r & "o-half in*es 9 l5g?4 ,! portion ( ! field into :i* ! armature fits is bor$ out to a diamet] ( "o & five-sixte5? in*es4 ,consid]able c>e is necess>y 9 p]=m+ ?is op]ation 9 ord] n to break ! field magnet ap>t by tak+ too heavy a cut4 ,illu/ration3 ,fig4 #beg4--;,details ( ! ,commutator4 ,! armature %\ld be turn$ d[n to a diamet] ( "o & "o-qu>t] in*es or "o-sixte5? ( an in* small] ?an ! tunnel 9 :i* x revolves betwe5 ! field magnets4 ,! c5t] ( ! armature is bor$ out to fit ! %aft4 ,figure #beg %[s a two-"p commutator = fitt+ to an armature ( ! ,siem5's ,h type4 ,x consi/s ( a %ort piece ( brass tub+ fitt$ on a fib] core & split l5g?-wise on two opposite sides1 s t ea* "p is insulat$ f ! o!r4 ,! fib] is drill$ ) a hole to fit tightly on ! %aft4 ,x is !n plac$ 9 a la! & turn$ d[n until a suitable piece ( brass tube c be driv5 on easily4 ,two l9es are !n m>k$ along ! tube diametrically opposite4 ,a %ort di/ance away f ea* ( ^! l9es1 & on ea* side ( !m1 bore two small holes to receive v small wood screws4 ,! screws %\ld be c\nt]-sunk4 ,x is v important t none ( ! screws %\ld g into ! fib] core f> en\gh to t\* ! %aft4 ,! commutator may !n be split along ea* ( ! l9es betwe5 ! screws ) a hacksaw4 ,! saw-cut %\ld be cont9u$ "r ?r\gh ! brass & slightly into ! insulat+ core4 ,! space betwe5 ! sections ( ! commutator %\ld be fitt$ ) well-fitt+ slips ( fib]1 glu$ 94 ,! commutator %\ld n[ be tru$ up & made p]fectly smoo?4 ,illu/ration3 ,fig4 #beh4--;,diagram %[+ h[ to connect ! ,armature ,w9d+ to ! ,commutator4 ,! commutator is provid$ ) a small brass ma*9e screw ?read$ into ea* section ne> ! edge z %[n 9 ,figure #beg4 ,^! screws are to receive ! ends ( ! armature w9d+ & s facilitate connections4 ,! commutator1 %aft & armature are assembl$ z %[n 9 ,figure #beh4 ,! armature may be held to ! %aft by a small set screw or a p94 ,! commutator %\ld fit on ! %aft v tightly s t x w n slip or twi/4 ,e "p ( ! armature & %aft t\*$ by ! armature w9d+ mu/ be insulat$ ) pap] :i* has be5 soak$ 9 %ellac until s(t4 ,! armature mu/ be left to dry be=e w9d+4 ,! armature %\ld next be w\nd ) ,no4 #bj ,b4 ,s4 gauge s+le-cotton-cov]$ magnet wire4 ,suffici5t wire %\ld be put on to fill up ! w9d+ space completely4 ,c>e %\ld be tak51 h[ev]1 n to put on too mu* wire or x w int]f]e ) ! field magnets & ! armature _c revolve4 ,aft] w9d+ ! armature1 te/ x c>efully to see t ! wire is ?or\ghly insulat$ f ! iron4 ,illu/ration3 ,fig4 #bei4--;,details ( ! ,wood5 ,base4 ,if ! insulation is correct1 pa9t ! :ole armature ) ?ick %ellac v>ni% & bake x 9 a w>m ov5 to set ! %ellac4 ,figure #beh is a diagram %[+ h[ ! w9d+ is made & connect$4 ,x is w\nd ab\t ! armature1 always 9 ! same direction1 j z if ! armature 7 an ord9>y electro-magnet4 ,! ends ( ! w9d+ are ea* connect$ to "o ( ! commutator sections by scrap+ ! wire & plac+ x "u ! screws4 ,! w9d+ space 9 ! field magnet %\ld be %ellack$1 & insulat$ ) br[n pap] by wrapp+ ! core ) a /rip ( pap] & cov]+ ! bobb9 ends ) circul> pieces made 9 two halves4 ,! field magnet is w\nd full ( ,no4 #bj ,b4 ,s4 gauge s+le-cotton-cov]$ wire4 ,! wire %\ld be put on 9 smoo?1 ev5 lay]s & ! w9d+ space completely fill$ up4 ,illu/ration3 ,fig4 #bfj4--,! ,pulley & ,be>+s4 ,! base = ! dynamo is a piece ( h>d wood1 five in*es long1 f\r in*es wide1 & five-eigh?s ( an in* ?ick4 ,! be>+s are small brass ca/+s ( ! dim5sions %[n 9 ,figure #bfj4 ,x is necess>y fir/ to make a wood5 patt]n & s5d x to ! f\ndry = ! ca/+s4 ,! be>+s are fa/5$ to ! project+ arms on ! field ca/+ by means ( ma*9e screws eight-?irty-seconds ( an in* 9 ?ickness4 ,! field magnet %\ld n be screw$ d[n on to ! base until ! armature runs easily & truly 9 ! tunnel4 ,! bru%es are made f ?9 gauge %eet-copp] accord+ to ! %ape & dim5sions %[n 9 ,figure #bfa4 ,!y are b5t at "r angles & m\nt$ on ! base on ei!r side ( ! commutator ) small r\nd-head$ wood screws4 ,! complet$ dynamo is %[n 9 ,figure #bfb4 ,"o end ( ! %aft is provid$ ) a small pulley to accommodate a small lea!r belt4 ,illu/ration3 ,fig4 #bfa4--,! ,bru%es4 ,! dynamo is connect$ z a %unt ma*9e1 t is1 "o t]m9al ( ! field magnet is connect$ to "o ( ! bru%es1 & ! o!r t]m9al to ! o!r bru%4 ,a wire is !n l$ f ea* ( ! bru%es to a b9d+-po/4 ,a %unt dynamo w only g5]ate :5 run 9 a c]ta9 direction4 ,9 ord] to make x g5]ate :5 run 9 ! opposite direction1 x is necess>y to rev]se ! field connections4 ,! dynamo j describ$ %\ld h an output ( f #aj to #ae watts & deliv] ab\t #f volts & #a #c_/d to #b #a_/b amp]es4 ,9 ord] to secure curr5t f ! dynamo x w fir/ be necess>y to magnetize ! field by connect+ x to sev]al batt]ies4 ,illu/ration3 ,,! ,,junior ,,dynamo ,,m\nt$ ,,on ,a ,,long ,,wood5 ,,base ,,& ,,belt$ ,,to ,a ,,groov$ ,,:eel ,,fitt$ ,,) ,a ,,crank ,,s ,,t ,,! ,,dynamo ,,c ,,be ,,run ,,at ,,high ,,spe$ ,,by ,,h& ,,p[]4 ,,! ,,illu/ration ,,also ,,%[s ,a ,,small ,,inc&esc5t ,,lamp ,,connect$ ,,to ,,! ,,dynamo ,,s ,,t ,,:5 ,,! ,,crank ,,is ,,turn$ ,,! ,,lamp ,,w ,,light4 ,x w be f\nd t ! dynamo w also op]ate z a v effici5t little motor1 b t on acc\nt ( hav+ a two-pole armature x mu/ be />t$ by giv+ ! %aft a twi/4 ,illu/ration3 ,fig4 #bfb4--;,complete ,dynamo4 ,x c be us$ z a g5]ator = light+ small lamps1 electro-plat+1 etc41 b _c be us$ = re*>g+ /orage cells on acc\nt ( hav+ a two-pole armature4 ,! dynamo may be driv5 ) a small wat] motor or f ! driv+-:eel ( a sew+-ma*9e4 ,be=e ! ma*9e w g5]ate z a dynamo1 x mu/ be connect$ to a batt]y & run z a motor4 ,?is w give ! field ! residual magnetism :i* is necess>y be=e x c produce curr5t itself4 ,,*apt] ,,xviii ,,an ,,electric ,,railway ,no toys loom up be=e ! m9d ( ! av]age boy ) m appeal to 8 love ( adv5ture ?an d railway c>s & tra9s4 ,9 ,engl&1 ! con/ruction & op]ation ( m9iature railways is ! hobby n only ( boys b ( gr[n m51 & on a scale t is h>dly appreciat$ 9 ?is c\ntry4 ,! height ( ambition ( _m boys is n only to own a m9iature railway sy/em b to build "o4 ,= "s unkn[n reason1 none ( ! boys' pap]s or books h h]et(ore giv5 any in=mation on ?is int]e/+ subject4 ,! c> %[n 9 ,figure #bfc is su* t x c be easily built by any boy will+ to ex]cise ! necess>y c>e & pati5ce 9 its con/ruction4 ,! fir/ op]ation is to cut out ! floor ( ! c>4 ,?is is a rectangul> piece ( h>d wood1 eight in*es long1 ?ree & "o-qu>t] in*es wide & "o-half ( an in* ?ick4 ,its exact %ape & dim5sions are %[n 9 ,figure #bfd4 ,! rectangul> hole cut 9 ! floor p]mits ! belt :i* drives ! :eels to pass d[n f ! c\nt]-%aft to ! axle4 ,illu/ration3 ,fig4 #bfc4--;,complete ,electric ,railway op]at$ by ,dry ,cells4 ,note h[ ! ,wires f ! ,batt]y are connect$ to ! ,rails by means ( ! ,wood5 ,conductors illu/rat$ 9 ,figure #bgg4 ,! two pieces =m+ ! :eel-be>+s are cut out ( %eet-brass accord+ to ! %ape & dim5sions %[n 9 ,figure #bfe4 ,! brass %\ld be "o-sixte5? ( an in* ?ick4 ,! two project+ pieces at ! top are b5t ov] at "r angles s t !y c be m\nt$ on ! "u side ( ! c> floor by small screws pass+ ?r\gh ! holes4 ,! holes :i* =m ! be>+s = ! ends ( ! axles ^u :i* ! :eels are m\nt$ %\ld be ?ree in*es ap>t4 ,! be>+s _c be plac$ 9 position on ! "u side ( ! c> floor until ! :eels & axles are ready1 b :5 ?is "w is done1 c>e %\ld be tak5 to see t !y l9e up & come exactly opposite to ea* o!r4 ,illu/ration3 ,fig4 #bfd4--;,details ( ! ,floor ( ! ,c>4 ,! :eels !mselves _c be made by ! "y exp]im5t] unless he has a la!4 ,!y are flang$ :eels1 "o & "o-eigh? in*es 9 diamet]1 & are turn$ f ca/ iron or brass4 ,su* :eels c be pur*as$ ready made1 or x may be possible to obta9 f "s brok5 toy a set :i* w prove suitable4 ,illu/ration3 ,fig4 #bfe4--;,details ( ! ,be>+ :i* supports ! ,:eel & ,axle4 ,ea* %aft is compos$ ( two pieces ( ,bessem] rod held toge!r by a %ort piece ( fib] rod hav+ a hole 9 ea* end into :i* "o end ( ea* piece ( iron rod is driv54 ,! :eels fit tightly on ! o!r end ( ea* ( ^! pieces4 ,!y %\ld be spac$ s z to run on rails two in*es ap>t4 ,illu/ration3 ,fig4 #bff4--,! ,:eels & ,axle4 ,! purpose ( ! fib] rod is to insulate ! halves ( ! axle f ea* o!r4 ,! electric curr5t :i* op]ates ! c> is c>ri$ by ! two rails :i* =m ! track1 & if ! axles 7 made 9 "o piece or ! halves jo9$ toge!r s z to =m an electrical connection1 ! batt]y furni%+ ! curr5t w\ld be %ort-circuit$1 because ! curr5t w\ld pass along ! two rails & across ! axles in/ead ( ?r\gh ! motor4 ,"o pair ( :eels are fitt$ ) a groov$ pulley "o in* 9 diamet]4 ,x is h>dly necess>y to say t ! :eels & axles %\ld be p]fectly align$1 & %\ld run true4 ,illu/ration3 ,fig4 #bfg4--,! ,motor4 ,! motor us$ to drive ! c> w prove m satisfactory if pur*as$ ready made4 ,a self-/>t+ ?ree-pole motor simil> to t %[n 9 ,figure #bfg w s]ve v nicely4 ,! wood5 base %\ld be remov$ & ! motor screw$ d[n firmly to ! floor ( ! c> z 9 ,figure #bfh4 ,"o t]m9al ( ! motor is connect$ to "o ( ! be>+s1 & ! o!r t]m9al to ! o!r be>+4 ,! motor is belt$ to a c\nt]%aft s t x w h suffici5t p[] to move ! c>4 ,x _c be directly connect$ or belt$ to ! axle1 because ! spe$ ( a small motor is s high t x has comp>atively little turn+ p[] or torque4 ,! spe$ mu/ be r$uc$ & ! torque increas$ be=e x w drive ! c>4 ,! c\nt]%aft consi/s ( two groov$ pulleys m\nt$ ^u an axle runn+ 9 two be>+s m\nt$ ^u ! floor ( ! c>4 ,! be>+s are made f a /rip ( heavy %eet-brass1 b5t at "r angles & fa/5$ to ! c> floor ) small screws4 ,! l>ge pulley1 ,a1 is "o in* & "o half 9 diamet] & ! small pulley1 ,b1 is five-sixte5?s ( an in* 9 diamet]4 ,! c\nt]%aft is m\nt$ 9 su* a position t a belt may be run f ! small pulley1 ,b1 to ! pulley m\nt$ on ! axle ( "o pair ( :eels4 ,a belt is also run f ! small pulley on ! motor to ! l>ge pulley1 ,a1 on ! c\nt]%aft4 ,! pulleys mu/ all be c>efully l9$ up s t ! belts w run 9 _! grooves )\t dang] ( slipp+ out4 ,illu/ration3 ,fig4 #bfh4--,! ,complete ,truck ( ! ,c> )\t ! ,body4 ,! %ield on ! plat=m at ea* end ( ! c> is made ( %eet-iron or t94 ,two small projections on ! bottom are b5t ov] at "r angles & us$ to secure ! %ields 9 position by driv+ a small tack ?r\gh !m into ! floor ( ! c>4 ,! /eps on ei!r side ( ea* plat=m are also made by b5d+ /rips ( %eet-iron or t9 & fa/5+ !m to ! c> ) small nails or tacks4 ,! c\pl] consi/s ( a /rip ( t9 hav+ a small hook sold]$ to ! end s t a trail c> may be atta*$ if desirable4 ,illu/ration3 ,fig4 #bfi4--,patt]n = ! ,sides & ,ends ( ! ,c>4 ,! c> is n[ ready = te/+1 & :5 held 9 ! h& s t ! :eels are free to run1 two cells ( dry batt]y %\ld be f\nd all t is necess>y to drive !m at a fair rate ( spe$4 ,! two wires lead+ f ! batt]y %\ld be connect$ to ! be>+s1 "o wire lead+ to ea* be>+4 ,x w require m ?an two cells1 h[ev]1 to drive ! :eels prop]ly :5 ! c> is on ! track1 ,all mov+ p>ts %\ld run freely & smoo?ly4 ,! c> may be us$ j z x is1 b if fitt$ ) a body & a top x w pres5t a mu* m reali/ic appe>ance4 ,! sides & ends ( ! c> body are made ( %eet-iron or t94 ,figure #bfi %[s ! patt]n & dim5sions = ^! p>ts4 ,!y may be made f "o piece ( metal eighte5 & "o-half in*es long & ?ree & ?ree-qu>t]s in*es wide4 ,! doors & w9d[s are cut out ) a pair ( t9-snips4 ,! small projections along ! top are b5t d[n at "r angles & ! ro( is fa/5$ to !m4 ,! dott$ l9es indicate ! places = b5d+ ^! projections & also ! sides & ends ( ! c>4 ,illu/ration3 ,fig4 #bgj4--,! ,ro( ( ! ,c>4 ,! ro( is made 9 two pieces4 ,x also is %eet-iron or t94 ,! ro( prop] is eight in*es long & f\r in*es wide4 ,x has a hole five & "o-half in*es long & "o & ?ree-qu>t]s in*es wide cut 9 ! c5t]4 ,a numb] ( small projections are left & b5t upw>d to support ! deck & to =m imitation v5tilators4 ,! deck is six in*es long & two & "o-qu>t] in*es 9 wid?4 ,x is plac$ 9 position on ! ro( & fa/5$ by sold]+4 ,! ro( is fa/5$ to ! sides & ends ( ! c> by sold]+4 ,x mu/ be b5t slightly to con=m ) ! curve at ! top ( ! front & ! re> ( ! c>4 ,illu/ration3 ,fig4 #bga4--,! ,complet$ ,c>4 ,! c> :5 complet$ w appe> z 9 ,figure #bga4 ,! track is made ( smoo? spr+ /eel1 "o-half in* wide & ei!r ,no4 #bj or ,no4 #bb gauge 9 ?ickness4 ,illu/ration3 ,fig4 #bgb4-;,details ( a ,wood5 ,tie4 ,! wood5 ties are ?ree & "o-half in*es long1 ?ree-qu>t]s ( an in* wide & ?ree-eigh?s ( an in* ?ick4 ,ea* tie has two saw-cuts1 exactly two in*es ap>t across ! top face4 ,?is "p ( ! "w is be/ p]=m$ 9 a mit]-box s t ! cuts w be p]fectly squ>e across ! ties4 ,a saw %\ld be us$ :i* w make a cut ( su* a size t ! /eel track w fit tightly into x4 ,! di/ance betwe5 ! two rails ( ! track1 or ! gauge1 z x is call$1 is two in*es4 ,illu/ration3 ,fig4 #bgc4-;,arrangem5t ( ,track4 ,! track is assembl$ z 9 ,figure #bgc4 ,! spr+ /eel is =c$ into ! saw-cuts 9 ! ties by tapp+ ) a light wood5 mallet4 ,! ties %\ld be spac$ along ! track ab\t ?ree in*es ap>t4 ,! "w ( lay+ ! track mu/ be v c>efully done s t ! c> :eels w n b9d at any spot4 ,curves %\ld n be too %>p1 or ! c> w n pass ar\nd4 ,! track may be laid out 9 a numb] ( diff]5t %apes1 "s ( :i* are %[n 9 ,figure #bgd4 ,illu/ration3 ,fig4 #bgd4--,?ree ,diff]5t ,patt]ns = lay+ out ! ,track4 ,a circle is ! easie/ =m ( track to make4 ,9 lay+ out a circle or any sort ( curv$ track1 ! outside rail mu/ necess>ily be made long] ?an ! inside "o4 ,! oval %ape is a v good =m to give ! track 9 a great _m cases1 especially :]e x is desirable = ! c> to h a long] pa? ?an t af=d$ by a circle4 ,illu/ration3 ,fig4 #bge4--;,details ( ! ,base ( ! ,cross-ov]4 ,9 ord] to make a figure-eight out ( ! track1 a cross+1 or cross-ov]1 z x is sometimes call$1 w be requir$4 ,?is is %[n 9 ,figure #bge4 ,a cross-ov] p]mits two tracks to cross ea* o!r )\t int]f]5ce4 ,x consi/s ( a wood5 base1 eight in*es squ>e & ?ree-eigh?s ( an in* ?ick4 ,f\r saw-cuts1 ea* pair exactly p>allel1 & two in*es ap>t1 are made at "r angles to ea* o!r across ! top surface ( ! base1 z %[n 9 ! illu/ration4 ,! track us$ on ! cross-ov] is semi-h>d hoop-brass1 "o-half ( an in* wide & ( ! same gauge z ! /eel track4 ,! brass is m easily b5t ?an ! /eel & is us$ = t reason1 x be+ practically impossible to b5d ! /eel track at "r angles )\t snapp+ x4 ,f\r pieces ( ! brass1 ea* five in*es long1 are b5t at "r angles exactly 9 ! c5t]4 ,f\r %ort pieces1 ea* "o & "o-half in*es long1 w also be requir$4 ,illu/ration3 ,fig4 #bgf4--,! ,complet$ ,cross-ov]4 ,! cross-ov] is assembl$ z %[n 9 ,figure #bgf4 ,! /rips m>k$ ,d are /rips ( v ?9 %eet-brass or copp]4 ,! purpose ( ^! /rips is to connect ! ends ( ! track on ! cross-ov] to ! ends ( ! track =m+ ! figure-eight s t ! cross-ov] w n be a dead section1 t is1 a section ( track :]e ! c> _c get any curr5t4 ,! long /rips1 b5t at "r angles to ea* o!r & m>k$ ,a1 ,a1 ,b1 ,b1 9 ! illu/ration1 are =c$ into ! saw-cuts 9 ! base ov] ! /rips m>k$ ,d4 ,! small pieces1 ,c1 ,c1 ,c1 ,c1 are plac$ 9 betwe5 ! long /rips1 leav+ a space betwe5 s t ! flanges ( ! c> :eels c pass4 ,! pieces1 ,c1 ,c1 ,c1 ,c1 %\ld =m a squ>e op5 at ! corn]s4 ,! two long /rips1 ,a1 ,a1 %\ld be at opposite corn]s diagonally across ! squ>e4 ,b & ,b %\ld occupy ! same relative position at ! o!r corn]s4 ,a & ,a are connect$ toge!r & ,b & ,b are connect$ toge!r by wires pass+ on ! "u side ( ! base4 ,! ends ( ! track =m+ ! figure-eight are =c$ into ! saw-cuts at ! edges ( ! base s t !y =m a good electrical connection ) ! small /rips m>k$ ,d4 ,x is q necess>y to use c>e 9 arrang+ a figure-eight track1 or !re w be dang] ( %ort-circuit+ ! batt]ies4 ,! outside rails ( ! figure-eight1 di/+ui%$ by ! lett] ,b 9 ! illu/ration1 %\ld be connect$ toge!r by ! cross-ov]4 ,! inside rails1 m>k$ ,a1 %\ld also be connect$ toge!r by ! cross-ov]4 ,9 ord] to make a good me*anical & electrical connection betwe5 ! ends ( ! rails :5 two or m sections ( track are us$ 9 lay+ out ! sy/em1 x is necess>y to ei!r sold] ! rails toge!r or else use a connector su* z t %[n 9 ,figure #bgg4 ,?is consi/s ( a small block ( wood hav+ a saw-cut across its upp] face & a piece ( ?9 %eet-brass set into ! cut4 ,! two rails are plac$ ) _! ends abutt+ & "o ( ^! connectors slipp$ up f b5ea? & =c$ on ! rails4 ,! piece ( ?9 brass set into ! wood5 block s]ves to make an electrical connection betwe5 ! two rails & also to hold !m firmly 9 position4 ,a small screw & a wa%] plac$ outside ! track & pass+ ?r\gh ! brass /rip w all[ a batt]y wire to be conv5i5tly atta*$4 ,illu/ration3 ,fig4 #bgg4--;,a ,connector = jo9+ ! ,ends ( ! ,rails4 ,! /eel rails %\ld be occasionally wip$ ) ma*9e oil or vasel9e to prev5t ru/+1 & also to all[ ! c> to run m freely :]ev] ! flanges ( ! :eels rub aga9/ ! rails 9 pass+ ar\nd a curve4 ,f\r dry cells or ?ree cells ( /orage batt]y %\ld be suffici5t to op]ate ! c> prop]ly4 ,if x is desirable1 a small rheo/at may be includ$ 9 ! batt]y circuit1 s t ! spe$ ( ! c> c be v>i$ at w4 ,! motor & ! :eels %\ld be c>efully oil$ s t !y w run )\t friction4 ,! belts %\ld n be s tight t !y cause friction or s loose t !y all[ ! motor to slip1 b %\ld be s adju/$ t ! motor runs freely & transmits its p[] to ! :eels4 ,! c> may be made rev]sible by fitt+ ) a small curr5t rev]s]1 b unless ! rev]s] is c>efully made ! dang] ( loss ( p[] ?r\gh poor contacts is q consid]able4 ,if ! c> is fitt$ ) a rev]s] ! h&le %\ld be arrang$ to project f ! c> 9 a conv5i5t place :]e x c be easily rea*$ by ! f+]s & ! c> s5t back or =? at w4 ,a railway sy/em su* z ?is c be elaborat$ & ext5d$ by add+ m ?an "o c> to ! l9e or su* features z bridges & /ations4 ,illu/ration3 ,fig4 #bgh4--;,a ,bump] = prev5t+ ! ,c> f leav+ ! ,rails4 ,! ends ( a bl9d section ( track1 t is1 a /raight piece ( track n "p ( a circle or curve s t ! c> c return1 %\ld be fitt$ ) a track bump]1 to prev5t ! c> leav+ ! rails4 ,illu/ration3 ,fig4 #bgi4--;,a ,design = a ,railway ,bridge4 ,no dim5sions are giv5 9 ,figures #bgi & #bhj1 %[+ designs = a bridge & a /ation1 because !y are be/ left to be det]m9$ by ! scale ^u :i* ! railway sy/em is to be ext5d$4 ,illu/ration3 ,fig4 #bhj4--;,a ,design = a ,railway ,/ation4 ,bo? ! bridge & ! /ation are v simple4 ,! bridge is built entirely ( wood1 ) ! exception ( ! /eel rails4 ,! /ation may be made out ( ?9 wood1 su* z cig>-box wood4 ,! doors1 w9d[s1 etc41 may be pa9t$ on ! walls4 ,if ?is is c>efully done1 x w give a v reali/ic appe>ance to y\r /ation4 ,,*apt] ,,xix ,,m9iature ,,light+ ,m9iature light+ is a field ( _m int]e/+ possibilities = ! "y exp]im5t]4 ,any labor exp5d$ along ?is l9e w result 9 some?+ f> m useful f a practical /&po9t ?an almo/ any ( ! o!r ?+s describ$ 9 ?is book4 ,m9iature lights1 op]at$ f batt]ies1 may be us$ 9 v>i\s ways2 to light d>k corn]s1 hallways1 or o!r places :]e a light is (t5 tempor>ily want$ )\t ! accompany+ dang] & nuisance ( mat*es or k]os5e lamps4 ,m9iature light+ has only be5 made practical by ! tung/5 filam5t lamp4 ,! filam5t1 or wire inside ! globe1 :i* becomes hot & emits ! light :5 ! curr5t is turn$ on1 is made ( tung/5 9 a tung/5 lamp4 ,9 ! e>li] lamps1 x 0 made ( c>bon4 ,! c>bon lamp is n[ seldom us$ & is highly ineffici5t :5 comp>$ to ! tung/54 99,a ,c>bon ,lamp99 consumes ab\t ?ree & "o-half watts ( curr5t = ea* c&le-p[] ( light1 :]eas a small tung/5 lamp uses only ab\t "o watt p] c&le-p[] small tung/5 lamp uses only ab\t "o watt p] c&le-p[]4 ,! tung/5 lamp is !re=e ?ree times z effici5t z a c>bon lamp1 & :5 us$ on a batt]y ( equal voltage x is possible to obta9 ! same am\nt ( light ) "o-?ird ( ! curr5t t w\ld be requir$ by a c>bon lamp4 ,illu/ration3 ,fig4 #bha4--,m9iature ,c>bon ,batt]y ,lamp4 ,c>bon lamps simil> to t %[n 9 ,figure #bha are made 9 a numb] ( diff]5t voltages4 ,! l[e/ voltage t x is practically possible to make a c>bon lamp = is ?ree & "o-half4 ,a ?ree-&-"o-half volt c>bon lamp is design$ to be op]at$ on small dry cells su* z fla%light batt]ies4 ,! ,e4 ,m4 ,f4 ( a dry cell is ab\t "o & "o-half volts1 b :5 ?ree small dry cells ( ! fla%light type are connect$ 9 s]ies & us$ to op]ate a lamp1 _! voltage drops1 & ! available ,e4 ,m4 ,f4 is only ab\t ?ree & "o-half volts4 ,f\r-volt c>bon lamps are int5d$ to be op]at$ on l>ge dry batt]ies or wet cells because !y d n lose _! voltage z quickly z small dry cells4 ,! table bel[ gives ! voltage & c&le-p[] ( ! v>i\s small c>bon lamps :i* are c>ri$ 9 /ock by mo/ electrical deal]s or supply h\ses3 99,,m9iature ,,c>bon ,,batt]y ,,lamps99 #c4e volts = fla%light batt]ies #d volts4 #b c&le-p[] #e4e volts = fla%light batt]ies #f volts4 #b c&le-p[] #f volts4 #d c&le-p[] #h volts4 #d c&le-p[] #aj volts4 #f c&le-p[] 99,tung/5 ,lamps99 are made = voltages z l[ z "o & "o-half1 & w light on "o cell ( dry batt]y4 ,! range ( voltages is q wide & v>i$4 ,a few ( ! mo/ common sizes are giv5 bel[3 99,,m9iature ,,tung/5 ,,batt]y ,,lamps99 #a4e volts4 = "o dry cell #b4e volts4 = two-cell fla%light batt]y #b4h volts4 = two-cell fla%light batt]y #c4e volts4 = ?ree-cell fla%light batt]y #c4h volts4 = ?ree-cell fla%light batt]y #d volts4 #d c&le-p[] #f volts4 #b c&le-p[] #f volts4 #d c&le-p[] #f volts4 #f c&le-p[] #f volts4 #h-aj-ab-af-bj-bd c&le-p[] ,illu/ration3 ,fig4 #bhb4--,m9iature ,tung/5 ,batt]y ,lamp4 ,to f9d ! approximate am\nt ( curr5t drawn f a batt]y by a tung/5 lamp1 divide ! c&le-p[] by ! voltage & ! result w be ! curr5t 9 amp]es4 ,= example1 a #f v4 #b c4 p4 lamp w require1 #b divid$ by #f1 or "o-?ird ( an amp]e4 ,six-volt tung/5 lamp giv+ a light great] ?an six c&le-p[] are only us$ on /orage batt]ies & are employ$ pr9cipally = automobile light+4 ,! filam5t ( a tung/5 lamp is mu* long] ?an t ( a c>bon lamp & is usually 9 ! =m ( a spiral or helix1 z %[n 9 ,figure #bhb4 ,! bases ( batt]y lamps1 ! base be+ ! l[] portion ( ! lamp1 :i* is made ( brass & fits into a socket or receptacle1 are made 9 ?ree diff]5t /yles3 m9iature1 c&elabra1 & ,ediswan4 ,illu/ration3 ,fig4 #bhc4--,lamps fitt$ respectively ) ,m9iature1 ,c&elabra1 & ,ediswan ,bases4 ,! m9iature & c&elabra bases h a ?read$ brass %ell on ! outside & a small brass contact-button on ! bottom4 ,!y are simil> except 9 respect to size4 ,! m9iature base is small] ?an ! c&elabra4 ,! ,ediswan base is a pla9 brass %ell hav+ two p9s on ! side & two contacts on ! bottom4 ,?is type ( base is only us$ 9 ?is c\ntry on automobiles4 ,! m9iature & ! c&elabra bases are /&>d = batt]y light+4 ,! m9iature base has _m advantages ov] ! c&elabra = ! "y exp]im5t]1 & %\ld be adopt$ 9 mak+ any ( ! app>atus describ$ 9 ?is *apt]4 ,^! ?ree bases are %[n 9 ,figure #bhc4 ,illu/ration3 ,fig4 #bhd4--,m9iature ,flat-,base ,porcela9 ,receptacle4 ,9 ord] to =m a good electrical connection betwe5 ! lamp & ! p[] wires "s sort ( a receptacle or socket is necess>y4 ,! mo/ common arrangem5t = ?is purpose is ! m9iature flat-base porcela9 receptacle %[n 9 ,figure #bhd4 ,?is type ( receptacle is us$ 9 places :]e x c be p]man5tly fa/5$ 9 position ) two small screws4 ,illu/ration3 ,fig4 #bhe4--,wea!r-pro( & ,p9-,sockets4 ,! devices %[n 9 ,figure #bhe are kn[n respectively z a porcela9 wea!r-pro( socket & a p9-socket4 ,sockets simil> to ! wea!r-pro( socket are also made ( wood4 ,! wea!r-pro( sockets are us$ 9 places :]e ! light is to be expos$ out-(-doors1 z = in/ance on a por*4 ,! small metal p>ts are seal$ 9 ! porcela9 & entirely protect$4 ,! p9-sockets & ! wood5 sockets are us$ pr9cipally on ,*ri/mas trees or 9 decorative outfits :]e lamps are hung 9 fe/oons4 ,! flat-base receptacle1 ! p9-socket1 & also ! wood5 socket w be f\nd v useful 9 mak+ ! app>atus describ$ f>!r on 9 ?is *apt]4 99,! ,wires99 us$ to c>ry ! curr5t 9 a m9iature light+ sy/em may be ( ! sort kn[n z annunciator or (fice wire if ! wires are to be run entirely indoors4 ,! wire %\ld n be small] ?an ,no4 #af ,b4 ,s4 gauge4 ,:5 ! wires are run outdoors1 on a por*1 or 9 "s o!r place expos$ to ! wea!r1 ! wire us$ %\ld be rubb]-cov]$4 ,hang+ lights or lights int5d$ to be adju/able %\ld be connect$ ) flexible conductor4 ,?is is made ( a numb] ( v f9e wires braid$ toge!r & insulat$ ) silk4 ,! wires us$ 9 a light+ sy/em %\ld n 9 any case be long] ?an x is necess>y to h !m4 ,:5 a batt]y is connect$ to a sy/em ( wires x is f\nd t ! voltage at ! end ( ! wires is mu* l[] ?an at a po9t ne> ! batt]y4 ,?is is call$ voltage drop1 & is mu* great] z ! wires gr[ long]4 ,a light plac$ at ! end ( two v long wires w n burn z brightly z x w\ld if connect$ to ! same batt]y by means ( %ort wires4 99,swit*es99 c be made by foll[+ ! sugge/ions giv5 9 ,*apt] ,,vii4 ,suitable swit*es c be pur*as$ = a few c5ts at a mo/ any electrical h\se & w prove v mu* neat] & effici5t4 ,!y %\ld pref]ably be ( any ( ! types %[n 9 ,figure #bhf4 99,! ,batt]ies99 us$ = m9iature light+ may be made up ( /orage cells1 dry cells or c>bon cyl9d] cells4 ,/orage cells w prove ! mo/ satisfactory1 provid$ t ! exp]im5t] has "s conv5i5t means ( re*>g+ !m or ( hav+ !m re*>g$4 ,/orage cells w be f\nd ( especial value :]ev] x is desirable to op]ate sev]al lights f "o batt]y4 ,c>bon cyl9d] cells are only suitable :]e "o cell is to be op]at$ at a "t4 ,if m ?an "o is us$1 ! batt]y is liable to become pol>iz$ & ! lamps w n burn brightly4 ,c>bon cyl9d] batt]ies are v inexp5sive to r5ew1 & w be f\nd ! *eape/ me?od ( light+ a small tung/5 lamp4 ,illu/ration3 ,fig4 #bhf4--,types ( ,batt]y ,swit*es suitable = ,m9iature ,light+4 ,if lamps requir+ m ?an two amp]es are to be op]at$ on dry cells1 ! latt] %\ld be connect$ 9 s]ies-multiple1 z %[n 9 ,figure #fi4 ,two sets ( dry cells connect$ 9 s]ies-multiple w give m ?an twice ! s]vice ( a s+le set4 ,lamps may be connect$ ei!r 9 multiple or 9 s]ies1 provid$ t ! prop] voltages ( bo? batt]y & lamps are us$4 ,:5 !y are to be connect$ 9 multiple1 ! voltage ( ! lamps %\ld be ! same z t ( ! batt]y4 ,:5 !y are to be us$ 9 s]ies1 ! voltage ( ! lamps multipli$ by ! numb] us$ %\ld equal ! voltage ( ! batt]y4 ,= example1 suppose t y wi% to use a numb] ( six-volt lamps on a six-volt /orage batt]y4 ,9 t case !y mu/ be connect$ 9 multiple4 ,b if x %\ld be t ! lamps are only two-volt lamps & y wi% to op]ate ?ree ( !m on a six-volt batt]y y w h to place !m 9 s]ies4 ,illu/ration3 ,fig4 #bhg4--;,h[ ,lamps are ,connect$ 9 ,multiple4 ,illu/ration3 ,fig4 #bhh4--;,h[ ,lamps are ,connect$ 9 ,s]ies4 ,x is sometimes desirable to arrange a lamp & two swit*es s t x c be turn$ (f or on f ei!r swit* indep5d5tly ( ! o!r4 ,?is is call$ ?ree-way wir+1 & is a v conv5i5t me?od ( arrang+ a light 9 a hallway4 ,if "o swit* is plac$ at ! top ( a /airway & ! o!r swit* at ! bottom1 a p]son c pass up/airs or d[n/airs1 light ! lamp ahead1 & turn x out z he passes ! la/ swit*1 no matt] 9 :i* direction ! previ\s us] ( ! light may h gone4 ,! swit*es are two-po9t swit*es1 & ! circuit %\ld be arrang$ z 9 ,figure #bhi4 ,! swit*-lev]s %\ld always re/ on "o ( ! contacts & nev] be left betwe51 z %[n 9 ! draw+4 ,illu/ration3 ,fig4 #bhi4--,?ree-way ,wir+ ,diagram4 ,! ,light may be turn$ (f or on f ei!r ,swit*4 ,!y are repres5t$ t way 9 ! illu/ration 9 ord] n to conceal ! contacts4 ,small brackets made ( brass & simil> to t %[n 9 ,figure #bij are = sale at _m electrical supply h\ses1 & w add a v reali/ic appe>ance to a m9iature light+ plant4 ,illu/ration3 ,fig4 #bij4--;,a ,lamp ,bracket = ,m9iature ,light+4 ,brackets may be con/ruct$ aft] ! plan %[n 9 ,figure #bia4 ,a wood5 socket or a p9-socket is m\nt$ on ! end ( a small piece ( brass tub+ :i* has be5 b5t into ! %ape %[n 9 ! illu/ration4 ,! o!r end ( ! tube is set into a wood5 block s t ! bracket may be m\nt$ on ! wall4 ,! wires f ! socket lead ?r\gh ! brass tube & ?r\gh ! back or top ( ! block4 ,illu/ration3 ,fig4 #bia4--;,a ,home-made ,bracket4 ,hang+ lights may be arrang$ by fitt+ a wood5 socket & a lamp ) a reflector z %[n 9 ,figure #bif4 ,! reflector consi/s ( a circul> piece ( t9 or %eet-alum9um hav+ a hole 9 ! c5t] l>ge en\gh to pass ! base ( a m9iature lamp4 ,! circle is !n cut along a /raight l9e f ! circumf]5ce to ! c5t]4 ,if ! edges are pull$ toge!r & lapp$ ! circul> %eet ( metal w take on a concave %ape & =m a %ade or reflector :i* w ?r[ ! light d[nw>ds4 ,! ov]lapp+ edges ( ! reflector %\ld be sold]$ or rivet$ toge!r4 ,! reflector is slipp$ ov] ! base ( ! lamp1 a small rubb] or felt wa%] hav+ be5 plac$ ov] ! base next to ! glass bulb s t ! reflector w n break ! lamp4 ,! lamp is !n screw$ into a socket & all[$ to hang d[nw>ds f a flexible conductor4 ,illu/ration3 ,fig4 #bib4--;,a ,hang+ ,lamp4 ,a v pretty effect c be secur$ by drill+ ! edges ( a reflector full ( small holes ab\t ?ree-sixte5?s ( an in* ap>t & !n hang+ %ort /r+s ( beads f ! holes4 ,! beads %\ld =m a hang+ fr+e ar\nd ! edge ( ! reflector1 & if !y are ( glass1 a pleas+ brilliancy is produc$4 ,figure #bic %[s h[ to make ! reflector4 ,illu/ration3 ,fig4 #bic4--;,h[ ! ,reflector is made4 ,! batt]ies = a m9iature light+ plant may be locat$ 9 a closet1 "u a /airway1 or 9 "s o!r out-(-!-way place4 ,wires f !re may be ext5d$ to v>i\s p>ts ( ! h\se1 su* z hallways1 closets1 ! cell> /airs1 ov] a %av+-mirror 9 ! ba?-room or 9 any d>k corn] :]e a light is (t5 tempor>ily ne$$4 ,! wires c be run beh9d picture-m\ld+s or along ! surbase & be almo/ entirely conceal$4 ,illu/ration3 ,fig4 #bid4--;,a ,?ree-,cell ,dry ,batt]y = use 9 ,h&-,lant]ns1 etc4 99,small ,batt]ies99 consi/+ ( ?ree small dry cells enclos$ 9 c>dbo>d box1 z %[n 9 ,figure #bid1 are on ! m>ket1 & may be b\ght at prices rang+ f ?irty to =ty c5ts1 dep5d+ ^u ! size & ! mak]4 ,"o ( ! mo/ conv5i5t & practical sizes ( ?is type ( batt]y has ! dim5sions %[n 9 ! illu/ration1 & ) its aid x is possible to con/ruct a numb] ( v useful electrical novelties & h\sehold articles 9 ! %ape ( portable electric lamps1 etc4 ,^! batt]ies are q small & are only int5d$ to op]ate v small lamps4 ,only "o lamp %\ld be us$ on ea* batt]y at a "t1 & x %\ld n be all[$ to burn long4 ,"s ( ^! batt]ies w give t5 to f\rte5 h\rs ( int]mitt5t s]vice b if all[$ to burn cont9u\sly w\ld only light ! lamp = ab\t five h\rs at ! mo/4 ,x is mu* ! bett] plan to use !m only = a few m9utes at a "t1 & !n turn ! light (f & all[ ! batt]y to recup]ate4 99,an ,electric ,h&-,lant]n99 is a v conv5i5t device :i* is q simple to make4 ,x consi/s ( a wood5 box l>ge en\gh to receive a ?ree-cell batt]y1 su* z t %[n 9 ,figure #bie4 ,! back ( ! box %\ld op5 & close on h+es & be fa/5$ ) a hook s t ! batt]y may be easily remov$ = r5ewal4 ,illu/ration3 ,fig4 #bie4--;,an ,electric ,h&-,lant]n4 ,a ?ree-&-"o-half-volt tung/5 lamp is m\nt$ on ! front ( ! lant]n & connect$ ) ! batt]y & a swit* s t ! light c be turn$ on & (f at w4 ,! swit* may be plac$ at ! top ( ! box s t ! f+]s ( ! same h& us$ to c>ry ! lant]n may be us$ to turn ! light on & (f4 ,! lant]n is fitt$ ) a lea!r /rap at ! top1 to be conv5i5t = c>ry+4 99,! ,ruby ,lant]n99 %[n 9 ,figure #bif is some:at simil> 9 arrangem5t to ! lant]n j describ$1 :i* may be us$ bo? z a h&-lant]n & a ruby light = develop+ photographs4 ,illu/ration3 ,fig4 #bif4--;,an ,electric ,ruby ,lant]n4 ,x consi/s ( a wood5 box to hold a ?ree-cell dry batt]y1 & is provid$ ) a h&le s t x may be easily c>ri$4 ,a swit* by :i* to turn ! lamp on & (f is m\nt$ on ! side ( ! box4 ,! light is furni%$ by a ?ree-&-"o-half-volt tung/5 lamp m\nt$ on ! front ( an incl9$ wood5 bo>d arrang$ z %[n 9 ! illu/ration s z to ?r[ ! light d[nw>d4 ,! sides & bottom ( ! box are groov$ ne> ! front edges s t a piece ( ruby glass may be ins]t$4 ,ruby glass = ?is purpose may be pur*as$ at almo/ any /ore deal+ 9 photograph]s' supplies4 ,! top is provid$ ) a %ield :i* is fa/5$ 9 position by means ( f\r small hooks aft] ! glass is 9 place4 ,! %ield is us$ 9 ord] to prev5t any :ite light f escap+ ?r\gh ! crack betwe5 ! glass & ! top ( ! box4 ,a ruby lamp ( ?is sort mu/ be made absolutely light-tight s t ! only light emitt$ is t :i* passes ?r\gh ! ruby glass4 ,if any :ite light escapes x is liable to fog & spoil any pictures 9 process ( developm5t4 ,illu/ration3 ,fig4 #big4--,! ,electric ,ruby ,lamp ) ,glass & ,%ield ,remov$4 ,by remov+ ! ruby glass & ! %ield1 z %[n 9 ,figure #big1 ! light is *ang$ into a h&-lant]n4 ,! back ( ! box %\ld be made removable s t ! batt]y c be replac$ :5 worn out4 99,a ,night-,light99 arrang$ to %9e on ! face ( ! clock s t ! "t may be easily told dur+ ! night )\t inconv5i5ce is %[n 9 ,figure #bih4 ,illu/ration3 ,fig4 #bih4--;,an ,electric ,night-,light = tell+ ! ,"t dur+ ! ,night4 ,x consi/s ( a flat wood5 box conta9+ a ?ree-cell dry batt]y & hav+ a small ?ree-&-"o-half-volt tung/5 lamp m\nt$ on ! top 9 ! front ) room = a clock to /& beh9d4 ,! batt]y & ! lamp are connect$ to a swit* s t ! light may be turn$ on & (f4 ,by atta*+ a long flexible wire & a pu%-button ( ! pe>-pu% type x is possible to place ! light on a table & run ! wire ) ! pu%-button atta*$ ov] to ! b$ s t "o may see ! "t dur+ ! night )\t gett+ up4 ,! bottom ( ! box %\ld be made removable s t a new batt]y may be ins]t$ :5 ! old "o is worn out4 99,! ,wat*-,light99 is 9 _m ways simil> to ! clock light j describ$--b is small]4 ,x consi/s ( a box j l>ge en\gh to receive a ?ree-cell fla%light batt]y4 ,a piece ( brass rod is b5t into ! =m ( a hook or crane f :i* to susp5d ! wat*4 ,illu/ration3 ,fig4 #bii4--;,a ,wat*-,light4 ,! light is suppli$ by a ?ree-&-"o-half-volt tung/5 fla%light bulb m\nt$ on ! top ( ! box 9 front ( ! wat*4 ,if desirable1 ! light may be fitt$ ) a small %ade or reflector s t x %9es only on ! dial & n 9 ! eyes4 ,! figures on ! face ( ! timepiece c !n be se5 mu* m pla9ly4 ,! lamp is m\nt$ 9 a small wood5 socket or a p9-socket pass+ ?r\gh a hole 9 ! top ( ! box1 s t ! wires are conceal$4 ,a small pu%-button is locat$ 9 "o ( ! =w>d corn]s ( ! box1 s t :5 x is press$ ! lamp w light4 ,two small b9d+-po/s m\nt$ at ! l[] "r-h& corn] ( ! box are connect$ directly across ! t]m9als ( ! swit*1 s t a flexible wire & a pu%-button c be connect$1 & ! light op]at$ f a di/ance4 99,an ,electric ,sc>f-,p999 c be made by almo/ any boy :o is skillful ) a pocket-knife4 ,! mat]ial f :i* ! p9 is made may be a piece ( bone1 ivory1 or me]s*aum4 ,x is c>v$ into %ape ) ! %>p po9t ( a p5knife & may be made to repres5t a skull1 dog's head1 an owl1 or "s o!r simple figure4 ,! inside is holl[$ out to receive a pea lamp4 ,pea lamps ) a cord & a plug atta*$ z %[n 9 ,figure #cjj may be pur*as$ f almo/ any electrical supply h\se4 ,! lamp is a m9iature c>bon bulb ab\t "o-eigh? ( an in* 9 diamet]4 ,! eyes1 nose1 & m\? ( ! figure are pi]c$ ) small holes1 s t :5 ! lamp is light$ ! light w %[ ?r\gh ! holes4 ,! figure %\ld be c>v$ d[n ?9 en\gh to be transluc5t & light up nicely4 ,illu/ration3 ,fig4 #cjj4--;,a ,pea ,lamp atta*$ to a ,flexible ,wire & a ,plug4 ,a l>ge p9 is cem5t$ or o!rwise fa/5$ to ! back ( ! figure s t x c be plac$ on ! necktie or ! lapel ( ! coat4 ,! lamp is remov$ f ! socket ( an electric fla%light & ! plug atta*$ to ! pea lamp screw$ into its place4 ,! pea lamp is ins]t$ inside ! figure & b\nd 9 place ) "s silk ?read4 ,!n :5 ! button is press$ on ! fla%light case1 ! p9 w light up & t9y beams ( light w %oot out f ! eyes1 nose1 & m\? ( ! figure4 ,illu/ration3 ,fig4 #cja4--;,f\r ,/eps 9 ,c>v+ a ,skull ,sc>f-,p94 #a4 ,! ,bone4 #b4 ,hole drill$ 9 ,base4 #c4 ,r\gh$ out4 #d4 ,f9i%$4 ,! draw+s 9 ,figure #cja %[ h[ to c>ve a skull sc>f-p94 ,x is made f a cyl9drical piece ( bone ab\t five-eigh?s ( an in* long & ?ree-eigh?s ( an in* 9 diamet]4 ,! fir/ op]ation is to drill a hole ?ree-eigh?s ( an in* deep into ! bottom4 ,! hole %\ld be l>ge en\gh 9 diamet] to pass ! pea lamp4 ,illu/ration3 ,fig4 #cjb4--,! ,complet$ ,p9 ready to be connect$ to a ,batt]y by remov+ ! ,lamp f a ,fla%light & screw+ ! ,plug into its ,place4 ,!n c>ve ! eyes & nose & tee?4 ,! draw+s w give a good idea ( ! /eps 9 ?is "p ( ! "w4 ,next r\nd (f ! top ( ! skull4 ,bore a small hole 9 ! back to receive ! p94 ,put ! light inside ( ! skull1 & aft] x is b\nd 9 position ! sc>f-p9 is f9i%$4 ,,*apt] ,,xx ,,miscellane\s ,,electrical ,,app>atus ,,h[ ,,electricity ,,may ,,be ,,g5]at$ ,,f ,,heat ,= ! pa/ c5tury !re has be5 on ! "p ( _m sci5ti/s & inv5tors a con/ant endeavor to h>ness ! sunlight4 ,! p[] :i* /reams d[n e day to our planet is incalculable4 ,! en]gy consum$ 9 ! sun & ?r[n (f 9 ! =m ( heat is s great t x makes any e>?ly ?+ seem inf9itesimal4 ,we c only feel ! heat f a l>ge fire a few feet away1 yet ! scor*+ summ] heat travels #ij1jjj1jjj miles be=e x rea*es u1 & ev5 !n our planet is receiv+ only ! smalle/ fractional "p ( ! total am\nt radiat$4 ,dr4 ,langley ( ! ,smi?sonian ,in/itute e/imat$ t all ! coal 9 ! ,/ate ( ,p5nsylvania w\ld be us$ by ! sun 9 a fraction ( a second if x 7 s5t up !re to supply en]gy4 ,p]haps1 "s day 9 ! future1 electric locomotives w haul _! /eel c>s swiftly f city to city by means ( electricity1 g5]at$ ) sun p[]4 ,p]haps en]gy f ! same s\rce w heat our dwell+s & furni% u light & p[]4 ,?is is n an idle dream1 b may "s day be an actuality4 ,x has already be5 c>ri$ out to "s ext5t4 ,a ,massa*usetts inv5tor has succe$$ 9 mak+ a device = g5]at+ electricity f sun en]gy4 ,! app>atus consi/s ( a l>ge frame1 9 appe>ance v mu* l a w9d[4 ,! glass panes are made ( violet glass1 beh9d :i* are _m hundr$ little metallic plugs4 ,! sun's heat1 imprison$ by ! violet glass1 acts on ! plugs to produce electricity4 ,"o ( ^! g5]ators expos$ to ! sun = t5 h\rs w *>ge a /orage batt]y & produce en\gh curr5t to run #cj l>ge tung/5 lamps = ?ree days4 ,illu/ration3 ,fig4 #cjc4--;,h[ ! ,copp] ,wires 7,c7 & ! ,silv] ,wires 7,i7 are twi/$ toge!r 9 ,pairs4 ,! pr9ciple ^u :i* ! app>atus works 0 discov]$ by a sci5ti/ nam$ ,seebeck1 9 #ahbb4 ,he succe$$ 9 produc+ a curr5t ( electricity by heat+ ! po9ts ( contact betwe5 two dissimil> metals4 ,any boy c make a simil> app>atus1 :i*1 :ile n giv+ en\gh curr5t = any practical purpose1 w s]ve z an exce$+ly int]e/+ & in/ructive exp]im5t4 ,cut =ty or fifty pieces ( ,no4 #af ,b4 ,s4 gauge ,g]man silv] wire into five-in* pieces4 ,cut an equal numb] ( simil> pieces ( copp] wire1 & twi/ ea* ,g]man silv] wire firmly toge!r ) "o ( copp] s z to =m a zig-zag arrangem5t z 9 ,figure #cjc4 ,illu/ration3 ,fig4 #cjd4--,wood5 ,r+4 ,next make two wood5 r+s ab\t f\r in*es 9 diamet] by cutt+ !m out ( a p9e bo>d4 ,place ! wires on "o ( ! r+s 9 ! mann] %[n 9 ,figure #cje4 ,place ! second r+ on top & clamp x d[n by means ( two or ?ree screws4 ,illu/ration3 ,fig4 #cje4--;,complete ,!rmopile4 ,an ,alcohol ,lamp %\ld be light$ & plac$ s t ! ,flame heats ! ,inside ,ends ( ! ,wires 9 ! ,c5t] ( ! ,wood5 ,r+4 ,! inn] junctures ( ! wires mu/ n t\* ea* o!r4 ,! out] ends %\ld be b5t out /raight & be spac$ equidi/antly4 ,! r+ %\ld be support$ by ?ree iron rods or legs4 ,! two t]m9als ( ! !rmopile z ! in/rum5t is call$1 %\ld be connect$ to b9d+-po/s4 ,place a small alcohol lamp or ,buns5 burn] 9 ! c5t]1 s t ! flame w play on ! inn] junctures ( ! wires4 ,a !rmopile ( ! size & type j describ$ w deliv] a consid]able am\nt ( electrical en]gy :5 ! inside t]m9als are good & hot & ! outside t]m9als fairly good4 ,! curr5t may be v easily detect$ by connect+ ! t]m9als to a telephone receiv] or galvanomet]4 ,by mak+ sev]al !rmopiles & connect+ !m 9 p>allel1 suffici5t curr5t c be obta9$ to light a small lamp4 ,,h[ ,,to ,,make ,a ,,reflectoscope ,a reflectoscope is a v simple =m ( a magic lant]n ) :i* x is possible to %[ pictures f po/-c>ds1 photographs1 etc4 ,! ord9>y magic lant]n requires a transp>5t lant]n slide1 b ! reflectoscope w make pictures f almo/ any?+4 ,! picture po/-c>ds or ! photographs t y h collect$ dur+ y\r vacation may be ?r[n on a scre5 & magnifi$ to ?ree or f\r feet 9 diamet]4 ,illu/rations clipp$ f a magaz9e or newspap] or an orig9al sket* or pa9t+ w likewise %[ j z well4 ,ev]y?+ is project$ 9 its actual colors4 ,if y put y\r wat* 9 ! back ( ! lant]n1 ) ! :eels & works expos$1 x w %[ all ! metallic colors & ! p>ts 9 motion4 ,illu/ration3 ,fig4 #cjf4--;,a ,reflectoscope4 ,! reflectoscope1 %[n 9 ,figure #cjf1 consi/s ( a rectangul> box n9e in*es long1 six in*es wide1 & six in*es high outside4 ,x may be built ( %eet-iron or t91 b is mo/ easily made f wood4 ,bo>ds ?ree-eigh?s ( an in* ?ick are heavy en\gh4 ,! me?ods ( mak+ an ord9>y box are too simple to ne$ description4 ,! box or case 9 ?is in/ance1 h[ev]1 mu/ be c>efully made & be light-tight1 t is1 z expla9$ be=e1 x mu/ n conta9 any cracks or small holes :i* w all[ light to escape if a lamp is plac$ inside4 ,a r\nd hole f two & "o-half to ?ree in*es 9 diamet] is cut 9 ! c5t] ( "o ( ! faces ( ! box4 ,! exact diamet] _c be giv5 "h because x w be det]m9$ by ! l5s :i* ! exp]im5t] is able to secure = 8 reflectoscope4 ,only "o l5s is requir$4 ,x mu/ be ( ! d\ble-convex v>iety1 & be f two & "o-half to ?ree in*es 9 diamet]4 ,a l5s is v easily secur$ f an old bicycle lant]n4 ,x %\ld be ( cle> glass4 ,illu/ration3 ,fig4 #cjg4--;,h[ ! ,l5s is ,arrang$ & ,m\nt$4 ,a tube1 six in*es long & ( ! prop] diamet] to fit tightly ar\nd ! l5s1 mu/ be made by roll+ up a piece ( %eet-t9 & sold]+ ! edges toge!r4 ,?is tube is ! "o label$ movable tube 9 ! illu/rations4 ,a second tube1 ?ree in*es long & ( ! prop] diamet] to j slip ov] ! fir/ tube1 mu/ also be made4 ,a flat r+ cut f /iff %eet-brass is sold]$ ar\nd ! outside ( ?is second tube1 s t x may be fa/5$ to ! front ( ! case by ?ree or f\r small screws 9 ! mann] %[n4 ,! hole 9 ! front ( ! box %\ld be only l>ge en\gh to receive ! tube4 ,! l5s is held 9 position ne> "o end ( ! movable tube by two /rong wire r+s4 ,^! r+s %\ld be made ( wire t is heavy & r spr+y1 s t !y w t5d to op5 aga9/ ! sides ( ! tube4 ,x is a good plan to sold] "o ( !m 9 position1 s t x _c move1 & !n put 9 ! l5s4 ,aft] ! l5s is 9 position1 ! second r+ %\ld be put 9 & pu%$ d[n aga9/ ! l5s4 ,d n attempt to put ! l5s 91 h[ev]1 until y are sure t ! metal has cool$ aga9 aft] sold]+1 or x w be liable to crack4 ,illu/ration3 ,fig4 #cjh4--;,a ,view ( ! ,reflectoscope f ! ,re>1 %[+ ! ,door1 etc4 ,! back ( ! box conta9s a small h+$ door ab\t f\r in*es high & five & "o-half in*es long4 ,! pictures t x is desir$ to project on ! scre5 are held aga9/ ?is door by two small brass clips1 z %[n 9 ,figure #cjh4 ,illu/ration3 ,fig4 #cji4--;,a ,view ( ! ,reflectoscope ) ! ,cov] remov$1 %[+ ! ,arrangem5t ( ! ,lamps1 etc4 ,! light = ! reflectoscope is mo/ conv5i5tly made by two #af-;c&le-p[] electric inc&esc5t lamps4 ,figure #cji %[s a view ( ! inside ( ! box ) ! cov] remov$1 look+ directly d[n4 ,! lamps fit into ord9>y flat-base porcela9 receptacles1 su* z t %[n 9 ,figure #caj4 ,two ( ^! receptacles are requir$1 "o = ea* lamp4 ,!y co/ ab\t t5 c5ts ea*4 ,illu/ration3 ,fig4 #caj4--;,a ,socket = hold+ ! ,lamp4 ,! reflectors are made ( t91 b5t z %[n 9 ,figure #caa4 ,!y are fa/5$ 9 position beh9d ! lamps by f\r small tabs4 ,x is possible to fit a reflectoscope ) gas or oil lamp to supply ! light1 b 9 t case ! box w h to be made mu* l>g]1 & provid$ ) *imneys to c>ry (f ! hot air4 ,! int]ior ( ! reflectoscope mu/ be pa9t$ a dead black by us+ a pa9t made by mix+ lampblack & turp5t9e4 ,! int]ior also includes ! inside ( ! t9 tubes4 ,! electric curr5t is l$ into ! lamps ) a piece ( flexible lamp-cord pass+ ?r\gh a small hole 9 ! case4 ,an atta*m5t-plug is fitt$ to ! o!r end ( ! cord1 s t x may be screw$ into any conv5i5t lamp-socket4 ,illu/ration3 ,fig4 #caa4--,! ,t9 ,reflector4 ,! pictures %\ld be %[n 9 a d>k room & project$ on a smoo? :ite %eet4 ,!y are plac$ "u ! spr+ clips on ! little door & ! door clos$4 ,! movable tube is !n slid back & =? until ! picture on ! scre5 becomes cle> & di/9ct4 ,! lant]n may be improv$ consid]ably by us+ tung/5 lamps ( #bb c4 p4 ea* 9 place ( ord9>y c4 p4 c>bon filam5t lamps4 ,if f\r small feet1 "o at ea* corn]1 are atta*$ to ! bottom ( ! case1 its appe>ance w be mu* improv$4 ,v l>ge pictures w t5d to appe> a little blurr$ at ! corn]s4 ,?is is due to ! l5s & _c be easily rem$i$4 ,,h[ ,,to ,,r$uce ,,! #aaj-v4 ,,curr5t ,,s ,,t ,,x ,,may ,,be ,,us$ ,,= ,,exp]im5t+ ,(t5times x is desirable to op]ate small electrical devices f ! #aaj-v4 light+ or p[] circuits4 ,alt]nat+ curr5t c be r$uc$ to ! prop] voltage by means ( a small /ep-d[n trans=m]1 su* z t describ$ 9 ,*apt] ,,xiii4 ,direct curr5t may be r$uc$ by means ( a resi/ance4 ,! mo/ suitable =m ( resi/ance = ! "y exp]im5t] to use is a lamp bank4 ,a lamp bank consi/s ( a numb] ( lamps connect$ 9 p>allel1 & arrang$ s t any device may be connect$ 9 s]ies ) x4 ,! lamps are set 9 sockets ( ! type kn[n z flat-base porcela9 receptacles1 su* z t %[n 9 ,figure #caj1 m\nt$ 9 a r[ ^u a bo>d & connect$ z %[n 9 ,fig4 #cab4 ,! curr5t f ! p[] l9e ent]s ?r\gh a swit* & a fuse & !n passes ?r\gh ! lamps be=e x rea*es ! device x is desir$ to op]ate4 ,! swit* is = ! purpose ( %utt+ ! curr5t on & (f1 :ile ! fuse w bl[ 9 case too mu* curr5t fl[s 9 ! circuit4 ,! am\nt ( curr5t t passes ?r\gh ! circuit may be accurately controll$ by ! size & numb] ( lamps us$ 9 ! bank4 ,! lamps may be screw$ 9 or out & ! curr5t alt]$ by "o-qu>t] ( an amp]e at a "t if desirable4 ,! lamps %\ld be ( ! same voltage z ! l9e ^u :i* !y are to be us$4 ,ea* #h-;c&le-p[]1 #aaj-v4 c>bon lamp us$ w p]mit "o-qu>t] ( an amp]e to pass4 ,ea* #af-;c&le-p[]1 #aaj-v4 lamp w pass approximately "o-half an amp]e4 ,a #cb-;c&le-p[] lamp ( ! same voltage w p]mit "o amp]e to fl[ 9 ! circuit4 ,illu/ration3 ,fig #cab4--,top ,view ( ,lamp ,bank1 %[+ h[ ! ,circuit is arrang$4 ,a & ,b are ! ,po/s to :i* %\ld be connect$ any ,device x#8s desirable to op]ate4 ,,an ,,induction ,,motor 99,an ,induction ,motor99 is a motor 9 :i* ! curr5ts 9 ! armature w9d+s are induc$4 ,an induction motor runs )\t any bru%es1 & ! curr5t f ! p[] l9e is connect$ only to ! field4 ,! field might be lik5$ to ! prim>y ( a trans=m]4 ,! curr5ts 9 ! armature !n con/itute a second>y w9d+ 9 :i* curr5ts are induc$ 9 ! same mann] z 9 a trans=m]4 ,an induction motor w op]ate only on alt]nat+ curr5t4 ,a small motor su* z t %[n 9 ,figure #bfg1 & hav+ a ?ree-pole armature1 is ! be/ type to use 9 mak+ an exp]im5tal induction motor4 ,remove ! bru%es f ! motor & b9d a piece ( b>e copp] wire ar\nd ! commutator s t x %ort-circuits ! segm5ts4 ,a s\rce ( alt]nat+ curr5t %\ld !n be connect$ to ! t]m9als ( ! field coil4 ,if y h a /ep-d[n trans=m]1 use x = ?is purpose1 b o!rwise connect x 9 s]ies ) a lamp bank su* z t j describ$4 ,place a swit* 9 ! circuit s t ! curr5t may be turn$ on & (f4 ,w9d a /r+ ar\nd ! end ( ! armature %aft s t x may be revolv$ at high spe$ by pull+ ! /r+ 9 some:at ! same mann] t y w\ld sp9 a top4 ,:5 all is ready1 give ! /r+ a %>p pull & imm$iately close ! swit* s t ! alt]nat+ curr5t fl[s into ! field4 ,if ?is is done prop]ly1 ! motor w cont9ue to run at high spe$1 & furni% p[] if desirable4 ,mo/ ( ! alt]nat+-curr5t motors 9 e-day use = furni%+ p[] = v>i\s purposes are induction motors4 ,!y are1 h[ev]1 self-/>t+1 & provid$ ) a holl[ armature1 :i* conta9s a c5trifugal gov]nor4 ,:5 ! motor is at re/ or j />t+1 f\r bru%es press aga9/ ! commutator & divide ! armature coils into f\r gr\ps4 ,aft] ! motor has atta9$ ! prop] spe$1 ! gov]nor is ?r[n out by c5trifugal =ce & pu%es ! bru%es away f ! commutator1 %ort-circuit+ all ! sections & mak+ ea* coil a complete circuit ( itself4 ,,electro-,,plat+ ,wat] conta9+ *emicals su* z sulphate ( copp]1 sulphuric acid1 nitrate ( nickel1 nitrate ( silv]1 or o!r metallic salts is a good conductor ( electricity4 ,su* a liquid is kn[n z an electrolyte4 ,x has be5 expla9$ 9 ,*apt] ,,iv t *emical action may be us$ to produce electricity & t 9 ! case ( a cell su* z t inv5t$ by ,volta1 ! z9c electrode gradually wa/es away & f9ally ent]s into solution 9 ! sulphuric acid4 ,x is possible exactly to rev]se ?is action & to produce :at is kn[n z electrolysis4 ,if an electrolyte 9 :i* a metal has be5 dissolv$ is prop]ly arrang$ s t a curr5t ( electricity may be pass$ ?r\gh ! solution1 ! metal w plate out1 or appe> aga9 ^u "o ( ! electrodes4 ,electrolysis makes possible electro-plat+ & ?\s&s ( o!r exce$+ly valuable & int]e/+ *emical processes4 ,m ?an "o-half ( all ! copp] produc$ 9 ! _w is produc$ electrolytically4 ,practically all plat+ ) gold1 silv]1 copp] & nickel is accompli%$ ) ! aid ( electricity4 ,^! op]ations are c>ri$ out on a v l>ge scale 9 ! v>i\s factories1 b x is possible to reproduce !m 9 any boy's work%op or laboratory1 ) v simple equipm5t4 ,! prop] *emicals1 a tank1 & a batt]y are ! only app>atus requir$4 ,! curr5t mu/ be suppli$ by /orage cells or a bi*romate batt]y because ! "w w require five or six amp]es = q a long p]iod4 ,a small rectangul> glass j> w make a fir/ class tank to hold ! electrolyte4 ,! simple/ electro-plat+ process1 & ! "o t ! exp]im5t] %\ld />t ) is copp]-plat+4 ,fill ! tank ?ree-qu>t]s full ( pure wat] & !n drop 9 "s cry/als ( copp]-sulphate until ! liquid has a deep blue color & w dissolve no m4 ,obta9 two copp] rods & lay !m across ! tank4 ,cut two pieces ( %eet copp] hav+ a tongue at ea* ( two corn]s s t !y c be hung 9 ! solution1 z %[n 9 ,figure #cac4 ,hang bo? ( ! %eets f "o ( ! copp] rods4 ,connect ?is rod to ! positive pole ( ! batt]y4 ,^! %eets are kn[n z ! anodes4 ,!n if a piece ( c>bon1 or "s metallic object is hung f ! o!r rod & connect$ to ! negative pole ( ! batt]y1 ! electro-plat+ w comm5ce4 ,! app>atus %\ld be all[$ to run = ab\t half an h\r & !n ! object hung f ! rod connect$ to ! negative pole ( ! batt]y %\ld be lift$ out & exam9$4 ,x w be f\nd ?ickly coat$ ) copp]4 ,x is absolutely necess>y to h ! poles ( ! batt]y connect$ 9 ! mann] /at$1 or no deposit ( copp] w take place4 ,objects :i* are to be electro-plat$ mu/ be free f all traces ( oil or grease & absolutely clean 9 e respect1 or ! plat+ w n be uni=m1 because x w n /ick to dirty spots4 ,illu/ration3 ,fig4 #cac4--;,a ,glass ,j> arrang$ to s]ve z an ,electro-,plat+ ,tank4 ,su* articles z keys1 key-r+s1 tools1 etc41 c be prev5t$ f ru/+ by coat+ ) nickel4 ,nickel-plat+ is v simil> to copp]-plat+4 ,in/ead1 h[ev]1 ( hav+ two copp] %eets susp5d$ f ! rod connect$ to ! positive pole ( ! batt]y1 !y mu/ be made ( nickel4 ,! electrolyte is compos$ ( "o "p ( nickel-sulphate dissolv$ 9 tw5ty p>ts ( wat] to :i* "o "p ( sodium-bisulphate is add$4 ,?is mixture is plac$ 9 ! tank in/ead ( ! copp]-sulphate4 ,! objects to be plat$ are hung f ! copp] rod connect$ to ! negative pole ( ! batt]y4 ,:5 ! nickel-plat$ articles are remov$ f ! ba? !y w h a dull1 :ite color kn[n z :ite nickel4 ,:5 :ite nickel is poli%$ ) a clo? :eel revolv+ at high spe$1 & kn[n z a buff+-:eel1 x w assume a high lu/]4 ,,h[ ,,to ,,make ,a ,,rheo/at ,x is (t5 desirable to regulate ! am\nt ( curr5t pass+ ?r\gh a small lamp1 motor1 or o!r electrical device op]at$ by a batt]y4 ,?is is accompli%$ by ins]t+ resi/ance into ! circuit4 ,a rheo/at is an arrangem5t = quickly alt]+ ! am\nt ( resi/ance at w4 ,a simple rheo/at is easily made by fitt+ a five-po9t swit* su* z t %[n 9 ,figure #ie ) sev]al coils ( ,g]man-silv] resi/ance wire4 ,g]man silv] has mu* m resi/ance ?an copp] wire1 & is us$1 !re=e1 because less w be requir$1 & x w occupy a small] space4 ,a five-po9t swit* w s]ve satisfactorily 9 mak+ a rheo/at1 b if a f9] graduation ( ! resi/ance is desir$ x w be necess>y to use "o hav+ m po9ts4 ,two l9es ( small wire nails are driv5 ar\nd ! outside ( ! po9ts1 & a ,g]man-silv] wire ( ,no4 #bd ,b4 ,s4 gauge w\nd 9 zig-zag fa%ion ar\nd ! nails f "o po9t to ! o!r4 ,illu/ration3 ,fig4 #cad4--;,a ,rheo/at4 ,! rheo/at is plac$ 9 s]ies ) any device x is desirable to control4 ,:5 ! h&le is on ! po9t to ! extreme left1 ! rheo/at (f]s no resi/ance to ! curr5t4 ,:5 ! lev] is plac$ on ! second po9t1 ! curr5t has to trav]se ! fir/ section ( ! ,g]man-silv] wire & w be appreciably affect$4 ,mov+ ! h&le to ! "r w increase ! resi/ance4 ,if ! rheo/at is connect$ to a motor1 ! spe$ c be increas$ or decreas$ by mov+ ! lev] back & =?4 ,9 ! same mann]1 ! light f a small inc&esc5t lamp may be dimm$ or increas$4 ,a ,,curr5t ,,rev]s] ,,or ,,pole-,,*ang+ ,,swit* ,a pole-*ang+ or curr5t rev]s+ swit* is useful to ! exp]im5t]4 ,= example1 if connect$ to a small motor1 ! motor c be made to run 9 ei!r direction at w4 ,a motor ) a p]man5t magnet field c be rev]s$ by m]ely *ang+ ! wires f ! batt]y s t ! curr5t fl[s ?r\gh ! circuit 9 ! opposite direction4 ,if ! motor is provid$ ) a field w9d+1 h[ev]1 ! only way t x c be made to run ei!r way is by rev]s+ ! field4 ,?is is be/ accompli%$ ) a pole-*ang+ swit*4 ,su* a swit* may be made by foll[+ ! same g5]al me?od ( con/ruction z t outl9$ on pages #ajg & #ajh1 b mak+ x accord+ to ! design %[n 9 ,figure #cae4 ,motors su* z ^? illu/rat$ c be made to rev]se by connect+ to a pole-*ang+ swit* 9 ! prop] mann]4 ,! two outside po9ts or contacts 7m>k$ ,d & ,d7 %\ld bo? be connect$ to "o ( ! bru%es on ! motor4 ,! middle contact1 ,c1 is connect$ to ! o!r bru%4 ,"o t]m9al ( ! field is connect$ to ! batt]y4 ,! o!r t]m9al ( ! field is connect$ to ! lev]1 ,a4 ,b connects to ! o!r t]m9al ( ! batt]y4 ,illu/ration3 ,fig4 #cae4--;,a ,pole-,*ang+ ,swit* or ,curr5t ,rev]s]4 ,! ,connect+ ,/rip is pivot$ s t ! ,h&le w op]ate bo? ! ,lev]s1 ,a & ,b4 ,:5 ! swit* h&le is pu%$ to ! left1 ! lev] ,a %\ld re/ on ! left-h& contact1 ,d4 ,! lev] ,b %\ld make contact ) ,c4 ,! motor w !n run 9 "o direction4 ,if ! h&le is pu%$ to ! "r s t ! lev]s ,a & ,b make contact respectively ) ,c & ,d 7"r-h&71 ! motor w rev]se & run 9 ! opposite direction4 ,a ,,complete ,,wireless ,,receiv+ ,,set ,_m exp]im5t]s may wi% to build a wireless receiv+ set :i* is p]man5tly connect$ & 9 :i* ! in/rum5ts are s m\nt$ t !y are readily portable & may be easily %ift$ f "o place to ano!r )\t hav+ to di/urb a numb] ( wires4 ,! receiv+ set %[n 9 ,figure #caf is made up ( "s ( ! sep>ate in/rum5ts describ$ 9 ,*apt] ,,xiv1 & illu/rates ! g5]al plan :i* may be foll[$ 9 arrang+ an outfit 9 ?is mann]4 ,illu/ration3 ,,complete ,,receiv+ ,,set1 ,,consi/+ ,,( ,,d\ble ,,slid] ,,tun+ ,,coil1 ,,detector ,,& ,,fix$ ,,cond5s]4 ,illu/ration3 ,,complete ,,receiv+ ,,set1 ,,consi/+ ,,( ,a ,,loose ,,c\pl] ,,9 ,,place ,,( ,,! ,,tun+ ,,coil1 ,,detector ,,& ,,fix$ ,,cond5s]4 ,! base is ( wood1 & is n9e in*es long1 sev5 in*es wide1 & "o-half ( an in* ?ick4 ,a d\ble-slid] tun+ coil1 simil> to t %[n 9 ,figure #bjc1 is fa/5$ to ! back "p ( ! base by two small wood-screws pass+ upw>ds ?r\gh ! base into ! tun] heads4 ,illu/ration3 ,fig4 #caf4 ,a ,complete ,wireless ,receiv+ ,outfit4 ,! fix$ cond5s] is enclos$ 9 a rectangul> wood5 block :i* is holl[$ out und]nea? to receive x & !n screw$ d[n to ! base 9 ! =w>d "r-h& corn]4 ,! detector is m\nt$ 9 ! =w>d left-h& "p ( ! base1 & 9 ! illu/ration is %[n z be+ simil> to t 9 ,figure #baj4 ,any type ( detector may1 h[ev]1 be sub/itut$4 ,! tun+ coil may be replac$ by a loose c\pl] if desirable1 b 9 t case ! base w h to be made l>g]4 ,! telephone receiv]s are connect$ to two b9d+-po/s m\nt$ alongside ! detector4 ,! circuit %[n 9 ,figure #bah is ! "o :i* %\ld be foll[$ 9 wir+ ! set4 ,! wires :i* connect ! v>i\s in/rum5ts %\ld be pass$ ?r\gh holes & along ! "u side ( ! base s t !y are conceal$4 ,,h[ ,,to ,,build ,a ,,tesla ,,high-,,frequ5cy ,,coil ,a ,tesla high-frequ5cy coil or trans=m] op5s a field ( wond]ful possibilities = ! amateur exp]im5t]4 ,innum]able weird & fasc9at+ exp]im5ts c be p]=m$ ) its aid4 ,:5 a ,leyd5 j> or a cond5s] dis*>ges ?r\gh a coil ( wire1 ! sp>k :i* c be se5 does n consi/ simply ( a s+le sp>k pass+ 9 "o direction1 z x appe>s to ! eye1 b 9 reality is a numb] ( sep>ate sp>ks alt]nately pass+ 9 opposite directions4 ,!y move s rapidly t ! eye is unable to di/+ui% !m4 ,! "t dur+ :i* ! sp>k appe>s to pass may only be a fraction ( a second1 b dur+ t %ort p]iod ! curr5t may h oscillat$ back & =? sev]al ?\s& times4 ,if ! dis*>ge f su* a ,leyd5 j> or a cond5s] is pass$ ?r\gh a coil ( wire act+ z a prim>y1 & ! prim>y is provid$ ) a second>y coil conta9+ a l>g] numb] ( turns1 ! second>y w produce a peculi> curr5t kn[n z high-frequ5cy electricity4 ,high-frequ5cy curr5ts rev]se _! direction ( fl[ or alt]nate f "o hundr$ ?\s& to "o million times a second4 ,illu/ration3 ,fig4 #cag4--;,illu/rat+ ! ,pr9ciple ( ! ,tesla ,coil4 ,a ,leyd5 ,j> dis*>ges ?r\gh ! ,prim>y ,coil & a ,high-,frequ5cy ,sp>k is produc$ at ! ,second>y4 ,high-frequ5cy curr5ts possess _m curi\s prop]ties4 ,!y travel only on ! surface ( wires & conductors4 ,a holl[ tube is j z good a conductor = high-frequ5cy curr5ts z a solid rod ( ! same diamet]4 ,high-frequ5cy curr5ts d n produce a %ock4 ,if y hold a piece ( metal 9 y\r h& y c take ! %ock f a high-frequ5cy coil ?r[+ a sp>k two or ?ree feet long ) sc>cely any s5sation save t ( a slight w>m?4 ,! ,tesla coil describ$ bel[ is ( a size be/ adapt$ = use ) a two-in* or ?ree-in* sp>k coil1 or a small high-pot5tial wireless trans=m]4 ,! purpose ( ! sp>k coil or ! trans=m] is to *>ge ! ,leyd5 j>s or cond5s] :i* dis*>ge ?r\gh ! prim>y ( ! ,tesla coil4 ,illu/ration3 ,fig4 #cah4--;,details ( ! ,wood5 ,r+s us$ z ! ,prim>y ,heads4 ,if ! "y exp]im5t] wi%es to make a ,tesla coil :i* w be suit$ to a small] sp>k coil1 = in/ance1 "o capable ( giv+ a "o-in* sp>k1 ! dim5sions ( ! ,tesla coil h]e9 describ$ c be cut exactly 9 half4 ,in/ead ( mak+ ! second>y twelve in*es long & ?ree in*es 9 diamet]1 make x six in*es long & "o & "o-half in*es 9 diamet]1 etc4 99,! ,prim>y99 consi/s ( eight turns ( ,no4 #aj ,b4 ,s4 gauge copp] wire w\nd ar\nd a drum4 ,! heads ( ! drum are wood5 r+s1 sev5 in*es 9 diamet] & "o-half in* ?ick4 ,a circul> hole f\r & "o-half in*es 9 diamet] is cut 9 ! c5t] ( ea* ( ! heads4 ,illu/ration3 ,fig4 #cai4--;,details ( ! ,cross ,b>s :i* support ! ,prim>y ,w9d+4 ,! cross b>s are two & "o-half in*es long1 ?ree-qu>t]s ( an in* ?ick & "o-half ( an in* wide4 ,six cross b>s are requir$4 ,!y are spac$ at equal di/ances ar\nd ! r+s & fa/5$ by means ( a brass screw pass+ ?r\gh ! r+4 ,:5 ! drum is complet$ x %\ld resemble a squirrel cage4 ,small grooves are cut 9 ! cross b>s to accommodate ! wire4 ,! wires %\ld pass ar\nd ! drum 9 ! =m ( a spiral & be spac$ ab\t five-sixte5?s ( an in* ap>t4 ,! ends ( ! wire %\ld be fa/5$ to b9d+-po/s m\nt$ on ! heads4 99,! ,second>y99 is a s+le lay] ( ,no4 #bf ,b4 ,s4 silk- or cotton-cov]$ wire w\nd ov] a c>dbo>d tube1 twelve in*es long & ?ree in*es 9 diamet]4 ,! tube %\ld be dri$ 9 an ov5 & !n giv5 a ?ick coat ( %ellac1 bo? inside & out1 be=e x is us$4 ,?is treatm5t w prev5t x f %r9kage & avoid ! possibility ( hav+ to rew9d ! tube 9 case ! wire %\ld become loose4 ,illu/ration3 ,fig4 #cbj4--,! ,second>y ,head4 ,! second>y is fitt$ ) two circul> wood5 heads j l>ge en\gh to fit tightly into ! tube1 hav+ a half-in* flange1 & an outside diamet] ( ?ree & sev5-eigh?s in*es4 99,! ,base99 ( ! coil is fifte5 in*es long & six in*es wide & is made ( wood4 ,! coil is assembl$ by plac+ ! prim>y across ! base & exactly 9 ! c5t]4 ,two long wood-screws pass+ ?r\gh ! base & into ! prim>y heads w hold x firmly 9 position4 ,! second>y is pass$ ?r\gh ! c5t] ( ! prim>y & support$ 9 t position by two h>d rubb] supports1 f\r in*es high1 sev5-eigh?s ( an in* wide & "o-half ( an in* ?ick4 ,a brass wood-screw is pass$ ?r\gh ! top "p ( ea* ( ! supports into ! second>y heads s t a l9e drawn ?r\gh ! axis ( ! second>y w co9cide ) a simil> l9e drawn ?r\gh ! axis ( ! prim>y4 ,illu/ration3 ,a ,,complete ,,coh]] ,,outfit ,,z ,,describ$ ,,on ,,page #bgd4 ,illu/ration3 ,,! ,,tesla ,,high ,,frequ5cy ,,coil4 ,! supports are made ( h>d rubb] in/ead ( wood1 because ! rubb] has a great] insulat+ value ?an ! wood4 ,high-frequ5cy curr5ts are v h>d to insulate1 & wood does n usually (f] suffici5t insulation4 ,a brass rod1 five in*es long & hav+ a small brass ball at "o end1 is m\nt$ on ! top ( ea* ( ! h>d-rubb] supports4 ,! ends ( ! second>y w9d+ are connect$ to ! brass rods4 ,illu/ration3 ,fig4 #cba4--;,end ,view ( ! ,complete ,tesla ,coil4 ,! l[] end ( ea* ( ! h>d-rubb] supports is fa/5$ to ! base by means ( a screw pass+ ?r\gh ! base into ! support4 ,9 ord] to op]ate ! ,tesla coil1 ! prim>y %\ld be connect$ 9 s]ies ) a cond5s] & a sp>k-gap z %[n 9 ,figure #cbd4 ,! cond5s] may consi/ ( a numb] ( ,leyd5 j>s or ( sev]al glass plates coat$ ) t9foil4 ,x is impossible to det]m9e ! numb] requir$ ahead ( "t1 because ! l5g? ( ! connect+ wires1 ! sp>k-gap1 etc41 w h consid]able influ5ce ^u ! am\nt ( cond5s] requir$4 ,! cond5s] is connect$ directly across ! second>y t]m9als ( ! sp>k coil4 ,:5 ! sp>k coil is connect$ to a batt]y & set into op]ation1 a snappy1 :ite sp>k %\ld jump across ! sp>k-gap4 ,if ! h& is br\ght close to "o ( ! second>y t]m9als ( ! ,tesla coil1 a small r$di%-purple sp>k w jump out to meet ! f+]4 ,illu/ration3 ,fig4 #cbb4--,! ,complete ,tesla ,coil4 ,adju/+ ! sp>k-gap by *ang+ its l5g? & also alt]+ ! numb] ( ,leyd5 j>s ( cond5s] plates w probably increase ! l5g? ( ! high-frequ5cy sp>k4 ,x may be possible also to l5g!n ! sp>k by disconnect+ "o ( ! wires f ! prim>y b9d+-po/s on ! ,tesla coil & connect+ ! wire directly to "o ( any "o ( ! turns =m+ ! prim>y4 ,9 ?is way ! numb] ( turns 9 ! prim>y is *ang$ & ! circuit is tun$ 9 ! same way t wireless app>atus is tun$ by *ang+ ! numb] ( turns 9 ! tun+ coil or helix4 ,illu/ration3 ,fig #cbc4--,%[+ h[ a ,glass-,plate ,cond5s] is built up ( ,alt]nate ,%eets ( ,t9foil & ,glass4 ,! weird beauty ( a ,tesla coil is only evid5t :5 x is op]at$ 9 ! d>k4 ,! two wires lead+ f ! second>y to ! brass rods & ! ball on ! ends ( ! rods w give =? a peculi> bru% dis*>ge4 ,if y take a piece ( metal 9 y\r h& & hold x ne> "o ( ! second>y t]m9als1 ! bru%+ w increase4 ,if y hold y\r h& ne> en\gh1 a sp>k w jump on to ! metal & into y\r body )\t y\r feel+ ! slighte/ s5sation4 ,if "o ( ! second>y t]m9als ( ! ,tesla coil is gr\nd$ by means ( a wire connect+ x to ! prim>y1 ! bru%+ at ! o!r t]m9al w increase consid]ably4 ,make two r+s out ( copp] wire4 ,"o ( !m %\ld be six in*es 9 diamet] & ! o!r "o f\r in*es 9 diamet]4 ,place ! small r+ inside ! l>ge "o & connect !m to ! second>y t]m9als4 ,! two circles %\ld be arrang$ s z to be conc5tric1 t is1 s t !y h a common c5t]4 ,! space betwe5 ! two coils w be fill$ ) a pretty bru% dis*>ge :5 ! coil is 9 op]ation4 ,illu/ration3 ,fig4 #cbd4--;,a ,diagram %[+ ! ,prop] ,me?od ( ,connect+ a ,tesla ,coil4 ,!re are s _m o!r exp]im5ts :i* may be p]=m$ ) a ,tesla coil t x is impossible ev5 to ?9k ( describ+ !m "h1 & ! "y exp]im5t] wi%+ to cont9ue ! "w fur!r is advis$ to g to "s libr>y & consult ! works ( ,nikola ,tesla1 :]e9 su* exp]im5ts are fully expla9$4 ,,conclusion ,unless ! av]age boy has mat]ially *ang$ 8 habits1 9 rec5t ye>s1 x matt]s n :at ! preface ( a book may conta91 = x w be unc]emoni\sly skipp$ ) h>dly m ?an a pass+ glance4 ,) ?is 9 m9d1 ! au?or has tri$ to /eal a m>* on y1 & in/ead ( writ+ a long] preface1 & includ+ "s mat]ial :i* might prop]ly belong 9 t place1 has add$ x "h 9 ! nature ( a conclusion1 ?9k+ t y w\ld be m likely to read x la/ ?an fir/4 ,"s "t ago1 :5 9 se>* = some?+ t might be describ$ 9 ?is book1 ,i ?\ght ( "s old boxes into :i* my ?+s _h be5 pack$ :5 ,i _h dismantl$ my work%op be=e go+ away to college4 ,!y _h be5 undi/urb$ = a numb] ( ye>s & ,i _h almo/ =gott5 :]e !y _h be5 put4 ,at la/ a l>ge box 0 une>!d f among/ a lot ( du/y furniture put away 9 ! attic4 ,i pri$ ! cov] (f & took ! ?+s out "o by "o & laid !m on ! floor4 ,"h 7 galvanomet]s1 microphones1 swit*es1 telegraph keys1 s\nd]s1 relays1 & o!r ?+s too num]\s to m5tion4 ,!y _h all be5 con/ruct$ s long ago t ,i 0 consid]ably amus$ & int]e/$ 9 ! mann] 9 :i* bolts1 screws1 pieces ( curta9 rod1 %eet-iron1 brass1 & o!r ?+s _h be5 tak5 to =m v>i\s p>ts ( ! in/rum5ts4 ,! b9d+-po/s _h almo/ 9 e case se5 s]vice z su* on dry cells be=e !y came into my h&s4 ,! only p>ts t x _h be5 necess>y to buy 7 a few r\nd-head$ brass screws & ! wire :i* =m$ ! magnets4 ,9 sev]al in/ances1 ! latt] 7 made s t !y might be easily remov$ & m\nt$ ^u ano!r in/rum5t4 ,! magnets on ! telegraph s\nd] c\ld be remov$ & fitt$ to =m "p ( an electric eng9e or motor4 ,"o p>ticul> ?+ :i* /ruck me v =cibly 0 ! lack ( f9i% & ! crud5ess :i* mo/ ( ! in/rum5ts %[$4 ,( c\rse x 0 impossible to avoid ! clumsy appe>ance :i* ! metal p>ts possess$1 s9ce !y 7 n orig9ally made = ! "p t !y 7 play+1 b ,i wi%$ t ,i _h tak5 a little m c>e to true up ?+s prop]ly or to smoo? & v>ni% ! wood1 or t ,i _h remov$ ! tool-m>ks & d5ts f ! metal "w by a little fil+4 ,if ,i _h done s1 ,i %\ld n[ be di/9ctly pr\d ( my "w4 ,t is n to say t ,i am 9 ! lea/ a%am$ ( x1 = my old traps c]ta9ly s]v$ _! purpose well1 ev5 if !y 7 n ornam5tal & 7 bett] back 9 _! box4 ,p]haps ,i might be excus$ = fail+ 9 ?is "p ( ! "w ?r\gh lack ( prop] tools1 & also because at t "t !re 7 no magaz9es or books publi%$ :i* expla9$ h[ to d su* ?+s1 & :5 ,i built my fir/ tun+ coils & detectors no?+ on t subject _h ev] be5 publi%$4 ,i _h to "w out su* problems = myself1 & gave m ?\ght to ! pr9ciples ^u :i* ! in/rum5ts op]at$ ?an to _! actual con/ruction4 ,! boys :o read ?is book h ! advantage ( in/ructions %[+ h[ to build app>atus t has actually be5 built & te/$4 ,y "k :at size ( wire to use & w n h to f9d x out = y\rself4 ,= t reason y ought to be able to give m "t to ! con/ruction ( su* ?+s4 ,! purpose ( ?is conclusion is simply a plea = bett] "w4 ,! ,am]ican boy is usually c>eless 9 ?is reg>d4 ,he (t5 comm5ces to build some?+ & !n1 gr[+ tir$ be=e x is f9i%$1 lays x aside only to =get x & und]take some?+ else4 ,f9i% :atev] y und]take4 ,! pr9ciple is a good "o4 ,rememb] also t c>e ) ! little details is :at insures success 9 ! :ole4 ,if 9 c>ry+ out y\r "w1 y get an idea1 d n hesitate to try x4 ,a good idea nev] refus$ to be develop$4 ,x is n necess>y to /ick absolutely to ! directions t ,i h giv54 ,!y w insure success if foll[$1 b if y ?9k y c make an improvem5t1 d s4 ,( c\rse1 su* a book z ?is _c1 9 ! nature ( ?+s1 be exhau/ive1 nor is x desirable1 9 "o s5se1 t x %\ld be4 ,i h tri$ to write a book :i*1 consid]$ z a :ole1 w\ld prove to be exhau/ive only 9 t x treats ( almo/ e phase ( practical electricity4 ,! pr9ciple 9 m9d has be5 to produce a "w :i* w\ld /imulate ! inv5tive faculties 9 boys1 & to guide !m until face to face ) ^? practical em]g5cies 9 :i* no book c be ( any assi/ance b :i* mu/ be ov]come by common s5se & ! ex]cise ( p]sonal +5uity4 ,! book is n z free f te*nical t]ms or phrases1 z x lay 9 my p[] to make x1 because c]ta9 ( ^? t]ms h a value & an e-day use :i* are a b5efit to ! "y exp]im5t] :o und]/&s !m4 ,any "o subject treat$ 9 ! v>i\s *apt]s ( ! ,boy ,electrician may be develop$ f> beyond t po9t to :i* ,i h tak5 x4 ,! railroad sy/em c\ld be fitt$ ) electric signals1 drawbridges1 & a numb] ( o!r devices4 ,_m new ideas sugge/ !mselves to ! ready-witt$ ,am]ican boy4 ,i %all always be pleas$ to he> f any boy :o builds any ( ! app>atus ,i h describ$1 &1 if possible1 to receive photographs ( ! "w4 ,i %\ld be glad to be ( any assi/ance to su* a lad1 b rememb] t "s ( ! draw+s & text 9 ?is book requir$ _m h\rs ev5 to complete a small portion1 & !re=e please d n write to ask h[ to build o!r app>atus n describ$ h]e94 ,&1 z ! future ye>s br+ new inv5tions & discov]ies1 no "o n[ kn[s b t1 "s day1 p]haps ,i w write ano!r ,boy ,electrician4 ,,! ,,end4