,?is file 0 produc$ f page images at ! ,int]net ,ar*ive4 ,transcrib]'s ,note ,?is book 0 transcrib$ f scans ( ! orig9al f\nd at ! ,int]net ,ar*ive4 ,i h includ$ ! ads = o!r books f\nd 9 ! back pages ( ^! scans4 ,,lessons ,,9 ,,wireless ,,telegraphy ,a ,,sy/ematic ,,elem5t>y ,,c\rse ,,9 ,,! ,,pr9ciples ,,( ,,wireless ,,telegraphy ,,& ,,! ,,electrical ,,laws ,,^u ,,:i* ,,x ,,dep5ds ,,by 99,a4 ,p4 ,morgan99 ,,?ird ,,edition1 ,revis$ & ,enl>g$ ,,publi%$ ,,by ,,cole ,,morgan ,publi%]s ( ,! ,arts & ,sci5ces ,s]ies ,p4 ,o4 ,box #adgc ,,new ,,york ,,city ,pr9t$ 9 ,u4,s4 ,a4 ,,copyright #aiab4 #aiag ,,by ,,cole ,,morgan ,,lessons ,,9 ,,wireless ,,telegraphy ,,introduction ,?is little book has be5 br\ght =w>d 9 ord] to supply ! dem& = a sy/ematic elem5t>y c\rse 9 ! pr9ciples ( wireless telegraph app>atus & ! electrical laws ^u :i* x dep5ds4 ,_m op]ators1 bo? amateur & pr(essional1 al?\gh p]fectly well able to s5d & receive messages1 d n ?or\ghly und]/& ! rudim5t>y !ory ( ! in/rum5ts4 ,x is readily realizable t x is q impossible to ent] into all ! eng9e]+ details 9 a book ( ?is size1 b at ! same "t x has be5 possible to pres5t a v compreh5sive treatise ( ! subject & embody suffici5t mat]ial to give a ?or\gh gr\nd+ 9 ! subject4 ,9 ord] to avoid repetition & confusion & to make ea* in/rum5t or pr9ciple :i* has be5 discuss$ /& di/9ctly by itself1 ! text has be5 divid$ into sep>ate lessons foll[+ 9 _! arrangem5t1 z f> z has be5 possible1 ! logical sequ5ce4 ,= ! same reason1 & also because ( lack ( space all details p]ta9+ to ! actual ma9t5ance & adju/m5t ( ! in/rum5ts has be5 embodi$ 9 ano!r book call$ ,! ,op]ation ( ,wireless ,telegraph ,app>atus4 ,,lesson ,,"o4 ,,magnetism4 99,natural ,magnets4 ,artificial ,magnets4 ,magnetic ,field ( ,=ce499 ,x 0 kn[n to ! anci5ts t c]ta9 h>d1 black /ones1 an iron ore consi/+ ( iron & oxyg5 f\nd notably at ,magnesia 9 ,asia ,m9or1 possess$ ! p[] ( attract+ small pieces ( iron or /eel4 ,?is almo/ magic attribute ( ! /one 0 e>ly turn$ to acc\nt 9 navigation & secur$ = x ! "n ( ,lode/one 7lead+-/one7 because ( its rem>kable prop]ty ( po9t+ nor? & s\? :5 susp5d$ by a ?read4 ,! "n ( magnet 7magnes lapis7 0 also giv5 to ^! /ones4 ,magnetism is ! peculi> prop]ty occassionally possess$ by c]ta9 bodies 7m especially by iron & /eel7 :]eby !y attract or repel "o ano!r4 ,if a piece ( h>d iron or /eel be rubb$ ) a lode/one x w be f\nd to h also acquir$ ! prop]ties ( ! /one4 ,if hung up by a ?read x w po9t nor? & s\?1 w attract light bits ( iron & if dipp$ into iron fil+s w cause ! latt] to cl+ 9 two small tufts ne> ! ends ) few1 if any1 ne> ! middle4 ,illu/ration3 ,,fig4 #a4 ,lode/one :i* has be5 ,dipp$ 9 ,fil+s to %[ ,poles ,?is indicates t ! attractive p[] ( ! magnet is conc5trat$ 9 two opposite p>ts4 ,^! p>ts are call$ ! ,poles4 ,! l9e jo9+ ! poles is ! ,magnetic ,axis4 ,artificial ,magnets are ^? made f /eel by ! aid ( a lode/one or "s o!r magnetis+ =ce4 ,! pr9cipal =ms ( artificial magnets are ! ,b> & ,horse%oe1 s call$ f _! %ape4 ,illu/ration3 ,,fig4 #b4 ,b> & ,horse%oe ,magnet4 ,if a magnet 7ei!r artificial or natural7 is susp5d$ by a ?read s t x may sw+ freely1 & a second magnet held 9 ! h& is pres5t$ successively to ! two poles ( ! fir/1 x w be obs]v$ t "o pole is attract$ & sw+s t[>d ! magnet held 9 ! h&1 b t ! o!r is repell$ & sw+s away4 ,illu/ration3 ,,fig4 #c4 ,lode/one susp5d$ f ?read s z to po9t ,nor? & ,s\?4 ,fur!rmore1 if ! poles ( ! susp5d$ magnet are m>k$ s z to easily be id5tifi$ x w be f\nd t x is always ! same pole t sw+s t[>ds ! nor?4 ,!re w\ld !re=e appe> to be two k9ds ( magnetism or at lea/ two k9ds ( magnetic poles4 ,! end sw++ t[>d ! nor? is t]m$ ! nor? seek+ pole & ! opposite end call$ ! s\? seek+ pole4 ,9 common p>lance !y are simply t]m$ ! ,nor? & ,s\? poles4 ,x is usual to m>k ! ,nor? ,pole ) ! lett] ,n4 ,!re is no kn[n insulator ( magnetism3 x passes ?r\gh ev]y?+4 ,a magnetic sub/ance is "o :i* (f]s little resi/ance to ! field ( =ce4 ,magnetism fl[s along c]ta9 l9es call$ ,l9es ( ,magnetic ,=ce4 ,^! l9es always =m clos$ pa?s or circuits4 ,! region 9 ! neighborhood ( a magnet ?r\gh :i* ^! l9es pass is call$ ! ,field ( ,=ce & ! pa? ?r\gh :i* !y fl[ is call$ ! ,magnetic ,circuit4 ,illu/ration3 ,,fig4 #d4 ,l9es ( ,=ce ar\nd a ,b> ,magnet4 ,! pa?s ( ! l9es ( =ce c be demon/rat$ by plac+ a piece ( pap] ov] a b> magnet & !n spr9kl+ iron fil+s ov] ! pap] :i* %\ld be j>r$ slightly 9 ord] t ! fil+s may be drawn into ! magnetic pa?s4 ,! fil+s arrange !mselves 9 curv$ l9es1 div]g+ f "o pole ( ! magnet & meet+ aga9 at ! opposite end4 ,! 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 ,! ph5om5a ( magnetism & its laws =m a v important bran* ( ! /udy ( electricity1 = !y play a "p 9 ! con/ruction & op]ation ( almo/ all electrical app>atus4 ,,lesson ,,two4 ,,magnetic ,,induction4 ,9 #ahca ,mi*ael ,f>aday1 ! great physici/1 made ! valuable discov]y t electric curr5ts are induc$ 9 a clos$ circuit by mov+ a magnet ne> x or vice v]sa1 by mov+ ! circuit across ! field ( =ce1 ,if a coil ( insulat$ wire be connect$ 9 circuit ) a suffici5tly delicate galvanomet] 7a galvanomet] is an in/rum5t = detect+ feeble electric curr5ts7 & a b> magnet sudd5ly plung$ into ! holl[ ( ! coil z %[n 9 ! illu/ration1 a mom5t>y curr5t w be indicat$ z fl[+ ?r\gh ! galvanomet] :ile ! magnet is be+ mov$ 9 ! coil4 ,if ! magnet is !n rapidly pull$ out ( ! coil ano!r mom5t>y curr5t w be obs]v$ to fl[ 9 ! opposite direction f ! =m]4 ,illu/ration3 ,,fig4 #e4 ,magnetic ,induction4 ,s long z ! magnet lies motionless 9 ! coil x induces no curr5ts4 ,! field ( =ce 9 ! neighborhood ( a magnet gr[s weak] z ! di/ance f ! magnet increases4 ,:5 ! magnet is plung$ into ! coil1 ! /r5g? ( ! magnetic field 9 ! vic9ity ( ! coil gr[s /rong] due to ! approa* ( ! magnet1 & :5 x is )drawn ! field becomes weak]4 ,curr5ts are only induc$ 9 ! coil :5 ! magnet is mov+1 or 9 o!r words :5 ! /r5g? ( ! magnetic field is *ang+1 ei!r increas+ or decreas+4 ,! curr5ts g5]at$ 9 ! coil are call$ induc$ curr5ts4 ,! action ( ! magnetic field 9 produc+ induc$ curr5ts is t]m$ ,induction4 ,,lesson ,,?ree4 ,,prim>y ,,cells4 ,,second>y ,,cells4 ,if a piece ( z9c is dipp$ 9 dilute sulphuric acid1 ! z9c w be attack$ by ! acid & replace hydrog5 9 x1 ! hydrog5 appe>+ z bubbles on ! z9c & pass+ (f z a gas4 ,illu/ration3 ,,fig4 #f4 ,simple ,voltaic ,cell ,if ! z9c is connect$ by means ( a wire1 ,w1 ) a /rip ( copp]1 ,c1 dipp+ 9 ! same solution1 ! z9c w /ill to cont9ue to dissolve b ! hydrog5 bubbles w n[ =m on ! surface ( ! copp] /rip z well z on ! z9c4 ,x w be f\nd t ! wire ,w becomes heat$4 ,if ! copp] & z9c are connect$ to a galvanomet] x w %[ ! pres5ce ( an electric curr5t pass+ ?r\gh ! circuit4 ,! cell may be consid]$ z a sort ( *emical furnace 9 :i* fuel is burn$ to drive ! curr5t4 ,! z9c is ! fuel4 ,! copp] is m]ely pres5t to pick up ! curr5t & takes no "p *emically4 ,if a numb] ( su* simple cells are prop]ly unit$1 ! z9c ( "o be+ jo9$ to ! copp] ( ! next & s on1 a batt]y is =m$4 ,! curr5t fl[s f ! copp]1 call$ ! positive pole1 ?r\gh ! wires 7:5 !y are jo9$7 to ! z9c or negative pole & back to ! copp] ?r\gh ! solution4 ,! electricity g5]at$ by ! cells ex]ts a c]ta9 pressure or t5d5cy to pass ?r\gh ! wires4 ,?is t5d5cy is call$ ! pot5tial4 ,! pot5tial is measur$ 9 volts4 ,! pot5tial 7also call$ ! electromotive =ce7 9 ! case ( ! ,voltaic ,cell j describ$ is #a4jg volts4 ,if ! copp] /rip is replac$ ) "o ( graphite or c>bon1 ! voltage w rise to #a4gc volts4 ,aft] a cell has be5 9 action = a %ort "t1 ! positive plate 7copp] or c>bon1 z ! case may be7 becomes cov]$ ) a film ( hydrog54 ,! cell is !n said to be pol>iz$4 ,! film ( gas bubbles p>tially %ields ! plate f contact ) ! liquid4 ,:5 ! plate becomes 9 ?is condition1 ! curr5t is mu* feebl] ?an :5 x is cle>4 ,! mo/ effective way ( remov+ ! hydrog5 is to add "s *emical to ! sulphuric acid solution :i* w comb9e *emically ) ! hydrog5 z soon z x appe>s4 ,! usual sub/ance is bi*romate ( pota%4 ,! voltage ( ! batt]y w rise to #b4b volts & ! pol>ization be /opp$ :5 bi*romate ( pota% is add$4 ,! bi*romate ( pota% ent]s into *emical action ) ! sulphuric acid & =ms *romic acid4 ,su* cells are usually t]m$ *romic acid cells4 ,"o ( ! pr9cipal disadvantages ( a cell su* z t j describ$ lies 9 ! fact t ! z9c is cont9u\sly consum$ :e!r ! cell is 9 action or n & 9 ord] to prev5t its rapid wa/e mu/ be lift$ out ( ! solution & wa%$ ea* "t aft] us+4 ,v>i\s me?ods h be5 devis$ = ov]com+ ?is objection1 ! mo/ prom95t ( ! result+ cells be+ kn[n z ! ,full]1 ,gordon & ,edison-,lal&e ,cells4 ,illu/ration3 ,,fig4 #g4 ,edison ,cell4 ,! liquid excitant ( ! ,gordon & ,edison-,lal&e cells is a /rong solution ( sodium hydroxide4 ,! positive pole ( ^! cells is a block ( compress$ copp] oxide & ! negative a pair ( z9c plates4 ,9 ! ,gordon cell ! positive is enclos$ 9 a por\s *amb]4 ,illu/ration3 ,,fig4 #h4 ,dry ,cell4 ,"o ( ! be/ kn[n =ms ( cell is ! dry cell4 ,x consi/s ( an out] %ell ( z9c =m+ ! negative electrode & a c5tral rod ( c>bon z ! positive4 ,! active ag5t ( ! cell is a pa/e compos$ pr9cipally ( sal ammoniac l9+ ! int]ior ( ! z9c %ell4 ,! depol>iz+ ag5t ( ! cell is manganese dioxide mix$ ) cru%$ c>bon & pack$ tightly ar\nd ! c>bon rod4 ,! cell is n z its "n implies p]fectly dry inside1 b ! *emicals are 9 pa/e =m4 ,! cell is seal$ at ! top by a bitum9\s comp\nd mak+ ! cell air tight & portable4 ,dry cells are only successful = int]mitt5t "w1 t is1 :]e !y are n requir$ to deliv] a heavy curr5t cont9u\sly4 ,!y det]iorate aft] long /&+ because ! moi/ure evaporates4 ,dry cells1 h[ev]1 are a v conv5i5t s\rce ( curr5t :]e ! dem& is n too great & portability is desir$4 ,! cells s f> describ$ are all ( ! type kn[n z prim>y cells4 99,,second>y ,,cells499 ,! /orage cell or second>y cell is made up ( plates ( lead1 or an alloy ( lead1 ca/ 9 ! =m ( a grid or framework ( b>s4 ,! spaces =m$ 9 ! plate by ! little b>s are fill$ ) a pa/e ( lead oxide4 ,! pa/e = ! positive plates are made ( r$ lead :ile li?>ge is us$ = ! negatives4 ,illu/ration3 ,,fig4 #i4 ,a ,/orage ,batt]y ,grid4 ,! positive & negative plates are plac$ alt]nately 9 a bundle ) a wood5 or rubb] sep>ator betwe51 !re always be+ "o m negative plate ?an positive4 ,! negative plates are all connect$ 9 p>allel at "o end ( ! cell by means ( lead connect+ /rips4 ,! positive plates are connect$ at ! o!r end4 ,! plates are plac$ 9 a j>1 usually glass or h>d rubb]1 & cov]$ ) a dilute sulphuric acid solution4 ,! /orage cell is !n connect$ to a dynamo1 ! positive pole ( ! cell be+ connect$ to ! positive pole ( ! dynamo & ! curr5t all[$ to fl[ ?r\gh until ! plates are =m$1 t is to say1 until ! pa/e 9 ! positive *anges to p]oxide ( lead & t 9 ! negative to spongy lead4 ,:5 ! cell is disconnect$ x w give out a curr5t ( its own la/+ until x becomes dis*>g$4 ,! *>g+ & dis*>g+ mu/ be repeat$ sev]al times be=e ! cell really becomes effici5t4 ,illu/ration3 ,,fig4 #aj4 ,/orage ,cells4 ,:at is effect$ 9 ! /orage cell is really ! /orage ( *emical en]gy & n ! /orage ( electricity1 =1 prop]ly speak+1 ! en]gy is put into ! =m ( *emical aff9ity & !re is 9 reality no m electricity actually 9 ! cell at ! end ( a *>ge ?an !re is :5 ! cell is dis*>g$4 ,! /orage batt]y is ! mo/ conv5i5t means ( absorb+ electrical en]gy at "o "t or place & us+ x at ano!r "t or place4 ,/orage cells are v (t5 employ$ 9 wireless /ations = em]g5cy purposes s t 9 case ! dynamo supply+ curr5t fails ! /ation w n be ?r[n out ( op]ation4 ,! voltage ( a /orage cell is ab\t two volts4 ,,lesson ,,f\r4 ,,electric ,,curr5ts4 99,! ,units ( ,measurem5t4 ,direct & ,alt]nat+ ,curr5ts4 ,ohm's ,law499 ,electric ,curr5ts may be divid$ into two classes kn[n z direct & alt]nat+ curr5t4 ,ei!r "o may be measur$ or qualifi$ by two electrical units call$ ! ,amp]e & ! ,volt4 ,! volt may be expla9$ by lik5+ x to ! unit ( pressure ( ! curr5t1 :ile ! amp]e measures ! unit rate ( curr5t fl[4 ,= example1 9 ! case ( wat] ! voltage corresponds to ! pressure 9 p\nds :ile ! amp]age w\ld indicate ! rate ( wat] fl[+4 ,illu/ration3 ,,fig4 #aa4 ,hydraulic ,analogy betwe5 ,voltage & ,amp]age4 ,! accompany+ sket*es %[ graphically ! analogy betwe5 ! voltage & amp]age ( an electric curr5t & ! pressure & volume ( a /ream ( wat]4 ,9 ! fir/ illu/ration a tank is %[n at a high elevation f :i* a small pipe leads4 ,! voltage or pressure 9 su* a pipe w\ld be high 9 comp>ison ) t 9 a pipe lead+ f a l[] tank4 ,9 ! second illu/ration ! pipe lead+ f ! tank is mu* l>g] ?an t f ! fir/ & consequ5tly ! amp]age or volume fl[+ is great] 9 comp>ison4 ,f ?is x may be readily se5 t e circuit ?r\gh :i* a curr5t is fl[+ mu/ exhibit bo? quantities4 ,! unit ( electrical "w or en]gy is ! ,watt4 ,sev5 hundr$ & =ty-six watts con/itute an electrical horse-p[]4 ,! numb] ( watts is indicat$ by ! voltage times ! amp]age4 ,?us ! am\nt ( en]gy 9 a circuit 9 :i* #ej amp]es at #ajj volts pressure are pass+ is #ej x #ajj or #e1jjj watts4 ,! ,c\l\mb repres5ts ! quantity ( electricity fl[+ 9 a circuit-:]e ! rate ( fl[ is "o amp]e p] second4 ,9 ord] to prop]ly indicate comp>ative am\nts ( en]gy ! elem5t ( "t mu/ also be tak5 into consid]ation4 ,"o watt pass+ = "o h\r is a watt-h\r4 ,sev5 hundr$ & =ty-six watts pass+ = "o h\r or "o watt pass+ = sev5 hundr$ & =ty-six h\rs is a horse-p[] h\r4 ,! in/rum5ts us$ = measur+ ! amp]age & voltage ( a circuit are call$ respectively ! ammet] & ! voltmet]4 ,t us$ = regi/]+ watt-h\rs is call$ ! integrat+ watt-met]4 ,illu/ration3 ,,fig4 #ab4 ,diagram ,%[+ ,alt]nat+ & ,direct ,curr5t4 ,direct curr5t is curr5t t passes or fl[s 9 "o direction only4 ,! curr5t ( all prim>y & second>y cells & ( c]ta9 =ms ( dynamos is direct4 ,alt]nat+ curr5t is curr5t t repeat$ly rev]ses its direction ( fl[4 ,a direct curr5t may be repres5t$ by a /raight l9e4 ,an alt]nat+ curr5t is %[n by a wavy l9e cross+ & recross+ a /raight l9e4 ,! curr5t gradually rises f z]o to a maximum & !n dies away4 ,x does n /op at ?is po9t h[ev]1 b />ts to rise aga91 ?is "t fl[+ 9 a rev]se direction4 ,aft] rea*+ a maximum x dies away aga9 & ! cycle is repeat$4 ,f a to c repres5ts a cycle & f a to b an alt]nation4 ,alt]nat+ curr5ts usually h a frequ5cy ( #cj1 #fj or #abj cycles p] second4 ,sixty is ! mo/ common frequ5cy4 ,_m wireless telegraph /ations n[ employ curr5ts hav+ a frequ5cy ( #ejj cycles4 99,ohm's ,law499 ,m5tion has be5 made above ( c]ta9 electrical magnitudes1 namely1 voltage or electromotive =ce & amp]age or /r5g? ( curr5t4 ,^! be> an important relation 9 det]m9+ a prop]ty ( an electric circuit call$ resi/ance4 ,no conduct+ body possesses p]fect electrical conductivity1 b pres5ts a c]ta9 am\nt ( ob/ruction or resi/ance to ! passage ( electricity4 ,! practical unit ( resi/ance is ! ,ohm4 ,x is repres5t$ by ! resi/ance (f]$ to an unv>y+ electric curr5t by a column ( m]cury at ! temp]ature ( melt+ ice1 #ad4deba grams 9 mass1 ( a con/ant cross sectional area & ( ! l5g? ( #ajf4c c5timetres4 ,! resi/ance ( a conductor is proportional to its l5g?1 t is1 provid$ two conductors are made ( ! same mat]ial & ( ! same diamet] & "o is twice z long z ! o!r1 ! resi/ance ( ! long] w be twice t ( ! %ort] conductor4 ,! resi/ance is inv]sely proportional to ! cross sectional area1 :i* is to say t a conductor ( small] cross section has a great] resi/ance ?an "o ( l>g] section4 ,! laws ( resi/ance are conv5i5tly express$ by ! foll[+ =mula call$ ,ohm's ,law4 ,c ,e_/,r :]e ,eelectromotive =ce 9 volts4 ,ccurr5t 9 amp]es4 ,rresi/ance 9 ohms4 ,if two factors are kn[n1 ! ?ird c be f\nd by sub/itution4 ,,lesson ,,five4 ,,electromagnetism4 99,! ,electromagnet4 ,! ,sol5oid499 ,if a curr5t ( electricity is pass$ ?r\gh a copp] wire1 ! wire w attract to itself iron fil+s1 etc41 z long z ! curr5t cont9ues to fl[4 ,!re is !n a magnetic field ar\nd ! wire4 ,z soon z ! curr5t is %ut (f ! fil+s drop away because ! field imm$iately disappe>s ) ! cessation ( ! curr5t4 ,illu/ration3 ,,fig4 #ac4 ,magnetic ,phantom ab\t a ,wire ,c>ry+ ,curr5t4 ,! l9es ( =ce fl[ ar\nd ! wire 9 a circle4 ,! circul> l9es ( ! field ( =ce surr\nd+ a /raight wire may be %[n by pass+ a wire v]tically ?r\gh a hole 9 ! c5tre ( a horizontal c>d4 ,iron fil+s are sift$ ov] ! c>d & a /rong curr5t pass$ ?r\gh ! wire4 ,on tapp+ ! c>d g5tly1 ! fil+s ne> ! wire set !mselves 9 conc5tric circles r\nd x4 ,! creation ( a magnetic field by a conductor 9 its own neighborhood :5 c>ry+ a curr5t ( electricity is "o ( ! mo/ important ph5om5a ( electrical sci5ce4 ,electrical en]gy mu/ be exp5d$ 9 produc+ a magnetic field4 ,:5 a curr5t ( electricity is turn$ on 9 a wire ! magnetic field gr[s ar\nd ! wire1 "s ( ! en]gy ( ! curr5t be+ us$ = ! build+ process4 ,?is reactive effect ( ! surr\nd+ magnetic field is "o reason :y electric curr5ts d n in/antly rise to _! full value4 ,illu/ration3 ,,fig4 #ad4 ,diagram %[+ h[ ,l9es ( ,=ce ,=m ab\t a ,loop ( ,wire4 ,if a wire is connect$ to a batt]y or "s o!r s\rce ( electric curr5t & a portion ( ! circuit twi/$ s z to =m a loop1 ! entire space enclos$ by ! loop w be a magnetic field & possess magnetic prop]ties4 ,by =m+ a wire into a spiral coil ! comb9$ effect ( ea* individual turn is conc5trat$ 9 a small space & a p[]ful field ( =ce is produc$4 ,if ! coil is provid$ ) an iron core1 ! l9es ( =ce c be conc5trat$ & w ex]cise a v p[]ful attractive effect ^u any neighbor+ masses ( iron or /eel4 ,su* a coil is call$ an electromagnet4 ,a holl[ coil )\t any core is call$ a sol5oid4 ,illu/ration3 ,,fig4 #ae4 ,magnetic ,phantom ab\t a ,coil ( ,wire4 ,sol5oids & electromagnets play a v important "p 9 ! con/ruction ( mo/ electrical in/rum5ts4 ,! /r5g? ( an electromagnetic coil is proportional to its amp]e turns4 ,! amp]e turns ( a coil are obta9$ by multiply+ ! numb] ( amp]es fl[+ ?r\gh ! coil by ! numb] ( turns ( wire compos+ x4 ,,lesson ,,six4 ,,dynamo ,,electric ,,ma*9]y4 99,! ,dynamo4 ,! ,alt]nator4 ,! ,motor499 ,! discov]y ( ! induction ( curr5ts 9 wires by mov+ !m across a magnetic field l$ to ! con/ruction ( electrical ma*9es1 call$ dynamos1 to g5]ate curr5t 9 place ( batt]ies4 ,! dynamo is p]haps ! mo/ important piece ( electrical app>atus !re is = x is ! s\rce ( n9ety-n9e p]c5t ( all ! electricity n[ 9 use4 ,x is practically necess>y 9 any case :]e a consid]able quantity ( electricity is us$ to h a dynamo on ! spot or else br+ ! curr5ts ov] a wire f "s supply /ation :]e dynamos are kept runn+4 ,! op]ation ( a dynamo is dep5d5t ^u curr5t induction4 ,x conta9s a sy/em ( clos$ conductors revolv+ 9 a magnetic field 9 su* a way z to cont9u\sly v>y ! numb] ( l9es ( =ce ?read+ among !m4 ,illu/ration3 ,,fig4 #af4 ,diagram %[+ ! pr9ciple ( ! ,dynamo4 ,! illu/ration %['s ! ideal simple dynamo1 :i* consi/s ( a loop ( wire arrang$ to revolve betwe5 ! poles ( a p]man5t magnet 9 ! direction ( ! arr[ & ar\nd a horizontal l9e z an axis4 ,! l9es ( magnetic =ce 7repres5t$ by ! f9e /raight l9es7 pass across f ,n to ,s z indicat$4 ,:5 9 ! position %[n1 ! coil ( wire encloses ! l>ge/ possible numb] ( l9es ( magnetic =ce4 ,:5 x has revolv$ n9ety degrees or a qu>t] ( a turn z %[n by ! dott$ l9es1 ! l9es ( =ce w be p>allel to ! plane ( ! coil & none w pass ?r\gh4 ,dur+ ?is qu>t] ( ! turn ! numb] ( l9es ( =ce has be5 decreas+4 ,dur+ ! next qu>t] ( a turn ! l9es w increase aga91 b w ?is "t pass ?r\gh f ! opposite side ( ! loop4 ,?is decrease & increase ( ! numb] ( l9es ( =ce pass+ ?r\gh ! loop g5]ates !re9 a curr5t ( electricity4 ,! same process is repeat$ dur+ ! next half ( a revolution4 ,h[ev]1 s9ce ! l9es ( =ce fl[ ?r\gh f opposite sides ( ! coil e half revolution1 ! curr5t rev]ses twice dur+ ! same p]iod4 ,9 ! illu/ration ! loop is repres5t$ z =m+ a complete clos$ circuit 9 itself4 ,9 ord] to draw any curr5t = ext]nal use "s me?od ( e/abli%+ connection to ! t]m9als ( ! coil mu/ be _h4 ,?is is furni%$ by two circul> r+s call$ collector r+s4 ,! little /rips ( metal or c>bon employ$ to =m contact ) ! r+s are call$ bru%es4 ,illu/ration3 ,,fig4 #ag4 ,simple ,alt]nator4 ,su* a ma*9e1 s equipp$ w deliv] alt]nat+ curr5ts & illu/rates ! pr9ciple ( ! alt]nat+ curr5t dynamo or alt]nator4 ,) ! aid ( a device call$ a commutator & consi/+ ( a r+ split 9 sections z %[n 9 ! illu/ration1 all ! successive curr5t impulses may be turn$ 9 ! same direction & ! curr5t made direct4 ,9 practice _m coils ( wire w\nd ar\nd an iron core call$ ! armature1 ! purpose ( :i* is to conc5trate ! magnetic l9es ( =ce1 are made to revolve 9 a p[]ful field betwe5 ! poles ( adjac5t electromagnets4 ,electromagnets are us$ because !y are capable ( produc+ a /rong] magnetic field ?an magnetiz$ b>s ( /eel4 ,! electromagnets us$ = ?is purpose are call$ field magnets4 ,! c5tral iron portion ^u :i* ! revolv+ coils are w\nd1 call$ ! armature1 is usually built up ( a numb] ( ?9 %eets ( s(t /eel call$ armature disks or lam9ations4 ,illu/ration3 ,,fig4 #ah4 ,simple ,dynamo %[+ ,commutator4 ,! mod]n armature is v complex4 ,a simple coil su* z ^? %[n 9 ,figs4 #ag & #ah w n yield a /eady curr5t = twice 9 ea* revolution ! electromotive =ce dies away to z]o4 ,! coils ( l>ge dynamos are gr\p$ s t "s ( !m are always active4 ,!re are ?ree g5]al me?ods ( supply+ curr5t to ! held magnets ( a dynamo1 kn[n z ! s]ies1 %unt & comp\nd w9d+s4 ,! s]ies dynamo is arrang$ s t ! coils ( ! held magnets are 9 s]ies ) ^? ( ! armature4 ,9 ! %unt dynamo1 ! coils ( ! held magnet =m a %unt to ! ma9 circuit & be+ made ( _m turns ( ?9 wire1 draw (f only a small fraction ( ! :ole curr5t4 ,illu/ration3 ,,fig4 #ai4 ,diagram ( ,dynamo ,field ,w9d+s4 ,! comp\nd dynamo is p>tly excit$ by %unt coils & p>tly by s]ies coils4 ,illu/ration3 ,,fig4 #bj4 ,motor ,g5]ator4 ,ea* v>iety ( dynamo w9d+ has a c]ta9 advantage dep5d+ ^u ! condition ( use4 ,9 ! case ( alt]nat+ curr5t dynamos1 ! field magnets are sometimes suppli$ f a sep>ate dynamo call$ an excit]4 ,9 o!r cases ! dynamo is provid$ ) two sets ( w9d+s1 "o connect$ to a commutator produc+ a direct curr5t :i* excites ! field coils & ! o!r connect$ to a set ( r+s & supply+ ! alt]nat+ curr5t4 ,9 case a supply ( ei!r direct or alt]nat+ curr5t is available & x is desirable to *ange ! supply f direct to alt]nat+ or vice v]sa1 x may be accompli%$ by employ+ a ,motor-,g5]ator4 ,a motor-g5]ator consi/s ( an electric motor op]at+ f ! s\rce ( curr5t supply on h& & driv+ a dynamo :i* supplies curr5t ( ! k9d desir$4 ,a motor is exactly ! rev]se ( a dynamo4 ,if a curr5t ( electricity is pass$ into a dynamo1 ! armature w be dragg$ ar\nd by ! mutual action ( ! curr5ts fl[+ 9 ! copp] conductors & ! magnetic field 9 :i* !y lie4 ,su* a device con/itutes a motor & may be employ$ to d useful "w4 ,motors are classifi$ z alt]nat+ & direct curr5t ma*9es accord+ly z !y are built to op]ate on ei!r k9d ( curr5t4 ,,lesson ,,sev54 ,,! ,,induction ,,coil4 ,! ,induction ,coil is an app>atus = produc+ curr5ts ( a v high electromotive =ce4 ,x consi/s ( a helix ( l>ge1 insulat$ wire surr\nd+ an iron core1 & ?is aga9 surr\nd$ by a second coil consi/+ ( _m ?\s& turns ( v f9e wire c>efully insulat$4 ,! inn] or prim>y coil is connect$ 9 s]ies ) a batt]y1 ! circuit also includ+ a device call$ an int]rupt]4 ,! object ( ! int]rupt] is to make & break ! prim>y circuit 9 rapid succession4 ,e "t ! curr5t is turn$ on 9 ! prim>y circuit1 ! prim>y coil creates a magnetic field :i* induces a curr5t 9 ! second>y 9 accordance ) ! laws ( induction4 ,illu/ration3 ,,fig4 #ba4 ,diagram ( ,induction ,coil4 ,likewise at e break 9 ! circuit caus$ by ! int]rupt]1 ! l9es ( =ce disappe> & a second curr5t impulse is induc$ 9 ! second>y coil4 ,z ! numb] ( l9es ( magnetic =ce creat$ & de/roy$ at ea* make & break is ! same1 ! two electromotive impulses 9 ! second>y are equal4 ,by add+ a cond5s]1 h[ev]1 ! curr5t at make is caus$ to take a consid]able fraction ( "t to gr[1 :ile at break ! cessation is in/antane\s 9 comp>ison4 ,! rate ( cutt+ ( ! l9es ( =ce is v mu* m rapid at break ?an at make !re=e4 ,! curr5ts at break manife/ !mselves z a brilliant torr5t ( sp>ks betwe5 ! ends ( ! second>y wires :5 !y are br\ght ne> en\gh toge!r4 ,! c5tral iron core ar\nd :i* ! coils are w\nd is = ! purpose ( increas+ or conc5trat+ ! numb] ( l9es ( =ce t pass ?r\gh ! coils4 ,magnetic l9es fl[ m easily ?r\gh iron ?an ?r\gh air & s pref] t pa?4 ,x is made up ( a bundle ( f9e iron wires 9 ord] to avoid induc$ curr5ts :i* w\ld be set up 9 ! iron 7 x a solid mass & s ret>d its rapidity ( magnetization or demagnetization z to hamp] ! effici5cy ( ! coil4 ,,lesson ,,eight4 ,,! ,,pr9ciple ,,( ,,! ,,trans=m]4 ,! trans=m] is a device = rais+ or l[]+ ,a ! electromotive =ce ( an alt]nat+ curr5t4 ,9 pr9ciple x consi/s ( two insulat$ coils ( wire call$ ! prim>y & ! second>y w\nd ar\nd an iron r+ z %[n 9 ! illu/ration4 ,illu/ration3 ,,fig4 #bb4 ,diagram %[+ ! pr9ciple ( a ,trans=m]4 ,if ! prim>y coil is connect$ to a s\rce ( alt]nat+ curr5t x w rapidly magnetize & demagnetize ! iron r+4 ,! magnetic l9es ?us creat$ w pass ?r\gh ! second>y coils sett+ up induc$ curr5ts4 ,! ratio ( ! electro-motive =ce ( ! induc$ curr5t to t ( ! prim>y curr5t is 9 direct proportion to ! ratio ( ! numb] ( turns 9 ! two coils4 ,= example1 if ! second>y conta9s twice z _m turns z ! prim>y1 its electro-motive =ce w be twice z great4 ,illu/ration3 ,,fig4 #bc4 ,op5 & ,clos$ ,core ,trans=m]s4 ,trans=m]s are ( two g5]al types1 ! op5 core & ! clos$ core4 ,clos$ core trans=m]s are ! mo/ effici5t4 ,! op5 core trans=m] is simil> 9 con/ruction to an induction coil1 ! core be+ a /raight b>1 :ile t ( ! clos$ core ma*9e is usually 9 ! =m ( a holl[ squ>e or rectangle4 ,9 practice1 ! cores ( trans=m]s are built up ( lam9ations1 usually ( ?91 s(t %eet iron /rips pil$ toge!r & %ap$ s z to con/itute a clos$ magnetic circuit ( rectangul> %ape 9 ord] to avoid con/ructional difficulties incurr$ 9 mak+ a r+4 ,,lesson ,,n9e4 ,,! ,,leyd5 ,,j> ,,& ,,cond5s]4 ,! ,leyd5 ,j>1 call$ aft] ! city ( ,leyd51 ,holl&1 :]e x 0 inv5t$1 is a =m ( cond5s] consi/+ ( a glass j> coat$ up to a c]ta9 height inside & out ) t9foil4 ,illu/ration3 ,,fig4 #bd4 ,leyd5 ,j>4 ,a ,leyd5 j> may be *>g$ by hold+ ! rod to ! prime conductor ( an electric ma*9e1 ! out] coat+ be+ held 9 ! h&4 ,if a piece ( wire connect$ to ! out] coat+ is !n br\ght ne> ! rod a brilliant snapp+ sp>k w pass across ! space4 ,any two conductors1 sep>at$ by an insulat+ m$ium t]m$ ! dielectric1 con/itute a cond5s] & possesses ! prop]ty ( receiv+ & reta9+ an electric *>ge4 ,if a *>g$ cond5s] or ,leyd5 j> is dis*>g$ sl[ly by all[+ ! electricity to pass ?r\gh a high resi/ance conductor ! fl[ ( curr5t increases 9 /r5g? at fir/ & !n gradually dies away4 ,if1 h[ev]1 ! cond5s] is dis*>g$ ?r\gh a coil ( wire ( "o or m turns1 ! dis*>ge consi/s ( a numb] ( excessively rapid oscillations or surg+s4 ,! fir/ ru% ( curr5t s]ves to m ?an empty ! cond5s] & *>ges x ! opposite way1 !n foll[s a rev]se dis*>ge1 :i* also ov]/eps itself & *>ges ! cond5s] ! same way z ! fir/ & s on1 ea* successive oscillation be+ weak] ?an ! "o be=e until ! dis*>ge dies away z 9 ,fig4 #cf4 ,! dis*>ge ( a cond5s] "u su* conditions consi/s ( a numb] ( successive sp>ks 9 rev]se directions4 ,! ability ( a cond5s] to receive & reta9 an electrical *>ge is t]m$ ! capacity & is measur$ by a unit call$ ! f>ad4 ,! f>ad is s l>ge a quantity1 h[ev]1 t x is nev] met 9 practise & = conv5i5ce ! micro-f>ad :i* is "o million? ( a f>ad has be5 adopt$4 ,a cond5s] ( "o f>ad capacity is su* z w\ld be rais$ to a pot5tial ( "o volt by a *>ge ( "o c\lomb ( electricity4 ,! capacity ( ! cond5s] is dep5d5t ^u ! ?ickness & nature ( ! insulat+ m$ium or dielectric4 ,! quality ( a dielectric :i* decides ! capacity ( a cond5s] 9 :i* x may be a "p is call$ its specific inductive capacity4 ,! foll[+ table %[s ! relative specific inductive capacity ( sev]al mat]ials1 air be+ ! /&>d3 ,,table ,,( ,,specific ,,inductive ,,capacities4 ,sub/ance4 ,con/ant4 ,air #a4jj ,p>aff9 #a4fh--b4dg ,petroleum #b4jb--b4ai ,gutta ,p]*a #c4jj ,h>d ,rubb] #b4bh ,mica #f4fd ,glass #f4gb--g4ch ,,lesson ,,t54 ,,! ,,e!r ,,& ,,! ,,electromagnetic ,,!ory ,,( ,,light4 ,all space is fill$ ) a weightless1 invisible m$ium call$ ,e!r4 ,x is ! sub/ance ) :i* ! univ]se is fill$1 x rea*es to ! />s & ?r\gh ! v e>? itself4 ,x has be5 kn[n = "s "t t light consi/s ( vibrations or motions 9 ! e!r4 ,9 #ahfg1 ,cl]k ,maxwell (f]$ ! !ory t ^! light waves are n m]ely me*anical motions ( ! e!r1 b are electrical undulations4 ,accord+ to ?is !ory1 ! ph5om5a ( electro-magnetism & ! ph5om5a ( light are all due to c]ta9 modes ( motion 9 ! e!r4 ,tw5ty ye>s lat]1 ,he9ri* ,h]tz discov]$ conv9c+ pro(s ( ,maxwell's !ory & succe$$ 9 produc+ electro-magnetic waves 9 su* a mann] t !y possess$ ! same prop]ties1 travel$ at ! same spe$1 & 7 capable ( be+ reflect$1 refract$1 pol>iz$1 etc4 ,illu/ration3 ,,fig4 #be4 ,h]tzian ,oscillator & ,resonator4 ,h]tz employ$ an app>atus consi/+ ( two metallic balls connect$ by metal rods to two metal %eets4 ,! two balls 7 also connect$ to ! second>y t]m9als ( an induction coil4 ,?is app>atus compris$ ! oscillator & s]v$ to create ! electro-magnetic waves4 ,9 ord] to detect ! waves1 he employ$ a resonator consi/+ ( a circle ( wire hav+ 9 x a m9ute sp>k gap capable ( f9e adju/m5t4 ,z soon z ! coil is set 9 op]ation a sp>k snaps across ! gap & sets up a tempor>y conduct+ pa? = ! surg+s t foll[4 ,ea* sp>k s5t by ! coil across ! gap consi/s ( a doz5 or s oscillations1 ea* la/+ less ?an a million? ( a second4 ,!n if ! resonator is plac$ a few feet away f ! oscillator & turn$ broadside on to ! oscillator1 x w be f\nd t small sp>ks jump across ! gap4 ,h]tz employ$ v>i\s arrangem5ts = reflect+ & pol>iz+ ! waves & def9itely prov$ t _! nature is ! same z t ( light4 ,,lesson ,,elev54 ,,electric ,,waves4 ,:5 a ,leyd5 j> dis*>ges "u ! conditions set =? 9 "o ( ! previ\s lessons1 portions ( ! en]gy ( ! curr5t or dis*>ge are ?r[n (f f ! conductor & d n return to x1 b g travel+ on 9 space4 ,if a curr5t is s5t ?r\gh a circuit1 z ! curr5t increases1 ! magnetic field also increases1 ! magnetic l9es enl>g+ & spread+ outw>d f ! conductor l ! ripples on a pond4 ,if ! curr5t is decreas$1 ! magnetic l9es all return back & close up ^u ! conductor1 ! en]gy all be+ re-absorb$ into ! circuit4 ,if electrical oscillations ( extreme rapidity su* z ^? g5]at$ by a cond5s] dis*>ge are sub/itut$ = a curr5t sl[ly ris+ & fall+1 "p ( ! en]gy radiates (f into ! e!r z electromagnetic waves & only a "p returns back4 ,! dis*>ge ( a ,leyd5 j> or cond5s] only oscillates :5 ! circuit conta9s a c]ta9 am\nt ( capacity & inductance 9 proportion to ! resi/ance ( ! circuit4 ,inductance is ! prop]ty ( a circuit by virtue ( :i* l9es ( =ce are develop$ ar\nd x4 ,circuits conta9+ a c]ta9 am\nt ( inductance1 capacity & resi/ance t5d to oscillate electrically at a c]ta9 frequ5cy4 ,illu/ration3 ,,fig4 #bf4 ,electric ,waves4 ,! electromagnetic waves ?r[n (f by ! a]ial sy/em foll[ ! cont\r ( ! e>? & s may cross m\nta9s or travel any:]e4 ,! waves emitt$ by ! ord9>y wireless /ation1 mak+ use ( an a]ial & a gr\nd are half waves t]m9at+ 9 ! e>? z %[n 9 ! illu/ration4 ,9 pass+ ov] ! e>? !y are accompani$ by gr\nd curr5ts :i* wa/e a c]ta9 am\nt ( _! en]gy 9 ov]com+ ohmic resi/ance & s r$uce ! int5sity ( ! waves4 ,= ?is reason propagation is always ! be/ ov] wat] or moi/ e>? ^: resi/ance is l[4 ,a fur!r peculi> weak5+ ( ! waves due to ! absorbtion tak+ place 9 ! air dur+ sunlight4 ,! diff]5ce betwe5 ! signals 9 ! day & _! /r5g? at night is v m>k$1 be+ mu* /rong] 9 ! lat] case4 ,,lesson ,,twelve4 ,,pr9ciples ,,( ,,wave ,,telegraphy4 ,wireless ,telegraphy z practic$ to-day is m]ely a me?od ( sett+ up electromagnetic waves 9 ! e!r & !n detect+ _! exi/5ce at a di/ant po9t4 ,x may be divid$ into f\r di/9ct & individual op]ations1 namely3 #a4 ,! g5]ation ( electrical oscillations4 #b4 ,! trans=mation ( electrical oscillations into electrical waves4 #c4 ,! trans=mation ( electrical waves into electrical oscillations4 #d4 ,! detection ( ! electrical oscillations4 ,we h already le>n$ h[ electrical oscillations may be g5]at$ by ! dis*>ge ( a ,leyd5 j> or a cond5s]4 ,9 ord] to p]=m ! fir/ two op]ations nam$ above1 x is !re=e m]ely necess>y to arrange a cond5s] 9 su* a way t x is mo/ effective4 ,! induction coil or trans=m] is employ$ to *>ge ! cond5s] because ! curr5ts ( ^! in/rum5ts are mu* m p[]ful ?an ^? ( a /atic electric ma*9e4 ,! induction coil is connect$ to a set ( batt]ies & a key s t ! p]iods dur+ :i* ! curr5t is on & (f may be controll$ at w by ! pressure ( ! f+]s4 ,illu/ration3 ,,fig4 #bg4 ,diagram ( ,wireless ,transmitt]4 ,! second>y ( ! coil is connect$ to a batt]y ( ,leyd5 j>s or a cond5s]4 ,! fact 0 m5tion$ above t a c]ta9 am\nt ( inductance 9 ! circuit is necess>y = ! production ( electrical oscillations ,?is is furni%$1 or at lea/ ! great] "p1 by a device call$ a helix :i* consi/s ( a coil ( heavy wire w\nd ar\nd a suitable framework4 ,! sp>k dis*>ge takes place across a device call$ a sp>k gap4 ,:5 ! key is press$1 ! high pot5tial curr5ts ( ! induction coil *>ge ! ,leyd5 j> or cond5s] & cause x to dis*>ge ?r\gh ! helix & across ! sp>k gap4 ,high frequ5cy oscillations are imm$iately creat$ 9 ?is "p ( ! circuit4 ,! sp>k gap1 cond5s] & t "p ( ! helix includ$1 con/itute ! clos$ circuit4 ,! electromagnetic waves ?r[n (f by su* an oscillatory sy/em w\ld n be v f> rea*+ 9 _! effects because ! di/urbances w\ld be conf9$ to ! imm$iate neighborhood ( ! app>atus1 s rec\rse is _h to ! a]ial & gr\nd4 ,! a]ial consi/s ( a network ( wires elevat$ high 9 ! air4 ,! gr\nd or e>? connection is simply a l>ge metal plate buri$ 9 moi/ e>? or ?r[n into ! sea4 ,by connect+ ! a]ial & gr\nd to ! helix 9 ! mann] %[n 9 ,fig4 #bg1 ! high frequ5cy curr5ts are caus$ to surge up & d[n ! a]ial sy/em into ! gr\nd & create v p[]ful electromagnetic waves :i* possess ! p[] ( excit+ electrical oscillations 9 ano!r a]ial ev5 ?\gh x may be locat$ _m miles away4 ,! exi/5ce ( ^! oscillations is made kn[n to ! receiv+ op]ator by a device kn[n z a detector1 describ$ fully 9 "o ( ! foll[+ lessons4 ,,lesson ,,?irte54 ,,! ,,a]ial4 ,! a]ial sy/em or ant5na might be t]m$ ! m\? & e> ( ! wireless /ation1 = x is ?is huge network ( wires /ret*+ high into ! air t emits or int]cepts ! electromagnetic waves ^u :i* su* sy/ems ( communication dep5d4 ,illu/ration3 ,,fig4 #bh4 ,g5]al ,types ( ,a]ials ,! value ( an a]ial is dep5d5t ^u its height above ! surface ( ! e>?4 ,! great] its height ! wid] w be ! field ( =ce or /ra9 set up 9 its neighborhood & consequ5tly m p[]ful electric waves w be develop$4 ,proximity to all l>ge conductors1 su* z smoke/acks1 telephone l9es1 etc41 is always avoid$ because ^! ob/acles w\ld absorb appreciable am\nts ( ! en]gy s5t out f ! /ation & also %ield x some:at f ! incom+ waves4 ,a]ials are usually con/ruct$ ( conductors made up ( a numb] ( wires /r&$ toge!r4 ,high frequ5cy curr5ts only travel ne> ! surface ( conductors & /r&$ wires consequ5tly (f] less resi/ance because !y possess m surface ?an a solid conductor ( equal cross section4 ,! a]ial is always c>efully insulat$ by means ( special high t5sion insulators1 made ( insulat+ composition mold$ into a corrugat$ b> hav+ iron r+s emb$d$ 9 ea* end to :i* ! wires may be fa/5$4 ,a]ials take _m diff]5t =ms1 b may be classifi$ into two g5]al gr\ps call$ ! v]tical a]ials & flat top a]ials4 ,v]tical a]ials compose ! grid1 fan1 cage & umbrella =ms4 ,flat top a]ials are kn[n z ! ,t1 inv]t$ ,u1 ,l & ,v types1 accord+ to _! %ape4 ,! ,pyramid ,a]ial is only employ$ 9 ultra-p[]ful /ations & is becom+ an obsolete =m4 ,! ,fan ,a]ial is a good type ( especial value 9 cr[d$ qu>t]s4 ,! ,grid ,a]ial is probably ! be/ =m ( v]tical a]ial1 b is gradually giv+ way to ^? ( ! flat top class4 ,! ,cage ,a]ial is r>ely us$ n[adays & may be consid]$ obsolete4 ,! ,umbrella ,a]ial is a v good type n[ be+ employ$ 9 _m high p[] /ations4 ,a metallic pole or ma/ insulat$ at ! base us$ to support ! wires1 s t x is "p ( ! a]ial itself4 ,! ,t ,a]ial is ! mo/ ne>ly p]fect & gives ! be/ all ar\nd results4 ,! ,l or ,horizontal type ( a]ial is us$ :]ev] x is desirable = any reason to s5d ! mo/ p[]ful waves 9 "o direction4 ,! ,v type is us$ :]e ! highe/ po9t mu/ be ne> ! /ation4 ,! wire lead+ into ! /ation1 f ! a]ial is call$ ! rat-tail or lead-94 ,x is always v c>efully insulat$ & usually ent]s ! /ation ?r\gh a hole 9 ! w9d[ or wall by means ( a w9d[ pane bu%+ or lead+-9 insulator4 ,c]ta9 a]ials possess a directive action1 t is !y radiate & receive messages 9 "s directions bett] ?an o!rs4 ,flat top a]ials possess ?is peculi>ity m noticeably ?an ! v]tical types4 ,flat top a]ials receive & radiate waves com+ f & go+ t[>ds a direction opposite to t 9 :i* ! free end po9ts4 ,illu/ration3 ,,fig4 #bi4 ,spiral ,a]ial4 ,! free end is ! opposite end to t to :i* ! rat-tail is connect$4 ,!re are two free ends on a ,t a]ial & s ?is =m radiates & receives its waves equally well 9 two directions4 ,! inv]t$ ,l & ,v types possess a v decid$ directive action4 ,c]ta9 a]ial =ms may be class$ z loop & /raightaway accord+ly z !y are connect$ & l$ into ! /ation4 ,9 ! /raightaway =m ( ant5na1 ! wires are connect$ toge!r z a :ole & "o rat-tail l$ into ! /ation4 ,9 ! loop =m ! wires are all connect$ toge!r & divid$ into two sections4 ,two wires are l$ into ! /ation4 ,! loop =m gives slightly bett] results 9 a %ort a]ial1 b 9 mo/ cases ! /raight away is decid$ly ! mo/ effici5t4 ,,lesson ,,f\rte54 ,,! ,,wireless ,,coil4 ,! induction coil us$ = wireless telegraph purposes diff]s f ! ord9>y coil commonly employ$ 9 ! laboratory 9 t x is usually built 9 a m sub/antial mann] & gives a heavi]1 m p[]ful dis*>ge f ! second>y4 ,induction coils ( ?is type are usually enclos$ 9 a /rong wood5 case fill$ ) insulat+ comp\nd & are sometimes t]m$ box coils4 ,!y are fitt$ ) an int]rupt] arrang$ to give a v long p]iod ( make & a %ort break4 ,coils giv+ sp>ks great] ?an six in*es 9 l5g? are usually provid$ ) an indep5d5t int]rupt] :i* may be "o ( sev]al types4 ,illu/ration3 ,fig4 #cj4 ,wireless ,sp>k ,coil4 ,! ord9>y indep5d5t int]rupt] consi/s ( ! usual =m ( int]rupt]1 b is op]at$ by ! magnetism ( a sep>ate electromagnet 9 place ( t ( ! coil prim>y itself4 ,an indep5d5t int]rupt] ( ?is type is usually provid$ ) screws = adju/+ ! spe$1 & ! duration ( make & break4 ,illu/ration3 ,,fig4 #ca4 ,indep5d5t ,int]rupt]4 ,! ,m]cury ,turb9e =m ( int]rupt] is a v unsuccessful type 9 :i* a /ream ( m]cury is made to play aga9/ a numb] ( saw-%ap$ metal tee?4 ,a spiral worm t]m9at+ 9 a nozzle-at ! top is rapidly revolv$ by an electric motor4 ,! l[] end ( ! tubul> worm dips into a m]cury res]voir s t :5 ! spiral is revolv$1 ! m]cury rises 9 ! tube by c5trifugal action & is ?r[n out f ! upp] end 9 ! =m ( a jet4 ,:5 ! revolv+ jet /rikes "o ( ! metal tee? ! circuit is made & :5 x passes betwe5 x is brok54 ,rais+ & l[]+ ! saw tee? s t ! m]cury /rikes ei!r ! l[] or upp] "p v>ies ! ratio ( "t ( ! make & break4 ,illu/ration3 ,,fig4 #cb4 ,electrolytic ,int]rupt]4 ,! electrolytic int]rupt] consi/s ( a ca?ode or negative electrode ( %eet lead imm]s$ 9 dilut$ sulphuric acid & an anode compos$ ( a piece ( plat9um wire plac$ 9 a porcela9 tube & project+ ?r\gh a small hole 9 ! bottom1 s t only a v small portion ( ! wire is expos$ to contact ) ! liquid4 ,:5 a /rong electric curr5t is pass$ ?r\gh ! acid electrolyte1 ! curr5t is v rapidly int]rupt$ by ! =mation ( gases on ! small plat9um electrode4 ,! numb] ( breaks p] second possible ) an electrolytic int]rupt] is extremely high4 ,a pot5tial ( at lea/ #dj volts is requir$ to op]ate su* an int]rupt]1 h[ev]4 ,,lesson ,,fifte54 ,,! ,,high ,,pot5tial ,,trans=m]4 ,! trans=m]1 l ! induction coil1 /eps up ! voltage ( ! curr5t to a value :]e x is suffici5t to *>ge ! cond5s]4 ,! trans=m] = wireless "w %\ld h a pot5tial ( f #ae1jjj to #dj1jjj volts4 ,sev]al manufactur]s claim advantage = l[ voltages & build ma*9es hav+ a pot5tial ( only ab\t #h1jjj volts1 b exp]im5ts h %[n t "u mo/ ord9>y conditions high] voltages p]mit great] range ( transmission4 ,bo? op5 & clos$ core ma*9es may be us$ ) good results4 ,probably1 h[ev]1 nei!r "o is ! be/4 ,! core ( a wireless trans=m] is built up ( %eet iron lam9ations to r$uce core losses & eddy curr5ts4 ,illu/ration3 ,,fig4 #cc4 ,high ,pot5tial ,clos$ ,core ,trans=m]4 ,illu/ration3 ,,fig4 #cd4 ,me?od ( ,protection aga9/ ,kick-,back ,! second>y w9d+s are v c>efully insulat$ ) empire clo? or pap] & may or may n be imm]s$ 9 oil accord+ly z !y are design$4 ,a trans=m]1 m especially ?an an induction coil1 produces a kick-back on ! l9e4 ,kick-back is a high pot5tial curr5t caus$ by ! c\nt] action ( curr5ts 9 ! cond5s] & a]ial sy/em1 due to ! fact t !y cont9ue to surge aft] ! curr5t has dropp$ to z]o or s l[ t x is unable ( its own accord to produce second>y curr5ts :i* w jump ! sp>k gap4 ,kick-back de/roys insulation & is liable to cause burn\ts ( o!r electrical in/rum5ts suppli$ f ! same sy/em4 ,x may be gu>d$ aga9/ by provid+ ! l9e ) a protective device :i* consi/s ( a cond5s] hav+ a capacity ( "o or two micro-f>ads plac$ directly across ! t]m9als ( ! trans=m] 9 s]ies ) two five-amp]e fuses4 ,a small sp>k gap op5 ab\t #a_/fd ( an in* wide is connect$ across ! t]m9als ( ! cond5s]4 ,9 case special protection is desir$ = "s in/rum5t 9 ! circuit1 su* z a met]1 a protective device %\ld be connect$ directly across its t]m9als4 ,,lesson ,,sixte54 ,,! ,,oscillation ,,cond5s]4 ,! ,oscillation ,cond5s] might almo/ be t]m$ ! mo/ important "p ( a wireless /ation4 ,transmitt+ ,cond5s]s usually take ! =m ( a batt]y ( ,leyd5 j>s arrang$ 9 a suitable case or conta9]4 ,v (t5 !y are plac$ 9 a tank ( oil to elim9ate bru% dis*>ges or leakage :i* takes place f ! edges ( ! t9foil4 ,illu/ration3 ,,fig4 #ce4 ,plate ,cond5s]4 ,leyd5 j>s are usually cov]$ ) v heavy t9foil or ?9 %eet copp] to prev5t bli/]+4 ,! be/ me?od1 h[ev]1 is to deposit a metallic cov]+ electrolytically4 ,! pr9ciple objection to ,leyd5 j>s is _! bulk4 ,glass plate cond5s]s are n s bulky or exp5sive & d n bli/]4 ,plate cond5s]s are sometimes m]ely plac$ 9 racks1 b m (t5 9 a tank ( oil to elim9ate all bru% dis*>ges4 ,cond5s]s are always made s z to be adju/able 9 ord] t ! capacity ( ! circuit may be c>efully regulat$4 ,only ! f9e/ select$ glass ( ! greate/ dielectric /r5g? is us$ 9 mak+ cond5s]s1 9 ord] to avoid all losses & possibility ( breakd[n4 ,:5ev] cond5s]s mu/ )/& a v heavy voltage1 !y may be connect$ 9 s]ies s t ! voltage is divid$ betwe5 !m & ! /ra9 is n s great4 ,?is me?od r$uces ! capacity j "o-half1 h[ev]1 & :5 us$ requires f\r times z _m plates or j>s1 z ! case may be1 ?an if !y 7 connect$ 9 "o multiple set4 ,,lesson ,,sev5te54 ,,! ,,helix4 ,! ,helix supplies ! great] "p ( ! inductance to ! clos$ circuit ( ! transmitt]4 ,x also acts z a trans=m]1 s]v+ to raise ! voltage ( ! curr5ts surg+ ?r\gh ! clos$ circuit & impress !m ^u ! a]ial sy/em4 ,! turns ( ! helix includ$ 9 ! clos$ circuit con/itute ! prim>y ( ! trans=m]1 :ile ^? 9 ! op5 circuit =m ! second>y4 ,a helix consi/s ( a heavy conductor1 ei!r brass or copp]1 wrapp$ ar\nd a suitable frame ( wood or h>d rubb]4 ,"s =ms consi/ ( a spiral ( copp] ribbon clamp$ betwe5 two cross-%ap$ frames4 ,illu/ration3 ,,fig4 #cf4 ,helix4 ,helixes are ( two k9ds1 kn[n z close or direct c\pl$ & loose or inductively c\pl$4 ,9 an inductively c\pl$ transmitt] ! prim>y & second>y are w\nd ^u sep>ate frames & are n connect$ toge!r4 ,! ,u4 ,s4 ,gov]nm5t ,radio regulations place a limit on ! am\nt ( damp+ p]missable 9 a transmitt]4 ,x has already be5 expla9$ 9 "o ( ! previ\s lessons h[ ! oscillations or surg+s ( ! sp>k dis*>ge rapidly die away4 ,a sp>k :i* ?us rapidly dies away is said to be rapidly damp$4 ,! damp+ ( a loose c\pl$ transmitt+ set is nev] z great z t ( a close c\pl$ set4 ,illu/ration3 ,,fig4 #cg4 ,a ,damp$ ,oscillation4 ,illu/ration3 ,close-,c\pl$ ,transmitt] vs4 ,loose-,c\pl$ ,transmitt] ,= ?is reason ! old /yle helixes are n[ practically obsolete & ! loose or inductively c\pl$ helix is ! "o mo/ commonly us$4 ,loose c\pl$ helixes are also (t5 t]m$ oscillation trans=m]s4 ,illu/ration3 ,,fig4 #ch4 ,an ,inductively ,c\pl$ ,helix4 ,an ord9>y transmitt] t5ds to emit two sets ( waves ( diff]5t l5g?4 ,by c>efully adju/+ ! c\pl+1 pure tra9s ( waves are =m$ by attract+ ! apices ( ! two sets ( waves into "o4 ,,lesson ,,eighte54 ,,sp>k ,,gaps4 ,a ,sp>k ,gap is ! m$ium across :i* ! oscillatory dis*>ge takes place4 ,x usually consi/s ( two electrodes ( z9c alloy1 nickel /eel or brass1 suitably m\nt$ on an insulat+ base & /&>ds4 ,illu/ration3 ,,fig4 #ci4 ,sp>k ,gap4 ,! electrodes are usually provid$ ) flanges or radiators :i* t5d to dissipate ! heat & keep !m cool4 ,if ! electrodes %\ld become v hot ! sp>k w\ld arc1 t is1 pass across ! gap )\t g5]at+ any electrical oscillations4 ,sp>k gap electrodes are usually flat or else holl[ on ! sp>k+ surface4 ,! prop] adju/m5t ( ! gap1 i4e41 ! di/ance betwe5 ! electrodes is a matt] ( ! utmo/ importance = !re is a po9t j :]e ! maximum am\nt ( en]gy w be radiat$4 ,illu/ration3 ,,fig4 #dj4 ,qu5*$ ,sp>k ,gap4 ,! ,qu5*$ ,gap1 consi/s ( a numb] ( brass or copp] disks plac$ 9 a pile1 ea* disk be+ sep>at$ f ! o!r by a ?9 mica r+4 ,! di/ance betwe5 two adjac5t disks is usually only ab\t 4#ja in*4 ,! effect ( ! qu5*$ gap is to consid]ably r$uce ! damp+ ( ! sy/em & make x possible to s5d signals v great di/ances ) ! consumption ( only comp>atively small am\nts ( en]gy4 ,illu/ration3 ,,fig4 #da4 ,rot>y ,sp>k ,gap4 ,! ,rot>y ,gap consi/s ( a numb] ( electrodes m\nt$ on a motor %aft & arrang$ to revolve rapidly4 ,! sp>k dis*>ge takes place betwe5 ! revolv+ electrodes & "o or two fix$ contacts4 ,! effect ( a rot>y gap is to consid]ably increase ! effici5cy ( ! transmitt] by all[+ ! cond5s] to become highly *>g$ be=e x dis*>ges & also r$uc+ ! possibility ( arc+ by keep+ ! electrodes cool & mov+4 ,rot>y gaps are ( two types1 syn*ron\s & non-syn*ron\s4 ,syn*ron\s rot>y gaps are m\nt$ directly on ! %aft ( ! g5]ator supply+ curr5t to ! transmitt] & arrang$ s t ! electrodes are opposite ea* o!r once dur+ ea* alt]nation ( ! curr5t4 ,! rot>y gap1 commonly us$ by amateur exp]im5t]s & consi/+ ( a too!d disk m\nt$ on ! %aft ( a small motor is ( ! non-syn*ron\s type4 ,rot>y gaps are sometimes enclos$ 9 an air tight case & ! electrodes arrang$ s t ! results obta9$ are *>act]i/ic ( bo? ! qu5*$ & rot>y gaps4 ,?is type ( gap is kn[n z ! rot>y qu5*$4 ,,lesson ,,n9ete54 ,,! ,,key4 ,"s means ( controll+ ! curr5ts fl[+ ?r\gh ! transmitt] 9 ord] to divide !m into p]iods correspond+ to ! dots & da%es ( ! ,morse ,code is necess>y4 ,?is is suppli$ by a h& op]at$ swit*1 call$ a key4 ,a key us$ = wireless purposes mu/ be mu* l>g] & heavi] ?an an ord9>y key employ$ = l9e "w 9 ord] to c>ry ! m p[]ful curr5ts4 ,9 spite ( ! size & weight ( a wireless key1 if x is prop]ly balanc$1 x may be h&l$ ) p]fect control & ease4 ,! contact po9ts ( a wireless key are necess>ily l>ge & heavy4 ,special alloys f\nd to be ! mo/ suitable = ! purpose are usually employ$4 ,a l>ge cond5s] hav+ a mica dielectric is v (t5 connect$ across ! contacts to r$uce ! sp>kl+4 ,illu/ration3 ,,fig4 #db4 ,wireless ,key4 ,9 v l>ge /ations :]e extremely heavy curr5ts mu/ be h&l$1 ! key controls a l>ge swit* op]at+ 9 oil4 ,e "t ! key is press$ ! swit* closes & :5 ! key is releas$1 op5s4 ,! curr5ts ( ! transmitt] are made & brok5 by ! swit* )\t pass+ ?r\gh ! key4 ,,lesson ,,tw5ty4 ,,a]ial ,,swit*es4 ,s9ce ! same a]ial is us$ bo? = transmitt+ & receiv+1 "s me?od ( quickly connect+ x to ei!r ! transmitt] or receiv+ app>atus mu/ be provid$4 ,?is is accompli%$ by means ( an a]ial swit*4 ,! be/ & mo/ effici5t swit* adopt$ g5]ally by ! comm]cial /ations is ! ,t type1 consi/+ ( a d\ble pole1 d\ble ?r[ swit* hav+ v long blades4 ,"o set ( contacts is m\nt$ on ! swit* base & ! second are c>ri$ on a ,t-%ap$ support f :i* ! swit* d]ives its "n4 ,! a]ial & gr\nd are connect$ to ! blades ( ! swit*4 ,! l[] contacts lead to ! transmitt+ app>atus & ! upp] ones to ! receiv+ in/rum5ts4 ,by simply mov+ ! swit* up or d[n ! a]ial & gr\nd may be connect$ to ei!r ! transmitt] or ! receptor at w4 ,illu/ration3 ,,fig4 #dc4 ,a]ial ,swit*4 ,a ?ird blade1 mu* %ort] ?an ! o!r two is usually provid$ & connect$ by means ( an insulat+ b> to ! o!r blades s t :5 !y are mov$ x also moves4 ,x connects ) a contact arrang$ s t :5 ! swit* is ?r[n into position = transmitt+ ! two come toge!r4 ,?is blade & contact are made a "p ( ! circuit supply+ curr5t to ! prim>y ( ! coil or trans=m] s t 9 case ! key %\ld be accid5tally t\*$ :ile receiv+ ! p[]ful dis*>ge ( ! transmitt] w\ld n de/roy ! adju/m5t ( ! detector4 ,,lesson ,,tw5ty-,,"o4 ,,an*or ,,gaps4 ,c]ta9 types ( a]ial swit*es require ! use ( :at is kn[n z an an*or gap4 ,an an*or gap consi/s ( a small insulat+ r+1 usually h>d rubb]1 hav+ two & sometimes ?ree electrodes set 9 ! p]iph]y & almo/ t\*+ ea* o!r at ! sp>k+ po9ts4 ,an*or gaps hav+ two electrodes are us$ 9 ! a]ial circuit ( mo/ ,break-9-,sy/ems to prev5t ! receiv+ curr5ts f fl[+ directly into ! gr\nd ?r\gh ! transmitt] )\t pass+ ?r\gh ! detector4 ,illu/ration3 ,,fig4 #dd4 ,an*or ,gaps4 ,a ,break-9 ,sy/em enables ! op]ator to he> ! signals ( any o!r /ation :i* may be transmitt+ at ! same "t :5 he is op]at+ 8 own key4 ,! ?ree-electrode an*or gap is commonly us$ on loop a]ial sy/ems4 ,two ( ! po9ts are connect$ to ! a]ial1 "o to ea* half & ! o!r to ! lead f ! helix4 ,! high pot5tial curr5ts f ! helix easily leap across ! little gap & divide betwe5 ! two halves ( ! a]ial4 ,,lesson ,,tw5ty-,,two4 ,,detectors4 ,! little bobb9s ( ! telephone receiv]s ex]t a v p[]ful *ok+ action ^u ! curr5ts ( high frequ5cy :i* effectually blocks _! passage & prev5ts !m f hav+ any action ^u ! receiv]4 ,! purpose ( ! detector is to *ange ^! curr5ts into su* z w fl[ readily ?r\gh ! magnets ( ! telephone receiv] & manife/ !mselves z s\nds recognizable f _! duration & p]iodicity z signals ( ! telegraph code4 ,illu/ration3 ,,fig4 #de4 ,electrolytic ,detector4 ,probably ! mo/ well kn[n =m is ! electrolytic detector :i* consi/s ( an exce$+ly f9e plat9um wire dipp+ into a cup ( dilute nitric acid f> en\gh to j t\* ! surface ( ! liquid4 ,! telephone receiv]s are connect$ to ! detector1 9 s]ies ) a batt]y4 ,! curr5t f ! detector causes bubbles to cont9u\sly =m on ! end ( ! wire & insulate x f ! liquid s t ! curr5t _c fl[4 ,:5 ! a]ial is /ruck by a wave1 ! feeble alt]nat+ curr5ts break d[n ! bubbles & p]mit ! curr5ts to fl[1 caus+ a s\nd 9 ! telephone receiv]s4 ,! detectors 9 mo/ common use to-day are ( ! cry/al or rectify+ type4 ,!re are a great _m diff]5t =ms ( ?is type ( detector1 ea* "o ( :i* possesses c]ta9 features mak+ x peculi>ly adaptable "u c]ta9 circum/ances4 ,illu/ration3 ,,fig4 #df4 ,silicon ,detector4 ,! silicon detector consi/s ( a flat surface ( highly poli%$ silicon ^u :i* re/s a brass po9t4 ,! ,pyron detector is compos$ ( a cry/al ( iron pyrites emb$d$ 9 a cup ( fusible metal4 ,a small wire spr+ be>s aga9/ ! surface ( ! cry/al4 ,! ,pyron detector is some:at h>d] to adju/ ?an o!r =ms ( cry/al detector1 b rema9s 9 a s5sitive condition mu* long]4 ,illu/ration3 ,,fig4 #dg4 ,p]ikon ,detector4 ,! ,p]ikon detector consi/s ( a cup ( fusible alloy 9 :i* are imb$d$ sev]al pieces ( a m9]al call$ z9cite4 ,ano!r cup conta9+ a fragm5t ( *alcopyrites or bornite is held 9 a cup c>ri$ on ! end ( a rotat+ rod4 ,! *alcopyrites is br\ght into contact ) "o ( ! cry/als ( z9cite & ! pressure adju/$ by means ( a spr+4 ,! ,p]ikon detector w op]ate )\t a batt]y1 b t latt] is necess>y 9 ord] to obta9 ! be/ results :5 receiv+ fa9t or f> away signals4 ,illu/ration3 ,,fig4 #dh4 ,gal5a ,detector4 ,! ,p]ikon ,electra detector is a v s5sitive =m ( ! regul> ,p]ikon detector fitt$ ) a micromet] adju/m5t4 ,! ,gal5a detector consi/s ( a cry/al ( t mat]ial to :i* contact is made by means ( a f9e wire spr+ ex]t+ v light pressure4 ,illu/ration3 ,,fig4 #di4 ,audion ,detector4 ,cry/al detectors act z rectifi]s & *ange ! alt]nat+ curr5ts ,into direct curr5ts1 :i* w pass ?r\gh ! telephone receiv]s4 ,m9]als us$ = ?is purpose are said to possess unilat]al conductivity1 t is1 !y conduct curr5ts bett] 9 "o direction ?an ! o!r & act mu* ! same z a valve :i* all[s wat] to fl[ 9 "o direction1 b n 9 ! o!r4 ,ano!r well kn[n detector ( ! valve type is t kn[n z ! ,audion1 consi/+ ( a small inc&esc5t lamp conta9+ a small grid & plate ( nickel4 ,:5 ! lamp is light$ by connect+ a batt]y to ! filam5t1 a fl[ ( ions pass+ f ! hot filam5t ?r\gh ! grid to ! plate is set up4 ,! grid & plate =m "p ( ! receiv+ circuit conta9+ ! telephones4 ,! fl[ ( ions c>ries ! oscillatory curr5ts f ! grid to ! plate1 b does n all[ !m to pass back aga94 ,9 ?is mann]1 ! alt]nat+ oscillatory curr5ts are conv]t$ into direct curr5ts1 :i* w pass ?r\gh ! telephone receiv]s4 ,illu/ration3 ,,fig4 #ej4 ,c>borundum ,detector4 ,! ,c>borundum detector1 z its "n implies1 is a device mak+ use ( ! unilat]al conductivity ( c>borundum4 ,?is =m ( detector is v s5sitive & has be5 employ$ = a numb] ( ye>s 9 all ! in/allations ( ! ,unit$ ,wireless ,telegraph ,co4 ,x consi/s ( a small cry/al ( c>borundum clamp$ tightly betwe5 two c>bon electrodes4 ,x may be us$ ) or )\t a batt]y4 ,! batt]y is pref]r$4 ,! ,magnetic detector is a v s5sitive device utiliz+ ! *anges 9 ! magnetic /ate ( iron1 :i* are caus$ by rapidly oscillat+ curr5ts4 ,if a core ( iron wires be plac$ 9 a v>y+ magnetic field1 ! magnetization ( ! iron w lag beh9d ! magnetiz+ =ce on acc\nt ( hy/]esis or magnetic friction4 ,illu/ration3 ,,fig4 #ea4 ,m>coni ,magnetic ,detector ,b if a rapidly oscillat+ curr5t is pass$ ?r\gh a coil surr\nd+ ! iron1 a sudd5 *ange 9 magnetization occurs1 suffici5t to induce an ,e4 ,m4 ,f4 9 a second coil surr\nd+ ! core & ?us op]ate a telephone receiv] 9 s]ies ) ?is coil4 ,! usual =m ( magnetic detector consi/s ( a belt ( f9e iron wires pass+ ov] two pulleys :i* are driv5 by clockwork4 ,a pair ( p]man5t magnets supply ! field :i* induces a cont9u\sly v>y+ magnetization 9 ! mov+ core4 ,! core passes ?r\gh ! c5tre ( a d\ble coil1 "o "p ( :i* is connect$ to ! telephone receiv]s & ! o!rs to ! a]ial & gr\nd4 ,,lesson ,,tw5ty-,,?ree4 ,,tun+ ,,coils4 ,! tun+ coil is a device consi/+ ( a l>ge numb] ( turns ( wire w\nd 9 ! =m ( a cyl9d] & provid$ ) "o or m slid+ contacts :i* c be br\ght into t\* ) any "o ( ! turns at w 9 ord] to increase or decrease ! electrical l5g? or p]iod ( ! circuit to suit ! incom+ waves4 ,illu/ration3 ,,fig4 #eb4 ,d\ble ,slide ,tun+ ,coil4 ,a circuit conta9+ a c]ta9 am\nt ( inductance1 capacity & resi/ance t5ds to oscillate at a c]ta9 frequ5cy4 ,!re=e1 ! oscillations 9 e transmitt+ set h a c]ta9 frequ5cy dep5d+ ^u ^! factors4 ,x is necess>y to adju/ ! receiv+ app>atus s t x possesses ! same frequ5cy z ! transmitt]4 ,! electro magnetic waves f ! transmitt+ /ation w /rike ! a]ial ( ! receiv+ /ation at a c]ta9 frequ5cy & induce curr5ce 9 x4 ,if ! receiv+ /ation is tun$ to ! same p]iod z ! transmitt] ea* wave w give a slight impulse to ! readily excit$ oscillations1 :i* w gr[ 9 int5sity j z small impulses giv5 to a p5dulum at ! "r times w make x sw+ viol5tly4 ,! purpose ( ! tun+ coil is to adju/ ! receiv+ circuit to ! same p]iod z t ( ! transmitt]4 ,tun+ coils are w\nd ( b>e copp] wire ov] a core compos$ ( a specially treat$ c>dbo>d tube4 ,! wires are spac$ ap>t s t !y d n t\* "o ano!r4 ,ei!r "o1 two or ?ree v>iable contacts or slid]s are provid$4 ,! coils are consequ5tly kn[n z s+le1 d\ble or ?ree slide tun]s4 ,a load+ coil is a supplem5t>y coil sometimes plac$ 9 s]ies ) ! regul> tun+ coil to give a great] inductance to ! circuit s t x may be giv5 a mu* l[] frequ5cy 9 ord] to receive waves ( great] l5g?4 ,,lesson ,,tw5ty-,,f\r4 ,,loose ,,c\pl]s4 ,a ,loose ,c\pl] or ,receiv+ ,trans=m] is a tun+ coil 9 :i* ! c\pl+1 z well z ! inductance1 is v>iable4 ,we h already expla9$ t an ord9>y transmitt+ set ?r[s (f two sets ( wave tra9s ( slightly diff]5t l5g?1 "o be+ some:at weak] ?an ! o!r4 ,illu/ration3 ,,fig4 #ec4 ,loose ,c\pl]4 ,! purpose ( ! loose c\pl] is n only to adju/ ! receiv+ set to ! p]iod ( ! transmitt] 9 ! mann] ( ! tun+ coil1 b by v>y+ ! c\pl+ to attract ! apices ( ! weak] tra9s ( waves to ! same apex z ! /rong] waves & s really create a pure wave out ( ! o!r two4 ,?is may be m easily und]/ood f ! accompany+ illu/ration :i* repres5ts diagrammatically a d\ble tra9 ( waves & a pure tra94 ,9 con/ruction1 ! loose c\pl] consi/s ( a prim>y w9d+ mu* ! same z an ord9>y tun+ coil provid$ ) a s+le slid]4 ,a second w9d+ call$ ! second>y1 divid$ into a numb] ( sections & adju/able by means ( a multi-po9t$ swit* m\nt$ on "o end1 slides 9 & out ( ! prim>y4 ,,lesson ,,tw5ty-,,five4 ,,fix$ ,,cond5s]s4 ,a fix$ cond5s] usually implies ! cond5s] us$ 9 ! receiv+ circuit to furni% "p ( ! necess>y capacity & to %unt ! telephone receiv]s1 or z 9 cases :]e a batt]y is us$ 9 connection ) ! detector to =ce ! curr5t to *oose a pa? ?r\gh ! comp>atively l[ resi/ance turns ( ! tun+ coil4 ,illu/ration3 ,,fig4 #ed4 ,fix$ ,cond5s]4 ,a fix$ cond5s]1 z its "n implies1 has a fix$ value or capacity4 ,x is usually con/ruct$ ( %eets ( t9foil int]pos$ betwe5 %eets ( ?9 p>aff9$ pap] or mica4 ,! capacity ( a fix$ cond5s] usually v>ies f 4#jjb to 4#jje micr(>ads4 ,an alt]nat+ curr5t passes readily ?r\gh a cond5s] b a direct curr5t is effectually block$4 ,:5 a direct curr5t is l$ into a cond5s] z %[n 9 ! diagram1 ! half ( ! cond5s] repres5t$ by ,a becomes positively *>g$4 ,:5 ,a receives a positive *>ge x repels ! positive *>ge f ,b & attracts ! negative ?us mak+ ,b negative4 ,!re is no *ange 9 ! direction ( ! curr5t aft] ! fir/ connection & ! *>ge rema9s fix$ & no curr5ts pass4 ,illu/ration3 ,,fig4 #ee4 ,if an alt]nat+ curr5t is appli$ to ! cond5s] :5 ,a receives a positive *>ge1 ,b becomes negative4 ,:5 ,a rev]ses & becomes negative ,b becomes positive4 ,?is process goes on1 ! two halves con/antly *ang+ _! *>ge ) ! result t ! curr5t cont9ues to fl[4 ,a fix$ cond5s] may occupy "o ( two places 9 a receiv+ circuit1 ei!r 9 s]ies ) ! tun+ coil & detector or directly across ! telephone receiv]s4 ,9 ! illu/ration ,a %[s a detector requir+ a batt]y ) a fix$ cond5s] 9 s]ies ) x & ! coil4 ,! oscillations set up 9 ! circuit by ! incom+ waves c readily pass ?r\gh ! cond5s] & effect ! detector because !y are alt]nat+4 ,if x 7 n = ! cond5s] ! direct batt]y curr5t w\ld pass ?r\gh ! tun+ coil in/ead ( ! detector because ( ! comp>atively l[ resi/ance ( ! =m]4 ,cry/al detectors d n require a batt]y & may be connect$ to a tun+ coil ) a cond5s] 9 s]ies & ! telephone receiv]s ei!r across ! t]m9als ( ! detector or across ! t]m9als ( ! cond5s]4 ,:5 9 ! latt] position1 ! prop] capacity = ! fix$ cond5s] w dep5d ^u ! resi/ance ( ! telephone receiv]s1 ! high] ! resi/ance ! less ! capacity t w be requir$ & vice v]sa4 ,,lesson ,,tw5ty-,,six4 ,,v>iable ,,cond5s]s4 ,! po9t ( %>pe/ resonance does n always happ5 to come on a turn ( ! tun] :]e x c be rea*$ by ! slid]4 ,! v>iable cond5s] makes x possible to adju/ ! circuit to ! exact po9t ( resonance4 ,illu/ration3 ,,fig #ef4 ,rot>y ,v>iable ,cond5s]4 ,v>iable cond5s]s are ( two g5]al types1 ! ,slid+ ,plate & ! ,rot>y ,v>iable4 ,! rot>y v>iable is ! mo/ conv5i5t & easy to manipulate4 ,x consi/s ( a numb] ( fix$ semi-circul> metal plates betwe5 :i* sw+s a set ( small] movable semicircul> plates4 ,! fix$ plates =m "o half ( ! cond5s] & ! movable plates ! o!r4 ,9 ?is way ! capacity ( ! cond5s] is v closely adju/able4 ,! movable plates are provid$ ) a po9t] mov+ ov] a graduat$ scale s t ! comp>ative am\nt ( capacity 9 ! circuit is indicat$4 ,! slid+ plate type ( cond5s] consi/s ( a numb] ( rectangul> fix$ plates betwe5 :i* slide a set ( movable plates4 ,! dielectric betwe5 ! plates ( a v>iable cond5s] is air4 ,!re are no losses ( en]gy due to hy/]esis 9 a cond5s] hav+ an air dielectric4 ,rot>y cond5s]s employ+ silk or "s su* mat]ial are n to be recomm5d$4 ,,lesson ,,tw5ty-,,sev54 ,,telephone ,,receiv]s4 ,telephone receiv]s employ$ = wireless telegraphy are ! same 9 pr9ciple z ! ord9>y telephone receiv] b diff] 9 con/ruction & detail slightly4 ,!y are always ( ! wat* case type1 ?is /yle be+ small & light1 & consi/ ( a r+ or horse%oe %ap$ p]man5t magnet ^u ! poles ( :i* are m\nt$ two small bobb9s conta9+ _m turns ( f9e insulat$ wire4 ,ov] ! magnets1 v close to b n q t\*+1 is plac$ a circul> diaphram ( ?9 %eet iron4 ,! l9es ( =ce creat$ by ! p]man5t magnet pass ?r\gh ! cores ( ! little bobb9 & ex]t a con/ant pull on ! diaphram4 ,! little bobb9s ( wire or electromagnets are connect$ 9 s]ies4 ,if a curr5t ( electricity is s5t ?r\gh !m !y w create a little field ( =ce ( _! own :i* w /r5g!n or decrease t ( ! p]man5t magnets accord+ 9 :i* direction ! curr5t fl[s4 ,ea* *ange 9 ! pull ex]t$ on ! diaphragm causes x to move & s5d out little s\nd waves :i* may be he>d :5 ! receiv] is held close4 ,we h already le>n$ t ! /r5g? ( a magnet dep5ds ^u ! amp]e turns4 ,suppose t a curr5t ( "o amp]e pass$ ?r\gh a coil conta9+ #ajj turns x #a amp4 #ajj amp]e turns4 ,if only "o-t5? ( an amp]e 0 available & we wi%$ to reta9 ! same magnetic /r5g? 9 ! coil1 ! numb] ( turns w\ld h to be increas$ to "o ?\s& 9 ord] = ! amp]e turns to rema9 equal2 #a_/aj amp4 x #a4jjj turns #ajj amp]e turns4 ,illu/ration3 ,,fig4 #eg4 ,types ( ,telephone ,head ,sets4 ,! curr5ts pass+ ?r\gh ! receiv] f ! detector are exce$+ly weak1 & s 9 ord] to produce ! maximum effect on ! diaphragm1 ! electromagnets mu/ be w\nd ) a l>ge numb] ( turns ( v f9e wire4 ,! resi/ance ( f9e wire is v great & = ?is reason wireless telephone receiv]s are usually t]m$ high resi/ance receiv]s4 ,w9d+ a receiv] ) _m turns ( f9e wire does n make x m s5sitive 9 ! true s5se ( ! ^w or f ! /&po9t ( effici5cy1 b makes x bett] suit$ to ! m9ute fluctuations ( a weak curr5t4 ,! classification ( receiv]s1 accord+ to _! resi/ance is a me?od ( indicat+ ! comp>ative numb] ( turns & ! f9ess ( ! wire us$ 9 w9d+ ! electromagnets4 ,receiv]s %\ld be w\nd ) copp] wire only4 ,wireless receiv]s come 9 pairs provid$ ) a head-b& s t !y may be securely clamp$ on ! e>s4 ,! receiv] cases are made ( rubb]1 composition1 brass & alum9um dep5d+ ^u ! design & manufacture4 ,x is immat]ial :i*4 ,,lesson ,,tw5ty-,,eight4 ,,! ,,hot ,,wire ,,ammet]4 ,! hot-wire ammet] is a device = indicat+ :5 ! transmitt+ circuits are prop]ly adju/$ & arrang$ to emit ! maximum am\nt ( en]gy4 ,x is plac$ 9 s]ies 9 ! a]ial circuit s t ! high frequ5cy curr5ts surg+ 9 ! latt] mu/ pass ?r\gh ! met] & indicate _! /r5g? by mov+ ! po9t] a c]ta9 di/ance ov] a graduat$ scale4 ,:5 a curr5t ( electricity fl[s ?r\gh a wire x develops a c]ta9 am\nt ( heat !re94 ,if ! wire is ( high resi/ance ! heat w be great en\gh to cause ! wire to exp&4 ,advantage has be5 tak5 ( ?is fact 9 ! con/ruction ( ! hot-wire ammet]4 ,?is device consi/s ( a piece ( plat9um wire or a plat9um alloy /ret*$ taut betwe5 two po/s4 ,! wire is includ$ 9 ! a]ial circuit4 ,! plat9um wire is connect$ to a sp9dle c>ry+ a po9t] 9 su* a mann] t :5 ! heat causes ! wire to exp& ! expansion is convey$ to ! sp9dle & ! po9t] moves ov] ! scale magnify+ ! motion4 ,! great] ! curr5t fl[+ ?r\gh ! wire ! great] w be ! deflection ( ! po9t]4 ,! scale is calibrat$ by comp>ison ) a /&>d met] to read 9 amp]es4 ,illu/ration3 ,,fig #eh4 ,diagram %[+ ! ,con/ructive ,pr9ciple ( a ,hot ,wire ,ammet]4 ,:5 a hot-wire ammet] is plac$ 9 circuit ! latt] is tun$ by mov+ ! position ( ! helix clips on ! helix1 alt]+ ! l5g? ( ! sp>k gap & ! cond5s] capacity until ! maximum deflection is indicat$4 ,x is !n remov$ f ! circuit4 ,,lesson ,,tw5ty-,,n9e4 ,,pot5tiomet] ,! pot5tiomet] is an in/rum5t = c>efully regulat+ ! voltage ( ! batt]y supply+ a detector ( ! electrolytic or c>borundum types ) curr5t4 ,x is necess>y to br+ ! pot5tial ( ! batt]y to a c]ta9 critical po9t :]e x is j insuffici5t to break d[n ! detector1 t is1 ov]come ! resi/ance :i* x (f]s to ! oscillatory curr5ts4 ,9 con/ruction1 ! pot5tiomet] usually consi/s ( a small rod w\nd ) ,g]man silv] wire & provid$ ) an adju/able contact4 ,graphite resi/ance rods are m]ely a *eap me?od ( mak+ a pot5tiomet] & are to be avoid$ z entirely unsatisfactory = ! purpose4 ,illu/ration3 ,,fig4 #ei4 ,pot5tiomet]4 ,,lesson ,,?irty4 ,,dead ,,end ,,losses ,,& ,,no ,,dead ,,end ,,swit*es4 ,practically e radio circuit includes an adju/able inductance ( "s sort1 usually consi/+ ( a lay] ( wire w\nd ov] a tube & arrang$ s t ! am\nt ( wire 9 ! circuit c be v>i$ by means ( a swit*1 a plug or a slid]4 ,^! me?ods ( v>iation are famili> 9 ! ord9>y tun+ coil1 loose c\pl]1 load+ coil1 etc4 ,illu/ration3 ,,fig4 #fj4 ,diagram repres5t+ ! effect ( ,di/ribut$ ,capacity4 ,if ! plug1 swit* or slid+ contact1 dep5d+ ^u ! me?od ( v>iation employ$1 is at ,e z 9 ,fig4 #fj s t only ! portion ( ! coil ,a ,e ,b is 9 ! circuit1 !n ! portion ,e ,f toge!r ) ,a ,e may =m an oscillator :i*1 9 ord] = ! read] to obta9 a bett] conception1 may be lik5$ to a sort ( second>y w9d+1 ) ,a ,e consid]$ z ! prim>y4 ,! oscillations ( ?is "p ( ! sy/em may produce "s v undesirable di/urbances1 especially s :5 ! frequ5cy ( ! curr5ts 9 ! circuit ,a ,e be> a c]ta9 relation to ! natural frequ5cy ( ! oscillator or ,e ,f4 ,! losses due to ! di/urbance ( ^! undesirable oscillations & also ^? result+ f eddy curr5ts induc$ 9 ! free portion or oscillator ,e ,f by ! magnetic flux ( ,a ,e are kn[n z dead-end effects4 ,^! losses are v mu* m noticeable 9 receiv+ circuits ?an 9 transmitt]s on acc\nt ( ! v weak curr5ts 9 ! =m] & ! importance ( pres]v+ all ! en]gy :5 x is already v small4 ,dead end losses take place pr9cipally 9 receiv+ trans=m]s1 load+ coils & tun+ coils4 ,! losses are mu* m m>k$ on %ort waves ?an long waves4 ,! pres5ce ( ^! highly objectionable losses1 & !y are l>ge en\gh to n only s]i\sly decrease ! /r5g? ( signals b also to make selective tun+ impossible1 may be avoid$ by only us+ coils :i* are j ! "r size s t !y c be entirely includ$ 9 ! circuit4 ,?is is a v easy matt] :5 only "o wave l5g? or at ! mo/1 two or ?ree wave l5g?s are to be receiv$1 because x is !n easily possible to quickly connect ! coil ( ! prop] size 9 ! circuit4 ,x is desirable h[ev] 9 mo/ /ations1 & especially s 9 amateur /ations t ! app>atus be univ]sal s z to be quickly & easily tunable to any wave l5g? )9 its range4 ,_m amateurs build l>ge loose c\pl]s hav+ a v wide wave l5g? range "u ! impression t !y h an ideal in/rum5t4 ,! tru? ( ! matt] is h[ev] t su* an arrangem5t is decid$ly ineffici5t especially on ! %ort] waves :5 only a portion ( ! w9d+s are 9 circuit & !re is a l>ge dead end portion4 ,! bett] types ( receiv+ trans=m]s are n[ provid$ ) no dead end loss swit*es :i* automatically break ! w9d+s up into a numb] ( gr\ps s t only t portion :i* is actually requir$ to tune ! circuit to a c]ta9 wave l5g? is 9 circuit & ! rema9d] ( ! coil is entirely disconnect$4 ,^! swit*es are locat$ at c]ta9 def9ite po9ts z previ\sly det]m9$ by measurem5ts ( ! coil ) ! aid ( a wave met]4 ,illu/ration3 ,,fig4 #fa4 ,diagram expla9+ h[ end losses are elim9at$ ,! diagram 9 ,fig4 #fa illu/rates ! pr9ciple ( su* an arrangem5t4 ,! po9ts m>k$ #a1 #b & #c are ! places 9 ! coil :]e ! swit*es are locat$ s z to divide ! w9d+ up into sep>ate p>ts4 ,suppose t x is necess>y to move ! slid] or swit* to su* a po9t on ! coil z repres5t$ by its position 9 ! illu/ration m>k$ ,e4 ,! swit* locat$ at #a w\ld !n automatically close z ! slid] or swit* mov$ pa/ #b & #c w\ld h[ev] /ill rema9 op5 because t "p ( ! w9d+ :i* !y connect w\ld n be requir$4 ,if x became necess>y to include m ( ! w9d+ 9 ! circuit1 #b & #c w\ld automatically close z ! slid] or swit* 0 mov$ along ! coil & op5 aga9 z x 0 mov$ back4 ,! automatic arrangem5t ( ! swit*es is easily accompli%$ 9 a numb] ( diff]5t mann]s by means ( lev]s1 cams1 trips1 or "s o!r me*anical means4 ,,lesson ,,?irty-,,"o4 ,,di/ribut$ ,,capacity ,,& ,,capacity ,,losses4 ,e coil ( wire possesses ! prop]ty1 n only ( c>ry+ a curr5t ( electricity b ( hold+ a *>ge ( electricity z well4 ,?is prop]ty is call$ capacity4 ,! capacity ( a cond5s] is its prop]ty = hold+ a *>ge ( electricity4 ,! capacity ( a coil is t]m$ its di/ribut$ capacity 9 ord] to di/+ui% x f ! capacity ( a cond5s]4 ,! di/ribut$ capacity ( a coil is due to ! cond5s] effect :i* exi/s betwe5 ! adjac5t turns ( ! wire4 ,! effect ( ?is di/ribut$ cond5s] is exactly ! same z if a small cond5s] 0 connect$ across ! ends ( ! coil z %[n 9 ! accompany+ illu/ration4 ,di/ribut$ capacity is v objectionable 9 mo/ receiv+ circuits because a radio detector dep5ds ^u voltage = its op]ation & :5 a circuit conta9s an appreciable am\nt ( di/ribut$ capacity ! voltage is consid]ably l[] ?an x w\ld be o!rwise4 ,! usual me?od ( r$uc+ ! di/ribut$ capacity ( a coil is to use wire hav+ comp>atively ?ick insulation s t ! wires are spac$ f>!r ap>t4 ,c]ta9 %ellacs & v>ni%es us$ 9 impregnat$ w9d+s increase ! specific dielectric capacity ( ! space betwe5 ! turns & increase ! di/ribut$ capacity ( ! w9d+4 ,! same objection to di/ribut$ capacity also holds good 9 ! case ( :at might be t]m$ capacity losses :i* are due to improp]ly arrang$ connections1 contact po9ts1 etc4 ,e pair ( leads or taps f a coil possesses capacity4 ,!y really =m a m9iature cond5s]1 ! wires correspond+ to ! t9foil or metal %eets ( ! cond5s] & ! air betwe5 be+ ! dielectric4 ,= t reason ! leads %\ld always be z f> ap>t f "o ano!r z possible & contact po9ts %\ld be z small z possible4 ,x is unwise to use d\ble conductor hav+ two p>allel conductors b\nd toge!r = lead+ out connections or connect+ radio app>atus4 ,if capacity losses & di/ribut$ capacity are r$uc$ to a m9imum 9 a circuit1 x is possible to employ m inductance ?an w\ld be o!rwise 9 ord] to tune ! circuit to a c]ta9 frequ5cy & ! voltage is !reby pres]v$ & full b5efit d]iv$ !refrom by ! *anges :i* x produces 9 ! detector4 ,,lesson ,,?irty-,,two4 ,,! ,,p\ls5 ,,arc ,,or ,,g5]ator4 99,me?od ( ,produc+ ,undamp$ ,oscillations = ,radio ,telegraphy & ,telephony499 ,a radio transmitt] ^: waves are g5]at$ by undamp$ oscillations has _m advantages ov] ! ord9>y sp>k transmitt]1 ! oscillations ( :i* are necess>ily damp$4 ,! effici5cy ( an undamp$ wave transmitt] is f> great] 9 almo/ e respect4 ,! selectivity at a receiv+ /ation li/5+ to undamp$ wave signals is v m>k$ 9 comp>ison to t :5 sp>k signals are receiv$4 ,! problem ( produc+ undamp$ oscillations by means ( an arc 0 fir/ solv$ by ,p\ls5 & is kn[n z ! ,p\ls5 arc or g5]ator4 ,?is type ( g5]ator is us$ = radio "w 9 ?is c\ntry1 by ! ,f$]al ,telegraph ,co41 9 ! /ations at ,sayville & ,tuck]ton1 9 _m ,u4 ,s4 ,naval /ations & on bo>d all ! ,u4 ,s4 fir/ l9e battle%ips4 ,illu/ration3 ,,fig4 #fb4 ,! ,p\ls5 ,arc = g5]at+ ,undamp$ ,oscillations4 ,an arrangem5t by :i* su* oscillatory curr5ts may be produc$ is %[n 9 its simple/ =m 9 ,fig4 #fb4 ,x consi/s ( an arc1 ar\nd :i* is %unt$ a cond5s] 9 s]ies ) an inductance4 ,! arc is connect$ to a s\rce ( direct curr5t1 pref]ably hav+ an ,e4 ,m4 ,f4 ( #ejj volts or m4 ,! positive electrode ( ! arc is copp]1 kept cool by circulat+ wat] ?r\gh a holl[ int]ior or a wat] jacket4 ,! gap 9 itself is enclos$ 9 a *amb] fill$ ) hydrog5 gas or a gas conta9+ hydrog54 ,! arcs 9 practical use = g5]at+ undamp$ oscillations are arrang$ s t !y op]ate 9 a /rong magnetic field4 ,! c>bon electrode is con/ruct$ s t x is sl[ly revolv$ by a small electric motor4 ,! hydrog5 gas atmosph]e 9 :i* ! arc is enclos$ is produc$ by a small fe$ cup1 simil> to ! ord9>y lubricat+ oil cup1 locat$ ov] ! case & fill$ ) alcohol :i* cont9u\sly drips into ! flame *amb]1 :]e x is vaporiz$ by ! heat4 ,arc transmitt]s ( l>ge capacity are n z exp5sive or z bulky z sp>k transmitt]s ( equal p[]4 ,! difficulties ( h&l+ & controll+ a l>ge am\nt ( p[] 9 connection ) a transmitt] ( ?is sort are also n z great z 9 ! case ( a sp>k transmitt]4 ,! cond5s] us$ ) an arc is n ne>ly s l>ge z t requir$ = a sp>k transmitt] ( equal capacity & ! voltage ( ! curr5t is mu* l[]4 ,cond5s] breakd[n1 leakage & insulation problems are !re=e n z great4 ,= telegraph+ ) damp$ transmitt]s1 a key :i* alt]nately makes & breaks ! prim>y circuit is suffici5t4 ,?is is n possible1 h[ev]1 ) an arc4 ,! di/ance betwe5 ! arc electrodes is usually great] ?an ! gap l5g? :i* ! dynamo voltage w\ld jump & =m an arc :5ev] ! key %\ld be clos$4 ,x is !re=e usual to arrange a key or relay s t x %ort circuits a portion ( ! a]ial inductance or helix :5 clos$4 ,?is %ort circuit is suffici5t to ?r[ ! circuit out ( tune s t x _c be he>d at ! receiv+ /ation )\t readju/+ ! in/rum5ts4 ,! ,p\ls5 arc may be us$ = radio telephony4 ,a telephone receiv] is arrang$ s z to v>y ! curr5ts & impress ! vibrations ( ! voice ^u ! oscillations set up by ! arc4 ,,lesson ,,?irty-,,?ree4 ,,receiv+ ,,undamp$ ,,waves4 ,,! ,,tick]4 ,a decid$ diff]5ce is enc\nt]$ betwe5 damp$ & undamp$ oscillations :5 receiv+ signals4 ,! ord9>y detector _c be us$ = receiv+ undamp$ oscillations )\t fir/ be+ prop]ly modifi$4 ,:5 telegraph+ ! dots & da%es ( ! code by undamp$ oscillations ! *ange tak+ place 9 ! detector circuit w\ld m]ely move ! telephone receiv] diaphragm f its normal position at ! beg9n+ ( ea* dot or da%1 caus+ a click to be he>d & no?+ m4 ,! telephone receiv] diaphragm w\ld rema9 9 a fix$ position j z long z ! waves f ! transmitt] kept com+ 9 dur+ ea* signal4 ,bo? dots & da%es w\ld be he>d simply z clicks & n appe> di/+ui%able f "o ano!r4 ,! mo/ common & p]haps also ! be/ me?od is to employ a device call$ a tick] 9 place ( ! detector = receiv+ undamp$ oscillations4 ,?is arrangem5t is illu/rat$ 9 ,fig4 #fc4 ,! left h& "p ( ! illu/ration is ! circuit diagram4 ,a detail ( ! tick] :eel is %[n at ! "r4 ,! cond5s] ,f ,c is ( comp>atively l>ge capacity & is fix$4 ,! cond5s] ,c is also fix$ b is ( mu* small] capacity4 ,f ,c is usually a cond5s] hav+ a capacity ( sev]al t5?s ( a micr(>ad :ile ,c has only a few ?\s&s ( a micr(>ad capacity4 ,illu/ration3 ,,fig4 #fc4 ,! ,p\ls5 ,tick] = receiv+ undamp$ ,waves4 ,t is ! tick] :eel & consi/s ( a small brass :eel hav+ a groove 9 ! p]iph]y l a pulley4 ,?is :eel is m\nt$ on ! %aft ( a small motor s t x c be revolv$ at high spe$4 ,a f9e wire is arrang$ to rub aga9/ ! groove 9 ! :eel & make contact ) ! latt]4 ,:5 ! :eel is revolv+ at high spe$1 ! wire does n make p]fect contact at all po9ts b t5ds to vibrate & to act z ! equival5t ( a v high spe$ int]rupt] by rapidly op5+ & clos+ ! circuit4 ,! basic idea 9 employ+ a device & a circuit ( ?is sort 9 receiv+ undamp$ waves is z foll[s3 ,:5 ! contact is brok5 at ! tick] :eel & ! cond5s] ,f ,c is disconnect$ f ! oscillat+ circuit =m$ by ! cond5s] ,c & ! second>y ( ! receiv+ trans=m]1 ! cond5s] ,c accumulates a relatively l>ge am\nt ( en]gy4 ,!n :5 ! tick] connects ! cond5s] ,f ,c 9 p>allel ) ,c1 ,f ,c takes ! major "p ( ! /or$ en]gy & dis*>ges x ?r\gh ! telephones ,p1 caus+ a click to be he>d 9 ! latt]4 ,! int]ruptions ( ! tick] are v rapid1 a great _m tak+ place dur+ ! duration ( a dot or a da%1 s t ! resultant clicks occur v close toge!r & ! dots & da%es s\nd v simil> to ! sp>k signals ( a transmitt] s5d+ =? damp$ waves4 ,! s5sitiv5ess ( ! tick] arrangem5t is v great1 9 fact mu* great] ?an t ( any detector4 ,,lesson ,,?irty-,,f\r4 ,,! ,,audion ,,amplifi]4 ,! audion amplifi] is an arrangem5t :]eby an ,a audion bulb su* z t :i* has already be5 describ$ 9 ! ,lesson on ,detectors is s connect$ t x acts z a relay & also amplifies m9ute pulsat+ electric impulses4 ,an ord9>y audion detector bulb w s]ve z an amplifi] bulb b x is usual to modify x some:at & provide a grid & a w+ on bo? sides ( ! filam5t z ?is arrangem5t gives ! be/ results4 ,! audion amplifi] is ( especial advantage 9 amplify+ weak wireless signals f a detector :i* w\ld o!rwise be unreadable4 ,x is n necess>y t ! audion amplifi] be us$ 9 connection ) ano!r audion s]v+ z a detector4 ,x w amplify ! signals ( any o!r =m ( detector su* z an electrolytic1 cry/al1 magnetic1 etc4 ,illu/ration3 ,,fig4 #fd4 ,! ,audion ,amplifi] ,circuit4 ,figure #fd %[s an audion amplifi] connect$ to an audion amplifi] connect$ to an audion detector s t ! signals f ! latt] w be greatly increas$ 9 /r5g?4 ,l ,c is a loose c\pl] connect$ to ! a]ial & gr\nd 9 ! ord9>y mann]4 ,p & ,s are respectively ! prim>y & second>y ( ! loose c\pl]4 ,b is ! w+ batt]y ( ! detector circuit & ,b is ! w+ batt]y ( ! amplifi] circuit4 ,t is ! telephone receiv] headset 9 :i* ! amplifi$ signals are he>d4 ,p & ,s are ! prim>y & second>y ( a small op5 core trans=m] call$ ! ,amplifi] ,coil4 ,! w9d+s conta9 a great _m turns ( v f9e wire4 ,! prim>y ( ! trans=m] is connect$ s z to be includ$ 9 ! w+ circuit ( ! detector4 ,x %\ld be notic$ t only "o t]m9al ( ! second>y is connect$ to ! amplifi] circuit1 ?is "o t]m9al be+ connect$ to ! grid ( ! amplifi] bulb4 ,an arrangem5t ( ?is sort1 :]e "o amplifi] bulb is us$ is call$ a "o /ep amplifi]4 ,amplifi]s hav+ two & ?ree bulbs1 respectively kn[n z two /ep & ?ree /ep amplifi]s give mu* great] amplification ?an a "o /ep amplifi] & are (t5 us$4 ,,lesson ,,?irty-,,five4 ,,hook-,,ups4 99,or ,me?ods ( ,connect+ ! ,in/rum5ts499 ,hook-ups or circuit diagrams %[+ ! mann] ( connect+ v>i\s in/rum5ts are well wor? consid]able /udy if "o is desir\s ( secur+ ! greate/ selectivity & di/ance f 8 app>atus4 ,!re are almo/ an endless numb] ( ways & comb9ations ( ways ( connect+ app>atus1 & /range to say1 diff]5t p seem to be able to secure ! be/ results ) widely diff]5t me?ods4 ,9 spite ( ! fact t circuits ( ?is k9d are v num]\s !y c all be r$uc$ to a few fundam5tal =ms & an und]/&+ ( ^! =ms w enable a p]son to devise 8 own hook-ups at w4 ,transmitt+ circuits are fundam5tally almo/ ! same4 ,! only real diff]5ce 9 arrangem5t is made by int]*ang+ ! cond5s] & sp>k gap4 ,ei!r "o may be plac$ across ! t]m9als ( ! induction coil or trans=m]4 ,!re is no diff]5ce 9 ! results4 ,illu/ration3 ,,fig4 #fe4 ,consid] ! circuit %[n 9 ! accompany+ illu/ration4 ,! action ( ! trans=m] is to *>ge ! cond5s] to su* a po9t t ! voltage is suffici5t to leap ! sp>k gap & cause a dis*>ge4 ,! ru% ( curr5t :i* is oscillatory takes place ?r\gh ! cond5s]1 sp>k gap & prim>y turns ( ! helix1 or 9 o!r words ?r\gh ! clos$ circuits4 ,! second>y turns ( ! helix1 :i* are ^? =m+ "p ( ! a]ial circuit1 are l>g] 9 numb] ?an ^? ( ! prim>y1 & because ( ?is ratio cause curr5ts ( high] voltage ?an ^? ( ! cond5s] to be impress$ ^u ! a]ial sy/em4 ,! curr5ts 9 ! a]ial sy/em surge up & d[n ! a]ial ?r\gh ! helix into ! gr\nd4 ,illu/ration3 ,,fig4 #ff4 ,receiv+ ,circuits4 ,a %[s a simple receiv+ circuit :]e9 a s+le slide tun+ coil is connect$ to a detector4 ,! high frequ5cy curr5ts g5]at$ 9 ! a]ial surge up & d[n ! sy/em & pass ?r\gh ! detector on _! way to ! gr\nd4 ,by mov+ ! slid] back & =? ! electrical l5g? ( ! circuit may be v>i$ to suit ! l5g? ( ! incom+ waves4 ,oscillations may be =c$ ^u su* a circuit1 t is1 if ! waves are v p[]ful !y w pass ?r\gh ! sy/em & effect ! detector no matt] :e!r ! slid] is adju/$ to suit !m or n4 ,?is w\ld cause int]f]5ce & confusion 9 case m ?an "o /ation 7 op]at+ at a "t4 ,by add+ a second slid] & a cond5s] z %[n 9 ,b1 ?is may be avoid$ to a consid]able ext5t1 = slid] ,no4 #a may be adju/$ to ! desir$ signals & slid] ,no4 #b plac$ 9 a position su* z w give ! bran* ( ! circuit f ! a]ial1 ?r\gh ! coil & into ! gr\nd ( :i* x is a "p1 a p]iod suit$ to ! objectionable wave & s c>ry (f ! latt] into ! gr\nd )\t effect+ ! detector4 ,! desir$ signals w pass into ! gr\nd ?r\gh ! o!r bran* ( ! circuit & op]ate ! detector :i* lies 9 _! pa?4 ,! selectivity ( ! outfit may be fur!r increas$ by ! addition ( a v>iable cond5s]4 ,a v>iable cond5s] may be plac$ 9 "o or m ( a great _m positions4 ,! accompany+ illu/rations %[ sev]al4 ,! effect ( a cond5s] plac$ 9 s]ies ) ! gr\nd or a]ial is j ! opposite ( t ( a load+ coil4 ,x decreases ! p]iod & %ort5s ! wave l5g? to :i* x is adapt$4 ,! ,amateur's ,wireless ,h&y ,book %[s ov] "o hundr$ wir+ diagrams />t+ f ! simple/ & go+ to ! mo/ complicat$ 9 a natural sequ5ce4 ,any ( ! ,foll[+ ,practical ,books 99w be s5t ,at ,once1 ,po/-paid on receipt ( price499 ,!re is v little dang] ( los+ curr5cy 9 a lett] if ! foll[+ directions are obs]v$3 ,cut a circul> hole ! diamet] ( ! co9 9 a piece ( c>dbo>d1 ( suffici5t size to fit closely 9 ! envelope4 ,! c>dbo>d %\ld be no ?ick] ?an ! co94 ,ins]t ! co9 9 ! hole & pa/e a piece ( pap] on bo? sides ( ! c>dbo>d to prev5t ! co9 f fall+ out4 ,,cole ,,morgan ,publi%]s ( ! ,arts & ,sci5ces ,s]ies ,p4 ,o4 ,box #adgc ,new ,york1 ,n4 ,y4 99,! ,boy ,electrician99 ,practical ,plans = ,electrical ,toys & ,app>atus1 ) an ,explanation ( ! ,pr9ciples ( ,ev]yday ,electricity4 99,by ,,alfr$ ,p4 ,,morgan499 ,au?or ( ,wireless ,telegraph ,con/ruction = ,amateurs & ,wireless ,telegraphy & ,telephony1 etc4 99,) full-page ,illu/rations & #cbd ,work+ ,draw+s & ,diagrams99 99by ! au?or4 #hvo41 ,clo?1 ,net ,price1 #b4jj499 ,?is is ! age ( electricity4 ,! mo/ fasc9at+ ( all books = a boy mu/ !re=e be "o deal+ ) ! my/]y ( ?is anci5t =ce & mod]n wond]1 ev5 a m]e li/ ( ^: s]vices is impossible4 ,! be/ qualifi$ ( exp]ts to in/ruct boys1 ,alfr$ ,p4 ,morgan1 has 9 a book f> sup]ior to any o!r ( its k9d told n only h[ to make all k9ds ( motors1 telegraphs1 telephones1 batt]ies1 etc41 & to d s economically1 b has expla9$ ! pr9ciples ^u :i* ^! dep5d = op]ation1 & h[ ! same ?+ is done 9 ! e-day _w be well pres5t$ & s attractive is ?is really great book t x w be an education = any bright boy to h x1 z well z ! be/ k9d ( a moral safegu>d1 by leav+ no "t or ?\ght = evil1 & a means ( future b5efit beyond ! p[] ( any "o to reckon4 ,glanc+ ov] ! pages ( ?is book1 "o _c b be impress$ by ! excell5t illu/rations1 cle>ness ( expression & ! l>ge numb] ( subjects t are cov]$4 ,x is beyond d\bt ! be/ book 9 ?is l9e t has ev] be5 writt5 or publi%$4 ,x is a book t w delight e boy :o has a lean+ t[>ds electrical exp]im5ts4 ,! au?or writes 9 a cle> & *atty /yle & :ile he has a ?or\gh te*nical k ( 8 subject he has succe$$ 9 treat+ x 9 a simple mann] s t x is readily intelligible to 8 "y read]s4 99,among ! ,*apt] ,head+s & ,cont5ts are399 ,magnets & ,magnetism--,/atic ,electricity--,/atic ,electric ,ma*9es--,cells & ,batt]ies--,electro-,magnetism & ,magnetic ,induction--,electrical ,units--,electrical ,appurt5ances--,electrical ,measur+ ,in/rum5ts--,bells1 ,al>ms & ,annunciators--,electric ,telegraphs--,microphones & ,telephones--,induction ,coils--,trans=m]s--,wireless ,telegraphy--,wireless ,telephony--,electric ,motors--,dynamos--,an ,electric ,railway--,m9iature ,light+--,miscellane\s ,electrical ,app>atus4 99,,read ,,:at ,,has ,,be5 ,,said ,,( ,,x499 ,ev5 a casual glance ?r\gh ! _m pages ( ! book does n fail to emphasize ! fact t ,mr4 ,alfr$ ,p4 ,morgan has inde$ succe$$ well 9 giv+ ! juv5ile electricians a "w t has long be5 s\ght4--,popul> ,electricity4 ,we h no hesitation 9 comm5d+ ! book to ! att5tion ( ! juv5ile audi5ce = :i* x is int5d$4--,bo/on ,po/4 ,a great book = ent]pris+ boys4 ,bright boys w highly appreciate x & feel l ?ank+ ! wideawake publi%]s = putt+ su* a reliable & int]e/+ "w 9 ! field4--,new ,hav5 ,j\rnal4 ,! book cov]s ! subject ( electricity ?or\ghly 9 all its phases & is a spl5did acquisition to any boy's libr>y4--,detroit ,times4 ,9 ?is age ( electricity a book l ! pres5t "o is bo? fasc9at+ & valuable especially to boys4 ,! book is attractive ) its _m illu/rations & w prove ( mu* educational value = any bright boy4--,zion's ,h]ald4 ,?is is an admirably complete & explicit h&book = "y boys :o fall "u ! spell ( t9k]+ ) electrical app>atus4--,bo/on ,transcript4 ,well pres5t$ & attractive ?is book w be a s\rce ( great b5efit & delight = any bright boy4--,new ,orleans ,times-,picayune4 99,price1 #b4jj1 ,po/paid99 ,,c\ntless ,,o!r ,,magaz9es1 ,,newspap]s ,,& ,,libr>ies ,,h ,,endors$ ,,?is ,,great ,,book4 ,,s5d ,,= ,a ,,copy ,,n[4 99,if y are int]e/$ 9 ?is great book1 write = our #h-page special99 99descriptive circul>499 99,wireless ,telegraphy & ,telephony ,simply ,expla9$99 ,by ,,alfr$ ,p4 ,,morgan4 99,a ,,new ,,book by ! au?or ( ,wireless ,telegraph ,con/ruction = ,amateurs499 ,?is is und\bt$ly "o ( ! mo/ complete & compreh5sive treatises on ! subject ev] publi%$1 & a close /udy ( its pages w enable "o to ma/] all ! details ( ! wireless transmission ( messages4 ,! au?or has fill$ a long-felt want & has succe$$ 9 furni%+ a lucid1 compreh5sible explanation 9 simple language ( ! !ory & practice ( wireless telegraphy & telephony4 ,! book treats ! subject f an entirely new /&po9t4 ,sev]al v novel & orig9al ideas h be5 c>ri$ out 9 its mak+4 ,x is well illu/rat$ by ov] "o hundr$ & fifty int]e/+ photographs & draw+s4 ,all diagrams h be5 made 9 p]spective %[+ ! in/rum5ts z !y actually appe> 9 practice4 ,! draw+s are c>efully key$ & label$4 ,_m ( ! photographs are accompani$ by phantom draw+s :i* reveal ! "n & purpose ( ea* "p4 ,x is a book :i* ! wireless exp]im5t] _c af=d to be )\t4 ,x w prove ev5 m valuable to ! layman4 ,among ! cont5ts are3 ,introductory4 ,wireless ,transmission & ,reception4 ,! ,e!r4 ,electrical ,oscillations4 ,electromagnetic ,waves4 ,! ,means = ,radiat+ & ,int]cept+ ,electric ,waves4 ,a]ial ,sy/ems4 ,e>? ,connection4 ,! ,transmitt+ ,app>atus4 ,curr5t ,supply4 ,sp>k ,coils & ,trans=m]s4 ,cond5s]s4 ,helixes4 ,sp>k ,gaps4 ,an*or ,gaps4 ,a]ial ,swit*es1 ,etc4 ,! ,receiv+ ,app>atus4 ,detectors1 ,etc4 ,tun+ ,coils & ,loose ,c\pl]s4 ,v>iable ,cond5s]s4 ,tun+ & ,c\pl+4 ,directive ,wave ,telegraphy4 ,! ,dignity ( ,wireless4 ,its ,applications & ,s]vice4 ,wireless 9 ! ,army & ,navy4 ,wireless on an ,a]oplane4 ,h[ a ,message is ,s5t & ,receiv$4 ,! ,wireless ,telephone4 ,! ,e>4 ,h[ ,we ,he>4 ,s\nd & ,s\nd ,waves4 ,! ,vocal ,cords4 ,! ,/ructure ( ,spee*4 ,! ,telephone ,transmitt] & ,receiv]4 ,! ,photophone4 ,! ,!rmophone4 ,! ,sel5ium ,cell4 ,h&somely ,b\nd 9 ,clo? ) ,emboss$ ,cov]4 7,po/paid1 #a4jj7 ,build ,y\r ,own ,wireless ,in/rum5ts ,complete ,up-to-!-,m9ute ,au!ntic ,practical ,,wireless ,,telegraph ,,con/ruction ,,= ,,amateurs ,by ,,alfr$ ,,p[ell ,,morgan #c;d ,,edition #bbj ,pages #afc ,illu/rations 99,price991 #a4ej1 99,po/paid99 99,h&somely ,b\nd 9 ,silk ,clo?99 ,?or\ghly up to date & unusually complete4 ,gives 9 m9ute detail1 full directions = con/ruct+ wireless app>atus & v>i\s outfits capable ( receiv+ f #ajj to #a1ejj miles & transmitt+ #c to #ajj miles4 ,also cle>ly expla9s ! purpose & action ( ea* in/rum5t4 ,directions = ,op]at+ & ,adju/+1 etc4 99,a ,,spl5did ,,treatise ,,( ,,wireless ,,along99 99,,con/ructive ,,l9es99 ,price1 #a4ej1 ,po/paid ,! value ( ?is book has be5 greatly increas$ by ! addition ( mu* new subject matt] & _m illu/rations ( rec5t int]e/4 ,! new text expla9s fully h[ to build ! mo/ rec5t =ms ( ,qu5*$ ,gaps4 ,rot>y ,gaps1 ,d\gh-,nut ,tun]s1 ,kick-back ,prev5t]s1 ,audion ,detectors & num]\s o!r in/rum5ts1 accompani$ by dim5sion$ work+ draw+s4 ,sev]al v int]e/+ & in/ructive photographs h be5 includ$4 ,i4--,introduction4 ,,ii4--,! ,app>atus4 ,,iii4--,a]ials & ,e>? ,connections4 ,,iv4--,induction ,coils4 ,v4--,int]rupt]s4 ,,vi4--,trans=m]s4 ,,vii4--,oscillation ,cond5s]s & ,leyd5 ,j>s4 ,,viii4--,sp>k ,gaps or ,oscillators4 ,,ix4--,transmitt+ ,helixes4 ,x4--,keys4 ,,xi4--,a]ial ,swit*es & ,an*or ,gaps4 ,,xii4--,hot ,wire ,ammet]4 ,,xiii4--,oscillation ,detectors4 ,,xiv4--,tun+ ,coils & ,tun+ ,trans=m]s4 ,,xv4--,receiv+ ,cond5s]s4 ,,xvi4--,telephone ,receiv]s & ,headb&s4 ,,xvii4--,op]ation4 ,,xviii4--,! ,amateur & ! ,wireless ,law4 ,h[ to ,secure a ,lic5se4 ,oscillation ,helix4 ,qu5*$ ,sp>k ,gap4 ,rot>y ,gaps4 ,kick-,back4 ,! ,v>iomet]4 ,new ,cry/al ,detectors4 ,! ,audion4--,app5dix4 ,,endors$ ,,by ,,wireless ,,clubs ,,?r\gh\t ,,! ,,c\ntry ,,z ,,be+ ,,! ,,mo/ ,,practical ,,book ,,publi%$ ,,on ,,wireless4 ,,if ,,y ,,are ,,int]e/$ ,,9 ,,wireless ,,y ,,ne$ ,,?is ,,book 99,model ,fly+ ,ma*9es99 99,,h[ ,,to ,,build ,,& ,,fly ,,!m99 ,w prove int]e/+ & valuable4 ,h y ev] built & fl[n a ,model ,rac]8 ,if n1 y h miss$ some?+4 ,price1 #be ,c5ts1 ,po/paid4 ,model ,a]oplan+ is "o ( ! mo/ fasc9at+ & in/ructive ( sports4 ,?\s&s ( "y m5 & boys h =m$ ,model ,a]o ,clubs & organiz$ ,fly+ ,conte/s ?r\gh\t ! c\ntry4 ,,model ,,fly+ ,,ma*9es ( ! ,arts & ,sci5ces s]ies is ! only book giv+ reliable data & in/ructions = ! con/ruction ( practical ,model ,a]oplanes4 ,,if ,,y ,,are ,a ,,beg9n]1 ?is is ! book t y ought to h4 ,x w />t y "r4 ,x tells h[ to build sev5 diff]5t types ( ma*9es1 />t+ ) ! simple/ ,monoplane & f9i%+ ) sev]al ,long ,di/ance ,rac+ ,models4 ,,if ,,y ,,are ,,int]e/$ ,,9 ,,model ,,a]oplan+1 ?is book w prove ! "o y h be5 look+ =4 ,gives valuable ,k9ks4 ,tells h[ to c>ve propell]s1 make w9d]s1 adju/ & fly ma*9es1 etc4 ,fully illu/rat$ ) l>ge size1 detail$ work+ draw+s1 %[+ ! exact size ( ea* "p4 ,twelve full-page plates4 ,pr9t$ on fir/-class pap]4 ,heavy cov] 9 ?ree colors4 ,s5t po/paid by return mail ^u receipt ( #be c5ts4 99,,e ,,model ,,aviator ,,ought ,,to ,,h ,a ,,copy99 99,exp]im5tal ,wireless ,con/ruction99 99,,eighty-,,six ,,pages ,,n9ety-,,?ree ,,illu/rations99 99,only #be ,c5ts1 ,po/paid99 ,"h at la/ is ! book :i* e "y exp]im5t] int]e/$ 9 con/ruct+ 8 own wireless app>atus has be5 look+ =4 ,a book :i* tells h[ to build app>atus :i* anyone w\ld be pr\d to own4 ,x is a m advanc$ book ?an ,wireless ,con/ruction & ,in/allation = ,beg9n]s1 & describes app>atus :i* is mu* m elaborate & s5sitive4 ,! in/rum5ts h all be5 ! subject ( consid]able exp]im5tal "w & /udy4 ,all ! app>atus has be5 put to practical te/ & c>efully improv$ by clev] exp]ts4 ,by pur*as+ ?is book y get ! b5efit ( va/ k & exp]i5ce & are enabl$ to build f> bett] in/rum5ts ?an by foll[+ y\r own designs & haphaz>d me?ods4 ,,! ,,trem5d\s ,,popul>ity ,,( ,,?is ,,valuable ,,little ,,book ,,is ,,only ,,an ,,indication ,,( ,,its ,,great ,,wor?4 ,x has only be5 on ! m>ket a %ort "t1 yet ! sales w und\bt$ly soon rea* a po9t :i* w\ld indicate t exp]im5t]s unque/ionably consid]1 t 9 proportion to its size1 x is ! be/ book on ! m>ket4 ,x does n describe any old or obsolete =ms ( wireless app>atus b only ! late/ types ( a]ials1 sp>k coils1 keys1 gaps1 cond5s]s1 helixes1 oscillation trans=m]s1 loose c\pl]s1 tun+ coils1 detectors1 load+ coils1 v>iable cond5s]s1 a]ial swit*es1 etc4 ,,x ,,is ,,"o ,,( ,,! ,,mo/ ,,detail$ ,,& ,,?or\gh ,,books ,,ev] ,,publi%$4 ,! in=mation is all int5sely practical4 ,complete directions & dim5sions are giv54 ,no?+ is left to be guess$ at4 ,! book mu/ really be se5 to be appreciat$4 99,p>tial ,cont5ts99 ,*apt] ,i4--,,! ,,a]ial4 ,! ,location ( ! ,/ation4 ,! ,con/ruction ( an ,op]at+ ,b5*4 ,! ,a]ial & ,gr\nd4 ,! ,supports or ,ma/s4 ,types ( ,a]ials4 ,h[ to ,erect an ,a]ial4 ,protection f ,lightn+1 ,etc4 ,*apt] ,,ii4--,,sp>k ,,coils4 ,! ,con/ruction ( ,sp>k ,coils4 ,a #a_/d-;in* ,sp>k ,coil4 ,a #a_/b-;in* ,sp>k ,coil4 ,a #a-;in* ,sp>k ,coil4 ,a #a #a_/b-;in* ,coil4 ,a #b-;in* ,coil4 ,s\rces ( ,curr5t4 ,dry ,cells4 ,/orage ,cells4 ,wireless ,keys1 ,etc4 ,*apt] ,,iii4--,,transmitt+ ,,app>atus ,,& ,,its ,,con/ruction4 ,/ep-d[n ,trans=m]s4 ,sp>k ,gaps4 ,! ,oscillation ,cond5s]4 ,leyd5 ,j>s4 ,helixes4 ,oscillation ,trans=m]s1 ,etc4 ,*apt] ,,iv4--,,! ,,receiv+ ,,app>atus ,,& ,,its ,,con/ruction4 ,a ,silicon ,detector4 ,a ,gal5a ,detector4 ,! ,d\ble ,slide ,tun+ ,coil4 ,h[ to ,make a ,fix$ ,cond5s]4 ,build+ a ,loose ,c\pl]4 ,! ,load+ ,coil4 ,h[ to ,make a ,v>iable ,cond5s]1 ,etc4 ,*apt] ,v4--,,arrangem5t ,,& ,,op]ation ,,( ,,! ,,app>atus4 ,a]ial ,swit*es4 ,! ,buzz] ,te/4 ,us+ ,m ,?an ,"o ,detector4 ,%unt+ ! ,detector4 ,complete ,outfits4 ,portable ,sets4 ,! ,op]ation ( ! ,/ation1 ,etc4 99,! ,new ,amateur's ,wireless99 99,h&y ,book99 ,,f\r? ,,edition ,completely ,revis$ & ,enl>g$ ,y ,_c ,af=d ,to ,be ,)\t ,?is ,book ,price #be ,c5ts1 ,po/paid ,if y want to be an exp]t & an au?ority y mu/ surr\nd y\rself ) all available aids & helps4 ,y h "o ( ! be/ 9 ! ,,amateur',s ,,wireless ,,h&y ,,book4 ,,!re ,,h ,,be5 ,,m ,,copies ,,( ,,?is ,,great ,,book ,,sold ,,?an ,,( ,,any ,,o!r ,,wireless ,,book4 ,x conta9s ne>ly ,,six ,,?\s& calls ( ,wireless ,/ations1 includ+ all ,l& ,/ations1 ,%ip ,/ations1 ,u4 ,s4 ,army & ,navy ,/ations & all ,,amateurs lic5s$ to date ( publication4 ,e regi/]$ /ation ( ! ,u4 ,s4 is includ$4 ,!y are all !re4 ,all ! calls are classifi$ alphabetically4 ,! li/ is ! mo/ reliable & complete 9 exi/5ce4 ,all obsolete /ations h be5 aboli%$4 ,all corrections & *anges h be5 made f ! (ficial li/s4 99,,b1 ,,t ,,is ,,n ,,all499 ,,! ,,codes1 ,,bo? ,,morse ,,& ,,cont95tal1 are %[n 9 ! =m ( two l>ge full-page *>ts pr9t$ 9 heavy black type s t !y c be read f a di/ance4 ,a ,,beg9n]',s ,,spe$ ,,*>t ( bo? ,codes s arrang$ t ! codes may be quickly le>n$ or consult$ is provid$4 ,,all ,,?is ,,abbreviations us$ s con/antly by ! wireless op]ator to save "t & labor are includ$4 ,!re are a c\ple ( pages ( !m4 99,,& ,,la/ ,,b ,,n ,,lea/99 ,ne>ly #ajj l>ge hook-ups ( wir+ diagrams fully illu/rat$ 9 a concise & cle> mann]4 ,loop & /raightaway a]ials1 gr\nds1 helixes1 sp>k gaps1 an*or gaps1 leyd5 j>s1 induction coils1 trans=m]s1 keys1 a]ial swit*es1 tun+ coils1 load+ coils1 loose c\pl]s1 v>iomet]s1 fix$ cond5s]s1 silicon1 electrolytic1 c>borundum1 p]ikon & audion detectors1 telephones1 pot5tiomet]s1 etc41 y c f9d !m all & h[ to connect4 ,a hook-up = any set accompani$ by full explanation4 ,none are miss+4 ,!y are all !re4 ,!re are no two alike4 ,! mo/ complete & reliable data ev] collect$4 ,! result ( ?\s&s ( exp]im5ts by "s ( ! mo/ fam\s wireless exp]ts 9 ! c\ntry4 ,read n[ be=e ! supply is exhau/$ or y =get4 ,y w be sorry if y don't4 99,,s5t ,,any:]e ,,po/paid ,,= #be ,,c5ts99 ,note3 ,?is book is always kept up-to-date by frequ5tly issu+ new editions4 ,s5d = ! late/ copy4 99,wireless ,con/ruction & ,in/allation = ,beg9n]s99 ,,sev5ty-,,?ree ,,pages ,,sixty-,,sev5 ,,illu/rations4 7,second ,edition47 ,a ,practical ,h&book giv+ detail$ in/ructions = ! ,con/ruction & ,op]ation ( a ,boy's ,wireless ,outfit4 99,only #be;c4 ,prepaid99 ,an indisp5sible book = ! "y wireless exp]im5t]4 ,x n alone %[s h[ to build ! v>i\s in/rum5ts b describes _! actual work+s & tells h[ to op]ate !m4 99,,e ,,boy ,,is ,,advis$ ,,to99 99,,s5d ,,= ,a ,,copy99 ,writt5 9 a v cle> & simple /yle1 ! book is invaluable to a beg9n]4 ,he w be able ) its aid to con/ruct simple app>atus ( ! late/ & approv$ type4 ,! in/rum5ts describ$ 9 ! book h be5 ! subject ( consid]able exp]im5tal "w & special /udy4 ,!y are model$ along simple l9es s t !y w be easy & inexp5sive to con/ruct1 b at ! same "t comb9e features :i* make !m v s5sitive & capable ( receiv+ or transmitt+ messages great] di/ances ?an "s m complicat$ app>atus4 99,,?is ,,book1 ,,consid]+ ,,its ,,wor?1 ,,is ,a ,,gift ,,at #be;c499 ,!re are no old or obsolete =ms ( wireless app>atus discuss$1 b only ! late/ types ( tun+ coils1 receiv+ trans=m]s1 fix$ cond5s]s1 keys1 sp>k coils1 detectors1 etc4 ,! book is illu/rat$ by num]\s detail$ work+ draw+s giv+ all dim5sions4 ,sev]al full-page views ( ! app>atus enable ! beg9n] to fully compreh5d ! text4 99,,! ,,mo/ ,,?or\gh ,,& ,,complete ,,elem5t>y ,,wireless99 99,,con/ruction ,,book ,,publi%$99 ,! pages on ! con/ruction & in/allation ( a]ials w be f\nd to be ( consid]able help to ! exp]im5t]1 = x is "h t ! mo/ tr\ble is exp]i5c$ by ! beg9n]4 ,! practical & helpful in=mation on ?is subject is alone wor? sev]al times ! co/ ( ! book4 99,,p>tial ,,cont5ts99 ,*apt] ,i4--99,,wireless ,,telegraphy994 ,an int5sely int]e/+ subject2 amateur wireless telegraphy2 ! purpose ( ! a]ial & gr\nd2 ! app>atus us$ to s5d messages2 ! app>atus us$ to receive messages4 ,*apt] ,,ii4--99,,a]ials ,,& ,,gr\nds994 ,:]e to put up ! a]ial2 types ( a]ials2 ! ,t a]ial2 ! ma/s2 ! wire2 insulators2 lead+ 9 ! wires2 ! gr\nd4 ,*apt] ,,iii4--99,,h[ ,,to ,,build ,,& ,,op]ate ,,! ,,simplex ,,d\ble ,,slide ,,receiv+ ,,outfit994 ,! tun+ coil2 ! tube2 ! slid]s2 ! fix$ cond5s]2 ! detector p>ts2 assembl+ ! set2 connect+ ! in/rum5ts2 op]ation4 ,*apt] ,,iv4--99,,h[ ,,to ,,build ,,! ,,simplex ,,loose ,,c\pl]1 ,,detector ,,& ,,cond5s]994 ,! base2 ! prim>y2 ! second>y2 ! pill>2 ! swit*2 ,h[ to make ! ,simplex cat :isk] detector2 ,h[ to make ! ,simplex fix$ cond5s]2 ,h[ to connect ! app>atus2 ,h[ to tune ) ! loose c\pl]2 ,h[ to adju/ ! detector4 ,*apt] ,v4--99,,telephone ,,receiv]s ,,& ,,headb&s499 ,*apt] ,,vi4--99,,h[ ,,to ,,build ,,! ,,simplex ,,sp>k ,,coil499 ,! core2 ! second>y2 ! cond5s]2 ! coil heads2 ! base2 ! int]rupt] p>ts2 ! bridge4 ,*apt] ,,vii4--99,,h[ ,,to ,,make ,,! ,,simplex ,,key994 ,*apt] ,,viii4--99,,h[ ,,to ,,connect ,,& ,,op]ate ,,! ,,app>atus994 ,h[ to connect & op]ate a complete wireless /ation2 ,h[ to op]ate2 ! code1 etc4 99,! ,op]ation ( ,wireless ,telegraph ,app>atus99 ,d y\r ,wireless fri5ds come to y = advice on con/ruct+ & op]at+ _! app>atus or d y g to !m = in=mation8 ,"h is a *ance = ,,y to become ! au?ority4 99,?is book is a necessity to e ,progressive ,exp]im5t]499 99,x %[s h[ to obta9 ! v highe/ effici5cy f any /ation1 & h[ to comply ) ! law4 ,h[ to tune1 adju/ y\r detector1 sp>k gap1 phones1 etc499 ,price1 #be ,c5ts1 ,po/paid4 ,?is book 0 writt5 = ! wireless exp]im5t] :o has pass$ ! amateur /age1 b expla9s h[ ! beg9n] also c obta9 ! v be/ results f 8 /ation4 ,x conta9s mu* useful in=mation to ?is end & _m k9ks4 99,,x ,,%[s ,,h[99 to receive or s5d on long or %ort wave l5g?s ) highe/ effici5cy1 to tune = longe/ di/ance reception ( messages1 to use ! buzz] te/1 h[ to te/ & connect cond5s]s1 receiv]s1 etc41 h[ to use receiv+ trans=m]s1 v>iomet]s1 etc41 all ) highe/ effici5cy 9 view4 99,,x ,,also ,,describes99 ! con/ruction & use ( a simple1 inexp5sive wave met] to tune ! /ation to any desir$ wave l5g?1 & tells h[ to obta9 a %>p wave & a pure wave4 99,,extracts ,,f ,,! ,,law99 are also giv5 9 su* a mann] t !y are easily und]/ood4 ,if y want to get ! be/ results f y\r /ation ?is is y\r opportunity4 99,?ree ,new ,books on ,home ,made99 99,electrical ,app>atus99 or r1 ?ree p>ts ( "o book1 ea* #be c5ts p] copy1 are n[ 9 prep>ation & %\ld be ready 9 ,june1 #aiag4 ,!y w cov] e k9d ( electrical app>atus1 includ+ prim>y & /orage batt]ies1 dynamos & motors1 induction coils1 rectifi]s1 trans=m]s1 telegraphs & telephones1 etc4--all ( :i* h actually be5 built4 ,! ?ree p>ts w also be furni%$ z a s+le volume 9 clo? cov]s at #a4jj p] copy1 po/paid4 ,if int]e/$1 simply s5d u a po/al & :5 ! books are ready we w s5d y full descriptions4 99,,cole ,,morgan99 ,publi%]s ( ! ,arts & ,sci5ces ,s]ies ,p4 ,o4 ,box #adgc ,,new ,,york1 ,n4 ,y4