,,! ,,telephone ,by ,pr(essor ,a4 ,e4 ,dolbe> ,,! ,,telephone ,) directions = mak+ a ,speak+ ,telephone ,illu/rat$ #ej c5ts ,,! ,,art ,,( ,,project+ ,a ,manual ( ,exp]im5tation 9 ,physics1 ,*emi/ry1 & ,natural ,hi/ory1 ) ! ,porte ,lumi]e & ,magic ,lant]n ,new ,edition ,revis$ ,illu/rat$ #b4jj ,,matt]1 ,,e!r1 ,,& ,,motion ,! ,factors & ,relations ( ,physical ,sci5ce ,illu/rat$ #a4ge ,lee & ,%ep>d ,publi%]s ,bo/on ,,! ,,telephone3 ,,an ,,acc\nt ,,( ,,! ,ph5om5a ( ,electricity1 ,magnetism1 & ,s\nd1 ,,z ,,involv$ ,,9 ,,its ,,action4 ,,) ,,directions ,,= ,,mak+ ,a ,,speak+ ,,telephone4 ,,by ,,pr(4 ,a4 ,e4 ,,dolbe>1 ,,tufts ,,college1 ,,au?or ,,( ,,! ,,art ,,( ,,project+1 ,,etc4 ,,bo/on3 ,,lee ,,%ep>d1 ,,publi%]s4 ,,copyright1 #ahgg1 ,,by ,a4 ,e4 ,,dolbe>4 ,,preface4 ,,! popul> exhibitions ( ! speak+-telephone dur+ ! pa/ six mon?s1 toge!r ) num]\s newspap] articles1 h creat$ a widespread int]e/ 9 ! in/rum5t2 & x has be5 ?\ght t a small book explanatory ( its action w\ld meet a public want4 ,x has seem$ to be necess>y to call att5tion to ! v>i\s ph5om5a & int]-actions ( ! =ces involv$2 & h5ce ! au?or has attempt$ to make pla9 & intelligible ! ph5om5a ( electricity1 magnetism1 & s\nd4 ,cuts h be5 ins]t$ :]e !y c\ld be useful 9 mak+ ! me*anical conditions m intelligible2 & a table ( tone-composition has be5 devis$1 :i* %[s at a glance ! con/itu5ts ( ! s\nds ( v>i\s musical in/rum5ts4 ,z ! speak+-telephone1 9 :i* magneto-electric curr5ts 7 utiliz$ = ! transmission ( spee* & o!r k9ds ( s\nds1 0 inv5t$ by me1 ,i h describ$ at "s l5g? my fir/ in/rum5t1 & h also giv5 explicit directions = mak+ a speak+-telephone :i* ,i "k1 by trial1 to be z effici5t z any hi!rto made2 b no?+ 9 ! book is to be tak5 z a d$ication ( ! inv5tion to ! public1 z /eps h already be5 tak5 to secure lett]s-pat5t accord+ to ! laws ( ! ,unit$ ,/ates4 ,a4 ,e4 ,,dolbe>4 ,,college ,,hill1 ,,mass4 ,,! ,,telephone4 ,,electricity4 ,,"s ( ! ph5om5a ( electricity are manife/$ ^u s l>ge a scale z to be ?ru/ ^u ! att5tion ( ev]ybody4 ,?us lightn+1 :i* accompanies s _m %[]s 9 w>m wea!r 9 almo/ e latitude1 has always excit$ 9 "s individuals a sup]/iti\s awe1 z be+ an exhibition ( sup]natural ag5cy2 & probably e "o feels m or less dread ( x dur+ a ?und]-%[]1 & ?is = ! reason t x affects s _m ( ! s5ses at ! same "t4 ,! fla% may be bl9d+ to ! eyes if ne> to u2 ! ?und] may be deaf5+ to ! e>s1 & s p[]ful z to %ake ! f\ndations ( ! hills1 & make ! gr\nd ^u :i* we /& to s5sibly move3 ^! ) ! rememb]$ de/ructive effects t h be5 witness$1 ( build+s demoli%$ & l>ge trees torn to spl9t]s 9 an in/ant1 are q suffici5t to raise a feel+ ( dread 9 ! /ronge/ m9d4 ,9 ! pol> regions1 bo? nor? & s\?1 :]e ?und]-/orms are less frequ5t1 ! atmosph]ic electricity assumes ! =m call$ ! aurora borealis1 or ! aurora au/ralis1 accord+ z x is se5 nor? or s\? ( ! equator4 ,m ?an two ?\s& ye>s ago x 0 notic$ by ! ,greeks t a c]ta9 k9d ( a m9]al :i* 0 ?r[n up on ! %ores ( ! ,m$it]ranean ,sea1 :5 rubb$ w\ld attract light bodies1 su* z %r$s ( silk or l95 & bits ( pap]4 ,to ?is sub/ance !y gave ! "n ( ,elektron1 & ! prop]ty develop$ ?us by friction 0 aft]w>ds call$ electricity4 ,9 #afjj ,dr4 ,gilb]t1 physician to ,que5 ,elizabe?1 publi%$ a book 9 :i* he describ$ num]\s exp]im5ts demon/rat+ t electricity c\ld be develop$ by friction ^u a great v>iety ( sub/ances1 su* z /ones1 gems1 & res9s4 ,! fir/ ma*9e = develop+ electricity 0 made by ,otto von ,gu]icke ( ,magdeburg1 ab\t #afhj4 ,8 ma*9e consi/$ ( a ball ( sulphur ab\t six in*es 9 diamet]1 :i* c\ld be rotat$4 ,if ! dry h& 7 held aga9/ ! sulphur :ile x 0 be+ turn$ 9 a d>k room1 ! sph]e appe>$ to emit light3 x also gave out a peculi> hiss+ or crackl+ s\nd4 ,newton exp]im5t$ a little ) electricity1 & notic$ t ! rubb] 0 an important elem5t 9 develop+ electricity4 ,he does n seem to h giv5 to ! subject ! same att5tion t he gave to "s o!r dep>tm5ts ( sci5ce4 ,_h he done s1 x is probable t he w\ld h advanc$ ! /udy a hundr$ ye>s2 t is to say1 he w\ld probably h left x at ! place :]e x actually 0 9 #agij4 ,s great 7 8 abilities t 9 "o lifetime he made great] additions to human k ?an all ! re/ ( mank9d _h made dur+ ! prec$+ ?\s& ye>s4 ,9 ! mon? ( ,june1 #ageb1 ,frankl9 made t memorable exp]im5t :i* immortaliz$ him4 ,he flew 8 kite to ! ?und]-cl\d1 practically ask+ ! "q ( ! lightn+ :e!r or n x 0 id5tical ) electricity4 ,! lightn+ came d[n ! wett$ tw9e to 8 h&1 & proclaim$ its id5tity4 ,= ! next =ty ye>s ! natural philosoph]s 9 bo? ,europe & ,am]ica only rung ! *anges ^u :at 0 kn[n4 ,!y flew kites to ! cl\ds2 !y made & *>g$ ,leyd5 j>s1 & dis*>g$ !m ?r\gh wires & *a9s & circuits ( clasp$ h&s1 & /udi$ ! attractions & repulsions manife/$ by electrifi$ bodies2 b !y add$ no?+ ( importance 9 ! way ( exp]im5ts4 ,9 #agia ,galvani1 a pr(essor ( anatomy at ,bologna1 ann\nc$ a manife/ation ( electricity t 0 new & ( a rem>kable "*1 hav+ its orig9 9 ! muscles ( animals1 & s 0 call$ animal electricity4 ,he _h "s frogs' legs prep>$ = eat+2 by *ance !y 7 plac$ ne> an electrical ma*9e ) :i* ,galvani 0 exp]im5t+1 s t a sp>k w\ld occasionally pass to ! legs1 :5 !y w\ld contract z (t5 z a sp>k pass$ to !m4 ,! motion 0 fir/ obs]v$ by 8 wife1 :o call$ 8 att5tion to ! ph5om5on2 & he v soon discov]$ t ! ?ighs ( a frog1 sk9n$ & susp5d$1 made a v good electroscope4 ,:ile exp]im5t+ 9 ?is way he made ano!r & m important discov]y2 namely1 t1 :5 ! muscles & n]ves ( ! frog's leg 7 t\*$ by pieces ( two diff]5t metals1 ! leg w\ld contract z be=e4 ,alex&] ,volta1 ano!r ,italian pr(essor1 :o _h inv5t$ ! electrophorus1 & 0 possess$ ( great exp]im5tal skill1 n[ turn$ 8 att5tion to ! exp]im5t ( ,galvani1 & v soon discov]$ t ! orig9 ( ! electricity t mov$ ! frogs' legs 0 n 9 ! legs !mselves1 b 9 ! metals us$4 ,! fir/ =m ( ! galvanic batt]y 0 ! result ( ,volta's inve/igations1 & 0 call$ ! ,voltaic pile4 ,?is pile consi/$ ( alt]nate disks ( z9c1 flannel1 & copp]1 pil$ "o on top ( ! o!r 9 con/ant succession 9 t ord]4 ,! flannel 0 moi/5$ ) salt & wat]1 or ) dilut$ sulphuric acid4 ,:5 ! fir/ z9c 0 connect$ ) ! la/ copp] by means ( a wire1 a p[]ful curr5t ( electricity 0 obta9$4 ,?is =m ( batt]y is n 9 use at all n[1 z mu* m effici5t means are kn[n = produc+ electricity2 b ?is 9 #ahjj1 :5 x 0 fir/ made kn[n 9 ,engl&1 0 v />tl+1 & 0 "o ( ^? surprises :i* h be5 s frequ5t s9ce !n 9 ! hi/ory ( electricity4 ,surpris+ ?+s 7 done by ,sir ,humphry ,davy1 ) a l>ge ,voltaic batt]y4 ,wat] 0 decompos$1 & ! metals potassium & sodium 7 fir/ sep>at$ f _! comp\nds ) oxyg54 ,bonap>te _h (f]$ a prize ( sixty ?\s& francs to ! p]son :o by 8 exp]im5ts & discov]ies %\ld advance ! k ( electricity & galvanism z mu* z ,frankl9 & ,volta did1 & ( ?ree ?\s& francs = ! be/ exp]im5ts :i* %\ld be made 9 ea* ye> on ! galvanic fluid4 ,?is latt] prize 0 aw>d$ to ,davy4 ,aft] ,davy's successes 9 #ahjf1 !re 0 no?+ ( importance 9 an exp]im5tal way add$ to ! k ( electricity1 until #ahbj1 :5 ,o]/$ ( ,cop5hag5 ann\nc$ t ! conduct+ wire ( a ,voltaic circuit acts ^u a magnetic ne$le1 & t ! ne$le t5ds to set itself at "r angles to ! wire4 ,?is 0 a k9d ( action altoge!r unexpect$4 ,?is obs]vation 0 ( ! utmo/ importance2 & at once ! philosoph]s 9 ,europe & ,am]ica set !mselves to inquire into ! new ph5om5on4 ,! laws ( ! motion ( ! magnetic ne$le :5 act$ ^u by a curr5t ( electricity trav]s+ a wire 7 successfully inve/igat$ by ,m4 ,amp]e ( ! ,fr5* ,academy4 ,he obs]v$ t :5ev] a wire ?r\gh :i* a curr5t ( electricity 0 pass+ 0 held ov] & p>allel ) a magnetic ne$le :i* 0 free to move1 & !re=e po9t$ to ! nor?1 if ! curr5t 0 mov+ t[>ds ! nor?1 ! nor? pole 0 deflect$ to ! we/2 if ! curr5t 0 mov+ t[>ds ! s\?1 ! s\? pole ( ! magnet 0 deflect$ t[>ds ! we/2 & t 9 all cases ! magnet t5d$ to set itself at "r angles to ! curr5t2 also t ?is angul> displacem5t dep5d$ ^u ! /r5g? ( ! curr5t4 ,?us orig9at$ ! galvanomet]1 an in/rum5t t n only detects ! exi/5ce ( an electric curr5t1 b enables u to det]m9e its direction & its /r5g?4 ,our pres5t k ( electrical laws is due1 9 a v l>ge measure1 to obs]vations made ) ?is in/rum5t4 ,( c\rse x has be5 v mu* modifi$1 & made almo/ incr$ibly s5sitive3 yet1 9 all galvanomet]s1 ! fundam5tal pr9ciple involv$ 9 _! /ructure is t ( ! action ( a curr5t ( electricity ^u a magnet1 :i* 0 fir/ notic$ by ,o]/$4 ,,magnets4 ,x is relat$ by ,nic&] t among ! %eph]ds :o t5d$ _! flocks ^u ! sides ( ,m\nt ,ida 0 "o nam$ ,magnes1 :o notic$1 t1 :ile tak+ 8 h]ds to pa/ure1 8 %eph]d's crook adh]$ to "s ( ! rocks4 ,f ?is man's "n "s h suppos$ ! "n magnet to h be5 d]iv$4 ,x is1 h[ev]1 g5]ally believ$ to h receiv$ its "n f ! anci5t city ( ,magnesia 9 ,asia ,m9or1 ne> :i* ! load/one or magnetic sub/ance 0 f\nd4 ,?is rock1 :i* possesses ! rem>kable prop]ty ( attract+ & hold+ to itself small pieces ( iron or /eel1 is n[ kn[n to be "o ( ! ores ( iron1 & is call$ magnetite by m9]alogi/s4 ,! iron is *emically comb9$ ) oxyg51 & =ms #gb4e p] c5t ( its weight4 ,!re is ano!r ore ( iron1 kn[n z hematite1 :i* conta9s sev5ty p] c5t ( iron2 b ! diff]5ce ( two & a half p] c5t ( iron 9 ! ore is en\gh to make ! diff]5ce betwe5 a magnetically in]t sub/ance1 & "o :i* may be able to lift a mass ( iron equal to _m times its own weight4 ,sir ,isaac ,newton is said to h worn 9 a f+]-r+ a small load/one weigh+ ?ree gra9s1 :i* w\ld lift sev5 hundr$ & fifty gra9s1 :i* is equal to two hundr$ & fifty times its own weight4 ,! mo/ p[]ful magnet n[ kn[n is own$ by ,m4 ,obelliane ( ,p>is4 ,x c lift =ty times its own weight4 ,l>ge pieces1 h[ev]1 d n support proportionally great] weights1 seldom m ?an "o or two times _! own weight4 ,!re are 9 _m places 9 ! _w imm5se b$s ( magnetic iron-ore4 ,su* are to be f\nd 9 ! ,adirondack region 9 ,nor!rn ,new ,york1 & 9 ,*e/] ,c\nty1 ,p5nsylvania4 ,! celebrat$ iron-m9es ( ,sw$5 consi/ ( x1 & 9 ,lapl& !re are sev]al l>ge m\nta9s ( x4 ,x mu/ n be inf]r$1 t1 because ! m9]al is call$ magnetite1 all specim5s possess ! prop]ty call$ magnetism4 ,! l>ge masses seldom manife/ any su* =ce1 any m ?an ord9>y pieces ( iron or /eel manife/ x3 yet any ( x w be attract$ by a magnet 9 ! same way z iron w be4 ,! mo/ p[]ful native magnets are f\nd 9 ,sib]ia1 & 9 ! ,h>tz1 a range ( m\nta9s 9 ,nor!rn ,g]many4 ,:5 a piece ( ?is magnetically end[$ ore is plac$ 9 a mass ( iron-fil+s1 x w be se5 t ! fil+s adh]e to x 9 greate/ quantity ^u two opposite ends or sides1 & ^! are nam$ ! poles ( ! magnet4 ,if ! piece be susp5d$ by a /r+ s z to turn freely1 x w inv>iably come to re/ ) ! same pole turn$ t[>ds ! nor?2 & ?is pole is !re=e call$ ! nor? pole ( ! magnet1 & ! action is call$ ! directive action4 ,?is directive action 0 kn[n to ! ,*9ese m ?an ?ree ?\s& ye>s ago4 ,9 trav]s+ ^? va/ /eppes ( ,t>t>y !y employ$ magnetic c>s1 9 :i* 0 ! figure ( a man1 ^: movable1 out/ret*$ arm always po9t$ to ! s\?4 ,dr4 ,gilb]t affirms t ! compass 0 br\ght f ,*9a to ,italy 9 #abfj1 by a travell] nam$ ,paulus ,v5etus4 ,:5 a piece ( h>d5$ /eel is rubb$ ^u a natural magnet1 x acquires ! same directive prop]ty2 &1 z ! /eel c\ld be easily %ap$ into a conv5i5t =m = use1 a /eel ne$le has g5]ally be5 us$ = ! ne$le ( a compass4 ,! directive p[] ( ! magnet has be5 & /ill is ( incalculable value to all civiliz$ nations4 ,ocean navigation w\ld be impossible )\t x1 & t]ritorial b\nd>ies are fix$ by means ( x2 b !re are o!r prop]ties & relations ( a magnet1 :i* h be5 discov]$ )9 ! la/ fifty ye>s1 :i* are de/9$ to be z important to mank9d z t ( ! compass has be54 ,9 #ahbe ,william ,/urgeon ( ,woolwi*1 ,eng41 discov]$ t if a copp] wire 7 w\nd ar\nd a piece ( s(t iron1 & a curr5t ( electricity s5t ?r\gh ! wire1 ! s(t iron w\ld become a magnet1 b w\ld reta9 its magnetism no long] ?an :ile ! curr5t ( electricity 0 pass+ ?r\gh ! coil4 ,! magnetism develop$ 9 ?is way 0 call$ electro-magnetism1 & ! iron s w\nd 0 call$ an electro-magnet4 ,! fir/ electro-magnet 0 made by w9d+ b>e wire ^u ! s(t iron4 ,?is me?od w n produce v /rong magnets4 ,9 #ahcj ,pr(4 ,h5ry insulat$ ! wire by cov]+ x ) silk1 & 0 ! fir/ to produce p[]ful magnets4 ,on a s(t iron b> ( fifty-n9e p\nds weight he us$ tw5ty-six coils ( wire1 ?irte5 on ea* leg1 all jo9$ to a common conductor by _! opposite ends1 & hav+ an aggregate l5g? ( sev5 hundr$ & tw5ty-eight feet4 ,?is app>atus 0 f\nd able to su/a9 a weight ( tw5ty-five hundr$ p\nds4 ,?is electro-magnet is n[ own$ by ,yale ,college4 ,! p[] ( ! electro-magnet is enorm\sly great] ?an t ( any p]man5t magnet4 ,a p]man5t magnet made by ,jam9 ( ,p>is1 :i* is made up ( _m /rips ( ?9 /eel b\nd toge!r1 & weigh+ f\r p\nds1 is able to support a weight ( "o hundr$ p\nds2 b ,dr4 ,j\le made an electro-magnet1 by arrang+ ! coils to advantage1 t w\ld support ?irty-five hundr$ times its own weight1 or "o hundr$ & =ty times ! proportionate load ( ,sir ,isaac ,newton's r+ magnet4 ,,! ,,galvanic ,,batt]y4 ,! orig9al =m ( ! galvanic batt]y z devis$ by ,volta1 & modifi$ b little dur+ ?irty ye>s1 consi/$ ( a cell to conta9 a fluid1 :i* 0 usually dilute sulphuric acid1 9 :i* two plates ( diff]5t metals 7 imm]s$3 ! metals us$ 7 g5]ally plates ( z9c & copp]1 or z9c & silv]4 ,su* plates1 :5 fir/ plac$ 9 ! liquid1 w give a v good curr5t ( electricity2 b x w n la/ long4 ,! reason ( ?is is easy to und]/&4 ,:5ev] a curr5t ( electricity is g5]at$ by *emical action ( a liquid ^u two diff]5t metals1 !re is always "s decomposition ( ! liquid1 & ?is decomposition takes place ^u ! plates !mselves2 & ! lib]at$ gases adh]e to ! plates1 & prev5t fur!r contact ) ! acid2 at ! same "t1 ! gases !mselves act ^u ! plates1 & g5]ate a curr5t ( electricity 9 ! opposite direction4 ,?is w ( c\rse int]f]e ) ! fir/ curr5t2 & v soon ! batt]y is useless until ! plates h be5 )drawn f ! liquid4 ,?is physico-*emical process t takes place 9 su* a batt]y is call$ ! pol>ization ( ! plates4 ,illu/ration3 ,,fig4 #a4 ,! accompany+ figure w help "o to und]/& ! actions go+ on 9 a batt]y cell ( ! k9d m5tion$4 ,let ,pt repres5t a plate ( plat9um1 & ,zn a plate ( z9c1 bo? plac$ 9 a vessel conta9+ hydro*loric acid1 :i* is also repres5t$ by ! symbols ,h,cl4 ,z su* molecules are extremely m9ute1 !re w ( c\rse be an imm5se numb] ( !m betwe5 ! plates4 ,! plates are n[ to be connect$ by a wire runn+ betwe5 !m ?r\gh ! air4 ,z soon z ^! conditions are fulfill$1 a hiss+ s\nd w be he>d com+ f ! cell1 & bubbles ( gas w be se5 to rise f ! plat9um plate3 ^! bubbles prove ^u analysis to be bubbles ( hydrog54 ,at ! same "t ! z9c w beg9 to dissolve1 =m+ :at proves by analysis to be ! *loride ( z9c2 & at ! same "t a curr5t ( electricity travels ?r\gh ! wire f ! plat9um to ! z9c4 ,! quantity ( electricity t is ?us g5]at$ is /rictly proportionate to ! quantity ( hydrog5 lib]at$1 :i* is also proportionate to ! weight ( z9c dissolv$2 & ?is1 9 turn1 is proportionate to ! surface ( ! metals expos$ to ! action ( ! acid4 ,n[1 x happ5s "u su* circum/ances z ! above1 t ! lib]at$ hydrog5 adh]es v /rongly to ! plat9um1 z !re is no?+ = x to unite ) *emically2 & !re=e ! plate w v soon be visibly cov]$ ) bubbles1 :i* may be scrap$ (f ) a fea!r or a swab1 b only to h ! same ?+ repeat$4 ,?is coat+ ( bubbles w prev5t ! acid f t\*+ ! plate1 & s practically dim9i%es ! surface ( x2 b ! quantity ( electricity g5]at$ be+ proportionate to ! surface expos$ to ! *emical action1 x w be und]/ood at once h[ su* pol>ization ( ! plates mu/ soon br+ ! batt]y to a /&/ill4 ,9 #ahcf ,pr(4 ,j4 ,f4 ,daniell ( ,london contriv$ a batt]y1 :i* has be5 call$ ! ,daniell ,cell1 9 :i* ! metal 7copp]7 t _h ! hydrog5 lib]at$ ^u x 0 sep>at$ by a por\s cell f ! z9c4 ,! z9c 0 imm]s$ 9 dilute sulphuric acid1 & ! copp] 9 an acid solution ( blue vitriol 7copp] sulphate74 ,! por\s cup did n prev5t ! electricity f pass+1 nor ! decomposition f tak+ place2 b ! hydrog51 :i* 9 ?is case w\ld h be5 lib]at$ at ! copp] plate1 at once unit$ ) oxyg5 !re1 :i* x got by decompos+ ! copp] sulphate3 h5ce wat] 0 =m$1 & copp] 0 deposit$ ^u ! copp] plate2 &1 be+ an excell5t conductor1 ! batt]y w\ld keep up a /rong action = a long "t4 ,mr4 ,grove1 also ( ,london1 9 #ahci inv5t$ a batt]y :i* /ill goes by 8 "n1 9 :i* ! hydrog5 plate is ( plat9um imm]s$ 9 /rong nitric acid1 enclos$ also 9 a por\s e>!n cell2 & ?is1 9 turn1 is plung$ into a vessel conta9+ dilute sulphuric acid & ! z9c4 ,9 ?is case ! lib]at$ hydrog5 imm$iately decomposes ! nitric acid1 :i* readily p>ts ) its oxyg52 wat] is ! product1 z 9 ! o!r case1 & ! nitric acid loses /r5g?4 ,/rips ( c>bon h be5 sub/itut$ = ! plat9um1 & ?is is call$ ! ,buns5 batt]y4 ,x is o!rwise l ! ,grove batt]y2 x gives a v p[]ful & con/ant curr5t & x is by ! use ( "o or ! o!r ( ^! batt]ies1 t mo/ ( ! exp]im5ts 9 electricity are p]=m$ 9 in/itutions ( le>n+1 &1 until lately1 mo/ 9 use = telegraphic purposes4 ,,o!r ,,means ,,= ,,g5]at+ ,,electricity4 ,,!rmo-,,electricity4 ,,if two /rips ( diff]5t metals1 su* z silv] & iron1 be sold]$ toge!r at "o end1 & ! o!r ends be connect$ ) a galvanomet]1 on heat+ ! sold]$ junction ( ! metals x w be f\nd t a curr5t ( electricity trav]ses ! circuit f ! iron to ! silv]4 ,if o!r metals be us$1 hav+ ! same size1 & ! same degree ( heat be appli$1 ! curr5t ( electricity ?us g5]at$ w give a great] or a less deflection1 :i* w be con/ant = ! metals employ$4 ,! two metals g5]ally employ$ are bismu? & antimony1 9 b>s ab\t an in* long & an eigh? ( an in* squ>e4 ,^! are sold]$ toge!r 9 s]ies s z to pres5t = faces ! ends ( ! b>s1 & ^! (t5 numb] z _m z fifty pairs4 ,su* a s]ies is call$ a !rmo-pile4 ,?is me?od ( g5]at+ electricity 0 discov]$ by ,seebeck ( ,b]l9 9 #ahba1 b ! !rmo-pile s mu* 9 use n[ 9 heat inve/igations 0 inv5t$ by ,nobili 9 #ahce4 ,! /r5g? ( ?is curr5t is n v great1 a s+le ,daniell cell be+ equal to n9e pairs ( ! /ronge/ comb9ation yet discov]$1 namely1 ! artificial sulphuret ( copp] ) ,g]man silv]4 ,,magneto-,,electricity4 ,illu/ration3 ,,fig4 #b4 ,x has already be5 m5tion$1 t ,o]/$ f\nd t a magnet :5 free to turn t5d$ to set itself at "r angles to a wire 9 :i* a curr5t ( electricity 0 pass+1 ?us demon/rat+ "s int]-action betwe5 electricity & magnetism2 b x rema9$ = ,f>aday to discov] ! conv]se fact1 namely1 t a magnet mov+ across a wire1 ! ends ( :i* 7 connect$ ) a galvanomet] or o!rwise clos$1 orig9at$ a curr5t ( electricity 9 ! wire1 ! direction ( :i* dep5d$ ^u ! direction ( ! movem5t ( ! magnet4 ,if ! wire 0 coil$ into a holl[ helix1 ! magnet 9 mov+ ?r\gh ! helix mov$ across1 t is1 at "r angles to all ! turns ( ! helix2 & ea* complete turn add$ to ! int5sity ( ! curr5t4 ,?is w be und]/ood by ref]5ce to ! diagram1 ,fig4 #b4 ,let ,g be a galvanomet] connect$ ) ! wires f a helix2 ,n ,s1 a p]man5t b> magnet4 ,if ! magnet be ?ru/ into ! coil1 a curr5t ( electricity w trav]se ! helix1 wire1 & galvanomet]1 & ! ne$le w indicate its direction4 ,if ! magnet be n[ )drawn1 a curr5t w move 9 ! opposite direction ?r\gh ! :ole circuit4 ,! electricity t is ?us orig9at$ is said to be induc$4 ,! quantity ( electricity t c be induc$ ?us is almo/ unlimit$1 dep5d+ ^u ! size & /r5g? ( ! magnet1 ! size ( ! wire1 & ! l5g? ( wire 9 ! coil4 ,!re are n[ _m =ms ( ma*9es = develop+ electricity f ! motion ( coils ( wire 9 front ( ! poles ( p]man5t magnets4 ,!y are g5]ally call$ magneto-electric ma*9es4 ,! action involv$ 9 ^! ma*9es is s important 9 its be>+ ^u telephony z to necessitate a full] description ( !m4 ,,magnetic ,,induction4 ,illu/ration3 ,,fig4 #c4 ,let ,n ,s1 ,fig4 #c1 be a b> ( h>d5$ /eel r5d]$ p]man5tly magnetic4 ,if n[ !re be br\ght ne> to x a bo>d-nail1 ! latt] w become a magnet ?r\gh ! inductive action ( ! fir/ magnet4 ,?is induc$ magnetism may be demon/rat$ by br++ a tack or o!r bit ( iron to ! end t is f>!/ f ! p]man5t magnet2 ! tack w adh]e to ! nail1 b w fall (f :5 ! nail is remov$ f ! neighborhood ( ! magnet4 ,by te/+ ! pol>ity ( ! nail1 x w be f\nd t ! end ne>e/ ! magnet w be a s\? pole if ! magnet has its nor? pole t[>ds x1 9 all cases hav+ a pol>ity opposite to t ( ! pole act+ ^u x4 ,! /r5g? ( ?is induc$ magnetism ?us develop$ dep5ds ^u ! di/ance ap>t ( ! magnet & ! iron1 be+ at its maximum :5 ! two t\*4 ,b ! tack itself is also made a magnet1 & w attract ano!r tack1 & t "o /ill ano!r1 ! numb] :i* c be ?us support$ be+ dep5d5t ^u ! /r5g? ( ! fir/ or induc+ magnet4 ,suppose n[ t we %\ld w9d a few feet ( wire ab\t ! nail1 & fa/5 ! two ends ( ! wire to an ord9>y galvanomet]1 & !n make ! nail to approa* ! p]man5t magnet4 ,! galvanomet] ne$le w\ld be se5 to move z ! nail approa*$2 &1 if ! latt] 7 all[$ to t\* ! magnet1 ! movem5t ( ! ne$le w\ld sudd5ly be mu* ha/5$1 b w\ld directly come to re/1 %[+ t1 s long z !re is no motion ( ! nail t[>ds or away f ! magnet1 no electricity is mov+ 9 ! wire1 al?\gh ! nail is a /rong magnet :ile x is 9 contact ) ! p]man5t magnet4 ,if ! nail be n[ )drawn1 ! two ph5om5a happ5 z be=e3 t is to say1 z ! nail rec$es x loses its magnetism2 & ! giv+-up ( its magnetism induces a curr5t ( electricity ?r\gh ! wire 9 ! opposite direction to t x _h :5 ! nail approa*$4 ,! curr5t ( electricity 9 ! opposite direction is indicat$ by ! galvanomet] ne$le1 :i* moves accord+ to ,amp]e's law m5tion$ on a prec$+ page4 ,x may be not$ "h t we h an effect q analog\s to t already m5tion$ on page #ba z ! exp]im5t ( ,f>aday4 ,9 "o case a p]man5t magnet is ?ru/ into a coil ( wire1 & 9 ! o!r a piece ( iron is made a magnet :ile enclos$ 9 a coil4 ,9 ea* case !re is g5]at$ a curr5t ( electricity :i* la/s no long] ?an ! me*anical motion ( ! p>ts la/s4 ,,magneto-,,electric ,,ma*9es4 ,su* transi5t curr5ts are practically useless1 & sev]al devices h be5 inv5t$ to make ! fl[ cont9u\s4 ,! common =m ( ma*9e = do+ ?is may be und]/ood by ref]5ce to ! diagram4 ,illu/ration3 ,,fig4 #d4 ,n ,s1 ,fig4 #d1 is ! p]man5t magnet1 :i* is b5t into a ,u =m 9 ord] to utilize bo? poles4 ,n' & ,s' are %ort rods ( s(t iron fa/5$ into a yoke-piece ,y1 also ( s(t iron4 ,coils ( wire surr\nd ea* ( ! rods z repres5t$1 ! ends ( ! wires connect+ ) ea* o!r & ) :at is call$ a pole-*ang]4 ,! :ole ( ?is "p is capable ( revolv+ ^u an axis ,p ,y by a pulley at ,p4 ,! action is z foll[s3 ,f _! position1 ! s(t-iron rods ,n' ,s' mu/ be magnets ?r\gh ! inductive action ( ! p]man5t magnet1 j z ! nail 0 made a magnet 9 l position4 ,s long z ! p>ts h ! relative position %[n 9 ! figure1 & !re is no motion1 no electricity c be develop$2 b1 if ! axis ,p ,y be turn$1 ,s'1 :i* repres5ts ! pol>ity ( ! rod opposite ,n1 w be los+ its induc$ magnetism2 &1 :5 half a revolution has be5 made1 t same pole w be :]e ,n' n[ is2 b x w !n h ,n' pol>ity in/ead ( ,s'2 t is1 x has be5 los+ s\? pol>ity z x rec$$ f ,n1 & ga9+ nor? pol>ity z x approa*$ ,s3 h5ce a curr5t ( electricity has /eadily be5 fl[+ ?r\gh ! coil 9 "o direction4 ,at ! same "t1 ! o!r rod ,n' has pass$ ?r\gh simil> phases2 & its envelop+ coil has _h a curr5t ( electricity induc$ 9 x 9 ! same direction z 9 ! fir/ coil4 ,?is d\bles ! int5sity ( ! curr5t2 & ! :ole is conduct$ by ! connect+-wires :]e ! curr5t is want$4 ,ma*9es h be5 built ^u ?is plan1 t conta9$ fifty or sixty p[]ful comp\nd p]man5t magnets1 & z _m wire coils1 ne$+ a /eam-eng9e ( eight or t5 horse-p[] to run !m4 ,a less cumb]some & mu* m effici5t magneto-electric ma*9e has be5 made by *ang+ ! =m ( ! s(t iron armature to some?+ l a %uttle1 & w9d+ ! wire inside ( x4 ,?is is call$ ! ,siem5's ,armature4 ,! late/ patt]n ( su* ma*9es is kn[n z ! ,gramme2 & its peculi>ity consi/s 9 ! sub/itution ( a broad r+ ( s(t iron = ! armature4 ,ab\t ?is r+ a good _m coils1 ( equal l5g?s1 ( insulat$ copp] wire are w\nd 9 su* a mann] t "o-half ( any turn 9 ! wire goes ?r\gh ! inside ( ! r+1 mak+ ! coils longitud9al4 ,! :ole ( ! armature ?us prep>$ is fix$ ^u a %aft1 s z to p]mit rotation1 & fix$ betwe5 ! poles ( a p[]ful ,jam9 magnet4 ,! ends ( ! coils are connect$ ) conductors ^u ! axis2 &1 :5 ! armature ?us con/ruct$ is rotat$1 a v con/ant & p[]ful curr5t ( electricity fl[s 9 a s+le direction1 unlike ! o!r =ms4 ,x is /at$1 t1 ) "o-horse p[]1 a light c be obta9$ equal to t f a batt]y ( fifty ,grove cells4 ,,second>y ,,curr5ts4 ,s long ago z #ahcf x 0 notic$ by ,pr(4 ,page ( ,salem1 t1 :5ev] a curr5t ( electricity 0 made to fl[ 9 a coil ( wire1 ano!r curr5t 9 ! opposite direction 0 induc$ 9 a coil t 0 p>allel ) ! fir/2 & also1 :5 ! curr5t 9 ! fir/ 0 brok51 ano!r curr5t 9 ! second coil w\ld fl[ 9 ! opposite direction to ! =m] "o4 ,^! curr5ts1 :i* are call$ second>y curr5ts1 are v transi5t4 ,no curr5t at all fl[s save at ! in/ant ( mak+ or break+ ! curr5t4 ,9 ?is respect1 we are rem9d$ ( ! behavior ( ! s(t iron )9 ! coil1 :i* gives orig9 to a curr5t ( electricity :5 x is made to approa* a magnet or rec$e f x1 b gives no curr5t s long z x is /ill4 ,^! second>y curr5ts 7 inve/igat$ by ,pr(4 ,h5ry1 result+ 9 ! discov]y ( _m curi\s & int]e/+ ph5om5a4 ,x w be suffici5t "h = me to ref] to :at are call$ induction coils1 :i* are developm5ts ( ! pr9ciples involv$ 9 electro-magnetism & electro-induction4 ,imag9e a rod ( s(t iron ( any size to be w\nd ) a coil ( wire1 ! ends ( ! wire to be s left t !y may be connect$ ) a galvanic batt]y4 ,ar\nd ?is coil let ano!r coil be w\nd ( v f9e & well-insulat$ wire2 ! t]m9al wires ( x to be left adju/able to any di/ance f ea* o!r4 ,n[1 ^u mak+ connection ) a batt]y to ! prim>y coil1 !re w be two results produc$ simultane\sly4 ,fir/1 ! s(t iron w be r5d]$ magnetic2 &1 second1 a curr5t ( electricity w be g5]at$ 9 ! second>y coil2 & ! /r5g? ( ?is second>y curr5t is v mu* increas$ by ! inductive action ( ! s(t iron t has be5 made a magnet4 ,:5 ! batt]y curr5t is brok51 ! iron loses its magnetism1 & a curr5t ( electricity is aga9 />t$ 9 ! second>y coil 9 ! opposite direction4 ,! en]gy ( ?is d]iv$ curr5t is s great t x w jump "s di/ance ?r\gh ! air1 & ?us is app>5tly unlike ! electricity t orig9ates 9 a batt]y4 ,an induction coil made by ,mr4 ,rit*ie = ! ,/ev5s ,in/itute at ,hobok51 ,n4,j41 has a prim>y coil ( #aie feet ( ,no4 #f wire4 ,! second>y coil is ov] fifty miles 9 l5g?1 & is made ( ,no4 #cf wire1 :i* is b 4#jje ( an in* 9 diamet]4 ,?is in/rum5t has giv5 a sp>k tw5ty-"o in*es 9 l5g?1 ) ?ree l>ge cells ( a bi*romate batt]y4 ,mr4 ,spottiswood ( ,london has j _h complet$ = him ! l>ge/ induction coil ev] made4 ,x has two prim>y coils1 "o conta9+ sixty-sev5 p\nds ( wire1 & ! o!r eighty-f\r p\nds1 ! wire be+ 4#jif in* 9 diamet]4 ,! second>y coil is two hundr$ & eighty miles long1 & has #cha1hej turns4 ,?is coil is made 9 ?ree p>ts1 ! diamet] ( ! wire 9 ! fir/ "p be+ 4#jjie in*2 ( ! second "p1 4#jae2 & ! ?ird "p1 4#jaa4 ,) five ,grove cells ?is induction coil has giv5 a sp>k =ty-two in*es long1 & has p]=at$ glass ?ree in*es ?ick4 ,! electricity ?us develop$ 9 second>y coils is ( ! same "* z t develop$ by friction2 & all ( ! exp]im5ts usually p]=m$ ) ! latt] may be repeat$ ) ! =m]1 _m ( !m be+ greatly height5$ 9 beauty & int]e/4 ,su*1 = in/ance1 are ! dis*>ges 9 vacuo 9 ,geisl] tubes1 exhibit+ /ratifications1 fluoresc5ce1 phosphoresc5ce1 ! production ( ozone 9 great quantity1 decomposition ( *emical comp\nds1 c4 ,! electricity develop$ by friction ^u glass1 wax1 res91 & o!r s-call$ non-conductors1 has h]et(ore be5 call$ /atic electricity1 = ! reason t :5 x 0 once orig9at$ ^u a surface x w\ld rema9 ^u x = an indef9ite "t1 or until "s conduct+ body t\*$ x1 & ?us gave x a way ( escape4 ,?us1 a cake ( wax if rubb$ ) a piece ( flannel1 or /ruck ) a cat-sk9 or a fox-tail becomes highly electrifi$1 & 9 a dry atmosph]e w rema9 s = mon?s4 ,common air has1 h[ev]1 always a notable quantity ( moi/ure 9 x2 &1 z wat] is a conductor ( electricity1 su* damp air mov+ ov] ! electrifi$ surface w c>ry (f v soon all ! electricity4 ,aga91 ! electricity develop$ ?r\gh *emical action 9 a batt]y & ?r\gh ! int]-action ( magnets & coils ( wire has be5 call$ dynamic electricity1 inasmu* z x nev] appe>$ to exi/ save :5 x 0 9 motion 9 a complet$ circuit4 ,?is1 h[ev]1 is n true2 = if "o ( ! wires f a galvanic batt]y be connect$ ) ! e>?1 & ! o!r wire be atta*$ to a delicate electromet]1 x w be f\nd t ! latt] gives evid5ce ( electrical excitem5t 9 ! same mann] z x does = ! electricity develop$ by friction 9 ano!r body4 ,?is is sometimes call$ t5sion1 & is v slight = a s+le cell2 b 9 a s]ies ( cells x becomes noticeable 9 o!r ways4 ,?us :5 ! t]m9als ( a s+le cell are tak5 9 ! h&s1 no effect is p]ceiv$3 if1 h[ev]1 ! t]m9als ( a batt]y consi/+ ( =ty or fifty cells be ?us tak51 a decid$ %ock is felt1 n to be comp>$ ?\gh ) ! %ock t w\ld be felt f ! dis*>ge ( a v small ,leyd5 j>4 ,! %ock f sev]al hundr$ cells w\ld be v dang]\s4 ,x 0 =m]ly d\bt$ t ! electricity w\ld pass betwe5 ! t]m9als ( a batt]y )\t actual contact ( ! t]m9als4 ,gassiot fir/ %[$ t ! sp>k w\ld jump betwe5 ! wires ( a batt]y ( a l>ge numb] ( cells be=e actual contact 0 made4 ,latt]ly ,mr4 ,de ,la ,rue has be5 measur+ ! di/ance across :i* ! sp>k w\ld jump1 us+ a batt]y ( a l>ge numb] ( cells4 ,i give 8 table z tak5 f ! ,proce$+s ( ! ,royal ,society3-- ,cells4 ,/rik+ di/ance4 #fjj 4#jjcc in*4 #a1bjj 4#jacj #a1hjj 4#jcde #b1djj 4#jece ,?is table %[s t ! /rik+ di/ance is v ne>ly z ! squ>e ( ! numb] ( cells4 ,?us1 ) #fjj cells ! sp>k jump$ 4#jjcc in*2 & ) d\ble ! numb] ( cells1 #a1bjj1 ! sp>k jump$ 4#jacj in*1 or )9 4#jjjb ( an in* z f> z f\r times ! fir/ di/ance4 ,?is leads "o to ask h[ big a batt]y w\ld be ne$$ to give a sp>k ( any giv5 l5g?1 say l a fla% ( lightn+4 ,"o cell w\ld give a sp>k 4#jjjjjjja in* long1 & a hundr$ ?\s& w\ld give a sp>k #ib in*es long4 ,a million cells w\ld give a sp>k #gfd feet long1 a v]itable fla% ( lightn+4 ,x is h>dly probable t s _m z a million cells w ev] be made into "o connect$ batt]y1 b x is n improbable t a hundr$ ?\s& cells may be4 ,de ,la ,rue has s9ce complet$ #h1jdj cells1 & f9ds t ! /rik+ di/ance ( t numb] is #j4cde in*1 a little m ?an "o-?ird ( an in*4 ,he also /ates t ! /rik+ di/ance increases fa/] ?an ! above indicat$ ratio1 z det]m9$ by exp]im5t+ ) a /ill l>g] numb] ( cells4 ,^! exp]im5ts & _m o!rs %[ t !re is no ess5tial diff]5ce betwe5 ! s-call$ /atic & dynamic electricity4 ,9 ! "o case x is develop$ ^u a surface :i* has su* a molecul> "* t x _c be conduct$ away1 e surface molecule be+ practically a little batt]y cell ) "o t]m9al free 9 ! air1 s t :5 a prop] conductor approa*es ! surface x receives ! electricity f millions ( cells1 & !re=e becomes /rongly electrifi$ s t a sp>k may at once be drawn f x4 ,,:at ,,is ,,electricity8 ,,!ories4 ,,num]\s attempts h be5 made to expla9 ! ph5om5a ( electricity4 ,z a g5]al ?+1 ^! ph5om5a are s utt]ly unlike o!r ph5om5a t h be5 expla9$ & are easily intelligible1 t x has q g5]ally be5 tak5 = grant$1 until lately1 t some?+ v diff]5t f ord9>y matt] & ! laws ( =ces applicable to x mu/ be involv$ 9 ! ph5om5a !mselves4 ,consequ5tly ! t]m impond]able 0 appli$ to x1--some?+ t 0 matt] m9us "s ( ! ess5tials ( matt]2 & z x 0 app>5t t1 :atev] x 01 x mov$1 app>5tly fl[$1 f "o place to ano!r1 ! t]m fluid 0 appli$ to x1 a t]m descriptive ( a c]ta9 =m ( matt]4 ,impond]able fluid 0 ! descriptive "n appli$ to electricity4 ,newton suppos$ t an excit$ body emitt$ su* a fluid t c\ld p5etrate glass4 ,:5 ! two facts ( electrical attraction & repulsion _h to be acc\nt$ =1 two !ories 7 prop\nd$1--"o by ,b5jam9 ,frankl91 ! o!r by ,dufay4 ,frankl9 suppos$ t electricity 0 a subtle1 impond]able fluid1 ( :i* all bodies conta9$ a c]ta9 normal quantity4 ,by friction or o!rwise ?is normal quantity 0 di/urb$4 ,if a body receiv$ m ?an its due %>e1 x 0 said to be positively electrifi$3 if x _h less ?an its normal quantity1 x 0 said to be negatively electrifi$4 ,frankl9 suppos$ ?is electric fluid to be highly self-repulsive1 & t x p[]fully attract$ ! p>ticles ( matt]4 ,accord+ to ,dufay1 !re are two electric fluids1 opposite 9 t5d5cy b equal 9 am\nt4 ,:5 associat$ toge!r 9 equal quantities1 !y neutralize ea* o!r completely4 ,a portion ( ?is neutral comp\nd fluid p]vades all matt] 9 its unexcit$ /ate4 ,by friction or o!rwise ?is comp\nd fluid is decompos$1 ! rubb] & ! body rubb$ ex*ang+ equal quantities ( opposite k9ds ) ea* o!r1 leav+ "o ( !m positively1 ! o!r negatively electrifi$4 ,^! two fluids 7 suppos$ to be self-repulsive1 b to attract ea* o!r3 s t1 if two bodies be *>g$ ) ei!r positive or negative electricity1 su* bodies w\ld mutually repel ea* o!r2 b if "o 0 *>g$ ) positive1 :ile ! o!r 0 *>g$ ) negative electricity1 ! two bodies w\ld mutually attract ea* o!r4 ,ei!r ( ^! two !ories may be us$ to illu/rate ! ph5om5a1 & s h done good s]vice 9 sy/ematiz+ ! facts4 ,x is evid5t t bo? ( !m _c be true1 & x is 9 ! highe/ degree probable t nei!r ( !m is true4 ,"s h suppos$ t !re 0 a k9d ( electric atmosph]e ab\t e atom ( matt]2 & /ill ano!r !ory1 n[ advocat$ by ,edlund ( ,/ockholm1 assumes t electricity is id5tical ) ! e!r by :i* radiant en]gy1 light & heat1 is transmitt$4 ,be=e a correct judgm5t c be =m$ ( ! nature ( any =ce1 x is necess>y to "k :at x c d1 :at k9d ( ph5om5a x c produce4 ,let u1 !n1 take a brief survey ( :at electricity c d4 #a/1 ,x c directly produce motion1 ?r\gh ! attractions & repulsions ( electrifi$ bodies1--z indicat$ by electromet]s1 ! rotation ( ! fly-:eel1 ! deflection ( ! galvanomet] ne$le4 ,x has be5 prov$ by ! ma!matical labors ( ,clausius1 & confirm$ by exp]im5t1 t1 :5 electricity p]=ms any me*anical "w1 s mu* electricity is lo/1 annihilat$ z electricity4 #b;d1 ,x c directly produce heat1 z %[n by pass+ a suffici5t quantity ( electricity ?r\gh a f9e plat9um wire3 ! wire becomes heat$1 & gl[s1 & x may ev5 be fus$ by ! int5sity ( ! heat4 ,! heat develop$ 9 ! s-call$ electric arc is s great z to fuse ! mo/ refractory sub/ances4 ,if a curr5t ( electricity f a batt]y be s5t ?r\gh a !rmo-pile1 "o ( ! faces ( ! pile w be heat$4 ,! heat ( ! sp>k f a ,leyd5 j> may be made to ignite gunp[d]1 & dissipate gold into vapor4 ,! heat produc$ by lightn+ is se5 :5 a live tree is /ruck by a p[]ful fla%3 ! sap ( ! tree is in/antly conv]t$ into /eam ( s high a t5sion z to explode ! tree1 scatt]+ x 9 small fragm5ts ov] a wide area4 ,! tips ( lightn+-rods (t5 exhibit ?is heat+ effect1 be+ fus$ by ! passage ( too great a quantity ( electricity4 ,9 ! e>ly "p ( ! pres5t c5tury x 0 demon/rat$ by ,c\nt ,rum=d1 & also by ,sir ,humphry ,davy1 t heat 0 b a =m ( molecul> motion4 ,s9ce !n ! exact relations betwe5 ! motion ( a mass ( matt] & ! equival5t heat h be5 exp]im5tally det]m9$ by ,j\le1 s t ! unit ( heat may be express$ 9 ! motion ( a mass ( matt]4 ,?is is d$ucible f a m g5]al law1 kn[n z ! cons]vation ( en]gy4 ,! application 9 ?is place is1 t :5ev] heat appe>s ?r\gh electric action1 z 9 ! above-m5tion$ places1 we "k t x /ill is only motion t is ! product1 only t ?is motion is n[ among ! molecules ( ! body1 in/ead ( ! motion ( ! :ole body 9 space1 z :5 a pi?-ball moves1 or a galvanomet]-ne$le turns4 #c;d1 ,x c directly produce light4 ,?is is se5 9 e sp>k f an electric ma*9e1 9 ! fla% ( lightn+1 & 9 ! electric light4 ,x has be5 %[n 9 numb]less ways1 t !re is no ess5tial diff]5ce betwe5 light & heat1 & t :at we call light is only ! active relation :i* c]ta9 rays ( radiant en]gy h to ! eyes4 ,9 ord] to make ?is pla91 suppose t a beam ( light1 say f ! sun1 be p]mitt$ to fall ^u a triangul> prism ( glass3 at once x is se5 t ! beam is deflect$1 & in/ead ( appe>+ a spot ( :ite light1 z x did be=e x 0 deflect$1 x n[ appe>s z a brilliant b& ( colors1 :i* is call$ ! sol> spectrum4 ,if n[ ?is spectrum be exam9$ z to ! di/ribution ( heat1 by mov+ a !rmo-pile ?r\gh x f ! blue end t[>ds ! r$ end1 x w be notic$ t ! galvanomet]-ne$le w be b slightly deflect$ at ! blue end2 b1 z ! !rmo-pile is mov$1 ! deflections are great] until x is pa/ ! r$ end1 :]e ! heat is greate/4 ,on ?is acc\nt x has be5 cu/om>y to say t ! r$ end ( ! spectrum 0 ! heat+ end4 ,) v>i\s pieces ( me*anism ! rays may be sep>at$ f ea* o!r1 & measur$2 & !n x appe>s t a r$ ray ( light has a wave l5g? ( ab\t #a_/cgjjj 941 & ! violet ray ab\t #a_/fjjjj 94 ,! rays beyond ! r$ h also be5 measur$1 & f\nd to be great] 9 l5g? uni=mly z "o rec$es f ! visible "p ( ! spectrum4 ,9 l mann]1 beyond ! blue end ! wave l5g?s become %ort] & %ort]2 & 9 ea* ( ^! directions ! spectrum t is invisible is mu* long] ?an ! visible "o4 ,n[1 x has also be5 f\nd t :]e a prism ( glass or o!r mat]ial is us$ to produce a spectrum1 x di/ributes ! rays v unev5ly2 t is1 t[>ds ! r$ end ( ! spectrum !y are v mu* cr[d$1 :ile t[>ds ! blue end !y are m disp]s$4 ,h5ce1 if "o 7 measur+ ! heat+ p[] ( su* a spectrum1 _m m rays w\ld fall ^u an equal surface ( ! !rmo-pile at ! r$ end ?an at ! blue end2 !re=e ! indications ( ! galvanomet] w\ld be fallaci\s4 ,be=e any ?+ def9ite c\ld be kn[n ab\t ! matt]1 x w\ld pla9ly be necess>y to "w ) an equal disp]sion ( all ! rays4 ,?is 0 effect$ a few ye>s ago by ,dr4 ,drap] ( ,new ,york4 ,he took ! spectrum produc$ by diffraction in/ead ( refraction1 & measur$ t4 ,9 t way x 0 f\nd t ! heat+ p[] ( ! spectrum is equal 9 e "p ( x2 & h5ce ! pictures 9 treatises on physics t repres5t ! heat+ p[] ( ! spectrum to be conc5trat$ at ! r$ end is n true save :]e ! spectrum is irregul>ly produc$4 ,z = vision1 ! me*anical /ructure ( ! eye is su* t radiant vibrations hav+ a wave l5g? betwe5 #a_/cgjjj 94 & #a_/fjjjj 94 c affect x1 :ile long] or %ort] wave l5g?s c n4 ,su* waves we call light1 b x is n at all improbable t "s animals & insects h eyes adapt$ to ei!r long] or %ort] wave-l5g?s2 9 :i* case1 :at w\ld be p]fectly d>k to u w\ld be light to !m4 ,x is a famili> en\gh fact1 t _m animals1 su* z dogs1 cats1 rats1 & mice1 c see 9 ! night4 ,"s horses may be tru/$ to keep 9 ! road 9 a d>k night1 :5 ! driv] _c see ev5 ! horse itself4 ,?is has usually be5 acc\nt$ = by say+ t _! eyes are con/ruct$ s z to collect a great] numb] ( lum9\s rays4 ,x is mu* bett] expla9$ by suppos+ _! eyes to be con/ruct$ to respond to wave-l5g?s ei!r great] or less ?an ^? ( mank9d4 ,a ray ( light1 !n1 consi/s ( a s+le l9e ( undulations ( a def9ite wave l5g?1 su* t if x falls ^u ! eye x w produce sight2 if x falls ^u a !rmo-pile x heats x by j ! same quantity t ano!r wave-l5g? w\ld heat x2 if x falls ^u matt] 9 un/able *emical relations1 x w d *emical "w1 dep5d+ ^u ! k9ds ( matt]4 ,a r$ ray is z effective = "s sub/ances z a violet ray is = o!rs4 ,! /atem5t1 !n1 s (t5 lately made to d c]ta9 analogical "w1 namely1 t a ray ( light consi/s ( ?ree di/9ct p>ts1 :i* may be sep>at$ f ea* o!r1 & are call$ heat1 light1 & *emical prop]ties1 is simply untrue4 ,:at a ray w d1 dep5ds ^u :at k9d ( a /ructure x falls on2 & :5 x has done t "w1 ( :atev] k9d x may be1 x ceases to exi/ z a ray4 ,if1 !re=e1 electricity c directly produce light1 x is simply produc+ motion1 z 9 ! case ( heat1 ! motion be+ ( su* a sort t ! eyes ( m5 are affect$ by x4 #d?1 ,x c produce magnetism4 ,a curr5t ( electricity pass+ ?r\gh a coil ( wire makes su* a coil a magnet1 :i* w set itself 9 ! direction ( ! magnetic m]idian ( ! e>?2 &1 if a b> ( s(t iron be plac$ 9 ! coil1 x becomes ! famili> electro-magnet2 &1 if h>d5$ /eel be put 9 x1 x becomes a p]man5t magnet4 ,?is leads to ! inquiry z to :at magnetism is4 ,we "k t x c produce motion by its mov+ at a di/ance a piece ( iron or ano!r magnet4 ,x w also su/a9 a mass ( matt] aga9/ gravity or "s o!r contr>y =ce4 ,?r\gh su* me*anism z magneto-electric ma*9es x produces electricity 9 great abundance1 :i* aga9 c be us$ to produce any ( ! effects ( electricity1--mov+ bodies by attraction or repulsion1 g5]at+ heat or light1 or aga9 mak+ a magnet4 ,b z all ( ^! are b v>i$ =ms ( motion1 ei!r ( a mass z a :ole1 or molecul>1 c x be d\bt$ = an in/ant1 t :at we call magnetism is b "s =m ( motion8 ,mu/ x n be ei!r "s =m ( matt]1 or "s =m ( motion8 ,if x 7 a =m ( matt]1 !n a magnet w\ld only be p]man5t s long z x 0 n us$2 = use implies consumption ( ! =ce2 &1 if ?is be matt] 9 any =m1 !n 9 a giv5 mass ( matt] !re c be b a def9ite quantity ( su* magnetic matt]1 & consumption mu/ less5 t quantity4 ,z a matt] ( fact1 !re is no p]ceptible less5+ ( ! p[] ( a magnet :5 x is prop]ly us$4 ,x is also a matt] ( fact1 t nei!r motion ( a mass1 nor electrical effects1 nor any o!r1 c be produc$ by ! action ( a magnet alone4 ,x is only :5 "s =m ( motion has be5 add$ to its own prop]ty1 t we get any k9d ( an effect f x3 h5ce all effects due to its action are resultants ( two =ces1 "o ( !m be+ common motion ( a mass ( matt]1 & ! o!r ! en]gy ( ! magnet4 ,h5ce we inf] t a magnet is a me*anism ( su* a /ructure z to *ange ! direction & "* ( ! motion :i* acts ^u x4 ,:5 ! :eel ( a common electrical ma*9e is turn$1 ! product is electricity1--a =ce v diff]5t f t :i* orig9ates x4 ,ord9>y me*anical motion goes 92 electricity comes out1 ! latt] be+ a modifi$ motion due to ! physical /ructure ( ! ma*9e4 ,9 l mann]1 a magnet may be consid]$ z a ma*9e by means ( :i* me*anical motion may be conv]t$ into "s o!r =m ( motion4 ,x is evid5t t molecul> /ructure is *iefly conc]n$ 9 ?is4 ,if a b> ( iron t exhibits no evid5ce ( magnetism :atev] be subject$ to torsion1 x w imm$iately become a magnet ) poles dep5d5t ^u ! direction ( ! twi/4 ,?is develop$ magnetism w re-act ^u a coil ( wire1 & s move a galvanomet] ne$le4 ,if ! b> be p]mitt$ to recov] its orig9al condition1 x w lose its magnetism1 :i* w at once re-appe> ^u twi/+ ! rod aga94 ,n[1 :5 ! rod is twi/$1 x is evid5t t !re is a molecul> /ra9 9 c]ta9 directions ?r\gh\t ! mass4 ,! conv]se exp]im5t illu/rates ! same ?+4 ,x has be5 f\nd1 t :5 a rod ( iron is made magnetic by ! action ( a curr5t ( electricity circulat+ ab\t x1 & at ! same "t pass+ longitud9ally ?r\gh x1 ! rod is slightly l5g!n$ & twi/$ 9 a direction t dep5ds ^u ! direction ( ! curr5t4 ,moreov]1 if a p]man5t magnet be heat$ to a r$ heat1 its magnetism is de/roy$2 = su* a heat all[s ! molecules to freely arrange !mselves )\t any ext]nal con/ra9t4 ,also1 if a p]man5t magnet be susp5d$ s z to give out a musical s\nd :5 x is /ruck1 ! magnetism w be mu* weak5$ by mak+ x ?us to vibrate4 ,9 ?is case1 z 9 ! o!r1 ! vibrations affect e molecule1 & s enable !m to re-adju/ !mselves to ! positions !y held be=e be+ magnetiz$4 ,! same ?+ happ5s :5 a b> ( iron is made magnetic ?r\gh ! inductive action ( ! e>?4 ,:5 ?is b> is held 9 ! direction ( ! magnetic dip1 x becomes b v slightly magnetiz$2 b1 if x be s held t :5 x is /ruck ) a hamm] x w r+1 t is1 give out a musical s\nd1 x w at once become decid$ly magnetic4 ,evid5tly ! e>?'s action t5ds to set ! molecules ( ! mass 9 a new position1 b cohesion prev5ts !m f assum+ x4 ,:5 ! molecules are made to vibrate1 !y c assume su* new positions m readily4 ,! molecules ( a magnet1 !n1 are diff]5tly arrang$ f ^? 9 an unmagnetiz$ piece ( iron or /eel2 &1 = e new arrangem5t ( ! molecules ( a mass ( any k9d1 we always h "s new physical prop]ty develop$4 ,! same id5tical sub/ance may appe> z *>coal1 coke1 plumbago1 an?racite coal1 & diamond4 ,h5ce a magnet is a ma*9e 9 :i* o!r =ces act+ ^u x are trans=m$ 9 "*1 & re-appe> z attractions & repulsions ( o!r k9ds ( matt]3 ?is trans=mation _c take place1 & h5ce magnetism _c become app>5t1 only ^u ! condition ( ano!r =ce act+ 9 conc]t ) x2 &1 if at any "t x may seem to be act+ )\t su* ext]nal =ce1 x is done at ! exp5se ( ! heat x has absorb$1 & !re=e ! magnet mu/ at su* "t be los+ temp]ature proportional to ! "w done4 ,?is ,i h discov]$ to be true by mak+ a magnet to ex]t its =ce 9 front ( a !rmo-pile1 :i* uni=mly exhibits a cool$ face "u su* conditions4 ,:at ! p>ticul> =m ( ! motion may be t we call magnetism1 is n yet made out2 b t x is "s =m ( motion1 is v evid5t4 ,! foll[+ exp]im5ts may ?r[ "s light ^u x4 ,la/ ,augu/ ,mr4 ,k]r read a pap] be=e ! ,briti% ,association ( ,sci5ce1 9 :i* 0 detail$ ! foll[+ exp]im5t3 ,! pole ( an electro-magnet 0 nicely poli%$ s z to reflect light l a mirror4 ,a beam ( sunlight 0 p]mitt$ to fall ^u x1 & be reflect$ to a conv5i5t place = exam9ation4 ,a curr5t ( electricity 0 s5t ?r\gh ! coil1 :i* ( c\rse r5d]$ ! iron magnetic2 & x 0 notic$ t ! light t 0 reflect$ f ! pole 0 circul>ly pol>iz$3 t is1 ! motion ( a ray1 in/ead ( be+ a simple undulatory movem5t1 0 n[ made to assume su* a motion z ! wat] f a g>d5-hose has :5 ! nozzle is swung r\nd 9 a circle :ile ! wat] is escap+ f x4 ,aft] read+ ! acc\nt ( x1 x occurr$ to me t ! conv]se exp]im5t might be tri$2 t is to say1 ! effect ( a circul>ly pol>iz$ beam ( light ^u a piece ( /eel4 ,by conc5trat+ a l>ge beam ( ord9>y plane pol>iz$ light ) a qu>tz l5s1 & pass+ x ?r\gh a qu>t] wave-plate at ! prop] angle1 a p[]ful beam ( circul>ly pol>iz$ light 0 obta9$4 ,at ! focus ( ?is beam a f9e cambric ne$le )\t magnetism 0 plac$ s t ! light pass$ x longitud9ally4 ,t5 m9utes' exposure 0 suffici5t to make x decid$ly magnetic4 ,h5ce ,i inf] t ! motions :i* we call magnetic attractions & repulsions may be q analog\s to su* helical motions2 also1 t ^! motions exi/ 9 e!r1 & evid5tly may be ei!r "r-h&$ or left-h&$4 ,w9d up on a p5cil a piece ( wire twelve or fifte5 in*es long1 mak+ a loose spiral4 ,br+ ! two ends ( ! spiral toge!r2 & note fir/ t "o is twi/$ to ! "r1 ! o!r to ! left4 ,if !y be twi/$ into ea* o!r1 !y w advance v easily2 b if a "r-h&$ spiral 7 to be int]lock$ ) ano!r l x1 & bo? turn$ 9 ! direction ( _! spiral1 !y w\ld sep>ate rapidly4 ,apply+ ?is conception to a magnet1 we might suppose t su* spiral motions w be set up 9 ! e!r by ! magnet1 & t su* motions re-act+ ^u ord9>y matt] affect x z attraction & repulsion2 & ?us we %\ld h at lea/ a conceivable me*anical explanation ( ! ph5om5on4 ,illu/ration3 ,,fig4 #e4 ,!re are numb]less exp]im5ts :i* might be giv5 to fur!r exhibit ! relation ( mass motion to magnetism1 b a s+le "o m mu/ suffice4 ,no rotation ( a magnet ^u its own axis c produce any effects ^u a curr5t t is ext]ior to x2 b if a loop ( wire be kept /ation>y adjac5t to a magnet1 z 9 ,fig4 #e1 :ile ! magnet revolves1 a curr5t ( electricity is produc$2 & if ! magnet be kept /ation>y1 & ! loop revolves1 a curr5t w also be produc$1 b 9 ! opposite direction4 ,"h1 z 9 all ! o!r cases1 no electricity is orig9at$1 save :5 motion is imp>t$ to "o or o!r ( ! p>ts4 ,?is exp]im5t is due to ,f>aday4 ,f all ^! cases we c come to b "o conclusion1 t bo? electricity & magnetism are b =ms ( motion2 electricity be+ a =m ( motion 9 ord9>y matt]1 = x _c be made to pass ?r\gh a vacuum1 :ile magnetism mu/ be a =m ( motion induc$ 9 ! e!r1 = x is z effective 9 a vacuum z out ( x2 electricity always ne$+ "s mat]ial conductor1 magnetism ne$+ no m ?an d radiant heat & light4 ,,velocity4 ,measurem5ts h be5 made ( ! velocity ( electricity2 bo? t ( high t5sion1 su* z ! sp>k f a ,leyd5 j>1 & also t f a batt]y4 ,! =m] 0 f\nd to h a velocity ov] #bjj1jjj miles a second1 :ile ! electricity f a batt]y may move z sl[ly z #ae1jjj or #bj1jjj miles a second2 b ?is is v l>gely a matt] ( conductors4 ,its velocity is seldom above #cj1jjj miles a second on ord9>y telegraphic l9es4 ,if ! electricity be us$ to give signals1 z 9 ord9>y telegraphy1 ! "t requir$ v>ies ne>ly z ! l5g? ( ! l9e1 & 9 any case is a mu* great] quantity4 ,prescott 9 8 "w on ! telegraph /ates t ! "t requir$ to produce a signal on ! electro-magnet at ! extremity ( a l9e ( #cjj miles ( ,no4 #h iron wire is ab\t 4#ja seconds1 & t ?is "t increases 9 a great] proportion ?an ! l5g? ( ! l9e2 = example1 on a l9e #fjj miles 9 l5g? x am\nts to ab\t 4#jc seconds4 ,he also /ates t x v>ies mu* ) ! k9d ( magnet us$1 "s =ms ( magnets be+ mu* m s5sitive ?an o!rs = ?is "w4 ,:eat/one prov$ a good _m ye>s ago t ! duration ( ! electric sp>k 0 less ?an "o million? ( a second4 ,:5 a swiftly mov+ body c only be se5 by an electric sp>k1 or fla% ( lightn+1 x looks z if x 7 quiesc5t4 ,?us a tra9 ( c>s ru%+ along at ! rate ( =ty or fifty miles p] h\r appe>s %>ply def9$1--ev5 ! driv+-:eels ( ! locomotive c be se5 9 detail1 :i* is impossible 9 cont9u\s light1--& all seems to be /&+ /ill4 ,9 l mann] w ! sails ( a w9dmill1 :i* may be turn+ at a rapid rate1 be se5 app>5tly at re/4 ,?is is because 9 ! %ort "t dur+ :i* !y are illum9at$ !y d n appreciably move4 ,i am n aw>e t any attempt has be5 made to measure ! velocity ( magnetism4 ,if1 h[ev]1 x be a =m ( motion 9 e!r1 x is probable t ! velocity is comp>able to ! velocity ( radiant en]gy1 light1 :i* is equal to ab\t #ahf1jjj miles a second4 ,,s\nd4 ,,be=e expla9+ ! relation t s\nd has to telephony1 x w be necess>y to make q pla9 :at s\nd is1 & h[ x affects ! sub/ance ( ! body ?r\gh :i* x moves4 ,if ,i /rike my p5cil ^u ! table1 ,i he> a snap t appe>s to ! e> to be simultane\s ) ! /roke3 if1 h[ev]1 ,i see a man ^u a some:at di/ant hill /rike a tree ) an axe1 ! s\nd does n rea* me until "s appreciable "t has pass$2 & x is not$1 t1 ! f>!r away ! place :]e a s-call$ s\nd orig9ates1 ! long] "t does x take to rea* any li/5]4 ,h5ce s\nd has 9 air a c]ta9 velocity :i* has be5 v accurately measur$1 & f\nd to be #a1jic feet p] second :5 ! temp]ature ( ! air is at ! freez+ po9t ( wat]4 ,z ! temp]ature increases1 ! velocity ( s\nd w increase a little m ?an "o foot = e ,fahr5heit degree2 s t at #fj deg4 ! velocity is #a1abe feet p] second4 ,?is is ! velocity 9 air4 ,9 wat] ! velocity is ab\t f\r times great]1 9 /eel sixte5 times1 9 p9e-wood ab\t t5 times4 ,,con/itution ,,( ,a ,,s+le ,,s\nd-,,wave4 ,if a p]son /&s at ! di/ance ( fifte5 or tw5ty rods f a cannon t is fir$1 he w fir/ see ! fla%1 !n ! cl\d ( smoke t ru%es f ! cannon's m\?1 !n ! gr\nd w be felt to tremble1 & la/ly ! s\nd w rea* 8 e> at ! same "t t a /rong puff ( air w be felt4 ,?is puff ( air is ! s\nd-wave itself1 travell+ at ! rate ( elev5 hundr$ feet or m p] second4 ,at ! in/ant ( explosion ( ! gunp[d]1 ! air 9 front ( ! cannon is v mu* compress$2 & ?is compression at once beg9s to move outw>ds 9 e direction1 s z to be a k9d ( a sph]ical %ell ( air con/antly increas+ 9 diamet]2 &1 :5ev] x rea*es an e>1 ! s\nd is p]ceiv$4 ,:5ev] su* a s\nd-wave /rikes ^u a solid surface1 z ^u a cliff or a build+1 x is turn$ back1 & ! reflect$ wave may be he>d2 9 :i* case we call x an e*o4 ,:5 a cannon is fir$1 we g5]ally he> ! s\nd repeat$1 s t x app>5tly la/s = a second or m2 b :51 z 9 ! fir/ case1 we he> ! s\nd ( a p5cil /ruck ^u ! table1 b a s+le %ort report is notic$1 & ?is1 z may be suppos$1 consi/s ( a s+le wave ( cond5s$ air4 ,illu/ration3 ,,fig4 #f4 ,illu/ration3 ,,fig4 #g4 ,imag9e a tun+-=k t is made to vibrate4 ,ea* ( ! prongs beats ! air 9 opposite directions at ! same "t4 ,look at ! physical condition ( ! air 9 front ( "o ( ^! prongs4 ,z ! latt] /rikes outw>ds1 ! air 9 front ( x w be driv5 outw>ds1 cond5s$2 &1 on acc\nt ( ! ela/icity ( ! air1 ! cond5sation w at once />t to travel outw>ds 9 e direction1--a wave ( d5s] air2 b directly ! prong rec$es1 beat+ ! air back 9 ! contr>y direction1 :i* w obvi\sly r>efy ! air on ! fir/ side4 ,b ! di/urbance we call r>efaction moves 9 air ) ! same velocity z a cond5sation4 ,we mu/ !re=e rememb]1 t j beh9d ! wave ( cond5sation is ! wave ( r>efaction1 bo? travell+ ) ! same velocity1 & !re=e always ma9ta9+ ! same relative position to ea* o!r4 ,n[1 ! =k vibrates a great _m times 9 a second1 & w consequ5tly g5]ate z _m ( ^! waves1 all ( !m con/itut$ alike1 & hav+ ! same l5g?2 by l5g? mean+ ! sum ( ! ?icknesses ( ! cond5sation & ! r>efaction4 ,suppose a =k to make "o hundr$ vibrations p] second3 at ! end ( ! second1 ! wave g5]at$ by ! vibration at ! beg9n+ ( ! second w\ld h travell$1 say1 elev5 hundr$ feet2 & ev5ly di/ribut$ betwe5 ! =k & ! out] limit1 w\ld be rang$ ! int]m$iate waves occupy+ ! :ole di/ance3 t is to say1 9 elev5 hundr$ feet !re w\ld be "o hundr$ s\nd-waves1 ea* ( !m evid5tly be+ elev5 feet long4 ,if ! =k made elev5 hundr$ vibrations p] second1 ea* ( ^! waves w\ld be "o foot long2 = s\nd-waves ( all l5g?s travel 9 air ) ! same rapidity4 ,"s late exp]im5ts seem to %[ t ! actual amplitude ( motion ( ! air1 :5 mov$ by su* a high s\nd z t f a small :i/le1 is less ?an ! million? ( an in*4 ,,pit*4 ,! pit* ( a s\nd dep5ds :olly ^u ! numb] ( vibrations p] second t produce x2 & if "o ( two s\nds consi/s ( twice z _m vibrations p] second z ! o!r "o1 !y diff] 9 pit* by ! int]val call$ 9 music an octave1 ?is latt] t]m m]ely signify+ ! numb] ( int]vals into :i* ! l>g] int]val is divid$ = ! ord9>y musical scale4 ,! diff]5ce betwe5 a high & a l[ s\nd is simply 9 ! numb] ( vibrations ( ! air rea*+ ! e> 9 a giv5 "t4 ,! small] int]vals into :i* ! octave is divid$ /& 9 ma!matical relations to ea* o!r :5 !y are prop]ly produc$1 & are repres5t$ by ! foll[+ fractions3-- ,c ,d ,e ,f ,g ,a ,b ,c #a #i_/h #e_/d #d_/c #c_/b #e_/c #ae_/h #b ,illu/ration ,^! numb]s are to be int]pret$ ?us3 ,suppose t we h a tun+-=k giv+ #bef vibrations p] second3 ! s\nd w be t ( ! /&>d or conc]t pit* = ! ,c on ! add$ l9e z %[n on ! /aff4 ,n[1 ,d :5 prop]ly tun$ w make #i vibrations :ile ,c makes b #h2 b1 z ,c 9 ?is case makes #bef1 ,d mu/ make #befx#i_/hbhh4 ,9 l mann] ,g is produc$ by #befx#c_/bchd1 & ,c above by #befx#beab1 & s on = any ( ! o!rs4 ,if o!r s\nds are us$ 9 ! octave above or bel[ ?is "o1 ! numb] ( vibrations ( any giv5 note may be f\nd by ei!r d\bl+ or halv+ ! numb] = ! correspond+ note 9 ! giv5 octave4 ,?us ,g bel[ w consi/ ( #chd_/baib1 & ,g above ( #chdx#bgfh4 ,dur+ ! pa/ c5tury !re has be5 a q /eady rise 9 ! /&>d pit*1 & ?is has be5 br\ght ab\t 9 a v curi\s & unsuspect$ way4 ,! tun+-=k has be5 ! in/rum5t to pres]ve ! pit*1 z x is ! be/ available in/rum5t = su* a purpose1 x be+ conv5i5t to use1 & does n v>y z mo/ o!r musical in/rum5ts d4 ,b a tun+-=k is br\ght to its pit* ) a file1 :i* w>ms x some:at1 s t at ! mom5t :5 x is 9 tune ) ! /&>d t is be+ duplicat$ x is above its normal temp]ature2 & :5 x cools its tone rises4 ,:5 ano!r is made ( l pit* ) ?is "o1 ! same ?+ is repeat$2 & s x has cont9u$ until ! /&>d pit* has ris5 ne>ly a tone high] ?an x 0 9 ,ha5del's "t4 ,! common ,a & ,c tun+-=ks to be _h 9 music /ores1 (t5 v>y a great deal f ! accept$ conc]t pit*4 ,su* z ! writ] has measur$ h be5 g5]ally too high2 sometimes be+ t5 or m vibrations p] second beyond ! prop] numb]4 ,! tun+-=ks made by ,m4 ,koe5ig ( ,p>is are accurate )9 ! t5? ( "o vibration1 ! ,c mak+ #bef vibrations 9 "o second4 ,,limits ,,( ,,audibility4 ,num]\s exp]im5ts h be5 made to det]m9e ! limits ( audible s\nds2 & "h x is f\nd t !re is a v great diff]5ce 9 individuals 9 _! ability to p]ceive s\nds4 ,helmholtz /ates t ab\t #bc vibrations p] second is ! fewe/ 9 numb] t c be he>d z cont9u\s s\nd2 if !y are few] 9 numb] ?an t1 ! vibrations are he>d z sep>ate di/9ct noises1 z :5 "o knocks ^u a door f\r or five times a second4 ,if "o c\ld knock ev5ly #bc times p] second1 he w\ld be mak+ a cont9u\s musical s\nd ( a v l[ pit*4 ,b ?is limit ( #bc is n ! limit = all3 "s c he> a cont9u\s s\nd ) z few z #af or #ah vibrations p] second1 :ile o!rs are z f> above ! m$ium z ?is is bel[ x4 ,! limits ( s\nd 9 musical in/rum5ts are ab\t all includ$ 9 ! range ( a #g-octave pian(orte f ,f to ,f1 say f #db to #e1dfj vibrations p] second4 ,b ?is high numb] is n any:]e ne> ! upp] limit ( audible s\nds = man4 ,v _m ( ! famili> s\nds ( insects1 su* z crickets & mosquitoes1 h a mu* high] pit*4 ,helmholtz puts ?is upp] limit at #ch1jjj vibrations p] second1 & ,despraetz at #cf1hej4 ,! discrepancy ( results is due solely to ! m>k$ diff]5ce 9 individuals z to ac\/ic p]ception4 ,= ! production ( high musical tones1 ,koe5ig ( ,p>is makes a set ( /eel rods4 ,a /eel rod ( a c]ta9 l5g?1 diamet]1 & temp]1 w give a musical s\nd :i* may be det]m9$4 ,! prop] l5g? = o!r rods = giv+ high] tones may be det]m9$ by ! rule t ! numb] ( vibrations is inv]sely proportional to ! squ>e ( ! l5g? ( ! rod4 ,! dim5sions ( ^! rods :5 made #b c4 m4 9 diamet] are z foll[s3-- ,l5g?4 ,vibrations4 #ff4b m4 m4 #bj1jjj #ei4a #be1jjj #ec4h #cj1jjj #ej4a #ce1jjj #dg4e #dj1jjj ,^! rods ne$ to be susp5d$ ^u loops ( silk1 & !y are /ruck ) a piece ( /eel s %ort z to be :olly beyond ! ability ( any e> to he> its r+4 ,no?+ b a %ort ?ud is to be he>d f x :5 x /rikes1 :ile f ! o!rs comes a di/9ct r++ s\nd4 ,9 exp]im5t+ ) su* a set ( /eel rods ,i h n f\nd any "o yet :o c\ld he> z _m z #be1jjj p] second1 my own limit be+ ab\t #ba1jjj4 ,b x has be5 exp]im5tally f\nd t *ildr5 & y\? h a p]ceptive p[] = high s\nds consid]ably above adults4 ,dr4 ,cl>5ce ,blake ( ,bo/on reports a case 9 8 aural practice1 ( a woman ^: he>+ _h be5 gradually dim9i%+ = "s ye>s until %e c\ld n he> at all ) "o e>1 & ! tick+ ( a wat* c\ld only be he>d ) ! o!r :5 ! wat* 0 held aga9/ ! e>4 ,aft] treatm5t x 0 discov]$ t ! s5sibility to high s\nds 0 v great1 & t %e c\ld he> ! /eel rod hav+ a tone ( #dj1jjj vibrations4 ,la/ ye> ,mr4 ,f4 ,galton1 ,f4,r4,s41 exhibit$ be=e ! ,sci5ce ,conf]5ce an in/rum5t 9 ! %ape ( a v small :i/le1 :i* he _h devis$ = produc+ a v high s\nd4 ,! :i/le _h a diamet] less ?an ! "o tw5ty-fif? ( an in*4 ,! l5g? c\ld be v>i$ by mov+ a plug at ! end ( ! :i/le4 ,x 0 easy to make a s\nd ^u su* an in/rum5t t 0 altoge!r out ( he>+-range ( any p]son4 ,mr4 ,galton tri$ "s v int]e/+ exp]im5ts ^u animals1 by us+ ^! :i/les4 ,he w5t ?r\gh ! ,zooelogical ,g>d5s1 & produc$ su* high s\nds ne> ! e>s ( all ! animals4 ,"s ( !m w\ld prick up _! e>s1 %[+ t !y he>d ! s\nd2 :ile o!rs app>5tly c\ld n he> x4 ,he decl>es t among all ! animals ! cat 0 f\nd to he> ! %>pe/ s\nd4 ,small dogs c also he> v %rill notes1 :ile l>g] ones c n4 ,cattle 7 f\nd to he> high] s\nds ?an horses4 ,! squeak ( bats & ( mice _c be he>d by _m p]sons :o c he> ord9>y s\nds z well z any2 %>pness ( he>+ hav+ no?+ to d ) ! limits ( he>+4 ,,effects ,,( ,,s\nd ,,^u ,,o!r ,,bodies4 ,if a vibrat+ tun+-=k be held close to a delicately susp5d$ body1 ! latt] w approa* ! =k1 z if impell$ by "s attractive =ce4 ,! exp]im5t c be made by fa/5+ a bit ( pap] ab\t an in* squ>e to a /raw five or six in*es long1 & !n susp5d+ ! /raw to a ?read1 s t x is balanc$ horizontally4 ,br+ ! vibrat+ tun+-=k )9 a qu>t] ( an in* ( ! pap]4 ,9 ?is case ! motion ( approa* is due to ! fact t ! pressure ( ! air is less close to a vibrat+ body ?an at a di/ance f x2 !re is !re=e a slightly great] pressure on ! side ( ! pap] away f ! =k ?an on ! side next to x4 ,if a vibrat+ tun+-=k be held ne> to ! e>1 & turn$ ar\nd1 !re may be f\nd f\r places 9 "o rotation :]e ! s\nd w be he>d b v fa9tly1 :ile 9 e o!r position x c be he>d pla9ly en\gh4 ,! ext9ction ( ! s\nd is due to :at is call$ int]f]5ce4 ,ea* ( ! prongs ( ! =k is giv+ out a s\nd-wave at ! same "t1 b 9 opposite directions1 ea* wave advanc+ outw>ds 9 e direction4 ,:]e ! r>efi$ "p ( "o wave exactly balances ! cond5s$ "p ( ! o!r1 !re ( c\rse ! s\nd w be ext+ui%$2 & ^! l9es ( int]f]5ce are f\nd to be hyp]bolas1 or1 if consid]$ ) ref]5ce to bo? entire waves1 two hyp]bolic surfaces4 ,,sympa!tic ,,vibrations4 ,:5 x is once und]/ood t a musical s\nd is caus$ by ! vibrations m or less frequ5t :i* only make ! diff]5ce we call pit*1 x might at once be inf]r$1 t if we h a body t is capable ( vibrat+ say a hundr$ times a second1 & x receives a hundr$ pulses or pu%es a second1 x w\ld 9 ?is way be made to vibrate4 ,suppose1 !n1 t we take two tun+-=ks1 ea* capable ( vibrat+ #bef times a second3 if "o be /ruck :ile ! o!r is left free1 ! =m] "o w be giv+ to ! air #bef impulses p] second1 :i* w rea* ! o!r =k1 ea* pulse t5d+ to move x a little1 ! cumulative result be+ to make x move p]ceptibly1 t is1 to give out a s\nd4 ,! pr9ciple is j ! same z t employ$ 9 ! common sw+4 ,"o pu% makes ! sw+ to move a little1 ^u its return ano!r is giv51 9 l mann] a ?ird1 & s on until a p]son may be swung _m feet high4 ,if a glass tumbl] be /ruck1 x gives out a musical s\nd ( a c]ta9 pit*1 :i* w set a piano-/r+ s\nd+ t is tun$ to ! same pit*1 provid$ t ! damp] be rais$4 ,x is said t "s p]sons' voices h brok5 tumbl]s by s++ p[]fully ne> !m ! same note :i* ! tumbl]s c\ld give out1 ! vibrations ( ! tumbl]s be+ s great z to ov]come cohesion ( ! molecules4 ,!re are v _m int]e/+ effects due to sympa!tic vibrations4 ,l>ge trees are sometimes uproot$ by w9d t comes 9 gu/s tim$ to ! rate ( vibration ( ! tree4 ,:5 troops ( soldi]s are to cross a bridge1 ! music ceases1 & ! ranks are brok51 le/ ! accumulat$ /ra9 ( tim$ vibrations %\ld break ! /ructure2 inde$1 su* accid5ts h sev]al times occurr$4 ,!re is n s mu* dang] to a bridge :5 x is heavily load$ ) m5 or ) cattle1 z :5 a few m5 g m>*+ ov] x4 ,:5 ! iron bridge at ,colebrooke ,dale 0 build+1 a fiddl] came along1 & said to ! workm5 t he c\ld fiddle _! bridge d[n4 ,! build]s ?\ght ?is boa/ a fiddle-de-dee1 & invit$ ! musician to fiddle away to 8 he>t's cont5t4 ,"o note aft] ano!r 0 /ruck ^u ! /r+s1 until "o 0 f\nd ) :i* ! bridge 0 9 sympa?y4 ,:5 ! bridge began to %ake viol5tly1 ! workm5 7 al>m$ at ! unexpect$ result1 & ord]$ ! fiddl] to /op4 ,"s halls & *ur*es are wret*$ly adapt$ to he> ei!r speak+ or s++ 94 ,if wires be /ret*$ across su* halls1 betwe5 ! speak]'s /& & ! opposite end1 !y w absorb ! pass+ s\nd-waves1 & w be made to sympa!tically vibrate1 ?us prev5t+ 9 a good degree ! int]f]+ e*oes4 ,! wire %\ld be r f9e piano-wire1 & x %\ld be /ret*$ s tightly z to give out a l[ musical s\nd :5 pluck$ ) ! f+]s4 ,9 a l>ge hall !re %\ld be tw5ty or m su* wires4 ,,resonance4 ,:5 a tun+-=k is /ruck1 & held out 9 ! air1 ! vibrations c be felt = a "t by ! f+]s2 b ! s\nd is h>dly audible unless ! =k be plac$ close to ! e>4 ,let ! /em ( ! =k re/ ^u ! table1 a *air1 or any solid body ( consid]able size1 & ! s\nd is s mu* increas$ 9 l\dness z to be he>d 9 e "p ( a l>ge room4 ,! reason appe>s to be1 t 9 ! fir/ case ! vibrations are s slight t ! air is n mu* affect$4 ,mo/ ( ! =ce ( ! vibration is absorb$ by ! h& t holds x2 b :5 ! /em re/s ^u a h>d body ( consid]able ext5t1 ! vibrations are giv5 up to x1 & e "p ( its surface is giv+ (f ! vibrations to ! air4 ,9 o!r words1 x is a mu* l>g] body t is n[ vibrat+1 & consequ5tly ! air is receiv+ ! amplifi$ s\nd-waves4 ,if ! /em ( ! =k _h be5 made to re/ ^u a bit ( rubb]1 ! s\nd w\ld n only n h be5 re-en=c$ 9 su* a way1 b ! =k w\ld v soon h be5 br\ght to re/2 = ,india rubb] absorbs s\nd vibrations1 & conv]ts !m into heat vibrations1 z is prov$ by plac+ su* a comb9ation ^u ! face ( a !rmo-pile4 ,if "o w b put 8 h& ^u a table or a *air-back 9 any room :]e a piano or an organ is be+ play$1 or :]e voices are s++1 especially 9 *ur*1 he _c fail to feel ! s\nd2 & if he notices c>efully he w p]ceive t "s s\nds make su* table or seat to %ake mu* m vigor\sly ?an o!rs1--a g5u9e case ( sympa!tic vibrations4 ,x is = ?is reason t special mat]ials & %apes are giv5 to p>ts ( musical in/rum5ts1 s t !y may respond to ! v>i\s vibrations ( ! /r+s or re$s4 ,= in/ance1 ! piano has an ext5sive ?9 bo>d ( spruce und]nea? all ! /r+s1 :i* is call$ ! s\nd+-bo>d4 ,?is bo>d takes up ! vibrations ( ! /r+s2 b1 unlike ! rubb]1 gives !m all out to ! air1 greatly re-en=c+ _! /r5g?1 & *ang+ some:at _! quality4 ,b ! air itself may act 9 l mann]4 ,9 almo/ any room or hall n m ?an fifte5 or tw5ty feet long1 a p]son c f9d "s tone ( ! voice t w seem to meet "s response f ! room4 ,"s %ort tunnels w f c]ta9 positions yield v p[]ful1 responsive1 resonant tones4 ,!re is c]ta9ly "o su* 9 ,c5tral ,p>k1 ,new ,york4 ,x is =ty or fifty feet long4 ,to a p]son /&+ 9 ! middle ( ?is1 & speak+ or mak+ any k9d ( a noise on a c]ta9 pit*1 ! resonance is almo/ deaf5+4 ,x is easy to und]/&4 ,:5 a column ( air enclos$ 9 a tube is made to vibrate by any s\nd ^: wave-l5g? is twice ! l5g? ( ! tube1 we h su* column ( air n[ fill$ ) ! cond5s$ "p ( ! wave1 & n[ ) ! r>efi$ "p2 & z ^! motions _c be conduct$ lat]ally1 b mu/ move 9 ! direction ( ! l5g? ( ! tube1 ! air has a v great amplitude ( motion1 & ! s\nd is v l\d4 ,if "o end ( ! tube be clos$1 !n ! l5g? mu/ be b "o-f\r? ( ! wave-l5g? ( ! s\nd4 ,take a tun+-=k ( any conv5i5t pit*1 say a ,c ( #eab vibrations p] second3 hold x :ile vibrat+ ov] a v]tical te/-tube ab\t eight in*es long4 ,no response w be he>d2 b1 if a little wat] be c>efully p\r$ into ! tube to ! dep? ( ab\t two in*es1 ! tube w respond l\dly1 s t x might be he>d ov] a l>ge hall4 ,9 ?is case ! l5g? ( ! air-column t 0 respond+1 be+ "o-f\r? ! wave-l5g?1 w\ld give tw5ty-f\r in*es z ! wave-l5g? ( t =k4 ,x is easy 9 ?is way to measure approximately ! numb] ( vibrations made by a =k4 ,lett+ l dep? ( tube1 d diamet] ( tube1 v velocity ( s\nd r$uc$ = temp]ature1 ,n numb] ( vibrations1 ,!n ,n v ------------ 7#d7ld774 ,:5 a vibrat+ tun+-=k is plac$ opposite ! emb\*ure ( an organ-pipe ( ! same pit*1 ! pipe w res\nd to x1 giv+ q a volume ( s\nd4 ,9 #ahgb x occurr$ to me1 t ! action ( an organ-pipe might be q l t ( a vibrat+ re$ 9 front ( ! emb\*ure4 ,z ! air is driv5 pa/ x f ! bell[s1 ! =m ( ! escap+ air w evid5tly be l a ?91 ela/ic /rip2 &1 hav+ consid]able velocity1 x w c>ry (f by friction a little ( ! air 9 ! tube3 ?is w ( c\rse r>efy ! air 9 ! tube some:at1 & a wave ( cond5sation w travel d[n ! tube4 ,at ! bottom1 be+ sudd5ly /opp$1 its re-action w be p>tly outw>ds1 & s w drive ! /rip ( air away f ! tube4 ,aft] ?is w foll[1 = a l reason1 ! o!r phase ( ! wave1 ! r>efaction1 :i* w sw+ ! /rip ( air t[>ds ! tube4 ,?is !ory ,i v]ifi$ by fill+ ! bell[s ) smoke1 & wat*+ ! motion ( ! escap+ air & smoke ) a /roboscope4 ,?is view is n[ advocat$ by an organ-build] 9 ,engl&1 ,h]man ,smi?2 b :e!r he discov]$ x be=e or aft] me1 ,i d n "k4 ,:5 a membrane vibrates1 its motion is g5]ally p]ceptible to ! eye2 & x may h a v great amplitude ( motion1 z 9 ! case ( ! drum2 & v>i\s in/rum5ts h be5 devis$ = ! /udy ( vibrations1 us+ membranes l rubb]1 gold-beat]'s sk91 or ev5 tissue pap]1 to receive ! vibrations4 ,"o ( ! musical in/rum5ts ( a =m] g5]ation ( boys 0 ! comb4 ,a /rip ( pap] 0 plac$ 9 front ( x1 & plac$ at ! m\?1 & sung ?r\gh1 ! pap] respond+ to ! pit* ) a loose nasal s\nd4 ,koe5ig fix$ a membrane across a small capsule1 "o side ( :i* 0 connect$ by a tube to any s\rce ( s\nd1 & ! o!r side to a gas-pipe & a small burn]4 ,a s\nd made 9 ! tube w\ld %ake ! flame1 & a mirror mov+ 9 front ( ! flame w\ld %[ a zigzag outl9e correspond+ to ! s\nd vibrations4 ,9 l mann] if a ?9 rubb] be /ret*$ ov] ! end ( a tube "o or two in*es 9 diamet] & f\r or five in*es long1 & a bit ( look+-glass "o-f\r? ( an in* squ>e be made fa/ to ! middle ( ! membrane1 ! motions ( ! latt] c be se5 by lett+ a beam ( sunlight fall ^u ! mirror s z to be reflect$ ^u a :ite wall or scre5 a few feet away4 7,fig4 #h47 ,illu/ration3 ,,fig4 #h4 ,:5 a s\nd is made 9 ?is tube1 ! spot ( light w at once assume "s peculi> =m1--ei!r a /raight l9e ) "s knots ( light 9 x1 or "s curve simple or comp\nd1 & su* z are kn[n z ,lissaj\s curves4 ,if1 :ile "s ( ^! =ms are ^u ! scre51 ! in/rum5t be mov$ sideways1 ! =ms w *ange to undulat+ l9es ) or )\t loops1 v>y+ ) ! pit* & int5sity1 b be+ alike = ! same pit* & int5sity4 7,fig4 #i7 ,?is in/rum5t ,i call$ ! opeidoscope4 ,illu/ration3 ,,fig4 #i4 ,! vibration ( a membrane & t ( a solid diff] *iefly 9 ! amplitude ( su* vibration4 ,! scrat* ( a p9 at "o end ( a long log c be he>d by an e> appli$ to ! o!r end ( ! log2 b e molecule 9 ! log mu/ move slightly2 & !re are all degrees ( movem5t betwe5 t visible to ! eye1 :i* we call mass motion1 & t call$ molecul> simply because we _c measure ! amplitude ( ! motion4 ,we may1 !n1 r\ghly divide all bodies into two classes1 z to _! relations to s\nd1--su* z re-en=ce x1 & su* z di/ribute x3 ! fir/ dep5d+ ^u ! =m ( ! body1 z relat$ to a p>ticul> s\nd2 ! second indep5d5t ( =m1 & respond+ to all ord]s ( vibrations4 ,air1 wood1 & metals belong 9 ?is latt] class4 ,! common toy-/r+ telegraph1 or lov]s' telegraph1 is an example ( ?is class4 ,two t9 boxes are connect$ by a /r+ pass+ ?r\gh ! middle ( ! bottom ( ea*4 ,:5 ! /r+ is /ret*$1 & a p]son speaks 9 "o box1 :at is said c be he>d by an e> appli$ at ! o!r4 ,if ! speak+-tubes be made ab\t f\r in*es 9 diamet]1 & ab\t f\r in*es deep1 !y are capable ( do+ mu* m s]vice ?an is g5]ally suppos$ to be possible4 ,i "k ( two l9es1 "o ( five hundr$ feet & ! o!r ( a ?\s& feet 9 l5g?1 ov] :i* "o c talk1 & be he>d ) di/9ctness4 ,9 ! l9e ( a ?\s& feet1 ! end ( ! tube is made ( %eepsk9 tightly /ret*$1 & ! l9e is made ( ,no4 #h cotton ?read4 ,! great] ! t5sion1 ! bett] is ! s\nd transmitt$4 ,! ?read is support$ at int]vals by runn+ ?r\gh a loop on ! ends ( cords n less ?an ?ree feet long1 atta*$ to supports4 ,! ?read pi]ces ! membrane1 & is atta*$ to a small button :i* is 9 contact ) ! membrane4 ,w9d & ra9 affect ?is l9e disadvantage\sly4 ,! o!r l9e ( five hundr$ feet1 betwe5 a pass5g] & a freight depot1 has ! tube end cov]$ ) /ret*$ calfsk94 ,in/ead ( ?read1 a copp]-relay wire is employ$ 7any small un9sulat$ wire w d z well74 ,?is p]mits a good t5sion1 & is unaffect$ by ! wea!r4 ,"o may /& 9 front ( x ab\t ?ree feet1 & conv]se ) ease1 & 9 an ord9>y tone4 ,! wire is support$ 9 loops ( /r+1 z 9 ! o!r4 ,musicians h 9 all times employ$ v>i\s in/rum5ts = ! production ( musical effects4 ,:i/les made ( bone 7 us$ by pre-hi/oric m51 "s ( !m hav+ f+]-holes s t diff]5t tones c\ld be produc$4 ,a /ag-horn t 0 bl[n l a flageolet1 & hav+ ?ree f+]-holes1 has also be5 f\nd2 :ile on ! old monum5ts ( ,egypt are pictur$ h>ps1 pipes ) sev5 f+]-holes1 a k9d ( flute1 drums1 tamb\r9es1 cymbals1 & trumpets4 ,9 lat] times ^! primeval =ms h be5 modifi$ into ! v>i\s in/rum5ts 9 use 9 ! mod]n or*e/ra4 ,x seems z if no musician _h ev] be5 int]e/$ 9 ! "q z to :y "o in/rum5t %\ld give out a s\nd s diff]5t f ano!r "o1 ev5 ?\gh x 0 s\nd+ ^u ! same pit*4 ,no "o c ev] mi/ake ! s\nd ( a viol91 or a horn1 or a piano1 = any o!r in/rum5t2 & no two p]sons h voices alike4 ,?is diff]5ce 9 tone1 :i* enables u to id5tify an in/rum5t by its s\nd or a fri5d by 8 voice1 is call$ quality ( tone1 or timbre4 ,ab\t tw5ty ye>s ago1 t great ,g]man physici/ ,helmholtz und]took ! inve/igation ( ?is subject1 & succe$$ 9 unravell+ ! :ole my/]y ( ! qualities ( s\nd4 ,he discov]$ fir/1 t a musical s\nd is v r>ely a simple tone1 b is made up ( sev]al tones1 sometimes z _m z t5 or fifte51 hav+ diff]5t degrees ( int5sity & pit*4 ,! l[e/ s\nd1 :i* is also ! /ronge/1 is call$ ! fundam5tal2 & x is ?is tone we mean :5 we speak ( ! pit* ( a s\nd1 z ! pit* ( middle ,c ^u a piano1 or ! pit* ( ! ,a /r+ on a viol94 ,! high] s\nds t accompany ! fundam5tal are call$ sometimes h>monics1 sometimes upp] p>tial tones1 b g5]ally ov]tones4 ,! "* or quality ( a s\nd dep5ds altoge!r ^u ! numb] & int5sity ( ^! ov]tones associat$ ) ! fundam5tal4 ,if a s\nd c be made ^u a pipe & a viol91 t consi/s :olly ( ! fundam5tal ) no ov]tones1 ! two in/rum5ts s\nd absolutely alike4 ,x is exce$+ly difficult to d ?is2 & su* s\nd :5 produc$ is smoo?1 b )\t "*1 & unpleas+4 ,second1 ,helmholtz discov]$ t ! ov]tones always /& 9 ! simple/ ma!matical relation to ! fundam5tal tone1--9 fact1 are simple multiples ( t tone1 be+ two1 ?ree1 f\r1 & s on1 times ! numb] ( vibrations ( x4 ,?is w be readily und]/ood by consid]+ ! position ( su* relat$ s\nds :5 !y are writt5 ^u ! /aff4 ,illu/ration ,if we />t ) ,c 9 ! bass z indicat$ 9 ! /aff1 call+ t ! fundam5tal1 !n ! notes t w repres5t ! above ratios are ^? indicat$ by small] notes1 :i* are ! ov]tones up to ! n9?4 ,! fir/ ov]tone1 be+ produc$ by twice ! numb] ( vibrations1 mu/ be ! octave2 ! second1 ! fif? ( ! second octave2 ! ?ird w be two octaves f ! fir/1 & s on3 ! numb] ( vibrations ( ea* ( ^! notes be+ ! numb] ( ! fundam5tal multipli$ by its ord] 9 ! s]ies4 ,tak+ ,c ) #abh vibrations1 we h = ?is s]ies3-- #abh x #a #abh ,c fundam5tal4 #abh x #b #bef ,c'4 #abh x #c #chd ,g'4 #abh x #d #eab ,c''4 #abh x #e #fdj ,e''4 #abh x #f #gfh ,g''4 #abh x #g #hif ,b''flat4 #abh x #h #a1jbd ,c'''4 #abh x #i #a1aeb ,d'''4 #abh x #aj #a1bhj ,e'''4 ,?is s]ies is cont9u$ up to ! limits ( he>+4 ,n[1 x appe>s t all in/rum5ts d n give ! complete s]ies3 inde$1 x is n possible to obta9 !m all ^u "s in/rum5ts4 ,ea* ( !m1 h[ev]1 :5 pres5t helps 9 ! g5]al effect :i* we call quality4 ,sometimes ! ov]tones are m prom95t ?an ! fundam5tal1 z :5 a piano-wire is /ruck ) a nail4 ,x has always be5 notic$ t x does n give out ! s\nd t is want$ :5 x is /ruck 9 ?is way4 ,h5ce x is ! art ( an in/rum5t-mak] to s con/ruct ! in/rum5t z to develop & re-en=ce su* tones z are pleas+1 & to suppress ! int]f]+ & disagreeable ov]tones4 ,piano-mak]s le>n$ by trial :]e 0 ! prop] place to /rike ! /ret*$ wire 9 ord] to develop ! mo/ musical s\nd ^u x2 b no reason c\ld be giv5 until x 0 obs]v$ t /rik+ x at a po9t ab\t "o-sev5? or "o-n9? its l5g? f ei!r end prev5t$ ! developm5t ( ! objectionable ov]tones1 ! sev5? & ! n9?4 ,h5ce !y c sc>cely be he>d 9 a prop]ly con/ruct$ in/rum5t4 ,^! ov]tones are v discordant ) ! l[] s\nds4 ,organ-pipes h _! specific qualities giv5 to !m by mak+ !m wide-m\!d1 n>r[-m\!d1 conical1 & s on2 %apes :i* exp]i5ce has det]m9$ give pleas+ s\nds ) diff]5t qualities4 ,! viol9 is an in/rum5t t seems to puzzle mak]s m ?an almo/ any o!r4 ,"s ( ! old viol9s made two hundr$ ye>s ago by ! ,amati family at ,cremona are wor? _m times _! weight 9 gold4 ,rec5t mak]s h tri$ 9 va9 to equal !m2 b1 :5 _! +5uity & skill h fail$1 !y decl>e t age has mu* to d ) su* in/rum5ts1 t age mell[s ! s\nd+ quality ( ! viol94 ,b ! ,cremona viol9s 7 j z extraord9>y in/rum5ts :5 !y left ! h&s ( ! mak]s z !y are n[2 & ! fame ( ! ,amati family z viol9-mak]s 0 ov] all ,europe :ile !y 7 liv+4 ,a good viol9 :5 well play$ gives an exquisite musical effect1 & on acc\nt ( its range & quality ( tones x is ! lead+ or*e/ral in/rum5t1 always pleas+ & satisfy+2 b 9 unskill$ h&s ev5 ! be/ ,cremona w give =? s\nds t make "o grieve t x 0 ev] inv5t$4 ,ov]tones ( all sorts & ) all degrees ( prom95ce may be easily develop$ ^u x3 !re=e ! skilful play] draws ! b[ at su* a place ^u ! /r+s z to develop ! ov]tones he wants1 & suppress ! ones n want$4 ,! usual rule is to draw ! b[ ab\t an in* bel[ ! bridge2 b ! place = ! b[ dep5ds ^u :]e ! f+]s are t /op ! /r+s1 & also ! pressure ^u x4 ,x requires an almo/ incr$ible am\nt ( practice to be able to play a viol9 v well4 ,9 ! accompany+ table w be f\nd ! compon5t p>ts ( tones ^u a few in/rum5ts 9 common use4 ,,tone ,,composition4 ,! compon5ts ( ! tones are indicat$ by l9es 9 ! column und]nea? ! figures repres5t+ ! s]ies4 ,?us ! n>r[-/opp$ organ-pipe gives a s\nd compos$ ( a fundam5tal1 & ov]tones ?ree1 five1 sev51 & n9e times ! numb] ( vibrations ( x4 ,,tone ,,composition4 ---------------------------------------- ---------------- ,,in/rum5ts4 #a #b #c #d #e #f #g #h #i #aj ---------------------------------------- ---------------- _/ ,wide /opp$ _/ ------------------------------ ,n>r[ _/ _/ _/ _/ _/ ------------------------------ ,n>r[ cyl9d] _/ _/ _/ _/ _/ _/ ,,organ ------------------------------ ,,pipes4 ,pr9cipal _/ _/ _/ 7,wood7 ------------------------------ ,conically _/ _/ _/ _/ n>r[ at top4 ------------------------------ ,flute _/ _/ _/ _/ ------------------------------ ,viol9 _/ _/ _/ _/ _/ _/ _/ _/ _/ _/ ------------------------------ ,piano _/ _/ _/ _/ _/ _/ _/ _/ ------------------------------ ,bell _/ _/ _/ _/ _/ _/ _/ ------------------------------ ,cl>ionet _/ _/ _/ _/ _/ ------------------------------ ,bassoon _/ _/ _/ _/ _/ _/ _/ ------------------------------ ,oboe _/ _/ _/ _/ _/ _/ _/ ---------------------------------------- ---------------- ,x mu/ n be inf]r$ t all ( ! ov]tones are ( equal /r5g?3 !y are v f> f t2 b ^! diff] 9 diff]5t in/rum5ts1 & x is ?is t con/itutes ! diff]5ce betwe5 a good in/rum5t & a poor "o ( ! same "n4 ,9 a few ( ! spaces v light l9es are made = ! purpose ( indicat+ t su* ov]tones are q weak4 ,= in/ance3 ! piano has ! six?1 sev5?1 & eigh? ?us m>k$2 ^! tones be+ suppress$ by ! me*anism1 z describ$ on a =m] page4 ,only a few ( ! _m =ms ( organ-pipes are giv52 b ^! are suffici5t to %[ :at a physical diff]5ce !re is betwe5 ! musical tones 9 su* pipes4 ,z = ! human voice1 x is v ri* 9 ov]tones2 b no two voices are alike1 !re=e x w\ld be impossible to tabulate ! compon5ts ( x 9 ! mann] !y are tabulat$ = musical in/rum5ts4 ,9 ,helmholtz's exp]im5ts 9 ! analysis ( s\nds1 use 0 made ( ! pr9ciple ( resonance ( a body ( air enclos$ 9 a vessel4 ,9 ! exp]im5t ) ! tun+-=k to det]m9e ! wave-l5g?1 p4 #gh1 x is rem>k$ t no response came until ! volume ( ! air 9 ! tube 0 r$uc$ to a c]ta9 l5g?1 :i* dep5d$ ^u ! vibration numb] ( ! =k4 ,if in/ead ( a te/-tube a bottle _h be5 tak51 ! result w\ld h be5 ! same4 ,e k9d ( a vessel c respond to "s tone ( a def9ite wave-l5g?1 & a sph]e has be5 f\nd to give ! be/ results4 ,^! are made ) a hole on "o side = ! s\nd-wave to ent]1 & a projection on ! opposite side1 ?r\gh :i* a hole ab\t ! "o-eigh? ( an in* is made1 ?is to be plac$ 9 ! e>4 ,any s\nd t is made 9 front ( ! l>ge orifice w n meet any response1 unless x be t p>ticul> "o :i* ! globe c naturally re-en=ce1 :5 x w be pla9ly he>d4 ,suppose1 !n1 "o has a s]ies ( tw5ty or m ( ^!1 graduat$ to ! prop] size = re-en=c+ s\nds 9 ! ratio ( "o1 two1 ?ree1 f\r1 & s on4 ,take any in/rum5t1 say a flute3 h "o to bl[ x ^u ! prop] pit* to respond to ! l>ge/ sph]e1 !n take ea* ( ! sph]es 9 _! ord]1 apply+ !m to ! e> :ile ! flute is be+ s\nd$4 ,:5 ! ov]tones are pres5t !y w be he>d pla9ly & di/9ct f ! fundam5tal s\nd4 ,9 l mann] any or all o!r s\nds may be /udi$4 ,b ,helmholtz did n /op aft] analyz+ s\nds ( s _m k9ds3 he inv5t$ a me?od ( syn!sis1 by :i* ! s\nds ( any k9d ( an in/rum5t c\ld be imitat$4 ,a tun+-=k1 :5 made to vibrate by an electric curr5t1 gives out a tone )\t h>monics or ov]tones4 ,s if a s]ies ( =ks ) vibration p]iods equal to ! numb]s ( ! s]ies ( ov]tones giv5 on p4 #hf be s arrang$ t any ( !m may be made to vibrate at w1 x is evid5t t ! result+ comp\nd tone w\ld be comp>able ) t f an in/rum5t hav+ su* ov]tones4 ,?us1 if ) a tun+-=k giv+ a fundam5tal ,c1 o!r =ks giv+ two1 ?ree1 & f\r times ! numb] ( ! fundam5tal 7 associat$1 ea* "o giv+ a simple tone1 we %\ld h = a resultant ! tone ( a flute1 z %[n on p4 #ia4 ,if "o1 ?ree1 five1 sev51 & n9e1 7 all s\nd$1 ! result+ tone w\ld be t ( ! cl>ionet1 & s on4 ,?is he actually accompli%$1 & n[ mak]s ( physical app>atus adv]tise j su* in/rum5ts4 ,helmholtz also contriv$ a set ( tun+-=ks1 :i*1 :5 b[$1 w give out ! v[el s\nds l ! voice4 ,x 0 rem>k$ ^u p4 #hi t x has g5]ally be5 consid]$ t age has a mell[+ effect ^u ! s\nd ( a viol94 ,once 9 possession ( ! facts conc]n+ s\nd t h be5 allud$ to on ! prec$+ pages1 x is easy to see h[ su* an op9ion %\ld arise1 & also ! fallacy ( x4 ,x is prov$ conclusively t ! ability to he> high s\nds decreases z "o gr[s old]4 ,z ! viol9 gives a v great numb] ( ov]tones1 ev5 up to ! limits ( audibility1 x is pla9 t if su* an in/rum5t %\ld n *ange 9 its quality ( tone 9 ! lea/ degree1 yet to a man :o play$ ^u x = a numb] ( ye>s x w\ld seem to *ange by subtract+ "s ( ! high] ov]tones f ! s\nd2 t is1 x w\ld seem to become mell[]4 ,!re is no evid5ce t su* a physical *ange takes place 9 ! in/rum5t4 ,x is n "h affirm$ t no *ange does take place4 ,x may be probable2 b all ! evid5ce we h is ! op9ions ( individuals ^: he>+ we "k does *ange2 & ?is *ange is compet5t to modify ! judgm5t z to ! quality ( ! s\nd 9 ! same direction4 ,be=e x c be affirm$ t su* a physical *ange does take place 9 ! viol9 z to make a p]ceptible diff]5ce 9 ! quality ( its tone1 x w be ne$ful to det]m9e accurately ! numb] & int5sity ( ! ov]tones at int]vals dur+ _m ye>s1 & !n to comp>e !m4 ,?is has n yet be5 done4 ,,=m ,,( ,a ,,comp\nd ,,s\nd-,,wave ,,9 ,,air4 ,^u p4 #fc is giv5 a picture ( ! =m ( a simple s\nd-wave 9 air1 :i*1 z describ$1 consi/s ( two p>ts1 a cond5sation & a r>efaction4 ,all simple s\nd-waves h su* a =m2 b :5 two or m s\nd-waves t /& 9 "s simple ratio to ea* o!r1 z d ! s\nds ( musical in/rum5ts1 are =m$ 9 air1 ! result+ wave is m or less complex 9 /ructure2 & :]e !re are _m compon5ts1 z !re are :]e a numb] ( diff]5t k9ds ( in/rum5ts are all s\nd+ at once1 x is well-nigh impossible to figure ev5 approximately ! =m ( su* wave-comb9ations4 ,x is g5]ally giv5 9 treatises ^u s\nd ) ord9ates repres5t+ ! factors ) _! relative int5sities4 ,:5 ! extremities ( ! ord9ates are connect$1 !re is drawn a curv$ l9e ) regul>ly recurr+ loops4 ,?is _c give a correct idea ( ! =m ( ! wave1 because ! motion ( a p>ticle ( air is n up & d[n l a float+ body ^u wav+ wat]1 b x is =w>d & back1 9 ! direction ( ! motion ( ! wave4 ,9 ,fig4 #aj ?ree simple s\nd-waves are ?us repres5t$ at #a1 #b1 & #c1 ^! hav+ ! wave-l5g? #a1 #b1 & #c4 ,9 #d1 ! ?ree are comb9$ into "o comp\nd wave1 & bett] %[ ! =m ( a transv]se section ( su* a s\nd-wave 9 ! air4 ,! organ-pipe call$ ! pr9cipal gives out su* a comp\nd wave z is se5 by ref]r+ to ! table on p4 #ia4 ,! second ov]tone1 h[ev]1 is q weak 9 t pipe1 :i* w\ld s modify ! =m z to less5 some:at ! d5sity at b1 & increase x at a4 ,illu/ration3 ,,fig4 #aj4 ,9 l mann] ! space 9 ! l5g? ( ! fundam5tal s\nd1 :atev] x may be1 is divid$ up into a numb] ( m9or cond5sations & r>efactions1 :i* may /r5g!n ea* o!r1 or s int]f]e z to *ange ! position ( bo?2 z is se5 9 ! figure at b1 :]e ! cond5sation due to wave #b int]f]es ) ! r>efaction ( #c4 ,,correlation4 ,,hav+ treat$ at "s l5g? ( ! ?ree factors involv$ 9 telephony1--namely1 electricity1 magnetism1 & s\nd1--x rema9s to foll[ up ! v>i\s /eps t h l$ to ! actual transmission ( musical s\nds & spee* ov] an ord9>y electric circuit4 ,x is /at$ ^u p4 #ca1 t1 :5 a curr5t ( electricity is pass$ ?r\gh a coil ( wire t surr\nds a rod ( s(t iron1 ! latt] is made a tempor>y magnet3 x loses its magnetic prop]ty ! in/ant t ! curr5t ceases4 ,if ! rod be ( consid]able size1 say a foot or m 9 l5g?1 & half an in* or m 9 diamet]1 & ! curr5t be /rong en\gh to make a p[]ful magnet ( x1 :5ev] ! curr5t f ! batt]y is brok51 ! b> may be he>d to give out a s+le click4 ,?is w happ5 z (t5 z ! curr5t is brok54 ,?is is occasion$ by a molecul> movem5t :i* results 9 a *ange ( l5g? ( ! b>4 ,:5 x is made a magnet1 x elongates ab\t #a_/bejjj ( its l5g?2 &1 :5 x loses its magnetism1 x sudd5ly rega9s its orig9al l5g?2 & ?is *ange is accompani$ ) ! s\nd4 ,?is s\nd 0 fir/ notic$ by ,pr(4 ,c4 ,g4 ,page ( ,salem1 ,mass41 9 #ahcg4 ,if "s means be devis$ = break+ su* a circuit m ?an fifte5 or sixte5 times a second1 we %all h a cont9u\s s\nd ) a pit* dep5d+ ^u ! numb] ( clicks p] second4 ,su* a device 0 fir/ inv5t$ by ! same man1 & 0 accompli%$ by fix+ ! armature ( an electro-magnet to a spr+ :i* 0 9 ! circuit :5 ! spr+ 0 press+ aga9/ a metallic knob1 at :i* "t ! curr5t made ! circuit 9 ! coil ( ! electro-magnet4 ,! magnet attract+ ! armature away f ! button broke ! circuit1 :i* ( c\rse de/roy$ ! magnetism ( ! magnet1 & all[$ ! spr+ to fly back aga9/ ! button1 to complete ! circuit & reproduce ! same s]ies ( *anges4 ,! rapidity ) :i* ! curr5t may be brok5 9 ?is way is only limit$ by ! /r5g? ( bo? spr+ & curr5t4 ,! great] ! t5sion ( ! spr+ ) a giv5 curr5t1 ! great] numb] ( vibrations w x make4 ,illu/ration3 ,,fig4 #aa4 ,suppose su* an int]mitt5t curr5t to pass ?r\gh ! coil surr\nd+ ! s(t iron rod1 #bef times p] second2 !n ! rod w\ld evid5tly give #bef clicks p] second1 :i* w\ld h ! pit* ( ,c4 ,:5 ^! clicks are produc$ 9 ! rod hold 9 ! h&1 ! s\nd is h>dly p]ceptible1 be+ l t ( a s\nd+ tun+-=k :5 held ?us4 ,9 ord] to /r5g!n x1 x is necess>y to place x on "s resonant surface4 ,x is cu/om>y to m\nt x ^u an oblong box ) "o or two holes 9 its upp] surface1 inasmu* z su* a =m is f\nd to give a l\d] response ?an any o!r1 & is ! %ape usually giv5 to ,a,eolian h>ps4 ,! accompany+ cut %[s ! comb9ation ( batt]y ,b1 ! circuit-break]1 & ! rod m\nt$ ^u ! box4 ,! wire ,w may evid5tly be ( any l5g?1 ! magnetiz$ rod & box respond+ to ! numb] ( vibrations ( ! spr+ ,s1 h[ long soev] ! circuit may be4 ,,helmholtz' ,,electric ,,int]ruptor4 ,9 "s ( ,helmholtz' exp]im5ts1 x 0 ess5tial to ma9ta9 ! vibrations ( a tun+-=k = a consid]able "t4 ,he effect$ ?is by plac+ a %ort electro-magnet betwe5 ! prongs ( ! =k1 & affix+ a plat9um po9t at ! end ( "o prong 9 su* a mann]1 t1 z ! prong desc5d$ 9 its vibration1 ! plat9um po9t dipp$ into a small cup ( m]cury t complet$ ! circuit4 ,:5 ! prong rec$$1 x 0 ( c\rse )drawn f ! m]cury1 & ! curr5t 0 brok54 ,z x is n possible = a tun+-=k to vibrate 9 m ?an "o p]iod1 su* an arrangem5t w\ld evid5tly make & break ! curr5t z _m times p] second z ! =k vibrat$4 ,:51 !re=e1 su* an int]ruptor is ins]t$ 9 ! circuit ) ! click-rod on its resonant box1 ! latt] mu/ give out j su* a s\nd z ! =k is giv+4 ,) su* a device1 x is possible to reproduce at almo/ any di/ance 9 a telegraphic circuit1 a s\nd ( a giv5 pit*4 ,x is !re=e a true telephone4 ,,reiss' ,,telephone4 ,! ease ) :i* membranes are ?r[n into vibrations correspond+ 9 p]iod to t ( ! s\nd+ body has already be5 allud$ to on p4 #hj2 & sev]al attempts h be5 made1 at diff]5t times1 to make membranes available 9 telephony4 ,! fir/ ( ^! attempts 0 made by ,philip ,reiss ( ,fri$ri*sdorf1 ,g]many1 9 #ahfa4 ,8 app>atus consi/$ ( a holl[ box1 ) two ap]tures3 "o 9 front1 9 :i* 0 ins]t$ a %ort tube = produc+ ! s\nd 91 & indicat$ by ! arr[ 9 ! cut1 ,fig4 #ab2 ! o!r on ! top4 ,?is 0 cov]$ ) ! membrane m1--a piece ( bladd] /ret*$ tight ov] x4 ,^u ! middle ( ! membrane1 a ?9 piece ( plat9um 0 glu$2 & ?is piece ( plat9um 0 connect$ by a wire to a screw-cup f :i* ano!r wire w5t to a batt]y4 ,illu/ration3 ,,fig4 #ab4 ,a plat9um f+]1 ,s1 re/$ ^u ! /rip ( plat9um1 b 0 made fa/ at "o end to ! screw-cup t connect$ ) ! o!r wire f ! batt]y4 ,n[1 :5 a s\nd is made 9 ! box1 ! membrane is made to vibrate p[]fully3 ?is makes ! plat9um /rip to /rike z (t5 ^u ! plat9um f+]1 & z (t5 to b\nd away f x1 ?us mak+ & break+ ! curr5t ! same numb] ( times p] second4 ,if1 !n1 a p]son s+s into ?is box :ile x is 9 circuit ) ! a=e-m5tion$ click-rod & box1 ! latt] w evid5tly *ange its pit* z (t5 z x is *ang$ by ! voice4 ,9 ?is app>atus we h a telephone ) :i* a melody may be reproduc$ at a di/ance ) di/9ctness4 ,b ! s\nds are n l\d1 & !y h a t9-trumpet quality4 ,if "o reflects ^u ! possibilities ( su* a me*anism1 & ^u ! conditions necess>y to produce a s\nd ( any giv5 quality1 z t ( ! voice or ( a musical in/rum5t z describ$ 9 prec$+ pages1 he w und]/& t x c reproduce only pit*4 ,x might "h be inf]r$ t some?+ m ?an a s+le pit* is transmitt$ if ! s\nd is l t ( a t9 trumpet z /at$3 b ! reason ( ?is is t1 :5ev] a curr5t is pass+ betwe5 two surfaces t c move only slightly on ea* o!r1 !re is always an irregul>ity 9 ! conduction1 s z to produce a k9d ( scrat*+ s\nd2 & x is ?is1 comb9$ ) ! o!r1 ! true pit*1 t gives ! "* to ! s\nd ( ?is in/rum5t4 ,dr4 ,wright f\nd t a s\nd ( consid]able int5sity c\ld be obta9$ by pass+ ! int]rupt$ curr5t ?r\gh ! prim>y wire ( a small induction coil1 & plac+ a conductor made ( two %eets ( silv]$ pap] plac$ back to back 9 ! second>y circuit4 ,! silv]$ pap] becomes rapidly *>g$ & dis*>g$1 mak+ a s\nd t c be he>d ov] a l>ge hall1 & hav+ ! same pit* z ! s5d+ in/rum5t4 ,,gray',s ,,telephones4 ,9 #ahgc ,mr4 ,eli%a ,gray ( ,*icago discov]$ t if an induction coil be made to op]ate by ! curr5t f any automatic circuit-break]1 & "o ( ! wires f ! second>y circuit be held 9 ! h& :ile ! dry f+] ( ! same h& is rubb$ ^u a sonor\s metallic plate1 ! o!r wire be+ 9 connection ) ! plate1 a musical s\nd w\ld be giv5 out by ! plate1 appe>+ to come f ! po9t ( contact ( ! f+] ) ! plate4 ,he !re=e contriv$ a musical in/rum5t ) a range ( two octaves1 9 :i* ! re$s 7 made to vibrate by electro magnets1 ! curr5t ent]+ any "o by depress+ ! appropriate key4 ,?is circuit is s5t ?r\gh ! prim>y wire ( an induction coil :ile "o ( ! t]m9als ( ! second>y coil is connect$ ) ! ?9 %eet metal t =ms "o head ( a %all[ wood5 drum ab\t eight in*es 9 diamet]1 :i* is s fix$ z to be rotat$ l a pulley4 ,! o!r t]m9al is held 9 ! h& :ile "o f+] ( ! same h& re/s ^u ! metallic surface4 ,:ile ! drum is turn$ ) ! o!r h&1 ! s\nds giv5 out h consid]able int5sity4 ,! fa/] ! drum is turn$1 ! l\d] d ! s\nds become1 ?\gh ! pit* rema9s ! same4 ,9 ?is case1 z 9 ! case m5tion$ on p4 #aje1 we h an electric curr5t pass+ betwe5 two surfaces t are mov+ ^u ea* o!r2 ! contact n be+ uni=m1 ! curr5t is v>y+ z well z int]mitt5t4 ,mr4 ,gray has also inv5t$ a musical telephone by means ( :i* _m musical s\nds may be simultane\sly transmitt$ & reproduc$4 ,! actual me*anism us$ is q complex1 & requires consid]able famili>ity ) electrical sci5ce 9 ord] to und]/& x2 b ! fundam5tal pr9ciple involv$ is n difficult to "o :o has compreh5d$ ! prec$+ descriptions4 ,suppose t we h a s]ies ( f\r /eel re$s1 ea* "o fix$ at "o end to "o pole ( a %ort electro-magnet1 :ile ! o!r end is left free to vibrate ov] ! o!r pole ( ! magnet & n q t\*+ x4 ,ea* ( ! re$s is to be tun$ to a diff]5t pit*1 say ! #a1 #c1 #e1 & #h ( ! scale4 ,^! electro-magnets ) _! atta*$ vibrators are to be atta*$ ea* to a resonant box 7see p4 #ic71 :i* c respond to t p>ticul> numb] ( vibrations p] second4 ,?is is ! receiv+ in/rum5t4 ,! s5d] consi/s ( a l set ( re$s tun$ to ! same pit*1 :i* c be made to vibrate at w by press+ a key :i* s5ds ! curr5t ( electricity ?r\gh its electro-magnet1 :i* makes & breaks ! curr5t4 ,imag9e "o ( ^! keys to be press$ d[n s z to make ! circuit complete3 ! s5d+ in/rum5t !n has "o ( its re$s1 let x be ! #a ( ! scale1 set 9 vibration2 ! int]mitt5t curr5t trav]ses ! :ole l9e1 go+ ?r\gh all f\r ( ! receiv+ in/rum5ts4 ,n[1 we "k f ! /udy ( ! action ( s\nd+ bodies1 t only "o ( ! f\r receiv]s is compet5t to vibrate 9 consonance ) ?is tone1 & ?is "o w respond2 t is1 ! vibrations are truly sympa!tic vibrations4 ,if1 in/ead ( mak+ ! #a ( ! scale 9 ! s5d+-in/rum5t1 ! #c _h be5 made1 ! curr5t w\ld h gone ?r\gh all ( ! receiv+ in/rum5ts j ! same z be=e1 b only "o ( !m c\ld take up t vibratory movem5t3 ?ree ( !m w\ld rema9 at re/1 ! #c respond+ l\dly4 ,9 l mann]1 any numb] ( vibrat+ re$s 9 ! s5d+ in/rum5t c make a correspond+ numb] ( re$s 9 ! receiv+ in/rum5t to vibrate1 provid$ ! latt] be exactly tun$ ) ! =m]4 ,ea* transmitt] is connect$ ) b a "p ( ! batt]y1 s t sev]al tones may be transmitt$ at ! same "t4 ,if ! p]=m] plays a piece ( music 9 its v>i\s p>ts1 e "p w be reproduc$3 ?us we h a comp\nd or multiple telephone4 ,?is in/rum5t has be5 us$ dur+ ! pa/ w9t] to give conc]ts 9 cities :5 ! p]=m] 0 9 a di/ant place4 ,x has also be5 us$ z a multiple telegraph2 z _m z eight op]ators s5d+ messages simultane\sly ov] ! same wire1--f\r 9 ea* direction1--)\t ! slighte/ int]f]5ce4 ,,bell',s ,,telephone4 ,pr(4 ,a4 ,graham ,bell ( ,bo/on indep5d5tly discov]$ ! same means = produc+ multiple effects ov] ! same wire2 b x appe>s he did n practically "w x out z completely z did ,mr4 ,gray4 ,b :ile ! latt] 0 *iefly employ$ 9 p]fect+ ! me?od z a telegraphic sy/em1 ,pr(4 ,bell _h set be=e himself ! m difficult problem ( transmitt+ spee*4 ,?is he has actually accompli%$1 z we h s (t5 be5 rem9d$ dur+ ! pa/ ye>4 ,?or\ghly conv]sant ) ! ac\/ic rese>*es ( ,helmholtz1 & keep+ 9 m9d ! complex =m ( ! air vibrations produc$ by ! human voice1 he attempt$ to make ^! vibrations produce correspond+ pulsations 9 an electric curr5t 9 ! mann] analog\s to ! electric int]rupt]4 ,obs]v+ t membranes :5 prop]ly /ret*$ c vibrate to any k9d ( a s\nd1 he s\ght to utilize !m = ?is purpose4 ,s did ,reiss2 b ,reiss ins]t$ ! vibrat+ membrane into ! circuit1 & x 0 q evid5t t su* a plan w\ld n answ]1 !re=e ! curr5t mu/ n be brok52 b c\ld an electric curr5t be int]f]$ ) )\t break+ ! connections8 ,! well-kn[n re-actions ( magnets ^u electrical curr5ts1 fir/ not$ by ,o]/$1 & fully develop$ by ,f>aday1 gave ! clew to ! solution4 ,a piece ( iron %\ld be made to vibrate by means ( s\nd vibrations1 s z to affect an electro-magnet & induce correspond+ electrical pulsations4 ,,fir/ ,,=m ,,( ,,speak+-,,telephone4 ,a membrane ( gold-beat]'s sk9 0 tightly /ret*$ ov] ! end ( a speak+-tube or funnel2 on ! middle ( ?is membrane a piece ( iron1 ,n ,s1 ,fig4 #ac1 0 glu$4 ,9 front ( ?is piece ( iron an electro-magnet ,m is s situat$ t its poles are opposite to x1 b n q t\*+ x4 ,"o ( ! t]m9al wires ( ! electro-magnet goes to ! batt]y ,b2 ! o!r goes to ! receiv+ in/rum5t ,r1 :i* consi/s ( a tubul> electro-magnet1 ! coil be+ enclos$ 9 a %ort tube ( s(t iron2 ! wire !nce goes to ! plate ,e'1 :i* is sunk 9 ! e>?4 ,on ! top ( ,r1 at ,p1 is a r loose1 ?9 disk ( iron1 :i* acts z an armature to ! electro-magnet bel[ x4 ,illu/ration3 ,,fig4 #ac4 ,suppos+ t all ! p>ts are ?us prop]ly connect$1 ! curr5t ( electricity f ! batt]y makes bo? ,m & ,r magnetic2 ! electro-magnet ,m w inductively make ! piece ( iron ,n ,s1 a magnet1 ) its poles unlike ^? ( ! induc+ electro-magnet2 & ! two w mutually attract ea* o!r4 ,if n[ ?is piece ( iron ,n ,s be made to move t[>d ,m1 a curr5t ( electricity w be induc$ 9 ! coils1 :i* w trav]se ! :ole circuit4 ,?is induc$ electricity w consi/ ( a s+le wave or pulse1 & its =ce w dep5d ^u ! velocity ( ! approa* ( ,n ,s to ,m4 ,a l pulse ( electricity w be induc$ 9 ! coils :5 ,n ,s is made to move away f ,m2 b ?is curr5t w move ?r\gh ! circuit 9 ! opposite direction1 s t :e!r ! pulsation goes f ,m to ,r1 or f ,r to ,m1 dep5ds simply ^u ! direction ( ! motion ( ,n ,s4 ,! electricity ?us g5]at$ 9 ! wire by su* vibratory movem5ts v>ies 9 /r5g? proportional to ! movem5t ( ! armature2 !re=e ! l9e wire betwe5 two places w be fill$ ) electrical pulsation exactly l ! a]ial pulsations 9 /ructure4 ,fig4 #aj1 p4 #ih1 may be us$ to illu/rate ! condition ( ! wire ?r\gh :i* ! curr5ts pass4 ,! d>k "p may repres5t ! /ronge/ "p ( ! wave1 :ile ! light] "p w\ld %[ ! weak] "p ( ! wave4 ,! *ief diff]5ce w\ld be1 t electricity travels s fa/1 t :at is !re repres5t$ z "o wave 9 air ) a l5g? ( two feet w\ld1 9 an electric wave1 be m ?an fifty miles long4 ,^! induc$ electric curr5ts are b v transi5t 7see p4 #ca72 & _! effect ^u ! receiv] ,r is to ei!r increase or decrease ! p[] ( ! magnet !re1 z !y are 9 "o direction or ! o!r1 & consequ5tly to v>y ! attractive p[] ex]cis$ ^u ! iron plate armature4 ,let a simple s\nd be n[ made 9 ! tube1 consi/+ ( #bef vibrations p] second3 ! membrane c>ry+ ! iron w vibrate z _m times1 & s _m pulses ( induc$ electricity w be impos$ ^u ! con/ant curr5t1 :i* w ea* act ^u ! receiv]1 & cause s _m vibrations ( ! armature ^u x2 & an e> held at ,p w he> ! s\nd ) ! same pit* z t at ! s5d+ in/rum5t4 ,if two or m s\nd-waves act simultane\sly ^u ! membrane1 its motions mu/ correspond ) su* comb9$ motions2 t is1 its motions w be ! resultant ( all ! s\nd-waves1 & ! correspond+ pulsations 9 ! curr5t mu/ reproduce at ,r ! same effect4 ,n[1 :5 a p]son speaks 9 ! tube1 ! membrane is ?r[n into vibrations m complex 9 /ructure ?an ^? j m5tion$1 diff]+ only 9 numb] & int5sity4 ,! magnet w cause responses f ev5 ! m9ute/ motion2 & !re=e an e> at ,r w he> :at is said at ! tube4 ,?is 0 ! in/rum5t exhibit$ at ! ,c5t5nial ,exposition at ,philadelphia1 & conc]n+ :i* ,sir ,william ,?ompson said on 8 return to ,engl&1 ,?is is ! greate/ by f> ( all ! m>vels ( ! electric telegraph4 ,! popul> impression has be51 conc]n+ ! telephone1 t ! s\nd 0 9 "s way convey$ ov] ! wire4 ,x w be obvi\s to e "o :o may read ?is1 t su* is v f> f be+ ! case4 ,! fact is1 x is a beautiful example ( ! conv]tibility ( =ces f "o =m to ano!r4 ,!re is fir/ ! initial vibratory me*anical motion ( ! air1 :i* is imp>t$ to ! membrane c>ry+ ! iron4 ,?is motion is conv]t$ into electricity 9 ! coil ( wire surr\nd+ ! electro-magnet1 & at ! receiv+-end is fir/ effective z magnetism1 :i* is aga9 conv]t$ into vibratory motion ( ! iron armature1 :i* motion is imp>t$ to ! air1 & s becomes aga9 a s\nd-wave 9 air l ! orig9al "o4 ,?is 0 ! fir/ speak+-telephone t 0 ev] con/ruct$1 s f> z ! writ] is aw>e1 b x 0 n a practicable in/rum5t4 ,_m s\nds 7 n reproduc$ at all1 &1 accord+ to ! report ( ! judges at ! ,philadelphia ,exposition1 "o ne$$ to %\t himself ho>se 9 ord] t he might be he>d at all4 ,,! ,,au?or',s ,,telephone4 ,= sev]al ye>s pa/ my regul>ly recurr+ duties h tak5 me ov] ! v>i\s subjects treat$ ( 9 ?is book1 & ea* "o has be5 ext5sively illu/rat$ 9 an exp]im5tal way1 & a consid]able numb] ( new pieces ( app>atus & new exp]im5ts to exhibit _! ph5om5a h be5 devis$ by me4 ,among ^!1 ,i w\ld m5tion ! foll[+3-- #a4 ,measurem5t ( ! elongation ( a magnetiz$ b>4 #b4 ,a magneto-electric telegraph4 #c4 ,an electro-magnetic in/rum5t = demon/rat+ ! rotation ( ! e>?4 #d4 ,! p]man5t magnetism ( ! magnetic phantom4 #e4 ,! conv]tibility ( s\nd into electricity4 #f4 ,! induction ( a vibrat+ magnet ^u an electric circuit4 #g4 ,! orig9ation ( electric waves 9 a circuit by a s\nd+ magnet4 #h4 ,! discov]y ( ! action ( ! air 9 a s\nd+ organ-pipe4 #i4 ,two or ?ree me?ods = /udy+ ! vibrations ( membranes4 #aj4 ,lissaj\s =ks = enl>g$ projections ( s\nd vibrations4 ,z soon1 !re=e1 z ,i gave att5tion to ! subject ( telephony1 ,i 0 able1 ) a few prelim9>y exp]im5ts1 to det]m9e ! prop] conditions = ! transmission ( spee* 9 an electric circuit2 &1 )\t ! slighte/ k ( ! me*anism :i* ,pr(4 ,bell _h us$1 ,i devis$ ! foll[+ arrangem5t = a speak+-telephone4 ,illu/ration3 ,,fig4 #ad4--,,my ,,fir/ ,,speak+ ,,telephone4 ,illu/ration3 ,,fig4 #ad4--;,,end ,,view4 ,my fir/ speak+-telephone1 ,fig4 #ad1 consi/$ ( a magnet made out ( half-in* r\nd /eel b5t into a ,u =m1 hav+ ! poles ab\t two in*es ap>t4 ,ov] ^! 7 slipp$ two bobb9s tak5 f an old telegraph regi/]1 & 7 already fitt$ to a half-in* core4 ,^! bobb9s1 two in*es & a half long1 7 w\nd ) cotton-cov]$ copp] wire1 ,no4 #bc1 ea* bobb9 conta9+ ab\t #aej feet4 ,?is magnet1 ) ! bobb9s slipp$ ^u its poles1 0 made fa/ to a po/ two or ?ree in*es high4 ,! /eel 0 made z /rongly magnetic z 0 possible1 & w\ld hold up ?ree or f\r times its own weight4 ,9 front ( ! poles1 a %eet ( ?9 /eel1 "o-fiftie? ( an in* ?ick1 0 made fa/ to an upright bo>d hav+ a hole cut ?r\gh x ?ree & a half in*es 9 diamet] 7,fig4 #ad1 end view72 ! plate 0 screw$ tightly to ?is bo>d1 s z to cov] ! hole2 & ! middle ( ! hole 0 at ! same height z ! two poles ( ! magnet4 ,! wires f ! two bobb9s 7 connect$1 z if to make an electro-magnet2 :ile ! two free t]m9als 7 to be connect$ ) ! l9e-wires4 ,( c\rse !re 7 two ( ^! in/rum5ts1 bo? alike2 & talk+ & s++ 7 reproduc$ ) ^!4 ,a v great numb] ( exp]im5ts h be5 made to det]m9e ! be/ conditions = ea* ( ! ess5tial p>ts1--! size & /r5g? ( ! magnet1 ! size ( ! bobb9s1 z to l5g? & f95ess ( wire1 ! be/ ?ickness = ! plate = absorb+ ! vibrations1 c42 & x is really surpris+1 h[ little is ! diff]5ce betwe5 v wide limits4 ,! foll[+ directions w enable any "o to con/ruct a speak+-telephone ) :i* good results may be obta9$4 ,! specifications w be = only "o in/rum5t2 ?\gh ( c\rse two in/rum5ts made alike w be necess>y = any purposes ( speak+ or o!r signals4 ,illu/ration3 ,,fig4 #ae4 ,illu/ration3 ,,fig4 #af4 ,procure ?ree common horse-%oe magnets ab\t six in*es long1 all ( ! same size2 ^! retail 9 ! m>ket at ab\t a doll> apiece4 ,!y %\ld be /rong en\gh to hold up sev]al times _! own weight ea*4 ,next1 h turn$ out ( good h>d wood1--su* z maple or boxwood1--two spools n ov] half an in* long & an in* & a half broad1 ! sides cut squ>e bo? inside & out1 z %[n at ,s1 ,fig4 #ae2 a hole ! ?ird ( an in* 9 diamet] is to be made ?r\gh ! spool4 ,into ?is hole is to be fitt$ a %ort rod ( s(t iron1 ,i1 ab\t an in* long1 :i* %\ld be a little r\nd$ at ! out] end4 ,! bobb9s may be w\nd ) z mu* insulat$ copp] wire z !y w hold4 ,! wire may be f ! "o-=tie? to ! "o-fiftie? ( an in* 9 diamet]1 z is mo/ conv5i5t to obta91 ! latt] size be+ pref]able4 ,! resi/ance ( su* bobb9s w probably be f two to ?ree ohms ea*4 ,! s(t-iron core ,i mu/ project backw>ds f> en\gh to be clamp$ betwe5 ! two out] magnets #a & #c1 :ile ! inn] "o1 #b1 is drawn back4 ,:5 ! bobb9s are 9 _! places1 & are clamp$ betwe5 ! upp] & l[] magnets1 !y w /& z %[n 9 ,fig4 #af1 :]e ! view is f above2 ! magnets be+ button$ d[n to ! block !y re/ on 7see ,fig4 #ag71 :i* at ! same "t holds ! s(t-iron rods ) ! bobb9s ^u !m4 ,! wires on ^! coils mu/ be connect$ 9 ! same way !y w\ld be 9 ord] to make opposite poles ( _! out] ends1 if a curr5t ( electricity 7 to be s5t ?r\gh ! coils4 ,an upright bo>d ,b 7,fig4 #ag7 six or sev5 in*es squ>e1 hav+ a r\nd hole f\r in*es 9 diamet] cut out f ! middle ( x1 mu/ be fix$ ne> ! end ( ! base-bo>d2 & ov] ?is hole is to be screw$ tightly a piece ( ?9 %eet iron or /eel2 x may be f ! "o-tw5tie? to ! "o-fiftie? ( an in* 9 ?ickness4 ,x does n seem to make mu* diff]5ce ab\t ! ?ickness ( ?is plate4 ,i h g5]ally got ! be/ results f a plate "o-fiftie? ( an in* ?ick4 ,! upright bo>d c>ry+ ?is plate mu/ be v rigid1 o!rwise ! plate w be kept tight to ! magnets all ! "t2 & "o ( ! conditions ( success 9 work+ is1 t ?is plate %all be z close z possible to ! magnet-ends1 b n to t\*3 !re=e fix ! bo>d tight1 & adju/ ! magnets by means ( ! button %[n on top ( !m 9 ! p]spective figure4 ,illu/ration3 ,,fig4 #ag4 ,! s\nds to be transmitt$1 ( :atev] sort !y may be1 are to be made on ! side ,p1 ,fig4 #af2 & likewise1 :5 ! in/rum5t is us$ z a receiv]1 ! e> is to be appli$ at ! same place4 ,a tube ab\t two in*es 9 diamet] may be made fa/ to ! front ( ! bo>d1 9 a l9e ) ! c5tre ( ! plate2 ?is w aid some:at 9 he>+4 ,:5 two or ?ree p]sons are to s+1 x w be be/ to h ea* "o suppli$ ) a tube to s+ ?r\gh2 "o end ( ! tube to be plac$ close to ! front ( ! plate4 ,! s\nd ( musical in/rum5ts1 su* z ! flute & ! cornet1 w be reproduc$ mu* l\d]1 if ! front ( su* in/rum5t be all[$ to re/ ^u ! rim ( ! hole 9 ! bo>d1 j 9 front ( ! plate4 ,x is noticeable t l[ talk+ c be he>d m di/9ctly ?an :5 a great ef=t is made2 b ! s\nds ?\gh di/9ct are n /rong at any "t1 & o!r s\nds s]i\sly int]f]e ) he>+4 ,x is probable t "s way w h]eaft] be devis$ = increas+ ! usefulness ( ! inv5tion by increas+ ! volume ( s\nd4 ,on acc\nt ( ! weakness ( ! s\nd x becomes necess>y to provide a call to attract ! att5tion ( "o 9 ! room4 ,?is may be accompli%$ by hav+ a small electric bell work$ by a "o or two cell batt]y4 ,ano!r way :i* ,i h f\nd to be q z effici5t is to h a rod ( iron or /eel ab\t a foot long1 & half an in* 9 diamet]1 b5t into a ,u =m4 ,:5 ?is is held by ! b5d1 & /ruck ^u ! floor or ) a /ick1 x vibrates p[]fully2 & if "o ( its prongs be p]mitt$ to /rike aga9/ ! plate ,p1 ,fig4 #af1 ! s\nd w be reproduc$ l\d en\gh to he> ov] a l>ge room4 ,i h nev] fail$ to call ) ?is :5 any "o 0 9 ! same room ) ! telephone4 ,:]ev] a telephone circuit has be5 made ^u telegraph poles hav+ o!r wires ^u !m1 ! inductive actions ( ! curr5ts ^u ! o!r wires has be5 f\nd to s]i\sly int]f]e ) ! action ( ! telephones1 inasmu* z ! latt] reproduce e o!r message4 ,"o skill$ 9 read+ by s\nd 9 ! ord9>y way c read ?r\gh ! telephone :at message is travell+ 9 a neighbor+ wire4 ,messages may be ?us read ^u wires z f> di/ant z t5 feet f ! telephone circuit4 ,x !re =e seems to be ess5tial t ea* telephone circuit %\ld be isolat$ f e o!r "o1 else !re c be no secrecy 9 messages4 ,a v int]e/+ effect 0 notic$ "o night :5 !re 0 a bright aurora display4 ,!re 0 a cont9u\s curr5t ?r\gh ! wires1 accompani$ ) s\nds :i* increas$ 9 int5sity z ! bright /ream]s pass$ by4 ,?is w probably lead to "s important results 9 sci5ce4 ,9 all probability ! telephone is z mu* 9 its infancy z 0 ord9>y telegraphy 9 #ahdj4 ,s9ce t "t ! sci5ces ( electricity & magnetism h _h ! mo/ ( _! gr[?1 & telegraphy has kept pace ) ! advanc+ k until its comm]cial importance is second to no o!r ag5cy4 ,v _m important pr9ciples t are invaluable 9 telegraphy to-day 7 :olly unkn[n 9 #ahdj2 b x may "h be not$ t 9 ! telephone1 z x n[ is1 !re is n a s+le pr9ciple t 0 n well en\gh kn[n 9 #ahdj4 ,?is w be app>5t to "o :o foll[s out ! ph5om5a f ! s5d] to ! receiv]4 ,fir/1 ! s\nd 9 air caus+ a correspond+ movem5t 9 a solid body1 iron4 ,?is iron1 act+ inductively ^u a magnet1 orig9ates magneto-electric curr5ts 9 a wire helix ab\t x2 & ^! travel to ano!r helix1 &1 re-act+ ^u ! magnet 9 x1 h electro-magnetic effects1 & increase & decrease ! /r5g? ( ! magnet2 & ?is v>iable magnetism affects ! plate ( iron 9 front ( t magnet1 & makes x to vibrate 9 a correspond+ mann]1 & ?us to re/ore to ! air 9 "o place ! vibrations absorb$ f ! air 9 ano!r place4 ,to "s x may seem /range t a simple ?+ z ! telephone is1 involv+ no?+ b pr9ciples famili> en\gh to e "o int]e/$ 9 physical sci5ce1 %\ld h wait$ ne>ly =ty ye>s to be inv5t$4 ,! reason is probably ?is3 ,m5 ( sci5ce1 z a rule1 d n feel call$ ^u to apply ! pr9ciples :i* !y may discov]4 ,!y are cont5t to be discov]+1 n inv5t+4 ,n[1 ! s*ools ( ! c\ntry ought to make ! y\? q famili> ) ! g5]al pr9ciples ( physical sci5ce1 t ! inv5tive ones--& !re are _m su*--may apply !m intellig5tly4 ,me*anism is all t /&s betwe5 u & a]ial navigation2 all t is necess>y to reproduce human spee* 9 writ+2 & all t is ne$$ to realize completely ! prophetic picture ( ! ,graphic1 ( ! orator :o %all at ! same in/ant address an audi5ce 9 e city 9 ! _w4 99 99 99 99 99 ,transcrib]'s ,notes3 ,! musical flat symbol is repres5t$ 9 ! text by flat4 ,page #ag1 prop]]ties *ang$ to prop]ties 7!re are o!r prop]ties7 ,page #db1 muturally *ang$ to mutually 7bodies w\ld mutually7 ,page #ajf1 outby *ang$ to out by 7giv5 out by !7