,transcrib]'s ,notes3      ,und]scores  
be=e & aft] a ^w or phrase indicate     
italics      9 ! orig9al text4    ,equal
 signs  be=e & aft] a ^w or phrase      
indicate bold      9 ! orig9al text4    
,c>at symbol  designates a sup]script4  
,und]score  is us$ to designates a      
subscript4    ,small capitals h be5     
conv]t$ to ,,solid capitals4            
,illu/rations h be5 mov$ s !y d n break 
up p>agraphs4    ,old or antiquat$      
spell+s h be5 pres]v$4    ,typographical
 errors h be5 sil5tly correct$ b o!r    
v>iations      9 spell+ & punctuation   
rema9 unalt]$4                          
,,! ,,telephone4                        
,a ,,lecture                            
,,entitl$                     ,,rese>*es
 ,,9 ,,electric ,,telephony1            
,,by ,,pr(essor ,,alex&] ,,graham       
,,bell1                                 
,,deliv]$ ,,be=e                    ,!  
,society ( ,telegraph ,eng9e]s1         
,,octob] #ca,,/1 #ahgg4                 
,,publi%$ ,,by ,,! ,,society1           

,,& ,,edit$ ,,by                        
,,lieut4-,,col4 ,,frank ,,bolton1       
,c4,e41 ,,hon4 ,,secret>y1              
,,&                 ,,william ,,edw>d   
,,langdon1 ,,act+ ,,secret>y4           
,london3                   ,e4 ,,& ,f4  
,n4 ,,spon1 #df1 ,,*>+ ,,cross4         
,new ,york3                             
#ddf1 ,,broome ,,/reet4                 
#ahgh4                     ,price ,"o   
,%ill+ & ,sixp5ce4           ,! "r (    
translation & reproduction is res]v$    
,,extracts ,,( ,,proce$+s ,,( ,,!       
,,society ,,( ,,telegraph ,,eng9e]s4    
,special ,g5]al ,meet+1 held at #be1    
,great ,george ,/reet1       ,we/m9/]1  
on ,w$nesday1 ! #ca/ ,octob]1 #ahgg4    
,,pr(essor ,,abel1 ,c4,b41 ,f4,r4,s41   
,presid5t1 9 ! ,*air4    ,! ,,presid5t3 
,g5tlem51 ! ,c\ncil ( ! ,society (      
,telegraph ,eng9e]s felt t !y 7 sure (  
do+ :at ! memb]s  w\ld consid] "r 9     
summon+ a special meet+ = ! two-fold    
purpose ( giv+ a welcome to ,pr(essor   
,bell to ?is c\ntry &  af=d+ ! ,memb]s  

an opportunity ( he>+ f him an acc\nt1  
:i* he has be5 s good z to promise to   
give u1 ( ! nature1  hi/ory1 &          
developm5t (1 :at may well be call$1 "o 
( ! mo/  int]e/+ discov]ies ( our age4  
,our "t is v preci\s ?is  ev5+4 ,we all 
desire to he> ev]y?+ ,pr(essor ,bell c  
tell u  on ?is subject1 & _m g5tlem5 w  
probably desire aft]w>ds to  ask        
que/ions or discuss ! subject1 = ,i see 
pres5t a great numb]  ( em95t sci5tific 
m54 ,i w n wa/e ano!r mom5t1 b at once  
call ^u ,pr(essor ,bell to comm5ce 8    
disc\rse on ! ,electric  ,telephone4    
,,rese>*es ,,9 ,,electric ,,telephony4  
,by ,,pr(essor ,,alex&] ,,graham ,,bell4
    ,,pr(essor ,,bell3 ,mr4 ,presid5t & 
,g5tlem5 ( ! ,society (  ,telegraph     
,eng9e]s4 ,x is to-night my pleasure1 z 
well z duty1 to  give y "s acc\nt ( !   
telephonic rese>*es 9 :i* ,i h be5  s   
long engag$4 ,_m ye>s ago my att5tion 0 
direct$ to !  me*anism ( spee* by my    
fa!r1 ,alex&] ,melville ,bell1 (        
,ed9burgh1 :o has made a life-long /udy 

( ! subject4 ,_m (  ^? pres5t may       
recollect ! inv5tion by my fa!r ( a     
means  ( repres5t+1 9 a wond]fully      
accurate mann]1 ! positions (  ! vocal  
organs 9 =m+ s\nds4 ,toge!r we c>ri$ on 
q a  numb] ( exp]im5ts1 seek+ to discov]
 ! correct me*anism (  ,engli% & =eign  
elem5ts ( spee*1 & ,i rememb] especially
 an  inve/igation 9 :i* we 7 engag$     
conc]n+ ! musical relations  ( v[el     
s\nds4 ,:5 v[el s\nds are :isp]$1 ea*   
v[el seems  to possess a p>ticul> pit* (
 its own1 & by :isp]+ c]ta9  v[els 9    
succession a musical scale c be di/9ctly
 p]ceiv$4 ,our  aim 0 to det]m9e !      
natural pit* ( ea* v[el2 b unexpect$    
difficulties made _! appe>ance1 = _m ( !
 v[els seem$ to  possess a d\ble        
pit*--"o due1 probably1 to ! resonance (
 ! air  9 ! m\?1 & ! o!r to ! resonance 
( ! air conta9$ 9  ! cavity beh9d !     
tongue1 compreh5d+ ! ph>ynx & l>ynx4    
,i hit ^u an exp$i5t = det]m9+ ! pit*   
:i* at t "t  ,i ?\ght to be orig9al )   
myself4 ,x consi/$ 9 vibrat+ a  tun+-=k 

9 front ( ! m\? :ile ! positions ( !    
vocal  organs = ! v>i\s v[el s\nds 7    
sil5tly tak54 ,x 0 f\nd  t ea* v[el     
position caus$ ! re9=cem5t ( "s p>ticul>
  =k or =ks4    ,i wrote an acc\nt ( ^! 
rese>*es to ,mr4 ,alex4 ,j4 ,ellis1 (   
,london1 :om ,i h v great pleasure 9    
see+ "h to-night4 ,9  reply he in=m$ me 
t ! exp]im5ts relat$ _h already be5     
p]=m$ by ,helmholtz1 & 9 a mu* m p]fect 
mann] ?an ,i _h  done4 ,inde$1 he said t
 ,helmholtz _h n only analys$ ! v[el    
s\nds into _! con/itu5t musical elem5ts1
 b _h actually  p]=m$ ! syn!sis ( !m4   
,he _h succe$$ 9 produc+1 artificially1 
c]ta9 ( ! v[el  s\nds by caus+ tun+-=ks 
( diff]5t pit* to vibrate  simultane\sly
 by means ( an electric curr5t4 ,mr4    
,ellis 0 k9d  en\gh to grant me an      
int]view = ! purpose ( expla9+ !        
app>atus employ$ by ,helmholtz 9 produc+
 ^! extraord9>y  effects1 & ,i sp5t !   
great] "p ( a delightful day ) him 9    
inve/igat+ ! subject4 ,at t "t1 h[ev]1  
,i 0 too slightly  acqua9t$ ) ! laws (  

electricity fully to und]/& !           
explanations giv52 b ! int]view _h !    
effect ( ar\s+ my  int]e/ 9 ! subjects (
 s\nd & electricity1 & ,i did n re/     
until ,i _h obta9$ possession ( a copy (
 ,helmholtz' great "w1#a  & _h attempt$1
 9 a crude & imp]fect mann] x is true1  
to  reproduce 8 results4 ,:ile reflect+ 
^u ! possibilities (  ! production (    
s\nd by electrical means1 x /ruck me t !
  pr9ciple ( vibrat+ a tun+-=k by !     
int]mitt5t attraction  ( an             
electro-magnet might be appli$ to !     
electrical production (  music4    ,i   
imag9$ to myself a s]ies ( tun+-=ks (   
diff]5t pit*es1  arrang$ to vibrate     
automatically 9 ! mann] %[n by          
,helmholtz1  ea* =k int]rupt+ at e      
vibration a voltaic curr5t2 & !  ?\ght  
occurr$1 8,:y %\ld n ! depression ( a   
key l t (  a piano direct ! int]rupt$   
curr5t f any "o ( ^! =ks1  ?r\gh a      
telegraph wire1 to a s]ies (            
electro-magnets op]at+ !  /r+s ( a piano
 or o!r musical in/rum5t1 9 :i* case a  

p]son  might play ! tun+-=k piano 9 "o  
place & ! music be audible  f !         
electromagnetic piano 9 a di/ant city80 
,! m ,i reflect$ ^u ?is arrangem5t ! m  
feasible did x  seem to me2 inde$1 ,i   
saw no reason :y ! depression ( a numb] 
(  keys at ! tun+-=k end ( ! circuit    
%\ld n be foll[$ by  ! audible          
production ( a full *ord f ! piano 9 !  
di/ant  city1 ea* tun+-=k affect+ at !  
receiv+ end t /r+ (  ! piano ) :i* x 0 9
 unison4 ,at ?is "t ! int]e/ :i*  ,i    
felt 9 electricity l$ me to /udy ! v>i\s
 sy/ems ( telegraphy  9 use 9 ?is c\ntry
 & 9 ,am]ica4 ,i 0 mu* /ruck ) !        
simplicity ( ! ,morse alphabet1 & ) !   
fact t x c\ld be  read by s\nd4 ,in/ead 
( hav+ ! dots & da%es record$ ^u  pap]1 
! op]ators 7 9 ! habit ( obs]v+ !       
duration ( !  click ( ! in/rum5ts1 & 9  
?is way 7 enabl$ to di/+ui%  by e> !    
v>i\s signals4    ,x /ruck me t 9 a     
simil> mann] ! duration ( a musical note
  might be made to repres5t ! dot or da%
 ( ! telegraph code1 s  t a p]son might 

op]ate "o ( ! keys ( ! tun+-=k piano    
ref]r$ to above1 & ! duration ( ! s\nd  
proce$+ f !  correspond+ /r+ ( ! di/ant 
piano be obs]v$ by an op]ator  /ation$  
!re4 ,x seem$ to me t 9 ?is way a numb] 
( di/9ct  telegraph messages might be   
s5t simultane\sly f ! tun+-=k  piano to 
! o!r end ( ! circuit1 by op]ators ea*  
manipulat+  a diff]5t key ( ! in/rum5t4 
,^! messages w\ld be read by  op]ators  
/ation$ at ! di/ant piano1 ea* receiv+  
op]ator  li/5+ = signals ( a c]ta9      
def9ite pit*1 & ignor+ all  o!rs4 ,9 ?is
 way c\ld be accompli%$ ! simultane\s   
transmission  ( a numb] ( telegraphic   
messages along a s+le wire1 ! numb]  be+
 limit$ only by ! delicacy ( ! li/5]'s  
e>4 ,! idea (  increas+ ! c>ry+ p[] ( a 
telegraph wire 9 ?is way took  complete 
possession ( my m9d1 & x 0 ?is practical
 end t ,i  _h 9 view :5 ,i comm5c$ my   
rese>*es 9 ,electric ,telephony4    ,9 !
 progress ( sci5ce x is univ]sally f\nd 
t complexity  leads to simplicity1 & 9  
n>rat+ ! hi/ory ( sci5tific  rese>* x is

 (t5 advisable to beg9 at ! end4    ,9  
glanc+ back ov] my own rese>*es ,i f9d x
 necess>y to  designate1 by di/9ct      
names1 a v>iety ( electrical curr5ts by 
means  ( :i* s\nds c be produc$1 & ,i   
%all direct y\r att5tion to  sev]al     
di/9ct species ( :at may be t]m$        
8telephonic0 curr5ts (  electricity4 ,9 
ord] t ! peculi>ities ( ^! curr5ts may  
be  cle>ly und]/ood1 ,i %all ask ,mr4   
,fro/ to project ^u ! scre5 a  graphical
 illu/ration ( ! diff]5t v>ieties4    ,!
 graphical me?od ( repres5t+ electrical 
curr5ts "h %[n is  ! be/ means ,i h be5 
able to devise ( /udy+ 9 an accurate    
mann] ! effects produc$ by v>i\s =ms (  
telephonic app>atus1  & x has l$ me to !
 conception ( t peculi> species (       
telephonic curr5t "h designat$ z        
undulatory1 :i* has r5d]$  feasible !   
artificial production ( articulate spee*
 by electrical  means4    ,illu/ration3 
,fig4 #a4    ,a horizontal l9e 7g g7 is 
tak5 z ! z]o ( curr5t1 &  impulses (    
positive electricity are repres5t$ above

 ! z]o l9e1  & negative impulses bel[ x1
 or vice v]s4    ,! v]tical ?ickness (  
any electrical impulse 7b or d71 measur$
  f ! z]o l9e1 indicates ! int5sity ( ! 
electrical curr5t  at ! po9t obs]v$1 & !
 horizontal ext5sion ( ! electric  l9e  
7b or d7 indicates ! duration ( !       
impulse4    ,n9e v>ieties ( telephonic  
curr5ts may be di/+ui%$1 b x w  only be 
necess>y to %[ y six ( ^!4 ,! ?ree      
prim>y v>ieties  designat$ z            
8int]mitt5t10 8pulsatory10 &            
8undulatory10 are  repres5t$ 9 l9es #a1 
#b1 & #c4    ,sub-v>ieties ( ^! c be    
di/+ui%$ z 8direct0 or 8rev]s$0  curr5ts
 accord+ z ! electrical impulses are all
 ( "o k9d or  are alt]nately positive & 
negative4 8,direct0 curr5ts may /ill    
fur!r be di/+ui%$ z 8positive0 or       
8negative10 accord+ z !  impulses are ( 
"o k9d or ( ! o!r4    ,an int]mitt5t    
curr5t is *>act]is$ by ! alt]nate       
pres5ce  & abs5ce ( electricity ^u !    
circuit2    ,a pulsatory curr5t results 
f sudd5 or in/antane\s *anges 9  !      

int5sity ( a cont9u\s curr5t2 &    ,an  
undulatory curr5t is a curr5t (         
electricity1 ! int5sity (  :i* v>ies 9 a
 mann] proportional to ! velocity ( !   
motion  ( a p>ticle ( air dur+ !        
production ( a s\nd3 ?us ! curve        
repres5t+ graphically ! undulatory      
curr5t = a simple musical  tone is !    
curve expressive ( a simple p5dul\s     
vibration--t is1  a s9usoidal curve4    
,telephonic curr5ts ( electricity may   
be3                    ,direct          
,positive #a    ,positive int]mitt5t    
curr5t4     ,int]mitt5t                 
,negative #b    ,negative      0        
0                   ----      ,rev]s$ #c
    ,rev]s$      0          0           
,direct  ,positive #d    ,positive      
pulsatory curr5t4     ,pulsatory        
,negative #e    ,negative      0       0
                   ----      ,rev]s$ #f 
,rev]s$      0       0                  
,direct  ,positive #g    ,positive      
undulatory curr5t4     ,undulatory      
,positive #h    ,negative      0       0

                   ----      ,rev]s$ #i 
,rev]s$      0       0    ,& "h ,i may  
rem>k1 t1 al?\gh ! conception ( !       
undulatory  curr5t ( electricity is     
entirely orig9al ) myself1 me?ods (     
produc+ s\nd by means ( int]mitt5t &    
pulsatory curr5ts h  long be5 kn[n4 ,=  
in/ance1 x 0 long s9ce discov]$ t  an   
electro-magnet gives =? a decid$ s\nd :5
 x is sudd5ly  magnetiz$ or demagnetiz$4
 ,:5 ! circuit ^u :i* x is plac$ is     
rapidly made & brok51 a succession (    
explosive noises proce$s f  ! magnet4   
,^! s\nds produce ^u ! e> ! effect ( a  
musical  note :5 ! curr5t is int]rupt$ a
 suffici5t numb] ( times  p] second4 ,! 
discov]y ( 8,galvanic ,music10 by       
,page1#b 9 #ahcg1  l$ inquir]s 9 diff]5t
 p>ts ( ! _w almo/ simultane\sly  to    
ent] into ! field ( telephonic rese>*2 &
 ! ac\/ical  effects produc$ by         
magnetization 7 c>efully /udi$ by       
,m>rian1#c  ,beatson1#d ,gassiot1#e ,de 
la ,rive1#f ,matteucci1#g ,guillem91#h  
,w]!im1#i ,w>tmann1#aj ,janni>1#aa      

,j\le1#ab ,laborde1#ac  ,legat1#ad      
,reis1#ae ,pogg5dorff1#af ,du           
,moncel1#ag ,delez5ne1#ah  & o!rs4#ai ,x
 %\ld also be m5tion$ t ,gore#bj obta9$ 
l\d musical notes f m]cury1 accompani$  
by s+ul>ly beautiful  crispations ( !   
surface dur+ ! c\rse ( exp]im5ts 9      
electrolysis2 ,page#ba produc$ musical  
tones f ,trevelyan's b>s  by ! action ( 
! galvanic curr5t2 & fur!r x 0 discov]$ 
by ,sullivan#bb t a curr5t ( electricity
 is g5]at$ by !  vibration ( a wire     
compos$ p>tly ( "o metal & p>tly (      
ano!r4  ,! curr5t 0 produc$ s long z !  
wire emitt$ a musical note1  b /opp$    
imm$iately ^u ! cessation ( ! s\nd4     
,= sev]al ye>s my att5tion 0 almo/      
exclusively direct$ to  ! production (  
an in/rum5t = mak+ & break+ a voltaic   
circuit ) extreme rapidity1 to take !   
place ( ! transmitt+  tun+-=k us$ 9     
,helmholtz' rese>*es4 ,i w n tr\ble y  )
 ! description ( all ! v>i\s =ms (      
app>atus t 7  devis$1 b w m]ely direct  
y\r att5tion to "o ( ! be/ (  !m1 %[n 9 

fig4 #b4 ,9 ! transmitt+ in/rum5t ,t1 a 
/eel re$  a is employ$1 :i* is kept 9   
cont9u\s vibration by ! action (  an    
electro-magnet e & local batt]y4 ,9 !   
c\rse ( its vibration  ! re$ /rikes     
alt]nately aga9/ two fix$ po9ts m1 l1 & 
?us completes alt]nately a local & a ma9
 circuit4 ,:5 ! key  ,k is depress$ an  
int]mitt5t curr5t f ! ma9 batt]y ,b is  
direct$ to ! l9e-wire ,w1 & passes ?r\gh
 ! electro-magnet ,e (  a receiv+       
in/rum5t ,r at ! di/ant end ( ! circuit1
 & !nce  to ! gr\nd ,g4 ,! /eel re$ ,a  
is plac$ 9 front ( ! receiv+  magnet1 & 
:5 its normal rate ( vibration is ! same
 z ! re$  ( ! transmitt+ in/rum5t x is  
?r[n into p[]ful vibration1  emitt+ a   
musical tone ( a simil> pit* to t       
produc$ by ! re$  ( ! transmitt+        
in/rum5t1 b if x is normally ( a diff]5t
  pit* x rema9s sil5t4    ,illu/ration3 
,fig4 #b4    ,illu/ration3 ,fig4 #c4    
,fig4 #d4 ,fig4 #e4    ,a glance at     
figs4 #c1 #d1 & #e w %[ ! arrangem5t (  
su*  in/rum5ts ^u a telegraphic circuit1

 design$ to enable a numb]  (           
telegraphic despat*es to be transmitt$  
simultane\sly along !  same wire4 ,!    
transmitt]s & receiv]s t are numb]$     
alike h  ! same pit* or rate (          
vibration4 ,?us ! re$ ( ,t is 9 unison  
) ! re$s ,t & ,r at all ! /ations ^u !  
circuit1 s t  a telegraphic despat* s5t 
by ! manipulation ( ! key ,k at !       
/ation %[n 9 fig4 #c w be receiv$ ^u !  
receiv+ in/rum5ts  ,k at all ! o!r      
/ations ^u ! circuit4 ,)\t go+ into     
details1 ,i %all m]ely say t ! great    
defects ( ?is plan (  multiple          
telegraphy 7 f\nd to consi/1 fir/ly1 9 !
 fact t  ! receiv+ op]ators 7 requir$ to
 possess a good musical e> 9  ord] to   
discrim9ate ! signals2 & secondly1 t !  
signals c\ld  only pass 9 "o direction  
along ! l9e 7s t two wires w\ld be      
necess>y 9 ord] to complete             
communication 9 bo? directions74 ,!     
fir/ objection 0 got ov] by employ+ !   
device :i* ,i t]m a  8vibratory         
circuit-break]10 %[n 9 ! next diagram1  

:]eby musical  signals c be             
automatically record$4    ,illu/ration3 
,fig4 #f4    ,fig4 #f %[s a receiv+     
in/rum5t ,r1 ) a vibratory              
circuit-break]  v atta*$4 ,! light      
spr+-lev] v ov]laps ! free end ( !  /eel
 re$ ,a1 & normally closes a local      
circuit1 9 :i* may be  plac$ a          
,morse-s\nd] or o!r telegraphic         
app>atus4 ,:5 ! re$  ,a is ?r[n into    
vibration by ! passage ( a musical      
signal1 !  spr+ arm v is ?r[n upw>ds1   
op5+ ! local circuit at !  po9t #e4 ,:5 
! spr+-arm v is s arrang$ z to h        
normally a  mu* sl[] rate ( vibration   
?an ! re$ ,a#a1 ! local circuit  is f\nd
 to rema9 p]man5tly op5 dur+ ! vibration
 ( ,a1 !  spr+-arm v com+ into contact )
 ! po9t #e only ^u !  cessation ( !     
receiv]'s vibration4 ,?us ! signals     
produc$ by !  vibration ( ! re$ ,a are  
reproduc$ ^u an ord9>y telegraphic      
in/rum5t 9 ! local circuit4    ,fig4 #g 
%[s ! application ( electric telephony  
to autographic  telegraphy4             

,illu/ration3 ,fig4 #g4    ,t1 ,t1 c41  
repres5t ! re$s ( transmitt+ in/rum5ts (
  diff]5t pit*1 ,r1 ,r1 c41 ! receiv]s  
at ! di/ant /ation  ( correspond+ pit*1 
&1 r1 r1 c41 ! vibratory                
circuit-break]s atta*$ to ! receiv+     
in/rum5ts1 & connect$  ) metallic       
bri/les1 #ba1 re/+ ^u *emically prep>$  
pap]  ,p4 ,! message1 or picture1 to be 
copi$1 is writt5 ^u a metallic  surface1
 ,f#j1 ) non-metallic ink1 & plac$ ^u a 
metallic  cyl9d] #g1 connect$ ) ! ma9   
batt]y ,b2 & ! *emically  prep>$ pap]   
,p1 ^u :i* ! message is to be receiv$1  
is plac$  ^u a metallic cyl9d] connect$ 
) ! local batt]y ,b at !  receiv+       
/ation4 ,:5 ! cyl9d]s at ei!r end ( !   
circuit are  rotat$ 9 ! direction ( !   
arr[s--b n necess>ily at ! same  rate ( 
spe$--a fac simile ( :atev] is writt5 or
 drawn ^u !  metallic surface ,f#j      
appe>s ^u ! *emically prep>$ pap] ,p4   
,! me?od by means ( :i* ! musical       
signals may be s5t  simultane\sly 9 bo? 
directions along ! same circuit is %[n 9

  our next illu/ration1 figures #h1 #i1 
& #aj4 ,! arrangem5t is simil>  to t %[n
 9 figures #c1 #d1 & #e1 except+ t !    
int]mitt5t  curr5t f ! transmitt+       
in/rum5ts is pass$ ?r\gh !  prim>y wires
 ( an induction coil1 & ! receiv+       
in/rum5ts are  plac$ 9 circuit ) !      
second>y wire4 ,9 ?is way free e>?      
communication is secur$ at ei!r end ( ! 
circuit1 & ! musical  signals produc$ by
 ! manipulation ( any key are receiv$ at
 all !  /ations ^u ! l9e4 ,! great      
objection to ?is plan is ! extreme      
complication ( ! p>ts & ! necessity (   
employ+ local & ma9  batt]ies at e      
/ation4 ,x 0 also f\nd by practical     
exp]im5t  t x 0 difficult1 if n         
impossible1 ^u ei!r ( ! plans  "h %[n1  
to transmit simultane\sly ! numb] (     
musical tones  t !ory %[$ to be         
feasible4 ,mature consid]ation reveal$ !
  fact t ?is difficulty lay 9 ! nature (
 ! electrical curr5t  employ$1 & 0      
f9ally obviat$ by ! inv5tion ( !        
undulatory  curr5t4    ,x is a /range   

fact t important inv5tions are (t5 made 
almo/  simultane\sly by diff]5t p]sons 9
 diff]5t p>ts ( ! _w1  & ! idea (       
multiple telegraphy z develop$ 9 !      
prec$+  diagrams seems to h occurr$     
indep5d5tly to no less ?an f\r  o!r     
inv5tors 9 ,am]ica & ,europe4 ,ev5 !    
details ( !  arrangem5ts ^u circuit--%[n
 9 figures #c1 #d1 #e1 & #h1 #i1        
#aj--;are  extremely simil> 9 ! plans   
propos$ by ,mr4 ,cromwell ,v>ley (      
,london1 ,mr4 ,eli%a ,gray ( ,*icago1   
,mr4 ,paul ,la ,c\r ( ,cop5hag51 &  ,mr4
 ,?omas ,edison ( ,new>k1 ,new ,j]sey4  
,into ! "q ( priority  ( inv5tion1 (    
c\rse1 x is n my int5tion to g to-night4
    ,illu/ration3 ,fig4 #h4 ,fig4 #i4   
,fig4 #aj4    ,t ! difficulty 9 ! use ( 
an int]mitt5t curr5t may be m  cle>ly   
und]/ood1 ,i %all ask y to accompany me 
9 my explanation  ( ! effect produc$ :5 
two musical signals ( diff]5t pit*  are 
simultane\sly direct$ along ! same      
circuit4 ,fig4 #aa %[s an  arrangem5t   
:]eby ! re$s a a ( two transmitt+       

in/rum5ts  are caus$ to int]rupt !      
curr5t f ! same batt]y1 ,b4 ,we %all    
suppose ! musical int]val betwe5 ! two  
re$s to be a major ?ird1  9 :i* case _! 
vibrations are 9 ! ratio ( #d to #e1    
i4e41  #d vibrations ( a are made 9 !   
same "t z #e vibrations (  a#a4 ,a#b &  
,b#b repres5t ! int]mitt5t curr5ts      
produc$1  #d impulses ( ,b#b be+ made 9 
! same "t z #e impulses ( ,a#b4  ,! l9e 
,a#b  ,b#b repres5ts ! resultant effect 
^u ! ma9 l9e  :5 ! re$s a & a#a are     
simultane\sly caus$ to make &  break !  
same circuit1 & f ! illu/ration y w     
p]ceive  t ! resultant curr5t1 :il/     
reta9+ a uni=m int5sity1  is less       
int]rupt$ :5 bo? re$s are 9 op]ation ?an
 :5 "o  alone is employ$4 ,by c>ry+ y\r 
?\ghts /ill fur!r y w  und]/& t :5 a    
l>ge numb] ( re$s ( diff]5t pit* or (   
diff]5t rates ( vibration are           
simultane\sly mak+ & break+ !  same     
circuit ! resultant effect ^u ! ma9 l9e 
is practically  equival5t to "o cont9u\s
 curr5t4    ,illu/ration3 ,fig4 #aa4    

,x w also be und]/ood t ! maximum numb] 
( musical  signals t c be simultane\sly 
direct$ along a s+le wire  )\t conflict 
dep5ds v mu* ^u ! ratio :i* !  8make0   
be>s to ! 8break20 ! %ort] ! contact    
made1 &  ! long] ! break1 ! great] !    
numb] ( signals t c  be transmitt$ )\t  
confusion1 & vice v]s4 ,! app>atus  by  
means ( :i* ?is !oretical conclusion has
 be5 v]ifi$ is  "h to-night1 & consi/s (
 an ord9>y p>l\r h>monium1 !  re$s ( :i*
 are op]at$ by w9d 9 ! usual mann]4 ,9  
front (  ea* re$ is arrang$ a metal     
screw1 aga9/ :i* ! re$ /rikes  9 ! c\rse
 ( its vibration4 ,by adju/+ ! screw !  
duration  ( ! contact c be made long or 
%ort4 ,! re$s are connect$  ) "o pole ( 
a batt]y1 & ! screws aga9/ :i* !y /rike 
communicate ) ! l9e-wire1 s t int]mitt5t
 impulses f !  batt]y are transmitt$    
along ! l9e-wire dur+ ! vibration ( !   
re$s4    ,illu/ration3 ,fig4 #ab4       
,illu/ration3 ,fig4 #ac4                
,illu/ration3 ,fig4 #ad4    ,we n[      
proce$ to ! next illu/ration4 ,)\t ent]+

 into !  details ( ! calculation y w see
 t ) a pulsatory curr5t  ! effect (     
transmitt+ musical signals simultane\sly
 is ne>ly  equival5t to a cont9u\s      
curr5t ( m9imum int5sity--see ,a#b      
,b#b1  fig4 #ab2 b :5 undulatory curr5ts
 are employ$ ! effect is  diff]5t--see  
fig4 #ac4 ,! curr5t f ! batt]y ,b is    
?r[n into  waves by ! inductive action (
 iron or /eel re$s ,m ,m1 vibrat$ 9     
front ( electro-magnets e e1 plac$ 9    
circuit ) ! batt]y2  ,a#b & ,b#b        
repres5t ! undulations caus$ 9 ! curr5t 
by !  vibration ( ! magnetis$ bodies1 & 
x w be se5 t !re are  f\r undulations ( 
,b#b 9 ! same "t z five undulations (   
,a#b4  ,! resultant effect ^u ! ma9 l9e 
is express$ by ! curve ,a#b   ,b#b1 :i* 
is ! algebraical sum ( ! s9usoidal      
curves ,a#b &  ,b#b4 ,a simil> effect is
 produc$ :5 rev]s$ undulatory curr5ts   
are employ$ z %[n 9 fig4 #ad1 :]e !     
curr5t is produc$ by  ! vibration (     
p]man5t magnets ,m ,m 9 front (         
electro-magnets  7e e71 unit$ ^u a      

circuit )\t a voltaic batt]y4 ,x w be   
und]/ood f figs4 #ac & #ad t ! effect ( 
transmitt+ musical  signals ( diff]5t   
pit*es simultane\sly along a s+le wire  
is  n to oblit]ate ! vibratory "* ( !   
curr5t z 9 !  case ( int]mitt5t &       
pulsatory curr5ts1 b to *ange ! %apes  (
 ! electrical undulations4 ,9 fact1 !   
effect produc$ ^u !  curr5t is precisely
 analog\s to ! effect produc$ 9 ! air by
 !  vibration ( ! induc+ bodies ,m ,m4  
,h5ce x %\ld be possible to  transmit z 
_m musical tones simultane\sly ?r\gh a  
telegraph wire  z ?r\gh ! air4 ,!       
possibility ( us+ undulatory curr5ts =  
! purposes ( multiple telegraphy enabl$ 
me to disp5se entirely  ) ! complicat$  
arrangem5ts ( ! circuit %[n 9 figs4 #c1 
#d1 #e1 & #h1 #i1 #aj1 & to employ a    
s+le batt]y = ! :ole  circuit1 reta9+   
only ! receiv+ in/rum5ts =m]ly %[n4 ,?is
  arrangem5t is repres5t$ 9 figs4 #ae1  
#af1 & #ag4 ,^u vibrat+ !  /eel re$ ( a 
receiv] ,r1 ,r1 at any /ation by any    
me*anical means1  ! correspond+ re$s at 

all ! o!r /ations are ?r[n into         
vibration1 reproduc+ ! signal4 ,by      
atta*+ ! /eel re$s to !  poles ( a      
p[]ful p]man5t magnet1 z %[n 9 fig4 #ai1
 ! signals  c be produc$ )\t ! aid ( a  
batt]y4    ,illu/ration3 ,fig4 #ae4     
,fig4 #af4 ,fig4 #ag4    ,illu/ration3  
,fig4 #ah4bc    ,i h =m]ly /at$ t       
,helmholtz 0 enabl$ to produce v[el     
s\nds artificially by comb9+ musical    
tones ( diff]5t pit*es  & int5sities4 ,8
 app>atus is %[n 9 fig4 #ah4 ,tun+-=ks (
  diff]5t pit* are plac$ betwe5 ! poles 
( electro-magnets 7a#a1  a#b1 c471 & are
 kept 9 cont9u\s vibration by ! action (
 an  int]mitt5t curr5t f ! =k b4        
,resonators #a1 #b1 #c1 c4 are  arrang$ 
s z to re9=ce ! s\nds1 9 a great] or    
less degree1  accord+ z ! ext]ior       
orifices are enl>g$ or contract$4       
,?us x w be se5 t ^u ,helmholtz's plan !
 tun+-=ks  !mselves produce tones (     
uni=m int5sity1 ! l\dness be+  v>i$ by  
an ext]nal re9=cem5t2 b x /ruck me t !  
same  results w\ld be obta9$1 & 9 a mu* 

m p]fect mann]1 by  caus+ ! tun+-=ks    
!mselves to vibrate ) diff]5t degrees  (
 amplitude4 ,i !re=e devis$ ! app>atus  
%[n 9 fig4 #ai1 :i*  0 my fir/ =m (     
articulat+ telephone4 ,9 ?is figure a   
h>p (  /eel rods is employ$ atta*$ to ! 
poles ( a p]man5t magnet  ,n4,s4 ,:5 any
 "o ( ! rods is ?r[n into vibration an  
undulatory  curr5t is produc$ 9 ! coils 
( ! electro-magnet ,e1 & !              
electro-magnet ,e attracts ! rods ( !   
h>p ,h ) a v>y+  =ce1 ?r[+ into         
vibration t rod :i* is 9 unison )  t    
vibrat$ at ! o!r end ( ! circuit4 ,n    
only s1 b !  amplitude ( vibration 9 !  
"o w det]m9e ! amplitude (  vibration 9 
! o!r1 = ! int5sity ( ! induc$ curr5t   
is det]m9$ by ! amplitude ( ! induc+    
vibration1 & !  amplitude ( ! vibration 
at ! receiv+ end dep5ds ^u !  int5sity (
 ! attractive impulses4 ,:5 we s+ into a
 piano1  c]ta9 ( ! /r+s ( ! in/rum5t are
 set 9 vibration  sympa!tically by !    
action ( ! voice ) diff]5t degrees (    
amplitude1 & a s\nd1 :i* is an          

approximation to ! v[el utt]$1  is      
produc$ f ! piano4 ,!ory %[s1 t1 _h !   
piano a v  mu* l>g] numb] ( /r+s to !   
octave1 ! v[el s\nds w\ld be  p]fectly  
reproduc$4 ,my idea ( ! action ( !      
app>atus1 %[n 9  fig4 #ai1 0 ?is3 ,utt] 
a s\nd 9 ! neighb\rhood ( ! h>p ,h1  &  
c]ta9 ( ! rods w\ld be ?r[n into        
vibration ) diff]5t  amplitudes4 ,at !  
o!r end ( ! circuit ! correspond+ rods (
  ! h>p ,h w\ld vibrate ) _! prop]      
relations ( =ce1 & !  timbre ( ! s\nd   
w\ld be reproduc$4 ,! exp5se ( con/ruct+
  su* an app>atus z t %[n 9 fig4 #ai    
det]r$ me f mak+ !  attempt1 & ,i s\ght 
to simplify ! app>atus be=e v5tur+ to  h
 x made4    ,illu/ration3 ,fig4 #ai4    
,illu/ration3 ,fig4 #bj4    ,i h be=e   
allud$ to ! inv5tion by my fa!r ( a     
sy/em (  physiological symbols =        
repres5t+ ! action ( ! vocal organs1  & 
,i _h be5 invit$ by ! ,bo/on ,bo>d (    
,education to conduct a  s]ies (        
exp]im5ts ) ! sy/em 9 ! ,bo/on s*ool = !
 deaf  & dumb4 ,x is well kn[n t deaf   

mutes are dumb m]ely because  !y are    
deaf1 & t !re is no defect 9 _! vocal   
organs to  incapacitate !m f utt]ance4  
,h5ce x 0 ?\ght t my fa!r's  sy/em (    
pictorial symbols1 popul>ly kn[n z      
visible spee*1 might  prove a means     
:]eby we c\ld tea* ! deaf & dumb to use 
_!  vocal organs & to speak4 ,! great   
success ( ^! exp]im5ts  urg$ ^u me !    
advisability ( devis+ me?ods ( exhibit+ 
!  vibrations ( s\nd optically1 = use 9 
tea*+ ! deaf & dumb4  ,= "s "t ,i c>ri$ 
on exp]im5ts ) ! manometric capsule  (  
,ko5ig1 & ) ! phonautograph ( ,lon      
,scott4 ,! sci5tific  app>atus 9 !      
,in/itute ( ,te*nology 9 ,bo/on 0 freely
 plac$ at  my disposal = ^! exp]im5ts1 &
 x happ5$ t at t "t  a /ud5t ( !        
,in/itute ( ,te*nology1 ,mr4 ,maurey1 _h
 inv5t$ an  improvem5t ^u !             
phonautograph4 ,he _h succe$$ 9 vibrat+ 
by  ! voice a /ylus ( wood ab\t a foot 9
 l5g? :i* 0 atta*$ to  ! membrane ( !   
phonautograph1 & 9 ?is way he _h be5    
enabl$  to obta9 enl>g$ trac+s ^u a     

plane surface ( smok$ glass4 ,)  ?is    
app>atus ,i succe$$ 9 produc+ v         
beautiful trac+s ( !  vibrations ( ! air
 = v[el s\nds4 ,"s ( ^! trac+s are  %[n 
9 fig4 #bj4 ,i 0 mu* /ruck ) ?is improv$
 =m (  app>atus1 & x occurr$ to me t !re
 0 a rem>kable lik5ess  betwe5 ! mann] 9
 :i* ?is piece ( wood 0 vibrat$ by !    
membrane ( ! phonautograph & ! mann] 9  
:i* ! ossicul  ( ! human e> 7 mov$ by ! 
tympanic membrane4 ,i det]m9$  !re=e to 
con/ruct a phonautograph modell$ /ill m 
closely  ^u ! me*anism ( ! human e>1 & =
 ?is purpose ,i s\ght  ! assi/ance ( a  
di/+ui%$ auri/ 9 ,bo/on1 ,dr4 ,cl>5ce   
,j4  ,blake4 ,he sugge/$ ! use ( ! human
 e> itself z a phonautograph1  in/ead ( 
mak+ an artificial imitation ( x4 ,!    
idea 0 novel &  /ruck me accord+ly1 & ,i
 reque/$ my fri5d to prep>e a specim5  =
 me1 :i* he did4 ,! app>atus1 z f9ally  
con/ruct$1 is %[n  9 fig4 #ba4 ,! /apes 
0 remov$ & a /ylus ( hay ab\t an  in* 9 
l5g? 0 atta*$ to ! end ( ! incus4 ,^u   
moi/5+  ! membrana-tympani & ! ossicul )

 a mixture ( glyc]9e &  wat]1 ! necess>y
 mobility ( ! p>ts 0 obta9$2 & ^u  s++  
into ! ext]nal artificial e> ! /ylus (  
hay 0 ?r[n  into vibration1 & trac+s 7  
obta9$ ^u a plane surface  ( smok$ glass
 pass$ rapidly und]nea?4 ,:ile engag$ 9 
^!  exp]im5ts ,i 0 /ruck ) ! rem>kable  
disproportion 9 weight  betwe5 !        
membrane & ! bones t 7 vibrat$ by x4 ,x 
occurr$ to me t if a membrane z ?9 z    
tissue pap] c\ld control  ! vibration ( 
bones t 71 comp>$ to x1 ( imm5se size & 
weight1 :y %\ld n a l>g] & ?ick]        
membrane be able to vibrate  a piece (  
iron 9 front ( an electro-magnet1 9 :i* 
case !  complication ( /eel rods %[n 9  
my fir/ =m ( telephone1 fig4  #ai1 c\ld 
be done away )1 & a simple piece ( iron 
atta*$ to a  membrane be plac$ at ei!r  
end ( ! telegraphic circuit4            
,illu/ration3 ,fig4 #ba4                
,illu/ration3 ,fig4 #bb4                
,illu/ration3 ,fig4 #bc4    ,fig4 #bb   
%[s ! =m ( app>atus t ,i 0 !n employ+ = 
produc+ undulatory curr5ts ( electricity

 = ! purposes (  multiple telegraphy4 ,a
 /eel re$ ,a 0 clamp$ firmly by "o      
extremity  to ! uncov]$ leg h ( an      
electro-magnet ,e1 & ! free end (  ! re$
 project$ above ! cov]$ leg4 ,:5 ! re$  
,a 0 vibrat$  9 any me*anical way1 !    
batt]y curr5t 0 ?r[n into waves1 &      
electrical undulations trav]s$ ! circuit
 ,b ,e ,w ,e1 ?r[+ into  vibration !    
correspond+ re$ ,a at ! o!r end ( !     
circuit4  ,i imm$iately proce$$ to put  
my new idea to ! te/ ( practical        
exp]im5t1 & = ?is purpose ,i atta*$ !   
re$ ,a 7fig4 #bc7  loosely by "o        
extremity to ! uncov]$ pole h ( !       
magnet1 &  fa/5$ ! o!r extremity to !   
c5tre ( a /ret*$ membrane  ( goldbeat]s'
 sk9 n4 ,i presum$ t ^u speak+ 9 !      
neighb\rhood ( ! membrane n x w\ld be   
?r[n into vibration  & cause ! /eel re$ 
,a to move 9 a simil> mann]1 occasion+  
undulations 9 ! electrical curr5t t w\ld
 correspond to !  *anges 9 ! d5sity ( ! 
air dur+ ! production ( ! s\nd2  & ,i   
fur!r ?\ght t ! *ange ( ! int5sity ( !  

curr5t  at ! receiv+ end w\ld cause !   
magnet !re to attract ! re$  ,a 9 su* a 
mann] t x %\ld copy ! motion ( ! re$ ,a1
 9  :i* case its movem5ts w\ld occasion 
a s\nd f ! membrane n  simil> 9 timbre  
to t :i* _h occasion$ ! orig9al         
vibration4    ,illu/ration3 ,fig4 #bd4  
,! results1 h[ev]1 7 unsatisfactory &   
disc\rag+4 ,my fri5d  ,mr4 ,?omas ,a4   
,watson1 :o assi/$ me 9 ?is fir/        
exp]im5t1  decl>$ t he he>d a fa9t s\nd 
proce$ f ! telephone at  8 end ( !      
circuit1 b ,i 0 unable to v]ify 8       
ass]tion4  ,aft] _m exp]im5ts att5d$ by 
! same only p>tially-successful         
results1 ,i det]m9$ to r$uce ! size &   
weight ( ! spr+ z  mu* z possible4 ,=   
?is purpose ,i glu$ a piece ( clock     
spr+1  ab\t ! size & %ape ( my ?umbnail1
 firmly to ! c5tre ( !  diaphragm1 & _h 
a simil> in/rum5t at ! o!r end 7fig4    
#bd72  we 7 !n enabl$ to obta9 di/9ctly 
audible effects4 ,i rememb]  an exp]im5t
 made ) ?is telephone1 :i* at ! "t gave 
me  great satisfaction & delight4 ,"o ( 

! telephones 0 plac$ 9 my  lecture-room 
9 ! ,bo/on ,univ]sity1 & ! o!r 9 !      
basem5t  ( ! adjo9+ build+4 ,"o ( my    
/ud5ts repair$ to ! di/ant  telephone to
 obs]ve ! effects ( articulate spee*1   
:ile ,i utt]$  ! s5t5ce1 8,d y und]/&   
:at ,i say80 into ! telephone plac$  9 !
 lecture-hall4 ,to my delight an answ] 0
 return$ ?r\gh  ! in/rum5t itself1      
articulate s\nds proce$$ f ! /eel  spr+ 
atta*$ to ! membrane1 & ,i he>d !       
s5t5ce1 8,yes1  ,i und]/& y p]fectly40  
,x is a mi/ake1 h[ev]1 to suppose  t !  
articulation 0 by any means p]fect1 &   
expectancy no  d\bt _h a great deal to d
 ) my recognition ( ! s5t5ce2  /ill1 !  
articulation 0 !re1 & ,i recognis$ !    
fact t !  indi/9ctness 0 entirely due to
 ! imp]fection ( ! in/rum5t4  ,i w n    
tr\ble y by detail+ ! v>i\s /ages ?r\gh 
:i*  ! app>atus pass$1 b %all m]ely say 
t aft] a "t ,i produc$  ! =m ( in/rum5t 
%[n 9 fig4 #be1 :i* s]v$ v well z  a    
receiv+ telephone4 ,9 ?is condition my  
inv5tion 0 exhibit$  at ! ,c5t5nial     

,exhibition 9 ,philadelphia4 ,!         
telephone %[n 9  fig4 #bd 0 us$ z a     
transmitt+ in/rum5t1 & t 9 fig4 #be z  a
 receiv]1 s t vocal communication 0 only
 e/abli%$ 9 "o  direction4              
,illu/ration3 ,fig4 #be4    ,ano!r =m ( 
transmitt+ telephone exhibit$ 9         
,philadelphia  int5d$ = use ) ! receiv+ 
telephone 7fig4 #be7 is repres5t$  by   
fig4 #bf4    ,a plat9um wire atta*$ to a
 /ret*$ membrane complet$ a voltaic     
circuit by dipp+ into wat]4 ,^u speak+  
to ! membrane1  articulate s\nds proce$$
 f ! telephone 9 ! di/ant room4 ,!      
s\nds produc$ by ! telephone became l\d]
 :5 dilute sulphuric  acid1 or a        
saturat$ solution ( salt1 0 sub/itut$ = 
! wat]4  ,audible effects 7 also produc$
 by ! vibration ( plumbago 9  m]cury1 9 
a solution ( bi*romate ( pota%1 9 salt &
 wat]1 9  dilute sulphuric acid1 & 9    
pure wat]4    ,! articulation produc$ f 
! in/rum5t %[n 9 fig4 #be 0  rem>kably  
di/9ct1 b its great defect consi/$ 9 !  
fact t x  c\ld n be us$ z a transmitt+  

in/rum5t1 & ?us two telephones  7       
requir$ at ea* /ation1 "o = transmitt+ &
 "o =  receiv+ spok5 messages4          
,illu/ration3 ,fig4 #bf4    ,x 0 det]m9$
 to v>y ! con/ruction ( ! telephone  %[n
 9 fig4 #bd1 & ,i s\ght by *ang+ ! size 
& t5sion  ( ! membrane1 ! diamet] &     
?ickness ( ! /eel spr+1  ! size & p[] ( 
! magnet1 & ! coils ( insulat$ wire     
ar\nd _! poles1 to discov] empirically !
 exact effect ( ea*  elem5t ( !         
comb9ation1 & ?us to d$uce a m p]fect   
=m ( app>atus4 ,x 0 f\nd t a m>k$       
increase 9 !  l\dness ( ! s\nds result$ 
f %ort5+ ! l5g? ( !  coils ( wire1 & by 
enl>g+ ! iron diaphragm :i* 0  glu$ to !
 membrane4 ,9 ! latt] case1 also1 !     
di/9ctness  ( ! articulation 0 improv$4 
,f9ally1 ! membrane ( goldbeat]s'  sk9 0
 disc>d$ entirely1 & a simple iron plate
 0  us$ in/ead1 & at once intelligible  
articulation 0 obta9$4  ,! new =m (     
in/rum5t is t %[n 9 fig4 #bg1 &1 z _h   
be5 long anticipat$1 x 0 prov$ t ! only 
use ( !  batt]y 0 to magnetize ! iron   

core ( ! magnet1 = !  effects 7 equally 
audible :5 ! batt]y 0 omitt$ & a  rod ( 
magnetiz$ /eel sub/itut$ = ! iron core (
 ! magnet4    ,x 0 my orig9al int5tion1 
z %[n 9 fig4 #ai1 & x 0 always  claim$  
by me1 t ! f9al =m ( telephone w\ld be  
op]at$ by  p]man5t magnets 9 place (    
batt]ies1 & num]\s exp]im5ts _h  be5    
c>ri$ on by ,mr4 ,watson & myself       
privately = ! purpose (  produc+ ?is    
effect4    ,illu/ration3 ,fig4 #bg4     
,at ! "t ! in/rum5ts 7 fir/ exhibit$ 9  
public ! results  obta9$ ) p]man5t      
magnets 7 n ne>ly s /rik+ z :5 a        
voltaic batt]y 0 employ$1 :]e=e we ?\ght
 x be/ to exhibit  only ! latt] =m (    
in/rum5t4    ,! int]e/ excit$ by ! fir/ 
publi%$ acc\nts ( ! op]ation  ( !       
telephone l$ _m p]sons to inve/igate !  
subject1 & ,i  d\bt n t numb]s (        
exp]im5t]s h indep5d5tly discov]$  t    
p]man5t magnets might be employ$ in/ead 
( voltaic batt]ies4  ,inde$ "o g5tleman1
 ,pr(essor ,dolbe>1 ( ,tufts ,college1 n
 only  claims to h discov]$ !           

magneto-electric telephone1 b ,i  und]/&
 *>ges me ) hav+ obta9$ ! idea f him    
?r\gh  ! m$ium ( a mutual fri5d4        
,illu/ration3 ,fig4 #bh4    ,a /ill m   
p[]ful =m ( app>atus 0 con/ruct$ by us+ 
a  p[]ful comp\nd horse-%oe magnet 9    
place ( ! /raight rod :i*  _h be5       
previ\sly us$ 7see fig4 #bh74 ,inde$ !  
s\nds produc$ by  means ( ?is in/rum5t 7
 ( suffici5t l\dness to be fa9tly       
audible to a l>ge audi5ce1 & 9 ?is      
condition ! in/rum5t 0  exhibit$ 9 !    
,essex ,in/itute1 9 ,salem1             
,massa*usetts1 on ! #ab?  ,feb4 #ahgg1  
on :i* occasion a %ort spee* %\t$ into a
 simil>  telephone 9 ,bo/on1 sixte5     
miles away1 0 he>d by ! audi5ce 9       
,salem4 ,! tones ( ! speak]'s voice 7   
di/9ctly audible to an  audi5ce ( #fjj  
p1 b ! articulation 0 only di/9ct at a  
di/ance ( ab\t #f feet4 ,on ! same      
occasion1 also1 a report ( !  lecture 0 
transmitt$ by ^w ( m\? f ,salem to      
,bo/on1 &  publi%$ 9 ! pap]s ! next     
morn+4    ,illu/ration3 ,fig4 #bi4    ,f

 ! =m ( telephone %[n 9 fig4 #bg to !   
pres5t =m (  ! in/rum5t 7fig4 #bi7 is b 
a /ep4 ,x is 9 fact ! arrangem5t  ( fig4
 #bg 9 a portable =m1 ! magnet ,f ,h be+
 plac$ inside  ! h&le & a m conv5i5t =m 
( m\?piece provid$4 ,!  arrangem5t ( ^! 
in/rum5ts ^u a telegraphic circuit is   
%[n 9  fig4 #cj4    ,illu/ration3 ,fig4 
#cj4    ,& "h ,i wi% to express my      
indebt$ness to sev]al sci5tific  fri5ds 
9 ,am]ica = _! co-op]ation & assi/ance4 
,i w\ld  specially m5tion ,pr(essor     
,peirce & ,pr(essor ,blake1 ( ,br[n     
,univ]sity1 ,dr4 ,*ann+1 ,mr4 ,cl>ke1 & 
,mr4 ,jones4 ,9 ,provid5ce1  ,rhode     
,isl&1 ^! g5tlem5 h be5 c>ry+ on toge!r 
exp]im5ts seek+ to p]fect ! =m (        
app>atus requir$1 &  ,i am happy to     
record ! fact t !y communicat$ to me ea*
 new  discov]y z x 0 made1 & e new /ep 9
 _! inve/igations4  ,x 01 ( c\rse1 almo/
 inevitable t ^! g5tlem5 %\ld  retrace  
mu* ( ! gr\nd t _h be5 gone ov] by me1 &
 s x  has happ5$ t _m ( _! discov]ies _h
 be5 anticipat$ by  my own rese>*es2    

/ill1 ! v hon\rable way 9 :i* !y f  "t  
to "t plac$ be=e me ! results ( _!      
discov]ies entitles  !m to my w>me/     
?anks & to my highe/ e/eem4 ,x 0 always 
my  belief t a c]ta9 ratio w\ld be f\nd 
betwe5 ! sev]al p>ts (  a telephone1 & t
 ! size ( ! in/rum5t 0 immat]ial2 b     
,pr(essor ,peirce 0 ! fir/ to demon/rate
 ! extreme smallness  ( ! magnets :i*   
might be employ$4 ,& "h1 9 ord] to %[  !
 p>allel l9es 9 :i* we 7 work+1 ,i may  
m5tion ! fact  t two or ?ree days aft]  
,i _h con/ruct$ a telephone ( !         
portable =m 7fig4 #bi71 conta9+ ! magnet
 inside ! h&le1 ,dr4  ,*ann+ 0 k9d en\gh
 to s5d me a pair ( telephones ( a      
simil>  patt]n1 :i* _h be5 inv5t$ by !  
,provid5ce exp]im5t]s4 ,!  conv5i5t =m (
 m\?piece %[n 9 fig4 #bi1 n[ adopt$ by  
me1 0  inv5t$ solely by my fri5d        
,pr(essor ,peirce4 ,i mu/ also express  
my obligations to my fri5d & associate1 
,mr4 ,?omas ,a4 ,watson1 (  ,salem1     
,massa*usetts1 :o has = two ye>s pa/    
giv5 me 8 p]sonal  assi/ance 9 c>ry+ on 

my rese>*es4    ,9 pursu+ my            
inve/igations ,i h ev] _h "o end 9 view1
 !  practical improvem5t ( electric     
telegraphy2 b ,i h come across  _m facts
 :i*1 :ile hav+ no direct be>+ ^u !     
subject (  telegraphy1 may yet possess  
an int]e/ = y4#bd    ,= in/ance1 ,i h   
f\nd t a musical tone proce$s f a piece 
(  plumbago or retort-c>bon :5 an       
int]mitt5t curr5t ( electricity is      
pass$ ?r\gh x1 & ,i h obs]v$ ! mo/      
curi\s audible effects  produc$ by !    
passage ( rev]s$ int]mitt5t curr5ts     
?r\gh !  human body4 ,a rheotome 0 plac$
 9 circuit ) ! prim>y wires (  an       
induction coil1 & ! f9e wires 7 connect$
 ) two /rips  ( brass4 ,"o ( ^! /rips 0 
held closely aga9/ ! e>1 & a  l\d s\nd  
proce$$ f x :5ev] ! o!r slip 0 t\*$ )  !
 o!r h&4 ,! /rips ( brass 7 next held "o
 9 ea* h&4  ,! induc$ curr5ts occasion$ 
a muscul> tremor 9 ! f+]s4 ,^u  plac+ my
 =ef+] to my e> a l\d crackl+ noise 0   
audible1  seem+ly proce$+ f ! f+]       
itself4 ,a fri5d :o 0 pres5t  plac$ my  

f+] to 8 e>1 b he>d no?+4 ,i reque/$ him
 to hold  ! /rips himself4 ,he 0 !n     
di/9ctly consci\s ( a noise 7:i*  ,i 0  
unable to p]ceive7 proce$+ f 8 f+]4 ,9  
?is case a  portion ( ! induc$ curr5ts  
pass$ ?r\gh ! head ( ! obs]v]  :5 he    
plac$ 8 e> aga9/ 8 own f+]3 & x is      
possible t  ! s\nd 0 occasion$ by a     
vibration ( ! surfaces ( ! e> &  f+] 9  
contact4    ,:5 two p]sons receive a    
%ock f a ,ruhmkorff's coil by clasp+    
h&s1 ea* tak+ hold ( "o wire ( ! coil ) 
! free h&1 a  s\nd proce$s f ! clasp$   
h&s4 ,! effect is n produc$ :5  ! h&s   
are moi/4 ,:5 ei!r ( ! two t\*es ! body 
( !  o!r a l\d s\nd comes f ! p>ts 9    
contact4 ,:5 ! arm (  "o is plac$ aga9/ 
! arm ( ! o!r1 ! noise produc$ c be     
he>d at a di/ance ( sev]al feet4 ,9 all 
^! cases a slight %ock  is exp]i5c$ s   
long z ! contact is pres]v$4 ,!         
introduction  ( a piece ( pap] betwe5 ! 
p>ts 9 contact does n mat]ially  int]f]e
 ) ! production ( ! s\nds1 b !          
unpleasant effects  ( ! %ock are avoid$4

    ,:5 an int]mitt5t curr5t f a        
,ruhmkorff's coil is pass$ ?r\gh  ! arms
 a musical note c be p]ceiv$ :5 ! e> is 
closely  appli$ to ! arm ( ! p]son      
exp]im5t$ ^u4 ,! s\nd seems to  proce$ f
 ! muscles ( ! =e-arm & f ! biceps      
muscle4  ,mr4 ,eli%a ,gray#be has also  
produc$ audible effects by ! passage (  
electricity ?r\gh ! human body4    ,an  
extremely l\d musical note is occasion$ 
by ! sp>k ( a  ,ruhmkorff's coil :5 !   
prim>y circuit is made & brok5 )        
suffici5t rapidity2 :5 two rheotomes (  
diff]5t pit* are caus$  simultane\sly to
 op5 & close ! prim>y circuit a d\ble   
tone  proce$s f ! sp>k4    ,a curi\s    
discov]y1 :i* may be ( int]e/ to y1 has 
be5 made  by ,pr(essor ,blake4 ,he      
con/ruct$ a telephone 9 :i* a rod (  s(t
 iron1 ab\t six feet 9 l5g?1 0 us$      
in/ead ( a p]man5t  magnet4 ,a fri5d    
sang a cont9u\s musical tone into !     
m\?piece (  a telephone1 l t %[n 9 fig4 
#bi1 :i* 0 connect$ ) !  s(t iron       
in/rum5t allud$ to above4 ,x 0 f\nd t ! 

l\dness  ( ! s\nd produc$ 9 ?is         
telephone v>i$ ) ! direction 9  :i* !   
iron rod 0 held1 & t ! maximum effect 0 
produc$  :5 ! rod 0 9 ! position ( !    
dipp+-ne$le4 ,?is curi\s  discov]y (    
,pr(essor ,blake has be5 v]ifi$ by      
myself4    ,:5 a telephone is plac$ 9   
circuit ) a telegraph l9e1 !  telephone 
is f\nd seem+ly to emit s\nds on its own
 acc\nt4 ,!  mo/ extraord9>y noises are 
(t5 produc$1 ! causes ( :i*  are at     
pres5t v obscure4 ,"o class ( s\nds is  
produc$ by !  inductive influ5ce (      
neighb\r+ wires & by leakage f !m1 !    
signals ( ! ,morse alphabet pass+ ov]   
neighb\r+ wires be+  audible 9 !        
telephone1 & ano!r class c be trac$ to  
e>?  curr5ts ^u ! wire1 a curi\s        
modification ( ?is s\nd reveal+  !      
pres5ce ( defective jo9ts 9 ! wire4     
,pr(essor ,blake in=ms me t he has be5  
able to use ! railroad  track =         
conv]sational purposes 9 place ( a      
telegraph wire1 &  he fur!r /ates t :5  
only "o telephone 0 connect$ ) !  track 

! s\nds ( ,morse op]at+ 7 di/9ctly      
audible 9 !  telephone1 al?\gh ! ne>e/  
telegraph-wires 7 at lea/ =ty  feet     
di/ant4    ,pr(essor ,peirce has obs]v$ 
! mo/ curi\s s\nds produc$ f  a         
telephone 9 connection ) a telegraph    
wire dur+ ! aurora  borealis2 & ,i h j  
he>d ( a curi\s ph5om5on lately obs]v$  
by ,dr4 ,*ann+4 ,9 ! city ( ,provid5ce1 
,rhode ,isl&1 !re is an  ov]h\se wire   
ab\t "o mile 9 ext5t ) a telephone at   
ei!r end4  ,on "o occasion ! s\nd (     
music & s++ 0 fa9tly audible  9 "o ( !  
telephones4 ,x seem$ z if "s "o 7       
practis+  vocal music ) a pian(orte     
accompanim5t4 ,! natural supposition  0 
t exp]im5ts 7 be+ made ) ! telephone at 
! o!r  end ( ! circuit1 b ^u inquiry ?is
 prov$ n to h be5 !  case4 ,att5tion    
hav+ ?us be5 direct$ to ! ph5om5on1 a   
wat*  0 kept ^u ! in/rum5ts1 & ^u a     
subsequ5t occasion ! same  fact 0 obs]v$
 at bo? ends ( ! l9e by ,dr4 ,*ann+ & 8 
fri5ds4 ,x 0 prov$ t ! s\nds cont9u$ =  
ab\t two h\rs1  & usually comm5c$ ab\t !

 same "t4 ,a se>*+ exam9ation (  ! l9e  
disclos$ no?+ abnormal 9 its condition1 
& ,i am unable  to give y any           
explanation ( ?is curi\s ph5om5on4 ,dr4 
,*ann+  has1 h[ev]1 address$ a lett] ^u 
! subject to ! editor (  "o ( !         
,provid5ce pap]s1 giv+ ! names ( su*    
songs z 7  recognis$1 ) full details ( !
 obs]vations1 9 ! hope t  publicity may 
lead to ! discov]y ( ! p]=m]1 & ?us af=d
 a  solution ( ! my/]y4    ,my fri5d    
,mr4 ,fr$]ick ,a4 ,g[] communicat$ to me
 a curi\s  obs]vation made by him reg>d+
 ! slight e>? connection requir$  to    
e/abli% a circuit = ! telephone1 &      
toge!r we c>ri$ on a  s]ies ( exp]im5ts 
) r />tl+ results4 ,we took a c\ple  (  
telephones & an insulat$ wire ab\t #ajj 
y>ds 9 l5g? into a  g>d51 & 7 enabl$ to 
c>ry on conv]sation ) ! greate/  ease :5
 we held 9 our h&s :at %\ld h be5 ! e>? 
wire1 s  t ! connection ) ! gr\nd 0 =m$ 
at ei!r end ?r\gh  our bodies1 our feet 
be+ clo!d ) cotton socks & lea!r boots4 
,! day 0 f9e1 & ! grass ^u :i* we /ood 0

 seem+ly  p]fectly dry4 ,^u /&+ ^u a    
gravel walk ! vocal s\nds1  ?\gh mu*    
dim9i%$1 7 /ill p]fectly intelligible1 &
 ! same  result occurr$ :5 /&+ ^u a     
brick wall "o foot 9 height1 b  no s\nd 
0 audible :5 "o ( u /ood ^u a block (   
free/one4    ,"o exp]im5t :i* we made is
 s v int]e/+ t ,i mu/ speak  ( x 9      
detail4 ,mr4 ,g[] made e>? connection at
 8 end ( ! l9e  by /&+ ^u a grass plot1 
:il/ at ! o!r end ( ! l9e ,i  /ood ^u a 
wood5 bo>d4 ,i reque/$ ,mr4 ,g[] to s+ a
 cont9u\s  musical note1 & to my        
surprise ! s\nd 0 v di/9ctly audible  f 
! telephone 9 my h&4 ,^u exam9+ my feet 
,i discov]$ t  a s+le blade ( grass 0   
b5t ov] ! edge ( ! bo>d1 & t  my foot   
t\*$ x4 ,! removal ( ?is blade ( grass 0
 foll[$ by  ! cessation ( ! s\nd f !    
telephone1 & ,i f\nd t !  mom5t ,i t\*$ 
) ! toe ( my boot a blade ( grass or !  
petal  ( a daisy ! s\nd 0 aga9 audible4 
,! "q w naturally arise1 ,?r\gh :at l5g?
 ( wire c !  telephone be us$8 ,9 reply 
to ?is ,i may say t ! maximum am\nt  (  

resi/ance ?r\gh :i* ! undulatory curr5t 
w pass1 & yet  reta9 suffici5t =ce to   
produce an audible s\nd at ! di/ant end1
  has yet to be det]m9$2 no difficulty  
has1 h[ev]1 be5 exp]i5c$  9 laboratory  
exp]im5ts 9 conv]s+ ?r\gh a resi/ance ( 
#fj1jjj  ohms1 :i* has be5 ! maximum at 
my disposal4 ,on "o occasion1 n  hav+ a 
rheo/at at h&1 ,i may m5tion hav+ pass$ 
! curr5t  ?r\gh ! bodies ( sixte5       
p]sons1 :o /ood h& 9 h&4 ,!  longe/ l5g?
 ( real telegraph l9e ?r\gh :i* ,i h    
attempt$  to conv]se has be5 ab\t #bej  
miles4 ,on ?is occasion no difficulty  0
 exp]i5c$ s long z p>allel l9es 7 n 9   
op]ation4 ,sunday  0 *os5 z ! day on :i*
 x 0 probable o!r circuits w\ld  be at  
re/4 ,conv]sation 0 c>ri$ on betwe5     
myself1 9 ,new ,york1  & ,mr4 ,?omas ,a4
 ,watson1 9 ,bo/on1 until ! op5+ (      
bus9ess  ^u ! o!r wires4 ,:5 ?is happ5$ 
! vocal s\nds 7 v  mu* dim9i%$1 b /ill  
audible4 ,x seem$1 inde$1 l talk+  ?r\gh
 a /orm4 ,conv]sation ?\gh possible c\ld
 be c>ri$ on )  difficulty1 ow+ to !    

di/ract+ nature ( ! int]f]+ curr5ts4    
,i am in=m$ by my fri5d ,mr4 ,preece t  
conv]sation has be5  successfully c>ri$ 
on ?r\gh a subm>9e cable1 sixty miles 9 
l5g?1 ext5d+ f ,d>tm\? to ! ,isl& (     
,gu]nsey1 by means (  h& telephones     
simil> to t %[n 9 fig4 #cj4             
,footnotes3    #a ,helmholtz4 ,die      
,lehre von dem ,tonempf9dung54 7,engli% 
,translation by ,alex&] ,j4 ,ellis1     
,!ory ( ,tone47    #b ,c4 ,g4 ,page4 8,!
 ,production ( ,galvanic ,music40       
,silliman's ,j\rn4  #ahcg1 xxxii4 p4    
#cif2 ,silliman's ,j\rn4 ,july1 #ahcg1  
p4 #ced2 ,silliman's  ,j\rn4 #ahch1     
xxxiii4 p4 #aah2 ,bibl4 ,univ4 7new     
s]ies71 #ahci1 ii4 p4 #cih4    #c ,j4   
,p4 ,m>rian4 ,phil4 ,mag4 xxv4 p4 #chb2 
,in/4 #ahde1 p4 #bj2 ,ar*4  de l'lectr4 
v4 p4 #aie4    #d ,w4 ,beatson4 ,ar*4 de
 l'lectr4 v4 p4 #aig2 ,ar*4 de ,sc4     
,phys4 et  ,nat4 7#b;d s]ies71 ii4 p4   
#aac4    #e ,gassiot4 ,see 8,treatise on
 ,electricity10 by ,de la ,rive1 i4 p4  
#cjj4    #f ,de la ,rive4 ,treatise on  

,electricity1 i4 p4 #cjj2 ,phil4 ,mag4  
xxxv4  p4 #dbb2 ,ar*4 de l'lectr4 v4 p4 
#bjj2 ,in/4 #ahdf1 p4 #hc2 ,comptes     
,r5dus1 xx4 p4 #abhg2 ,comp4 ,r5d4 xxii4
 p4 #dcb2 ,pogg4 ,ann4 lxxvi4 p4  #fcg2 
,ann4 de ,*im4 et de ,phys4 xxvi4 p4    
#aeh4    #g ,matteucci4 ,in/4 #ahde1 p4 
#cae2 ,ar*1 de l'lectr4 v4 #chi4    #h  
,guillem94 ,comp4 ,r5d4 xxii4 p4 #bfd2  
,in/4 #ahdf1 p4 #cj2 ,ar*4 d4  ,sc4     
,phys4 7#b;d s]ies71 i4 p4 #aia4    #i  
,g4 ,w]!im4 ,comp4 ,r5d4 xxii4 pp4 #ccf1
 #edd2 ,in/4 #ahdf1 pp4 #fe1  #ajj2     
,pogg4 ,ann4 lxviii4 p4 #adj2 ,comp4    
,r5d4 xxvi4 p4 #eje2 ,in/4 #ahdh1  p4   
#adb2 ,ann4 de ,*im4 et de ,phys41      
xxiii4 p4 #cjb2 ,ar*4 d4 ,sc4 ,phys4 et 
,nat4 viii4 p4 #bjf2 ,pogg4 ,ann4       
lxxvii4 p4 #dc2 ,b]l4 ,b]4 iv4 p4 #aba4 
#aj ,elie ,w>tmann4 ,comp4 ,r5d4 xxii4  
p4 #edd2 ,phil4 ,mag4 7#c;d s]ies71     
xxviii4 p4 #edd2 ,ar*4 d4 ,sc4 ,phys4 et
 ,nat4 7#b;d s]ies71 i4 p4 #dai2  ,in/4 
#ahdf1 p4 #bij2 ,monats*]4 d4 ,b]l4     
,akad4 #ahdf1 p4 #aaa4    #aa ,janni>4  

,comp4 ,r5d1 xxiii4 p4 #cai2 ,in/4      
#ahdf1 p4 #bfi2 ,ar*4 d4  ,sc4 ,phys4 et
 ,nat4 7#b;d4 s]ies71 ii4 p4 #cid4      
#ab ,j4 ,p4 ,j\le4 ,phil4 ,mag4 xxv4 pp4
 #gf1 #bbe2 ,b]l4 ,b]4 iii4 p4 #dhi4    
#ac ,laborde4 ,comp4 ,r5d4 l4 p4 #fib2  
,cosmos1 xvii4 p4 #ead4    #ad ,legat4  
,brix4 ,z4 ,s4 ix4 p4 #abe4    #ae      
,reis4 8,tlphonie40 ,polyte*nic ,j\rn4  
clxviii4 p4 #ahe2  ,bttg]'s ,notizbl4   
#ahfc1 ,no4 #f4    #af ,j4 ,c4          
,pogg5dorff4 ,pogg4 ,ann4 xcviii4 p4    
#aib2 ,b]l9]  ,monatsb]4 #ahef1 p4 #acc2
 ,cosmos1 ix4 p4 #di2 ,b]l4 ,b]4 xii4 p4
 #bda2  ,pogg4 ,ann4 lxxxvii4 p4 #aci4  
#ag ,du ,moncel4 ,expos1 ii4 p4 #abe2   
also1 iii4 p4 #hc4    #ah ,delez5ne4    
8,s\nd produc$ by ,magnetization10      
,bibl4 ,univ4 7new  s]ies71 #ahda1 xvi4 
p4 #djf4    #ai ,see ,london ,j\rn4     
xxxii4 p4 #djb2 ,polyte*nic ,j\rn4 ex4  
p4 #af2  ,cosmos1 iv4 p4 #dc2           
,gls5]--,trait gnral1 c4 p4 #cej2       
,dove4-,rep]t4  vi4 p4 #eh2 ,pogg4 ,ann4
 xliii4 p4 #daa2 ,b]l4 ,b]4 i4 p4 #add2 

,ar*4 d4  ,sc4 ,phys4 et ,nat4 xvi4 p4  
#djf2 ,kuhn's ,encyclopdia d] ,physik1  
pp4  #ajad-ajba4    #bj ,gore4 ,proce$+s
 ( ,royal ,society1 xii4 p4 #bag4    #ba
 ,c4 ,g4 ,page4 8,vibration (           
,trevelyan's b>s by ! galvanic  curr5t40
 ,silliman's ,j\rnal1 #ahej1 ix4 pp4    
#aje-ajh4    #bb ,sullivan4 8,curr5ts ( 
,electricity produc$ by ! vibration (   
,metals10 ,phil4 ,mag4 #ahde1 p4 #bfa2  
,ar*4 de l'lectr4 x4 p4 #dhj4    #bc ,! 
full description ( ?is figure w be f\nd 
9 ,mr4 ,alex&]  ,j4 ,ellis's translation
 ( ,helmholtz's "w1 8,!ory ( ,tone40    
#bd ,see ,rese>*es 9                    
,telephony4--,trans4 ( ,am]ican ,acad4 (
 ,arts  & ,sci5ces1 vol4 xii4 p4 #a4    
#be ,eli%a ,gray4 ,eng4 ,pat4 ,spec4    
,no4 #bfdf1 ,aug4 #ahgd4                
,,useful ,,books ,,on ,,telegraphy1 c4  
,j publi%$1 ,p>ts ,,xiii4 & ,,xiv41 9 "o
 vol4                           demy    
#hvo1 sew$1 #es4                ,j\rnal 
( ! ,society ( ,telegraph ,eng9e]s1     
,,includ+ ,,orig9al ,,communications    

,,on ,,telegraph ,,&                    
,,electrical ,,sci5ce4                  
,edit$ by ,major ,,frank ,,bolton & ,j4 
,,sivewright4                        ,to
 be cont9u$ qu>t]ly4                    
99       99       99       99       99  
#hvo1 clo?1 #is4               ,reports 
( ! ,committee on ,electrical ,/&>ds    
appo9t$ by ! ,briti% ,association4      
,revis$ by ,sir ,w4 ,,?omson1 ,dr4 ,j4  
,p4 ,,j\le1                             
,pr(essors ,,cl>k1 ,,maxwell1           
& ,,fleem+ ,,j5k94     ,) a ,report to !
 ,royal ,society on ,units ( ,electrical
 ,resi/ance1                          by
 ,pr(essor ,f4 ,j5k94                   
,edit$ by ,pr(essor ,,fleem+ ,,j5k91    
,f4,r4,s4                               
,plates4                       99       
99       99       99       99           
,small fol41 bo>ds1 #bs4 #f;d4          
,exp]im5tal ,inve/igation ( ! ,laws :i* 
gov]n                ! ,propagation ( ! 
,electric ,curr5t 9                     
,long ,telegraph ,cables4               

,by ,,latim] ,,cl>k4                    
99       99       99       99       99  
,fcap4 #hvo1 clo?1 #es4                 
,a ,h&book ( ,electrical ,te/+4         
,by ,h4 ,r4 ,,kempe1                    
,assoc4 ( ! ,society ( ,telegraph       
,eng9e]s4                       99      
99       99       99       99           
#hvo1 clo?1 #ahs4                       
,electricity & ! ,electric ,telegraph4  
,by ,,geo4 ,b4 ,,prescott4              
,) #ejd ,woodcut ,illu/rations4         
99       99       99       99       99  
#abmo1 clo?1 #cs4 #f;d4                 
,memorials1 ,sci5tific & ,lit]>y1       
( ,&rew ,crosse1 ! ,electrician4        
99       99       99       99       99  
,cr[n #hvo1 clo?1 #hs4                  
,electricity3 its ,!ory1 ,s\rces1 &     
,applications4                          
,by ,,john ,t4 ,,sprague1               
,memb] ( ! ,society ( ,telegraph        
,eng9e]s              ,) ,n9ety-"o      
,woodcuts & ,?irty valuable ,tables4    
99       99       99       99       99  

#hvo1 clo?1 #is4                ,mod]n  
,practice ( ! ,electric ,telegraph4     
,by ,,frank ,l4 ,,pope4                 
,?ird ,edition1 ) num]\s ,wood          
,engrav+s4                       99     
99       99       99       99           
,cr[n #hvo1 clo?1 #abs4 #f;d4           
,electrical ,tables & ,=mul = ! ,use (  
,telegraph ,inspectors & ,op]ators4     
,compil$ by                     ,,latim]
 ,,cl>ke & ,,rob]t ,,sab9e4             
,) ,wood ,engrav+s4                     
99       99       99       99       99  
#cbmo1 roan1 #fs42 int]leav$ ) rul$ pap]
 = (fice use1 #is42           pr9t$ on  
,india pap] = ! wai/coat pocket1 #fs4   
,a ,pocket ,book ( ,useful ,=mul &      
,memor&a                   = ,civil &   
,me*anical ,eng9e]s4                    
,by ,,guild=d ,l4 ,,moleswor?1          
,mem4 ,in/4 ,c4,e41 ,consult+ ,eng9e] to
 !                 ,gov]nm5t ( ,india = 
,/ate ,railways4              ,revis$1 )
 consid]able ,additions by ! ,au?or2    
toge!r ) a valuable contribution on     

,telegraphs by ,r4 ,s4 ,,br\gh4         
,,synopsis ,,( ,,cont5ts4               
,survey+1 ,levell+1 etc4                
,/r5g? & ,weight ( ,mat]ials4           
,e>?work1 ,brickwork1 ,masonry1 ,ar*es1 
etc4            ,/ruts1 ,columns1       
,beams1 & ,trusses4            ,floor+1 
,ro(+1 & ,ro( ,trusses4                 
,gird]s1 ,bridges1 etc4                 
,railways & ,roads4                     
,hydraulic ,=mul4            ,canals1   
,sew]s1 ,wat]works1 ,docks4             
,irrigation & ,breakwat]s4              
,gas1 ,v5tilation1 & ,w>m+4             
,heat1 ,light1 ,col\r1 & ,s\nd4         
,gravity--,c5tres1 ,=ces1 & ,p[]s4      
,millwork1 ,tee? ( ,:eels1 ,%aft+1 etc4 
,work%op ,recipes4            ,sundry   
,ma*9]y4            ,animal ,p[]4       
,/eam & ! ,/eam ,eng9e4                 
,wat]-p[]1 ,wat]-:eels1 ,turb9es1 etc4  
,w9d & ,w9dmills4            ,/eam      
,navigation1 ,%ip ,build+1 ,tonnage1    
etc4            ,gunn]y1 ,projectiles1  
etc4            ,weights1 ,measures1 &  

,money4            ,trigonometry1 ,conic
 ,sections1 & ,curves4                  
,telegraph4            ,m5suration4     
,tables ( ,areas & ,circumf]5ce1 & ,arcs
 ( ,circles4            ,log>i?ms1      
,squ>e & ,cube ,roots1 ,p[]s4           
,reciprocals1 etc4            ,useful   
,numb]s4            ,diff]5tial &       
,integral ,calculus4                    
,algebraic ,signs4                      
,telegraphic ,con/ruction & ,=mul4      
99       99       99       99       99  
,fcap4 #hvo1 clo?1 #as4 #f;d4           
,electro-,telegraphy1                   
,by ,,fr$]ick ,s4 ,,bee*ey1             
,telegraph ,eng9e]4                     
,a ,book = ,beg9n]s4                    
99       99       99       99       99  
,cr[n #hvo1 clo?1 #ds4 #f;d4            
,guide = ! ,electric ,te/+ ( ,telegraph 
,cables1                             ,by
 ,capta9 ,v4 ,,hoskl,r4                 
,plates4                                
,,cont5ts4                    ,!        
,conductivity ( ! ,copp]4               

,! ,*>ge ( ! ,cable4                    
,insulation ( ! ,cable4                 
,insulation ( a ,jo9t4                  
,! ,situation & ,greatness ( a ,fault4  
,te/+ & ,lay+ ( a ,cable4               
,=mul1 ,tables1 etc4                    
99       99       99       99       99  
,london3                    ,e4  ,f4 ,n4
 ,,spon1 #df1 ,,*>+ ,,cross4            
,,new ,,york3 #ddf1 ,,broome ,,/reet4