,transcriber's ,notes3      ,underscores
  before and after a word or phrase     
indicate italics      in the original   
text4    ,equal signs  before and after 
a word or phrase indicate bold      in  
the original text4    ,carat symbol     
designates a superscript4    ,underscore
  is used to designates a subscript4    
,small capitals have been converted to  
,,solid capitals4    ,illustrations have
 been moved so they do not break up     
paragraphs4    ,old or antiquated       
spellings have been preserved4          
,typographical errors have been silently
 corrected but other variations      in 
spelling and punctuation remain         
unaltered4                              
,,the ,,telephone4                      
,a ,,lecture                            
,,entitled                              
,,researches ,,in ,,electric            
,,telephony1                      ,,by  
,,professor ,,alexander ,,graham ,,bell1
                                        
,,delivered ,,before                    

,the ,society of ,telegraph ,engineers1 
,,october #ca,,st1 #ahgg4               
,,published ,,by ,,the ,,society1       
,,and ,,edited ,,by                     
,,lieut4-,,col4 ,,frank ,,bolton1       
,c4,e41 ,,hon4 ,,secretary1             
,,and                 ,,william ,,edward
 ,,langdon1 ,,acting ,,secretary4       
,london3                   ,e4 ,,and ,f4
 ,n4 ,,spon1 #df1 ,,charing ,,cross4    
,new ,york3                             
#ddf1 ,,broome ,,street4                
#ahgh4                     ,price ,one  
,shilling and ,sixpence4           ,the 
right of translation and reproduction is
 reserved          ,,extracts ,,of      
,,proceedings ,,of ,,the ,,society ,,of 
,,telegraph ,,engineers4        ,special
 ,general ,meeting1 held at #be1 ,great 
,george ,street1       ,westminster1 on 
,wednesday1 the #cast ,october1 #ahgg4  
,,professor ,,abel1 ,c4,b41 ,f4,r4,s41  
,president1 in the ,chair4    ,the      
,,president3 ,gentlemen1 the ,council of
 the ,society of  ,telegraph ,engineers 

felt that they were sure of doing what  
the members  would consider right in    
summoning a special meeting for the     
two-fold  purpose of giving a welcome to
 ,professor ,bell to this country and   
affording the ,members an opportunity of
 hearing from him an account1  which he 
has been so good as to promise to give  
us1 of the nature1  history1 and        
development of1 what may well be called1
 one of the most  interesting           
discoveries of our age4 ,our time is    
very precious this  evening4 ,we all    
desire to hear everything ,professor    
,bell can tell us  on this subject1 and 
many gentlemen will probably desire     
afterwards to  ask questions or discuss 
the subject1 for ,i see present a great 
number  of eminent scientific men4 ,i   
will not waste another moment1 but at   
once  call upon ,professor ,bell to     
commence his discourse on the ,electric 
,telephone4          ,,researches ,,in  
,,electric ,,telephony4      ,by        
,,professor ,,alexander ,,graham ,,bell4

    ,,professor ,,bell3 ,mr4 ,president 
and ,gentlemen of the ,society of       
,telegraph ,engineers4 ,it is to-night  
my pleasure1 as well as duty1 to  give  
you some account of the telephonic      
researches in which ,i have been  so    
long engaged4 ,many years ago my        
attention was directed to the  mechanism
 of speech by my father1 ,alexander     
,melville ,bell1 of  ,edinburgh1 who has
 made a life-long study of the subject4 
,many of  those present may recollect   
the invention by my father of a means   
of representing1 in a wonderfully       
accurate manner1 the positions of  the  
vocal organs in forming sounds4         
,together we carried on quite a  number 
of experiments1 seeking to discover the 
correct mechanism of  ,english and      
foreign elements of speech1 and ,i      
remember especially an  investigation in
 which we were engaged concerning the   
musical relations  of vowel sounds4     
,when vowel sounds are whispered1 each  
vowel seems  to possess a particular    

pitch of its own1 and by whispering     
certain  vowels in succession a musical 
scale can be distinctly perceived4 ,our 
aim was to determine the natural pitch  
of each vowel2 but unexpected           
difficulties made their appearance1 for 
many of the vowels seemed to  possess a 
double pitch--one due1 probably1 to the 
resonance of the air  in the mouth1 and 
the other to the resonance of the air   
contained in  the cavity behind the     
tongue1 comprehending the pharynx and   
larynx4    ,i hit upon an expedient for 
determining the pitch which at that time
  ,i thought to be original with myself4
 ,it consisted in vibrating a           
tuning-fork in front of the mouth while 
the positions of the vocal  organs for  
the various vowel sounds were silently  
taken4 ,it was found  that each vowel   
position caused the reinforcement of    
some particular  fork or forks4    ,i   
wrote an account of these researches to 
,mr4 ,alex4 ,j4 ,ellis1 of  ,london1    
whom ,i have very great pleasure in     

seeing here to-night4 ,in  reply he     
informed me that the experiments related
 had already been  performed by         
,helmholtz1 and in a much more perfect  
manner than ,i had  done4 ,indeed1 he   
said that ,helmholtz had not only       
analysed the vowel  sounds into their   
constituent musical elements1 but had   
actually  performed the synthesis of    
them4    ,he had succeeded in producing1
 artificially1 certain of the vowel     
sounds by causing tuning-forks of       
different pitch to vibrate              
simultaneously by means of an electric  
current4 ,mr4 ,ellis was kind  enough to
 grant me an interview for the purpose  
of explaining the  apparatus employed by
 ,helmholtz in producing these          
extraordinary  effects1 and ,i spent the
 greater part of a delightful day with  
him in  investigating the subject4 ,at  
that time1 however1 ,i was too slightly 
acquainted with the laws of electricity 
fully to understand the  explanations   
given2 but the interview had the effect 

of arousing my  interest in the subjects
 of sound and electricity1 and ,i did   
not rest  until ,i had obtained         
possession of a copy of ,helmholtz'     
great work1#a  and had attempted1 in a  
crude and imperfect manner it is true1  
to  reproduce his results4 ,while       
reflecting upon the possibilities of    
the production of sound by electrical   
means1 it struck me that the  principle 
of vibrating a tuning-fork by the       
intermittent attraction  of an          
electro-magnet might be applied to the  
electrical production of  music4    ,i  
imagined to myself a series of          
tuning-forks of different pitches1      
arranged to vibrate automatically in the
 manner shown by ,helmholtz1  each fork 
interrupting at every vibration a       
voltaic current2 and the  thought       
occurred1 8,why should not the          
depression of a key like that of  a     
piano direct the interrupted current    
from any one of these forks1  through a 
telegraph wire1 to a series of          

electro-magnets operating the  strings  
of a piano or other musical instrument1 
in which case a person  might play the  
tuning-fork piano in one place and the  
music be audible  from the              
electromagnetic piano in a distant      
city80    ,the more ,i reflected upon   
this arrangement the more feasible did  
it  seem to me2 indeed1 ,i saw no reason
 why the depression of a number of  keys
 at the tuning-fork end of the circuit  
should not be followed by  the audible  
production of a full chord from the     
piano in the distant  city1 each        
tuning-fork affecting at the receiving  
end that string of  the piano with which
 it was in unison4 ,at this time the    
interest which  ,i felt in electricity  
led me to study the various systems of  
telegraphy  in use in this country and  
in ,america4 ,i was much struck with the
  simplicity of the ,morse alphabet1 and
 with the fact that it could be  read by
 sound4 ,instead of having the dots and 
dashes recorded upon  paper1 the        

operators were in the habit of observing
 the duration of the  click of the      
instruments1 and in this way were       
enabled to distinguish  by ear the      
various signals4    ,it struck me that  
in a similar manner the duration of a   
musical note  might be made to represent
 the dot or dash of the telegraph code1 
so  that a person might operate one of  
the keys of the tuning-fork piano       
referred to above1 and the duration of  
the sound proceeding from the           
corresponding string of the distant     
piano be observed by an operator        
stationed there4 ,it seemed to me that  
in this way a number of distinct        
telegraph messages might be sent        
simultaneously from the tuning-fork     
piano to the other end of the circuit1  
by operators each manipulating  a       
different key of the instrument4 ,these 
messages would be read by  operators    
stationed at the distant piano1 each    
receiving operator  listening for       
signals of a certain definite pitch1 and

 ignoring all  others4 ,in this way     
could be accomplished the simultaneous  
transmission  of a number of telegraphic
 messages along a single wire1 the      
number  being limited only by the       
delicacy of the listener's ear4 ,the    
idea of  increasing the carrying power  
of a telegraph wire in this way took    
complete possession of my mind1 and it  
was this practical end that ,i  had in  
view when ,i commenced my researches in 
,electric ,telephony4    ,in the        
progress of science it is universally   
found that complexity  leads to         
simplicity1 and in narrating the history
 of scientific  research it is often    
advisable to begin at the end4    ,in   
glancing back over my own researches ,i 
find it necessary to  designate1 by     
distinct names1 a variety of electrical 
currents by means  of which sounds can  
be produced1 and ,i shall direct your   
attention to  several distinct species  
of what may be termed 8telephonic0      
currents of  electricity4 ,in order that

 the peculiarities of these currents may
 be  clearly understood1 ,i shall ask   
,mr4 ,frost to project upon the screen a
  graphical illustration of the         
different varieties4    ,the graphical  
method of representing electrical       
currents here shown is  the best means  
,i have been able to devise of studying 
in an accurate  manner the effects      
produced by various forms of telephonic 
apparatus1  and it has led me to the    
conception of that peculiar species of  
telephonic current here designated as   
undulatory1 which has rendered  feasible
 the artificial production of articulate
 speech by electrical  means4           
,illustration3 ,fig4 #a4    ,a          
horizontal line 7g g7 is taken as the   
zero of current1 and  impulses of       
positive electricity are represented    
above the zero line1  and negative      
impulses below it1 or vice vers4    ,the
 vertical thickness of any electrical   
impulse 7b or d71 measured  from the    
zero line1 indicates the intensity of   

the electrical current  at the point    
observed1 and the horizontal extension  
of the electric  line 7b or d7 indicates
 the duration of the impulse4    ,nine  
varieties of telephonic currents may be 
distinguished1 but it will  only be     
necessary to show you six of these4 ,the
 three primary varieties  designated as 
8intermittent10 8pulsatory10 and        
8undulatory10 are  represented in lines 
#a1 #b1 and #c4    ,sub-varieties of    
these can be distinguished as 8direct0  
or 8reversed0  currents according as the
 electrical impulses are all of one kind
 or  are alternately positive and       
negative4 8,direct0 currents may still  
further be distinguished as 8positive0  
or 8negative10 according as the         
impulses are of one kind or of the      
other4    ,an intermittent current is   
characterised by the alternate presence 
and absence of electricity upon the     
circuit2    ,a pulsatory current results
 from sudden or instantaneous changes in
  the intensity of a continuous current2

 and    ,an undulatory current is a     
current of electricity1 the intensity of
  which varies in a manner proportional 
to the velocity of the motion  of a     
particle of air during the production of
 a sound3 thus the curve  representing  
graphically the undulatory current for a
 simple musical  tone is the curve      
expressive of a simple pendulous        
vibration--that is1  a sinusoidal curve4
                 ,telephonic currents of
 electricity may be3                    
,direct  ,positive #a    ,positive      
intermittent current4     ,intermittent 
,negative #b    ,negative      0        
0                   ----      ,reversed 
#c    ,reversed      0          0       
,direct  ,positive #d    ,positive      
pulsatory current4     ,pulsatory       
,negative #e    ,negative      0       0
                   ----      ,reversed  
#f    ,reversed      0       0          
,direct  ,positive #g    ,positive      
undulatory current4     ,undulatory     
,positive #h    ,negative      0       0

                   ----      ,reversed  
#i    ,reversed      0       0    ,and  
here ,i may remark1 that1 although the  
conception of the undulatory  current of
 electricity is entirely original with  
myself1 methods of  producing sound by  
means of intermittent and pulsatory     
currents have  long been known4 ,for    
instance1 it was long since discovered  
that  an electro-magnet gives forth a   
decided sound when it is suddenly       
magnetized or demagnetized4 ,when the   
circuit upon which it is placed is      
rapidly made and broken1 a succession of
 explosive noises proceeds from  the    
magnet4 ,these sounds produce upon the  
ear the effect of a musical  note when  
the current is interrupted a sufficient 
number of times  per second4 ,the       
discovery of 8,galvanic ,music10 by     
,page1#b in #ahcg1  led inquirers in    
different parts of the world almost     
simultaneously  to enter into the field 
of telephonic research2 and the         
acoustical  effects produced by         

magnetization were carefully studied by 
,marrian1#c  ,beatson1#d ,gassiot1#e ,de
 la ,rive1#f ,matteucci1#g ,guillemin1#h
  ,wertheim1#i ,wartmann1#aj            
,janniar1#aa ,joule1#ab ,laborde1#ac    
,legat1#ad ,reis1#ae ,poggendorff1#af   
,du ,moncel1#ag ,delezenne1#ah  and     
others4#ai ,it should also be mentioned 
that ,gore#bj obtained  loud musical    
notes from mercury1 accompanied by      
singularly beautiful  crispations of the
 surface during the course of           
experiments in  electrolysis2 ,page#ba  
produced musical tones from ,trevelyan's
 bars  by the action of the galvanic    
current2 and further it was discovered  
by ,sullivan#bb that a current of       
electricity is generated by the         
vibration of a wire composed partly of  
one metal and partly of another4  ,the  
current was produced so long as the wire
 emitted a musical note1  but stopped   
immediately upon the cessation of the   
sound4    ,for several years my         
attention was almost exclusively        

directed to  the production of an       
instrument for making and breaking a    
voltaic  circuit with extreme rapidity1 
to take the place of the transmitting   
tuning-fork used in ,helmholtz'         
researches4 ,i will not trouble you     
with the description of all the various 
forms of apparatus that were  devised1  
but will merely direct your attention to
 one of the best of  them1 shown in fig4
 #b4 ,in the transmitting instrument ,t1
 a steel reed  a is employed1 which is  
kept in continuous vibration by the     
action of  an electro-magnet e and local
 battery4 ,in the course of its         
vibration  the reed strikes alternately 
against two fixed points m1 l1 and  thus
 completes alternately a local and a    
main circuit4 ,when the key  ,k is      
depressed an intermittent current from  
the main battery ,b is  directed to the 
line-wire ,w1 and passes through the    
electro-magnet ,e of  a receiving       
instrument ,r at the distant end of the 
circuit1 and thence  to the ground ,g4  

,the steel reed ,a is placed in front of
 the receiving  magnet1 and when its    
normal rate of vibration is the same as 
the reed  of the transmitting instrument
 it is thrown into powerful vibration1  
emitting a musical tone of a similar    
pitch to that produced by the reed  of  
the transmitting instrument1 but if it  
is normally of a different  pitch it    
remains silent4    ,illustration3 ,fig4 
#b4    ,illustration3 ,fig4 #c4 ,fig4   
#d4 ,fig4 #e4    ,a glance at figs4 #c1 
#d1 and #e will show the arrangement of 
such  instruments upon a telegraphic    
circuit1 designed to enable a number  of
 telegraphic despatches to be           
transmitted simultaneously along the    
same wire4 ,the transmitters and        
receivers that are numbered alike have  
the same pitch or rate of vibration4    
,thus the reed of ,t is in unison  with 
the reeds ,t and ,r at all the stations 
upon the circuit1 so that  a telegraphic
 despatch sent by the manipulation of   
the key ,k at the  station shown in fig4

 #c will be received upon the receiving 
instruments  ,k at all the other        
stations upon the circuit4 ,without     
going into  details1 ,i shall merely say
 that the great defects of this plan of 
multiple telegraphy were found to       
consist1 firstly1 in the fact that  the 
receiving operators were required to    
possess a good musical ear in  order to 
discriminate the signals2 and secondly1 
that the signals could  only pass in one
 direction along the line 7so that two  
wires would be  necessary in order to   
complete communication in both          
directions74 ,the  first objection was  
got over by employing the device which  
,i term a  8vibratory circuit-breaker10 
shown in the next diagram1 whereby      
musical  signals can be automatically   
recorded4    ,illustration3 ,fig4 #f4   
,fig4 #f shows a receiving instrument   
,r1 with a vibratory circuit-breaker  v 
attached4 ,the light spring-lever v     
overlaps the free end of the  steel reed
 ,a1 and normally closes a local        

circuit1 in which may be  placed a      
,morse-sounder or other telegraphic     
apparatus4 ,when the reed  ,a is thrown 
into vibration by the passage of a      
musical signal1 the  spring arm v is    
thrown upwards1 opening the local       
circuit at the  point #e4 ,when the     
spring-arm v is so arranged as to have  
normally a  much slower rate of         
vibration than the reed ,a#a1 the local 
circuit  is found to remain permanently 
open during the vibration of ,a1 the    
spring-arm v coming into contact with   
the point #e only upon the  cessation of
 the receiver's vibration4 ,thus the    
signals produced by the  vibration of   
the reed ,a are reproduced upon an      
ordinary telegraphic  instrument in the 
local circuit4    ,fig4 #g shows the    
application of electric telephony to    
autographic  telegraphy4                
,illustration3 ,fig4 #g4    ,t1 ,t1 c41 
represent the reeds of transmitting     
instruments of  different pitch1 ,r1 ,r1
 c41 the receivers at the distant       

station  of corresponding pitch1 and1 r1
 r1 c41 the vibratory  circuit-breakers 
attached to the receiving instruments1  
and connected  with metallic bristles1  
#ba1 resting upon chemically prepared   
paper  ,p4 ,the message1 or picture1 to 
be copied1 is written upon a metallic   
surface1 ,f#j1 with non-metallic ink1   
and placed upon a metallic  cylinder #g1
 connected with the main battery ,b2 and
 the chemically  prepared paper ,p1 upon
 which the message is to be received1 is
 placed  upon a metallic cylinder       
connected with the local battery ,b at  
the  receiving station4 ,when the       
cylinders at either end of the circuit  
are  rotated in the direction of the    
arrows--but not necessarily at the same 
rate of speed--a fac simile of whatever 
is written or drawn upon the  metallic  
surface ,f#j appears upon the chemically
 prepared paper ,p4    ,the method by   
means of which the musical signals may  
be sent  simultaneously in both         
directions along the same circuit is    

shown in  our next illustration1 figures
 #h1 #i1 and #aj4 ,the arrangement is   
similar  to that shown in figures #c1   
#d1 and #e1 excepting that the          
intermittent  current from the          
transmitting instruments is passed      
through the  primary wires of an        
induction coil1 and the receiving       
instruments are  placed in circuit with 
the secondary wire4 ,in this way free   
earth  communication is secured at      
either end of the circuit1 and the      
musical  signals produced by the        
manipulation of any key are received at 
all the  stations upon the line4 ,the   
great objection to this plan is the     
extreme  complication of the parts and  
the necessity of employing local and    
main  batteries at every station4 ,it   
was also found by practical experiment  
that it was difficult1 if not           
impossible1 upon either of the plans    
here shown1 to transmit simultaneously  
the number of musical tones  that theory
 showed to be feasible4 ,mature         

consideration revealed the  fact that   
this difficulty lay in the nature of the
 electrical current  employed1 and was  
finally obviated by the invention of the
 undulatory  current4    ,it is a       
strange fact that important inventions  
are often made almost  simultaneously by
 different persons in different parts of
 the world1  and the idea of multiple   
telegraphy as developed in the preceding
  diagrams seems to have occurred       
independently to no less than four      
other inventors in ,america and ,europe4
 ,even the details of the  arrangements 
upon circuit--shown in figures #c1 #d1  
#e1 and #h1 #i1 #aj--;are  extremely    
similar in the plans proposed by ,mr4   
,cromwell ,varley of  ,london1 ,mr4     
,elisha ,gray of ,chicago1 ,mr4 ,paul   
,la ,cour of ,copenhagen1 and  ,mr4     
,thomas ,edison of ,newark1 ,new        
,jersey4 ,into the question of priority 
of invention1 of course1 it is not my   
intention to go to-night4               
,illustration3 ,fig4 #h4 ,fig4 #i4 ,fig4

 #aj4    ,that the difficulty in the use
 of an intermittent current may be more 
clearly understood1 ,i shall ask you to 
accompany me in my explanation  of the  
effect produced when two musical signals
 of different pitch  are simultaneously 
directed along the same circuit4 ,fig4  
#aa shows an  arrangement whereby the   
reeds a a of two transmitting           
instruments  are caused to interrupt the
 current from the same battery1 ,b4 ,we 
shall  suppose the musical interval     
between the two reeds to be a major     
third1  in which case their vibrations  
are in the ratio of #d to #e1 i4e41  #d 
vibrations of a are made in the same    
time as #e vibrations of  a#a4 ,a#b and 
,b#b represent the intermittent currents
 produced1  #d impulses of ,b#b being   
made in the same time as #e impulses of 
,a#b4  ,the line ,a#b  ,b#b represents  
the resultant effect upon the main line 
when the reeds a and a#a are            
simultaneously caused to make and  break
 the same circuit1 and from the         

illustration you will perceive  that the
 resultant current1 whilst retaining a  
uniform intensity1  is less interrupted 
when both reeds are in operation than   
when one  alone is employed4 ,by        
carrying your thoughts still further you
 will  understand that when a large     
number of reeds of different pitch or of
  different rates of vibration are      
simultaneously making and breaking the  
same circuit the resultant effect upon  
the main line is practically  equivalent
 to one continuous current4             
,illustration3 ,fig4 #aa4    ,it will   
also be understood that the maximum     
number of musical  signals that can be  
simultaneously directed along a single  
wire  without conflict depends very much
 upon the ratio which the  8make0 bears 
to the 8break20 the shorter the contact 
made1 and  the longer the break1 the    
greater the number of signals that can  
be transmitted without confusion1 and   
vice vers4 ,the apparatus  by means of  
which this theoretical conclusion has   

been verified is  here to-night1 and    
consists of an ordinary parlour         
harmonium1 the  reeds of which are      
operated by wind in the usual manner4   
,in front of  each reed is arranged a   
metal screw1 against which the reed     
strikes  in the course of its vibration4
 ,by adjusting the screw the duration   
of the contact can be made long or      
short4 ,the reeds are connected  with   
one pole of a battery1 and the screws   
against which they strike  communicate  
with the line-wire1 so that intermittent
 impulses from the  battery are         
transmitted along the line-wire during  
the vibration of the  reeds4            
,illustration3 ,fig4 #ab4               
,illustration3 ,fig4 #ac4               
,illustration3 ,fig4 #ad4    ,we now    
proceed to the next illustration4       
,without entering into the  details of  
the calculation you will see that with a
 pulsatory current  the effect of       
transmitting musical signals            
simultaneously is nearly  equivalent to 

a continuous current of minimum         
intensity--see ,a#b  ,b#b1  fig4 #ab2   
but when undulatory currents are        
employed the effect is  different--see  
fig4 #ac4 ,the current from the battery 
,b is thrown into  waves by the         
inductive action of iron or steel reeds 
,m ,m1 vibrated in  front of            
electro-magnets e e1 placed in circuit  
with the battery2  ,a#b and ,b#b        
represent the undulations caused in the 
current by the  vibration of the        
magnetised bodies1 and it will be seen  
that there are  four undulations of ,b#b
 in the same time as five undulations of
 ,a#b4  ,the resultant effect upon the  
main line is expressed by the curve ,a#b
   ,b#b1 which is the algebraical sum of
 the sinusoidal curves ,a#b and  ,b#b4  
,a similar effect is produced when      
reversed undulatory currents  are       
employed as shown in fig4 #ad1 where the
 current is produced by  the vibration  
of permanent magnets ,m ,m in front of  
electro-magnets  7e e71 united upon a   

circuit without a voltaic battery4 ,it  
will be  understood from figs4 #ac and  
#ad that the effect of transmitting     
musical  signals of different pitches   
simultaneously along a single wire is   
not to obliterate the vibratory         
character of the current as in the  case
 of intermittent and pulsatory currents1
 but to change the shapes  of the       
electrical undulations4 ,in fact1 the   
effect produced upon the  current is    
precisely analogous to the effect       
produced in the air by the  vibration of
 the inducing bodies ,m ,m4 ,hence it   
should be possible to  transmit as many 
musical tones simultaneously through a  
telegraph wire  as through the air4 ,the
 possibility of using undulatory        
currents for  the purposes of multiple  
telegraphy enabled me to dispense       
entirely  with the complicated          
arrangements of the circuit shown in    
figs4 #c1  #d1 #e1 and #h1 #i1 #aj1 and 
to employ a single battery for the whole
  circuit1 retaining only the receiving 

instruments formerly shown4 ,this       
arrangement is represented in figs4 #ae1
 #af1 and #ag4 ,upon vibrating the      
steel reed of a receiver ,r1 ,r1 at any 
station by any mechanical means1  the   
corresponding reeds at all the other    
stations are thrown into  vibration1    
reproducing the signal4 ,by attaching   
the steel reeds to the  poles of a      
powerful permanent magnet1 as shown in  
fig4 #ai1 the signals  can be produced  
without the aid of a battery4           
,illustration3 ,fig4 #ae4 ,fig4 #af4    
,fig4 #ag4    ,illustration3 ,fig4      
#ah4bc    ,i have formerly stated that  
,helmholtz was enabled to produce vowel 
sounds artificially by combining musical
 tones of different pitches  and        
intensities4 ,his apparatus is shown in 
fig4 #ah4 ,tuning-forks of  different   
pitch are placed between the poles of   
electro-magnets 7a#a1  a#b1 c471 and are
 kept in continuous vibration by the    
action of an  intermittent current from 
the fork b4 ,resonators #a1 #b1 #c1 c4  

are  arranged so as to reinforce the    
sounds1 in a greater or less degree1    
according as the exterior orifices are  
enlarged or contracted4    ,thus it will
 be seen that upon ,helmholtz's plan the
 tuning-forks  themselves produce tones 
of uniform intensity1 the loudness being
  varied by an external reinforcement2  
but it struck me that the same  results 
would be obtained1 and in a much more   
perfect manner1 by  causing the         
tuning-forks themselves to vibrate with 
different degrees  of amplitude4 ,i     
therefore devised the apparatus shown in
 fig4 #ai1 which  was my first form of  
articulating telephone4 ,in this figure 
a harp of  steel rods is employed       
attached to the poles of a permanent    
magnet  ,n4,s4 ,when any one of the rods
 is thrown into vibration an undulatory 
current is produced in the coils of the 
electro-magnet ,e1 and the              
electro-magnet ,e attracts the rods of  
the harp ,h with a varying  force1      
throwing into vibration that rod which  

is in unison with  that vibrated at the 
other end of the circuit4 ,not only so1 
but the  amplitude of vibration in the  
one will determine the amplitude of     
vibration in the other1 for the         
intensity of the induced current  is    
determined by the amplitude of the      
inducing vibration1 and the  amplitude  
of the vibration at the receiving end   
depends upon the  intensity of the      
attractive impulses4 ,when we sing into 
a piano1  certain of the strings of the 
instrument are set in vibration         
sympathetically by the action of the    
voice with different degrees of         
amplitude1 and a sound1 which is an     
approximation to the vowel uttered1  is 
produced from the piano4 ,theory shows1 
that1 had the piano a very  much larger 
number of strings to the octave1 the    
vowel sounds would be  perfectly        
reproduced4 ,my idea of the action of   
the apparatus1 shown in  fig4 #ai1 was  
this3 ,utter a sound in the             
neighbourhood of the harp ,h1  and      

certain of the rods would be thrown into
 vibration with different  amplitudes4  
,at the other end of the circuit the    
corresponding rods of  the harp ,h would
 vibrate with their proper relations of 
force1 and the  timbre of the sound     
would be reproduced4 ,the expense of    
constructing  such an apparatus as that 
shown in fig4 #ai deterred me from      
making the  attempt1 and ,i sought to   
simplify the apparatus before venturing 
to  have it made4    ,illustration3     
,fig4 #ai4    ,illustration3 ,fig4 #bj4 
,i have before alluded to the invention 
by my father of a system of             
physiological symbols for representing  
the action of the vocal organs1  and ,i 
had been invited by the ,boston ,board  
of ,education to conduct a  series of   
experiments with the system in the      
,boston school for the deaf  and dumb4  
,it is well known that deaf mutes are   
dumb merely because  they are deaf1 and 
that there is no defect in their vocal  
organs to  incapacitate them from       

utterance4 ,hence it was thought that my
 father's  system of pictorial symbols1 
popularly known as visible speech1 might
  prove a means whereby we could teach  
the deaf and dumb to use their  vocal   
organs and to speak4 ,the great success 
of these experiments  urged upon me the 
advisability of devising methods of     
exhibiting the  vibrations of sound     
optically1 for use in teaching the deaf 
and dumb4  ,for some time ,i carried on 
experiments with the manometric capsule 
of ,koenig1 and with the phonautograph  
of ,lon ,scott4 ,the scientific         
apparatus in the ,institute of          
,technology in ,boston was freely placed
 at  my disposal for these experiments1 
and it happened that at that time  a    
student of the ,institute of            
,technology1 ,mr4 ,maurey1 had invented 
an  improvement upon the phonautograph4 
,he had succeeded in vibrating by  the  
voice a stylus of wood about a foot in  
length which was attached to  the       
membrane of the phonautograph1 and in   

this way he had been enabled  to obtain 
enlarged tracings upon a plane surface  
of smoked glass4 ,with  this apparatus  
,i succeeded in producing very beautiful
 tracings of the  vibrations of the air 
for vowel sounds4 ,some of these        
tracings are  shown in fig4 #bj4 ,i was 
much struck with this improved form of  
apparatus1 and it occurred to me that   
there was a remarkable likeness  between
 the manner in which this piece of wood 
was vibrated by the  membrane of the    
phonautograph and the manner in which   
the ossicul  of the human ear were moved
 by the tympanic membrane4 ,i determined
  therefore to construct a phonautograph
 modelled still more closely  upon the  
mechanism of the human ear1 and for this
 purpose ,i sought  the assistance of a 
distinguished aurist in ,boston1 ,dr4   
,clarence ,j4  ,blake4 ,he suggested the
 use of the human ear itself as a       
phonautograph1  instead of making an    
artificial imitation of it4 ,the idea   
was novel and  struck me accordingly1   

and ,i requested my friend to prepare a 
specimen  for me1 which he did4 ,the    
apparatus1 as finally constructed1 is   
shown  in fig4 #ba4 ,the stapes was     
removed and a stylus of hay about an    
inch in length was attached to the end  
of the incus4 ,upon moistening  the     
membrana-tympani and the ossicul with a 
mixture of glycerine and  water1 the    
necessary mobility of the parts was     
obtained2 and upon  singing into the    
external artificial ear the stylus of   
hay was thrown  into vibration1 and     
tracings were obtained upon a plane     
surface  of smoked glass passed rapidly 
underneath4 ,while engaged in these     
experiments ,i was struck with the      
remarkable disproportion in weight      
between the membrane and the bones that 
were vibrated by it4 ,it  occurred to me
 that if a membrane as thin as tissue   
paper could control  the vibration of   
bones that were1 compared to it1 of     
immense size and  weight1 why should not
 a larger and thicker membrane be able  

to vibrate  a piece of iron in front of 
an electro-magnet1 in which case the    
complication of steel rods shown in my  
first form of telephone1 fig4  #ai1     
could be done away with1 and a simple   
piece of iron attached to a  membrane be
 placed at either end of the telegraphic
 circuit4    ,illustration3 ,fig4 #ba4  
,illustration3 ,fig4 #bb4               
,illustration3 ,fig4 #bc4    ,fig4 #bb  
shows the form of apparatus that ,i was 
then employing for  producing undulatory
 currents of electricity for the        
purposes of  multiple telegraphy4 ,a    
steel reed ,a was clamped firmly by one 
extremity  to the uncovered leg h of an 
electro-magnet ,e1 and the free end of  
the reed projected above the covered    
leg4 ,when the reed ,a was vibrated  in 
any mechanical way1 the battery current 
was thrown into waves1 and  electrical  
undulations traversed the circuit ,b ,e 
,w ,e1 throwing into  vibration the     
corresponding reed ,a at the other end  
of the circuit4  ,i immediately         

proceeded to put my new idea to the test
 of practical  experiment1 and for this 
purpose ,i attached the reed ,a 7fig4   
#bc7  loosely by one extremity to the   
uncovered pole h of the magnet1 and     
fastened the other extremity to the     
centre of a stretched membrane  of      
goldbeaters' skin n4 ,i presumed that   
upon speaking in the  neighbourhood of  
the membrane n it would be thrown into  
vibration  and cause the steel reed ,a  
to move in a similar manner1 occasioning
  undulations in the electrical current 
that would correspond to the  changes in
 the density of the air during the      
production of the sound2  and ,i further
 thought that the change of the         
intensity of the current  at the        
receiving end would cause the magnet    
there to attract the reed  ,a in such a 
manner that it should copy the motion of
 the reed ,a1 in  which case its        
movements would occasion a sound from   
the membrane n  similar in timbre to    
that which had occasioned the original  

vibration4    ,illustration3 ,fig4 #bd4 
,the results1 however1 were             
unsatisfactory and discouraging4 ,my    
friend  ,mr4 ,thomas ,a4 ,watson1 who   
assisted me in this first experiment1   
declared that he heard a faint sound    
proceed from the telephone at  his end  
of the circuit1 but ,i was unable to    
verify his assertion4  ,after many      
experiments attended by the same only   
partially-successful  results1 ,i       
determined to reduce the size and weight
 of the spring as  much as possible4    
,for this purpose ,i glued a piece of   
clock spring1  about the size and shape 
of my thumbnail1 firmly to the centre of
 the  diaphragm1 and had a similar      
instrument at the other end 7fig4 #bd72 
we were then enabled to obtain          
distinctly audible effects4 ,i remember 
an experiment made with this telephone1 
which at the time gave me  great        
satisfaction and delight4 ,one of the   
telephones was placed in my             
lecture-room in the ,boston ,university1

 and the other in the basement  of the  
adjoining building4 ,one of my students 
repaired to the distant  telephone to   
observe the effects of articulate       
speech1 while ,i uttered  the sentence1 
8,do you understand what ,i say80 into  
the telephone placed  in the            
lecture-hall4 ,to my delight an answer  
was returned through  the instrument    
itself1 articulate sounds proceeded from
 the steel  spring attached to the      
membrane1 and ,i heard the sentence1    
8,yes1  ,i understand you perfectly40   
,it is a mistake1 however1 to suppose   
that the articulation was by any means  
perfect1 and expectancy no  doubt had a 
great deal to do with my recognition of 
the sentence2  still1 the articulation  
was there1 and ,i recognised the fact   
that the  indistinctness was entirely   
due to the imperfection of the          
instrument4  ,i will not trouble you by 
detailing the various stages through    
which  the apparatus passed1 but shall  
merely say that after a time ,i produced

  the form of instrument shown in fig4  
#be1 which served very well as  a       
receiving telephone4 ,in this condition 
my invention was exhibited  at the      
,centennial ,exhibition in              
,philadelphia4 ,the telephone shown in  
fig4 #bd was used as a transmitting     
instrument1 and that in fig4 #be as  a  
receiver1 so that vocal communication   
was only established in one  direction4 
,illustration3 ,fig4 #be4    ,another   
form of transmitting telephone exhibited
 in ,philadelphia  intended for use with
 the receiving telephone 7fig4 #be7 is  
represented  by fig4 #bf4    ,a platinum
 wire attached to a stretched membrane  
completed a voltaic  circuit by dipping 
into water4 ,upon speaking to the       
membrane1  articulate sounds proceeded  
from the telephone in the distant room4 
,the  sounds produced by the telephone  
became louder when dilute sulphuric     
acid1 or a saturated solution of salt1  
was substituted for the water4  ,audible
 effects were also produced by the      

vibration of plumbago in  mercury1 in a 
solution of bichromate of potash1 in    
salt and water1 in  dilute sulphuric    
acid1 and in pure water4    ,the        
articulation produced from the          
instrument shown in fig4 #be was        
remarkably distinct1 but its great      
defect consisted in the fact that it    
could not be used as a transmitting     
instrument1 and thus two telephones     
were required at each station1 one for  
transmitting and one for  receiving     
spoken messages4    ,illustration3 ,fig4
 #bf4    ,it was determined to vary the 
construction of the telephone  shown in 
fig4 #bd1 and ,i sought by changing the 
size and tension  of the membrane1 the  
diameter and thickness of the steel     
spring1  the size and power of the      
magnet1 and the coils of insulated wire 
around their poles1 to discover         
empirically the exact effect of each    
element of the combination1 and thus to 
deduce a more perfect  form of          
apparatus4 ,it was found that a marked  

increase in the  loudness of the sounds 
resulted from shortening the length of  
the  coils of wire1 and by enlarging the
 iron diaphragm which was  glued to the 
membrane4 ,in the latter case1 also1 the
 distinctness  of the articulation was  
improved4 ,finally1 the membrane of     
goldbeaters'  skin was discarded        
entirely1 and a simple iron plate was   
used instead1 and at once intelligible  
articulation was obtained4  ,the new    
form of instrument is that shown in fig4
 #bg1 and1 as had  been long            
anticipated1 it was proved that the only
 use of the  battery was to magnetize   
the iron core of the magnet1 for the    
effects were equally audible when the   
battery was omitted and a  rod of       
magnetized steel substituted for the    
iron core of the magnet4    ,it was my  
original intention1 as shown in fig4    
#ai1 and it was always  claimed by me1  
that the final form of telephone would  
be operated by  permanent magnets in    
place of batteries1 and numerous        

experiments had  been carried on by ,mr4
 ,watson and myself privately for the   
purpose of  producing this effect4      
,illustration3 ,fig4 #bg4    ,at the    
time the instruments were first         
exhibited in public the results         
obtained with permanent magnets were not
 nearly so striking as when a  voltaic  
battery was employed1 wherefore we      
thought it best to exhibit  only the    
latter form of instrument4    ,the      
interest excited by the first published 
accounts of the operation  of the       
telephone led many persons to           
investigate the subject1 and ,i  doubt  
not that numbers of experimenters have  
independently discovered  that permanent
 magnets might be employed instead of   
voltaic batteries4  ,indeed one         
gentleman1 ,professor ,dolbear1 of      
,tufts ,college1 not only  claims to    
have discovered the magneto-electric    
telephone1 but ,i  understand charges me
 with having obtained the idea from him 
through  the medium of a mutual friend4 

,illustration3 ,fig4 #bh4    ,a still   
more powerful form of apparatus was     
constructed by using a  powerful        
compound horse-shoe magnet in place of  
the straight rod which  had been        
previously used 7see fig4 #bh74 ,indeed 
the sounds produced by  means of this   
instrument were of sufficient loudness  
to be faintly  audible to a large       
audience1 and in this condition the     
instrument was  exhibited in the ,essex 
,institute1 in ,salem1 ,massachusetts1  
on the #abth  ,feb4 #ahgg1 on which     
occasion a short speech shouted into a  
similar  telephone in ,boston1 sixteen  
miles away1 was heard by the audience in
  ,salem4 ,the tones of the speaker's   
voice were distinctly audible to an     
audience of #fjj people1 but the        
articulation was only distinct at a     
distance of about #f feet4 ,on the same 
occasion1 also1 a report of the  lecture
 was transmitted by word of mouth from  
,salem to ,boston1 and  published in the
 papers the next morning4               

,illustration3 ,fig4 #bi4    ,from the  
form of telephone shown in fig4 #bg to  
the present form of  the instrument     
7fig4 #bi7 is but a step4 ,it is in fact
 the arrangement  of fig4 #bg in a      
portable form1 the magnet ,f ,h being   
placed inside  the handle and a more    
convenient form of mouthpiece provided4 
,the  arrangement of these instruments  
upon a telegraphic circuit is shown in  
fig4 #cj4    ,illustration3 ,fig4 #cj4  
,and here ,i wish to express my         
indebtedness to several scientific      
friends in ,america for their           
co-operation and assistance4 ,i would   
specially mention ,professor ,peirce and
 ,professor ,blake1 of ,brown           
,university1 ,dr4 ,channing1 ,mr4       
,clarke1 and ,mr4 ,jones4 ,in           
,providence1  ,rhode ,island1 these     
gentlemen have been carrying on together
  experiments seeking to perfect the    
form of apparatus required1 and  ,i am  
happy to record the fact that they      
communicated to me each new  discovery  

as it was made1 and every new step in   
their investigations4  ,it was1 of      
course1 almost inevitable that these    
gentlemen should  retrace much of the   
ground that had been gone over by me1   
and so it  has happened that many of    
their discoveries had been anticipated  
by  my own researches2 still1 the very  
honourable way in which they from  time 
to time placed before me the results of 
their discoveries entitles  them to my  
warmest thanks and to my highest esteem4
 ,it was always my  belief that a       
certain ratio would be found between the
 several parts of  a telephone1 and that
 the size of the instrument was         
immaterial2 but  ,professor ,peirce was 
the first to demonstrate the extreme    
smallness  of the magnets which might be
 employed4 ,and here1 in order to show  
the parallel lines in which we were     
working1 ,i may mention the fact  that  
two or three days after ,i had          
constructed a telephone of the  portable
 form 7fig4 #bi71 containing the magnet 

inside the handle1 ,dr4  ,channing was  
kind enough to send me a pair of        
telephones of a similar  pattern1 which 
had been invented by the ,providence    
experimenters4 ,the  convenient form of 
mouthpiece shown in fig4 #bi1 now       
adopted by me1 was  invented solely by  
my friend ,professor ,peirce4 ,i must   
also express  my obligations to my      
friend and associate1 ,mr4 ,thomas ,a4  
,watson1 of  ,salem1 ,massachusetts1 who
 has for two years past given me his    
personal  assistance in carrying on my  
researches4    ,in pursuing my          
investigations ,i have ever had one end 
in view1 the  practical improvement of  
electric telegraphy2 but ,i have come   
across  many facts which1 while having  
no direct bearing upon the subject of   
telegraphy1 may yet possess an interest 
for you4#bd    ,for instance1 ,i have   
found that a musical tone proceeds from 
a piece of  plumbago or retort-carbon   
when an intermittent current of         
electricity is  passed through it1 and  

,i have observed the most curious       
audible effects  produced by the passage
 of reversed intermittent currents      
through the  human body4 ,a rheotome was
 placed in circuit with the primary     
wires of  an induction coil1 and the    
fine wires were connected with two      
strips  of brass4 ,one of these strips  
was held closely against the ear1 and a 
loud sound proceeded from it whenever   
the other slip was touched with  the    
other hand4 ,the strips of brass were   
next held one in each hand4  ,the       
induced currents occasioned a muscular  
tremor in the fingers4 ,upon  placing my
 forefinger to my ear a loud crackling  
noise was audible1  seemingly proceeding
 from the finger itself4 ,a friend who  
was present  placed my finger to his    
ear1 but heard nothing4 ,i requested him
 to hold  the strips himself4 ,he was   
then distinctly conscious of a noise    
7which  ,i was unable to perceive7      
proceeding from his finger4 ,in this    
case a  portion of the induced currents 

passed through the head of the observer 
when he placed his ear against his own  
finger3 and it is possible that  the    
sound was occasioned by a vibration of  
the surfaces of the ear and  finger in  
contact4    ,when two persons receive a 
shock from a ,ruhmkorff's coil by       
clasping  hands1 each taking hold of one
 wire of the coil with the free hand1 a 
sound proceeds from the clasped hands4  
,the effect is not produced when  the   
hands are moist4 ,when either of the two
 touches the body of the  other a loud  
sound comes from the parts in contact4  
,when the arm of  one is placed against 
the arm of the other1 the noise produced
 can be  heard at a distance of several 
feet4 ,in all these cases a slight shock
  is experienced so long as the contact 
is preserved4 ,the introduction  of a   
piece of paper between the parts in     
contact does not materially  interfere  
with the production of the sounds1 but  
the unpleasant effects  of the shock are
 avoided4    ,when an intermittent      

current from a ,ruhmkorff's coil is     
passed through  the arms a musical note 
can be perceived when the ear is closely
  applied to the arm of the person      
experimented upon4 ,the sound seems to  
proceed from the muscles of the fore-arm
 and from the biceps muscle4  ,mr4      
,elisha ,gray#be has also produced      
audible effects by the passage of       
electricity through the human body4     
,an extremely loud musical note is      
occasioned by the spark of a            
,ruhmkorff's coil when the primary      
circuit is made and broken with         
sufficient rapidity2 when two rheotomes 
of different pitch are caused           
simultaneously to open and close the    
primary circuit a double tone  proceeds 
from the spark4    ,a curious discovery1
 which may be of interest to you1 has   
been made  by ,professor ,blake4 ,he    
constructed a telephone in which a rod  
of  soft iron1 about six feet in length1
 was used instead of a permanent        
magnet4 ,a friend sang a continuous     

musical tone into the mouthpiece of  a  
telephone1 like that shown in fig4 #bi1 
which was connected with the  soft iron 
instrument alluded to above4 ,it was    
found that the loudness  of the sound   
produced in this telephone varied with  
the direction in  which the iron rod was
 held1 and that the maximum effect was  
produced  when the rod was in the       
position of the dipping-needle4 ,this   
curious  discovery of ,professor ,blake 
has been verified by myself4    ,when a 
telephone is placed in circuit with a   
telegraph line1 the  telephone is found 
seemingly to emit sounds on its own     
account4 ,the  most extraordinary noises
 are often produced1 the causes of which
  are at present very obscure4 ,one     
class of sounds is produced by the      
inductive influence of neighbouring     
wires and by leakage from them1 the     
signals of the ,morse alphabet passing  
over neighbouring wires being  audible  
in the telephone1 and another class can 
be traced to earth  currents upon the   

wire1 a curious modification of this    
sound revealing  the presence of        
defective joints in the wire4           
,professor ,blake informs me that he has
 been able to use the railroad  track   
for conversational purposes in place of 
a telegraph wire1 and  he further states
 that when only one telephone was       
connected with the  track the sounds of 
,morse operating were distinctly audible
 in the  telephone1 although the nearest
 telegraph-wires were at least forty    
feet distant4    ,professor ,peirce has 
observed the most curious sounds        
produced from  a telephone in connection
 with a telegraph wire during the aurora
  borealis2 and ,i have just heard of a 
curious phenomenon lately observed  by  
,dr4 ,channing4 ,in the city of         
,providence1 ,rhode ,island1 there is an
  overhouse wire about one mile in      
extent with a telephone at either end4  
,on one occasion the sound of music and 
singing was faintly audible  in one of  
the telephones4 ,it seemed as if some   

one were practising  vocal music with a 
pianoforte accompaniment4 ,the natural  
supposition  was that experiments were  
being made with the telephone at the    
other  end of the circuit1 but upon     
inquiry this proved not to have been the
  case4 ,attention having thus been     
directed to the phenomenon1 a watch  was
 kept upon the instruments1 and upon a  
subsequent occasion the same  fact was  
observed at both ends of the line by    
,dr4 ,channing and his  friends4 ,it was
 proved that the sounds continued for   
about two hours1  and usually commenced 
about the same time4 ,a searching       
examination of  the line disclosed      
nothing abnormal in its condition1 and  
,i am unable  to give you any           
explanation of this curious phenomenon4 
,dr4 ,channing  has1 however1 addressed 
a letter upon the subject to the editor 
of  one of the ,providence papers1      
giving the names of such songs as were  
recognised1 with full details of the    
observations1 in the hope that          

publicity may lead to the discovery of  
the performer1 and thus afford a        
solution of the mystery4    ,my friend  
,mr4 ,frederick ,a4 ,gower communicated 
to me a curious  observation made by him
 regarding the slight earth connection  
required  to establish a circuit for the
 telephone1 and together we carried on a
  series of experiments with rather     
startling results4 ,we took a couple  of
 telephones and an insulated wire about 
#ajj yards in length into a  garden1 and
 were enabled to carry on conversation  
with the greatest  ease when we held in 
our hands what should have been the     
earth wire1 so  that the connection with
 the ground was formed at either end    
through  our bodies1 our feet being     
clothed with cotton socks and leather   
boots4  ,the day was fine1 and the grass
 upon which we stood was seemingly      
perfectly dry4 ,upon standing upon a    
gravel walk the vocal sounds1  though   
much diminished1 were still perfectly   
intelligible1 and the same  result      

occurred when standing upon a brick wall
 one foot in height1 but  no sound was  
audible when one of us stood upon a     
block of freestone4    ,one experiment  
which we made is so very interesting    
that ,i must speak  of it in detail4    
,mr4 ,gower made earth connection at his
 end of the line  by standing upon a    
grass plot1 whilst at the other end of  
the line ,i  stood upon a wooden board4 
,i requested ,mr4 ,gower to sing a      
continuous  musical note1 and to my     
surprise the sound was very distinctly  
audible  from the telephone in my hand4 
,upon examining my feet ,i discovered   
that  a single blade of grass was bent  
over the edge of the board1 and that  my
 foot touched it4 ,the removal of this  
blade of grass was followed by  the     
cessation of the sound from the         
telephone1 and ,i found that the  moment
 ,i touched with the toe of my boot a   
blade of grass or the petal  of a daisy 
the sound was again audible4    ,the    
question will naturally arise1 ,through 

what length of wire can the  telephone  
be used8 ,in reply to this ,i may say   
that the maximum amount  of resistance  
through which the undulatory current    
will pass1 and yet  retain sufficient   
force to produce an audible sound at the
 distant end1  has yet to be determined2
 no difficulty has1 however1 been       
experienced  in laboratory experiments  
in conversing through a resistance of   
#fj1jjj  ohms1 which has been the       
maximum at my disposal4 ,on one         
occasion1 not  having a rheostat at     
hand1 ,i may mention having passed the  
current  through the bodies of sixteen  
persons1 who stood hand in hand4 ,the   
longest length of real telegraph line   
through which ,i have attempted  to     
converse has been about #bej miles4 ,on 
this occasion no difficulty  was        
experienced so long as parallel lines   
were not in operation4 ,sunday  was     
chosen as the day on which it was       
probable other circuits would  be at    
rest4 ,conversation was carried on      

between myself1 in ,new ,york1  and ,mr4
 ,thomas ,a4 ,watson1 in ,boston1 until 
the opening of business  upon the other 
wires4 ,when this happened the vocal    
sounds were very  much diminished1 but  
still audible4 ,it seemed1 indeed1 like 
talking  through a storm4 ,conversation 
though possible could be carried on with
  difficulty1 owing to the distracting  
nature of the interfering currents4     
,i am informed by my friend ,mr4 ,preece
 that conversation has been             
successfully carried on through a       
submarine cable1 sixty miles in  length1
 extending from ,dartmouth to the       
,island of ,guernsey1 by means of  hand 
telephones similar to that shown in fig4
 #cj4    ,footnotes3    #a ,helmholtz4  
,die ,lehre von dem ,tonempfindungen4   
7,english  ,translation by ,alexander   
,j4 ,ellis1 ,theory of ,tone47    #b ,c4
 ,g4 ,page4 8,the ,production of        
,galvanic ,music40 ,silliman's ,journ4  
#ahcg1 xxxii4 p4 #cif2 ,silliman's      
,journ4 ,july1 #ahcg1 p4 #ced2          

,silliman's  ,journ4 #ahch1 xxxiii4 p4  
#aah2 ,bibl4 ,univ4 7new series71 #ahci1
 ii4 p4 #cih4    #c ,j4 ,p4 ,marrian4   
,phil4 ,mag4 xxv4 p4 #chb2 ,inst4 #ahde1
 p4 #bj2 ,arch4  de l'lectr4 v4 p4 #aie4
    #d ,w4 ,beatson4 ,arch4 de l'lectr4 
v4 p4 #aig2 ,arch4 de ,sc4 ,phys4 et    
,nat4 7#b;d series71 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 ,arch4 de l'lectr4 v4 p4
 #bjj2 ,inst4 #ahdf1 p4 #hc2 ,comptes   
,rendus1 xx4 p4 #abhg2 ,comp4 ,rend4    
xxii4 p4 #dcb2 ,pogg4 ,ann4 lxxvi4 p4   
#fcg2 ,ann4 de ,chim4 et de ,phys4 xxvi4
 p4 #aeh4    #g ,matteucci4 ,inst4      
#ahde1 p4 #cae2 ,arch1 de l'lectr4 v4   
#chi4    #h ,guillemin4 ,comp4 ,rend4   
xxii4 p4 #bfd2 ,inst4 #ahdf1 p4 #cj2    
,arch4 d4  ,sc4 ,phys4 7#b;d series71 i4
 p4 #aia4    #i ,g4 ,wertheim4 ,comp4   
,rend4 xxii4 pp4 #ccf1 #edd2 ,inst4     
#ahdf1 pp4 #fe1  #ajj2 ,pogg4 ,ann4     

lxviii4 p4 #adj2 ,comp4 ,rend4 xxvi4 p4 
#eje2 ,inst4 #ahdh1  p4 #adb2 ,ann4 de  
,chim4 et de ,phys41 xxiii4 p4 #cjb2    
,arch4 d4 ,sc4 ,phys4 et  ,nat4 viii4 p4
 #bjf2 ,pogg4 ,ann4 lxxvii4 p4 #dc2     
,berl4 ,ber4 iv4 p4 #aba4    #aj ,elie  
,wartmann4 ,comp4 ,rend4 xxii4 p4 #edd2 
,phil4 ,mag4 7#c;d series71  xxviii4 p4 
#edd2 ,arch4 d4 ,sc4 ,phys4 et ,nat4    
7#b;d series71 i4 p4 #dai2  ,inst4      
#ahdf1 p4 #bij2 ,monatscher4 d4 ,berl4  
,akad4 #ahdf1 p4 #aaa4    #aa ,janniar4 
,comp4 ,rend1 xxiii4 p4 #cai2 ,inst4    
#ahdf1 p4 #bfi2 ,arch4 d4  ,sc4 ,phys4  
et ,nat4 7#b;d4 series71 ii4 p4 #cid4   
#ab ,j4 ,p4 ,joule4 ,phil4 ,mag4 xxv4   
pp4 #gf1 #bbe2 ,berl4 ,ber4 iii4 p4     
#dhi4    #ac ,laborde4 ,comp4 ,rend4 l4 
p4 #fib2 ,cosmos1 xvii4 p4 #ead4    #ad 
,legat4 ,brix4 ,z4 ,s4 ix4 p4 #abe4     
#ae ,reis4 8,tlphonie40 ,polytechnic    
,journ4 clxviii4 p4 #ahe2  ,bttger's    
,notizbl4 #ahfc1 ,no4 #f4    #af ,j4 ,c4
 ,poggendorff4 ,pogg4 ,ann4 xcviii4 p4  
#aib2 ,berliner  ,monatsber4 #ahef1 p4  

#acc2 ,cosmos1 ix4 p4 #di2 ,berl4 ,ber4 
xii4 p4 #bda2  ,pogg4 ,ann4 lxxxvii4 p4 
#aci4    #ag ,du ,moncel4 ,expos1 ii4 p4
 #abe2 also1 iii4 p4 #hc4    #ah        
,delezenne4 8,sound produced by         
,magnetization10 ,bibl4 ,univ4 7new     
series71 #ahda1 xvi4 p4 #djf4    #ai    
,see ,london ,journ4 xxxii4 p4 #djb2    
,polytechnic ,journ4 ex4 p4 #af2        
,cosmos1 iv4 p4 #dc2 ,glsener--,trait   
gnral1 c4 p4 #cej2 ,dove4-,repert4  vi4 
p4 #eh2 ,pogg4 ,ann4 xliii4 p4 #daa2    
,berl4 ,ber4 i4 p4 #add2 ,arch4 d4  ,sc4
 ,phys4 et ,nat4 xvi4 p4 #djf2 ,kuhn's  
,encyclopdia der ,physik1 pp4           
#ajad-ajba4    #bj ,gore4 ,proceedings  
of ,royal ,society1 xii4 p4 #bag4    #ba
 ,c4 ,g4 ,page4 8,vibration of          
,trevelyan's bars by the galvanic       
current40 ,silliman's ,journal1 #ahej1  
ix4 pp4 #aje-ajh4    #bb ,sullivan4     
8,currents of ,electricity produced by  
the vibration of  ,metals10 ,phil4 ,mag4
 #ahde1 p4 #bfa2 ,arch4 de l'lectr4 x4  
p4 #dhj4    #bc ,the full description of

 this figure will be found in ,mr4      
,alexander  ,j4 ,ellis's translation of 
,helmholtz's work1 8,theory of ,tone40  
#bd ,see ,researches in                 
,telephony4--,trans4 of ,american ,acad4
 of ,arts  and ,sciences1 vol4 xii4 p4  
#a4    #be ,elisha ,gray4 ,eng4 ,pat4   
,spec4 ,no4 #bfdf1 ,aug4 #ahgd4         
,,useful ,,books ,,on ,,telegraphy1 c4  
,just published1 ,parts ,,xiii4 and     
,,xiv41 in one vol4                     
demy #hvo1 sewed1 #es4                  
,journal of the ,society of ,telegraph  
,engineers1               ,,including   
,,original ,,communications ,,on        
,,telegraph ,,and                       
,,electrical ,,science4                 
,edited by ,major ,,frank ,,bolton and  
,j4 ,,sivewright4                       
,to be continued quarterly4             
99       99       99       99       99  
#hvo1 cloth1 #is4               ,reports
 of the ,committee on ,electrical       
,standards                  appointed by
 the ,british ,association4             

,revised by ,sir ,w4 ,,thomson1 ,dr4 ,j4
 ,p4 ,,joule1                           
,professors ,,clark1 ,,maxwell1         
and ,,fleeming ,,jenkin4     ,with a    
,report to the ,royal ,society on ,units
 of ,electrical ,resistance1            
by ,professor ,f4 ,jenkin4              
,edited by ,professor ,,fleeming        
,,jenkin1 ,f4,r4,s4                     
,plates4                       99       
99       99       99       99           
,small fol41 boards1 #bs4 #f;d4         
,experimental ,investigation of the     
,laws which govern                the   
,propagation of the ,electric ,current  
in                          ,long       
,telegraph ,cables4                     
,by ,,latimer ,,clark4                  
99       99       99       99       99  
,fcap4 #hvo1 cloth1 #es4                
,a ,handbook of ,electrical ,testing4   
,by ,h4 ,r4 ,,kempe1                    
,assoc4 of the ,society of ,telegraph   
,engineers4                       99    
99       99       99       99           

#hvo1 cloth1 #ahs4                      
,electricity and the ,electric          
,telegraph4                             
,by ,,geo4 ,b4 ,,prescott4              
,with #ejd ,woodcut ,illustrations4     
99       99       99       99       99  
#abmo1 cloth1 #cs4 #f;d4                
,memorials1 ,scientific and ,literary1  
of ,andrew ,crosse1 the ,electrician4   
99       99       99       99       99  
,crown #hvo1 cloth1 #hs4                
,electricity3 its ,theory1 ,sources1 and
 ,applications4                         
,by ,,john ,t4 ,,sprague1               
,member of the ,society of ,telegraph   
,engineers              ,with           
,ninety-one ,woodcuts and ,thirty       
valuable ,tables4                       
99       99       99       99       99  
#hvo1 cloth1 #is4                ,modern
 ,practice of the ,electric ,telegraph4 
,by ,,frank ,l4 ,,pope4                 
,third ,edition1 with numerous ,wood    
,engravings4                       99   
99       99       99       99           

,crown #hvo1 cloth1 #abs4 #f;d4         
,electrical ,tables and ,formul for the 
,use of                   ,telegraph    
,inspectors and ,operators4             
,compiled by                            
,,latimer ,,clarke and ,,robert         
,,sabine4                               
,with ,wood ,engravings4                
99       99       99       99       99  
#cbmo1 roan1 #fs42 interleaved with     
ruled paper for office use1 #is42       
printed on ,india paper for the         
waistcoat pocket1 #fs4                ,a
 ,pocket ,book of ,useful ,formul and   
,memoranda                   for ,civil 
and ,mechanical ,engineers4             
,by ,,guildford ,l4 ,,molesworth1       
,mem4 ,inst4 ,c4,e41 ,consulting        
,engineer to the                        
,government of ,india for ,state        
,railways4              ,revised1 with  
considerable ,additions by the ,author2 
together with a valuable contribution on
                        ,telegraphs by  
,r4 ,s4 ,,brough4                       

,,synopsis ,,of ,,contents4             
,surveying1 ,levelling1 etc4            
,strength and ,weight of ,materials4    
,earthwork1 ,brickwork1 ,masonry1       
,arches1 etc4            ,struts1       
,columns1 ,beams1 and ,trusses4         
,flooring1 ,roofing1 and ,roof ,trusses4
            ,girders1 ,bridges1 etc4    
,railways and ,roads4                   
,hydraulic ,formul4            ,canals1 
,sewers1 ,waterworks1 ,docks4           
,irrigation and ,breakwaters4           
,gas1 ,ventilation1 and ,warming4       
,heat1 ,light1 ,colour1 and ,sound4     
,gravity--,centres1 ,forces1 and        
,powers4            ,millwork1 ,teeth of
 ,wheels1 ,shafting1 etc4               
,workshop ,recipes4            ,sundry  
,machinery4            ,animal ,power4  
,steam and the ,steam ,engine4          
,water-power1 ,water-wheels1 ,turbines1 
etc4            ,wind and ,windmills4   
,steam ,navigation1 ,ship ,building1    
,tonnage1 etc4            ,gunnery1     
,projectiles1 etc4            ,weights1 

,measures1 and ,money4                  
,trigonometry1 ,conic ,sections1 and    
,curves4            ,telegraph4         
,mensuration4            ,tables of     
,areas and ,circumference1 and ,arcs of 
,circles4            ,logarithms1       
,square and ,cube ,roots1 ,powers4      
,reciprocals1 etc4            ,useful   
,numbers4            ,differential and  
,integral ,calculus4                    
,algebraic ,signs4                      
,telegraphic ,construction and ,formul4 
99       99       99       99       99  
,fcap4 #hvo1 cloth1 #as4 #f;d4          
,electro-,telegraphy1                   
,by ,,frederick ,s4 ,,beechey1          
,telegraph ,engineer4                   
,a ,book for ,beginners4                
99       99       99       99       99  
,crown #hvo1 cloth1 #ds4 #f;d4          
,guide for the ,electric ,testing of    
,telegraph ,cables1                     
,by ,captain ,v4 ,,hoskl,r4             
,plates4                                
,,contents4                    ,the     

,conductivity of the ,copper4           
,the ,charge of the ,cable4             
,insulation of the ,cable4              
,insulation of a ,joint4                
,the ,situation and ,greatness of a     
,fault4                    ,testing and 
,laying of a ,cable4                    
,formul1 ,tables1 etc4                  
99       99       99       99       99  
,london3                    ,e4  ,f4 ,n4
 ,,spon1 #df1 ,,charing ,,cross4        
,,new ,,york3 #ddf1 ,,broome ,,street4