Aug. 24, 1876] 



NATURE 



353 



TELEPHONES AND OTHER APPLICATIONS 

 OF ELECTRICITY 



IN a recent number we gave some account of the 

 telephone of Mr. Ehsha Gray; in the present article 

 we propose to refer to another form of this instrument, as 

 also to the so-called electric telegraph without conductors, 

 and its relation to electric tuning-forks. For our infor- 

 mation, as well as for the illustrations, we are indebted to 

 papers by M. Ch. Bontemps, in our French contemporary. 

 La Nahwe. To begin with the last-mentioned applica- 

 tion of electricity. 



For this new process of telegraphy it is claimed that we 

 may communicate with any person at any distance with- 

 out having taken the precaution of previously establish ing 

 a continuous wire between the two stations. 



M. Bourbouze, in 1870, in continuation of previous 

 experiments, attempted at Paris to utilise the Seine as a 

 conductor between two stations, the Jena and Austerlitz 

 bridges. This attempt, if successful, would then have 

 been of great practical value, as it would have enabled 

 besieged Paris to communicate with the outside world. 

 An electric pile placed on the Jena bridge sent alternative 

 currents to Austerlitz bridge. These currents were re- 

 ceived in a galvanometer invented by M. Bourbouze, and 

 read by the oscillation of the needle to right or left. The 

 experiment appeared successful ; the elements of a lan- 

 guage were proved in this attempt. There was no oppor- 

 tunity, however, of further testing its utility ; a mission 

 was organised for the purpose of establishing a station 

 beyond the lines, but ere it could be carried out the 

 armistice rendered further experiment unnecessary. M. 

 Bourbouze tas, however, again taken the matter up ; but 

 it is necessary to be on our guard against cherishing 

 hopes which seem premature. 



M. de Parville points out very well the objection which 

 common sense suggests, " Suppose," he says, " that we 

 should all wish to speak by this means from one end of a 

 city to the other. Each possesses his talking-needle and 

 his pile. Each needle goes marching ceaselessly to right, 

 to left, obeying everybody at once. It will speak for all 

 correspondents at the same time. Messages will get en- 

 tangled and completely mixed up. Here is a new Tower of 

 Babel, We won't be able any longer to understand each 

 other. The electric wire of the ordinary telegraph, on the 

 contrary, serves as a track of union, and shuts the door to 

 indiscretions. Thus, yes, we may communicate to a 

 distance without a wire ; no, we should not be able to 

 supply by this new system, since we should find ourselves 

 in the condition of a crowd speaking at once miscellane- 

 ously, without being able to make itself understood. For 

 the new system to become applicable, it would be neces- 

 sary to find the means of giving to each ciirrent an indi- 

 viduality which would enable a correspondent to recognise 

 it among the thousands of currents which may circulate 

 at one time. We have no right to doubt the future, and 

 we may hope that some day such a means will be dis- 

 covered ." 



In this connection let us explain the remarkable work 

 of a Danish engineer, M. Paul Lacour. How can we give 

 to each current an individuality which will enable us to 

 recognise it ? 



When we consider the most common acoustical pheno- 

 mena, for example, the transmission of an air played by 

 an orchestra, which is perceived by all the audience at 

 considerable distances from the executants, we have some 

 difficulty in analysing this effect. Physics tells us that 

 the sounds produced by each instrument have their 

 proper tone and their distinct measure ; in other words, 

 the notes which come from a violin, a flute, a trombone, 

 correspond to different vibrations transmitted by the 

 atmosphere and characteristic of each note. Besides, 

 the rhythm in the succession of the notes, which makes 

 the measure in music, produces the cadence, constituting 



with the tonality and the timbre of the instruments the 

 general effect of the air which impresses itself upon us. 

 The transmission is so precise that an ear detects in this 

 assembly of performers a mistimed note, anything out of 

 tune in the midst of the harmony of the air. In our ex- 

 position it is the mistimed note which will serve us as a 

 landmark. 



Suppose a series of three tuning-forks vibrating con- 

 tinuously and producing — the first, 100 vibrations per 

 second ; the second, 300 ; and the third, 500. It is easy 

 to conceive that each of these tuning-forks may interrupt 

 and establish an electric current with intermissions regu- 

 lated by the number of its vibrations. If we have three 

 tuning-forks identical with the three former, we can con- 

 ceive each group to be placed at the extremity of an 

 electric hne serving as a medium of connection. We 

 shall see reproduced the phenomenon of the musical air 

 transmitted to a distance : the three transmitting tuning- 

 forks act respectively on the three receiving forks by 

 means of the medium which connects them. 



Let us admit, meantime, that by an effort of the will we 

 may either set a-going or stop any one of these tuning- 

 forks in accordance with a cadence that will not neces- 

 sarily coincide with its regular action, we shall find at the 

 other extremity in the symmetry of the perturbed instru- 

 ment, the same discordant manifestations. The mis- 

 timed note will be as faithfully transmitted as the har- 

 monic vibrations. The bearing of a practical realisation 

 of this conception will be easily understood ; it opens the 

 way to the indefinite multiplication of diverse transmis- 

 sion by the same conductor ; it is also the germ of a 

 solution of transmission by multiple conductors, with the 

 power of individualising each current. 



Fig. I. — Transmitting tuning-fork. 



What is necessary to the fulfilment of this condition ? 

 I, It is necessary to construct tuning-forks whose move- 

 ment is maintained by an electric current ; this problem 

 has been solved. 2. It is necessary that these forks emit 

 currents whose phases correspond exactly with their 

 movement, a problem which has also been solved. 3, 

 Finally, we must be able, in a very small interval of time, 

 say one second, to arrest and put in action a great number 

 of times (100 at least) each of these forks. This last point 

 is the only one which presents any difficulty. We see 

 that this difficulty is only a problem of construction ; it is 

 necessary to operate with very small masses in order easily 

 to overcome inertia. The success of M, Marcel Deprez 

 authorises us in thinking that the third condition may be 

 realised. 



We shall conclude this part of the subject by a reference 

 to figures. We shall show how a diapason vibrating con- 

 tinuously can send currents of the same intermittence 

 along an electric line. Fig. i represents the necessary 

 apparatus. The arm n of the tuning-fork encounters 

 alternately the platinum of the tongue c, whose opening 

 is regulated by the screw v. A current entering by 4 is 

 closed every time that the extremity « touches the slip c, 

 and is opened when the vibration of the tuning-fork is 

 away from the extremity ny there is only required for this 

 that by the wire /j issuing by the exterior conductor, the 

 line, there be propagated a series of electric undulations 

 reproduced exactly in the material vibrations of the arm 

 of the tuning-fork. 



We have, however, to show how we can determine and 

 mark the character of an intermittent current arriving by 

 the telegraphic wire. Fig. 2 represents the arrangement 



