354 



NATURE 



\Aug. 24, 1876 



of the intermediate station traversed by the line L L ; 

 A, B, C are three tuning-forks similar to those of the 

 transmitting station. The fork B, for example, which is in 

 unison with the current, v/ill enter into vibration while the 

 others remain mute. This fork B will then touch the 

 platinum tongue (shown in Fig. 3), and there will be estab- 

 lished in the circuit bb' 2^ local current of the pile u 

 whose poles are applied respectively to a, b, c, and to 

 a', b', d. This local current will be intermittent in pro- 





Fig. 2.— Intermediate station. 



portion to the time of the tuning-fork, but on account of 

 the rapidity of the pulsations it will shoiv itself in many 

 cases as a constant current either by etifecting chemical 

 decomposition, by causing the deviation of an electric 

 needle, or by energising an electro-magnet. 



Fig, 3 shows the arrangement which has been estab- 

 lished to produce interruptions for correspondence by 

 means of the regulated vibrations of the tuning-fork. The 



4©-^ 



Fig. 3. — Manipulator. 



manipulator C, which can oscillate around a central axis, 

 rests sometimes on c sometimes on c". Acording as the 

 lever c is supported on c' or <r", it closes the circuit of the 

 intermittent current emitted by the tuning-fork, either by 

 the earth of the transmitting station or by the earth of 

 the receiving station, after traversing the guiding wire. 



It would seem, then, that the only objection to the 

 practical realisation of the system of multiplying corre- 



spondence in one or more directions, lies in the greater or 

 less facility with which a tuning-fork can be stopped and 

 put in action ; it is a question of mass, and cunning 

 fingers will certainly some day devise for us apparatus 

 sufficiently small to realise this desideratum. 



With regard to the telephone, an instrument allied in 

 some respects to the apparatus above referred to, we shall 

 specially refer here to that which bears the name of M. 

 Reuss. For an account of Mr. Gray's instrument, see 

 vol. xiv., p. 30. The arrangement adopted 

 by M, Reuss will be seen in Figs. 4 and 5 — 

 the former representing the transmitting appa- 

 ratus, and the latter the receiving apparatus. 



At the station at which the musical air is 

 played (Fig. 4) a wide tube T issuing from a 

 box K receives the vibrations of air produced 

 by the instrument. The purpose of the box 

 is to collect and strengthen the sound. On 

 the upper part is stretched a membrane w, 

 which vibrates in unison with the impulses it 

 receives. To transform the movements of this 

 membrane into the harmonious emissions and 

 interruptions of an electric current, it is suffi- 

 cient to establish a series of connections easy 

 to conceive. 



Suppose that a pile, one of whose poles is 

 the earth, is attached by the other electrode 

 to a handle marked 2 in Fig. 4 ; from this 

 a metaUic conductor formed by a thin plate 

 of copper / and ending in a disc of platinum o, leads 

 the current in front of a point borne by the lever 

 a be. Every time that the membrane m is raised, the 

 point touching the disc, the current will be established ; 

 on the other hand it will be broken when the membrane 

 returns to its normal state. The box K is represented cut 

 away at the upper part in order to show the arrangement 

 of the membrane and the electric communication which 

 repeats the vibrations. In order to transmit 

 to any distance 100, 200, 500 kilometres the 

 electric current, it is necessary that a line 

 should issue from the knob i (Fig. i), and be 

 attached to knob 3 (Fig. 2, which represents 

 the receiving apparatus). The latter is formed 

 by an iron rod d d, around which is rolled 

 insulated copper wire, one extremity of which 

 ends at the knob 3, and the other in the earth 

 by the screw 4, for the purpose of completing 

 the circuit of the pile of the issuing station. 

 The rod, dd, is of the size of a knitting-needle ; 

 the coil, ^, formed by the combined wire and 

 rod, is supported on a box, B, having very 

 thin sides ; above is the lid, D. The object 

 of the whole arrangement is to strengthen the 

 vibrations which are produced by the succes- 

 sive interruptions of the current across the 

 rod, dd. 



What is noteworthy in this system is that 

 the vibrations of the rod, d d, are exactly 

 synchronous with those of the membrane, in, 

 and consequently with those of the instru- 

 ment, the air from which has been played in 

 the tub, T. Not only is the measure indi- 

 cated, but the tonality as well, the two ele- 

 ments which make up the melody, height of 

 sound, and interval of notes, all is reproduced 

 automatically without possibility of error. 

 To complete the description, we must add 

 that there is on Fig. i, a lever, is, and an electro-magnet, 

 E E, the ordinary appendages of a Morse telegraph. Also 

 on Fig. 2 is seen the manipulatory lever ; there is also a 

 receiver, not represented in the figure. 



In order to appreciate the full value of the telephone, 

 it is necessary to examine the form given to the box, K ; 

 the best arrangement hitherto discovered consists in 

 bending the sides so as to amplify the effect on the mem- 



