368; Prof. Hughes on the Action of Sonorous Vibrations. [May 9, 



diameter. In it are four separate pieces of willow charcoal, each one 

 quarter of an inch long, and two terminals of the same material. The 

 terminals are fastened in the tube, and connect exteriorly with the line 

 and interiorly with the four loose pieces, thus:-— 



Here A is made to press on B, C, D, E, F, and Gr, until the resist- 

 ance offered to the electrical current is about one-third that of the 

 line upon which it is to be employed. It may be attached to a resonant 

 board by the ends A or Gr. If the result was simply due to vibrations, 

 we should have A and B making greater contact at a different time 

 from F and G, and consequent interference. If it was a simple 

 shaking or moving of B, C, D, E, and F, it could produce no change, 

 as if B pressed more strongly on 0, it would be less on A, and also if 

 the tube was attached by the centre we should have no effect ; but if 

 the effect is due to a swelling or enlargement of B, C, D, E, F, it 

 would make no difference where it is attached to the resonant board, 

 as is actually the case. Again reduce the pressure of A upon B, &c, 

 until they are not in contact, and no trace of current can be perceived 

 by shaking the tube. The instant the sonorous vibrations pass in the 

 tube there is electric contact to a remarkable degree, which could only 

 have taken place by the molecules enlarging their sphere under the 

 influence of the sonorous vibrations. 



It is impossible to say what can be the applications or the effects of 

 the discovery which I have had the honour of bringing before the 

 Royal Society, for the whole question has been studied with crude 

 materials, and scarcely sufficient time has elapsed to enable me to con- 

 sider its ultimate uses. I do not desire to assert that there is any- 

 thing in what I have brought forward that is superior to or equal to 

 other transmitters used for telephony. It is as loud and far more 

 sensitive than any I have yet heard, and it may be increased by multi- 

 plication of transmitting contacts in quantity or intensity ; the loud- 

 ness is at present limited by the capability of the receiver. The mate- 

 rials at my disposal, and the arrangement of them, have not yet been 

 sufficiently studied. I only wished to show that it is possible to 

 transmit clear and intelligent articulate speech, and to render audible 



