616 
Proceedings of the Royal Society 
the beautiful and successful demonstration of the action of the 
phonograph, both by Professor Fleeming Jenkin. In the former of 
these, as we learned, one end of a thread was attached to the one 
side of the light suspended coil of a Thomson ink recorder, and the 
other to the paper disc of an ordinary mechanical telephone. This 
was done at the two communicating stations. When the sending 
disc was agitated by the voice, the coil to which it was attached 
twisted round in the powerful and uniform magnetic field in which 
it was placed, and dispatched corresponding electric current waves 
to the receiving instrument, the coil of which was thereby moved 
similarly in its field, and transferred its motion to its paper disc. 
A more beautiful manipulation of an exquisitely designed and 
executed apparatus it is not easy to conceive. In the phonograph 
we have as it were a mechanical telephone, with the string connect- 
ing the discs cut, and nothing left of it but the two ends stiffened 
into pricking pins. Instead of the sending disc dealing directly 
with the receiving one, its energy is employed in imprinting, by 
means of the pricker, its vibrations on the tinfoil, and this imprint, 
when again vivified by the energy of the rotating drum, reproduces 
the vibrations which originally stamped it. 
After two such demonstrations, it may be held as proved that the 
electric telephone is equivalent to a mechanical telephone with an 
electro-magnetic intervening action instead of a mechanical one. It 
seems therefore a hopeless task to seek for indications of molecular 
action where mechanical action declares itself so manifestly. The 
mechanical action of the voice and of the membrane of the tympanum 
of the ear is above question, and that mechanical vibrations are dealt 
to the sending instrument, and emitted by the receiving one, is equally 
undoubted; but the intervening electric agency, how generated in 
the one and how transformed in the other, is a fair field for discus- 
sion. The action is novel, and it is surely a likely inquiry to inves- 
tigate whether its explanation by the first principle that comes to 
hand, viz., the push-and-pull of the discs, fully covers the case. 
The question may be raised, for instance, whether the mere impact 
of the waves of air on the iron disc may not affect its magnetic 
condition by internal change or vibration,* so as to excite currents 
without vibrations of the push-and-pull kind, or whether in 
* Something like this was suggested hy Professor Forbes. 
