626 
Proceedings of the Royal Society 
ear. By attentive listening a faint ticking is heard, and if we wish 
to hear it without strain we must add another cell or two to the 
battery. The sounds emitted by the coil are very faint, and cannot 
be excited by the voice or even a tuning-fork. With small battery 
power the coil may be made to sound, but with a strong battery it 
may be heard at some distance from the ear. Thus the coil which 
we thrashed almost to death to send a message receives one without 
demur. W e now insert in the coil a piece of soft iron, and we have 
a duet of two undistinguishable ticks, the principal part being per- 
formed by the iron. Here again the receiving action is immensely 
better than the sending, and leads us to suspect that our rough efforts 
to send were mere bungling, due to our ignorance of the right way 
to do it. If now we bring a magnet and place the soft iron pin on 
its pole, or screw it into the pole, a sudden bound is made in the 
loudness of the sound, and with the one cell water current we can 
hear a few inches off. Whatever vibrations were effected in the 
pin by itself now grow immensely more pronounced when it is made 
magnetic. We may now replace the coil in its core in the 
telephone, for our arrangement is nothing else than a telephone with- 
out a disc. The sending and receiving powers are now more nearly 
on a par, for we found that the gentle tap of a pencil can now be 
sent. Let us now, in imitation of Professor Tait and Mr Blyth’s 
experiments, put a piece of glass or pasteboard, or wood or other 
non-conducting substance, on the core. The sound waxes thereby 
louder, as was explained by the plate acting as an ordinary resonator. 
Lift any one of these the smallest thing from the core, and it acts as 
a dead wall to stop the sound of the core. In place of these, let us 
take a series of conducting metal plates of lead, German silver, 
copper, and silver, all equally thick and as nearly as possible of 
the same temper. When we place one of these on the core we hear 
the same resonance as in the non-conductor, but we also perceive 
what appears to be a new and separate action set up by the plate on 
its own account, and as we change from disc to disc we find that 
the sound grows with the conductivity of the plate till we reach 
silver, which is very audible. When now we put an iron disc of 
similar size and temper, a sound is heard which completely eclipses 
the loudest of the others. All these discs when held slightly away 
from the core sound louder than when touching it, and the cul- 
