of Edinburgh, Session 1877-78. 
711 
one-third of an ohm, in place of the twenty or thirty ohms when the 
coil is made up of 180 feet of the much finer wire. 
I have had no opportunity of satisfactorily testing the limits to 
which the sounder is restricted, but it would probably work well 
enough when the resistance did not exceed ten or fifteen ohms per 
Daniell cell. A marked advantage is usually found to attend the 
sending of the currrent in that direction, which increased the power 
of the magnets of the telephones. And in using the sounder a little 
skill will elicit a considerably augmented effect. 
The principle of split currents may be applied to other purposes ; 
it might offer a ready method of communicating with two adjoining 
stations on a railway from any intermediate point — that is to say, 
at any point between the two extreme telephones we could attach a 
battery or a telephone for sounding to, or communicating with, the 
attendants at the extreme telephones ; or, if a battery be permanently 
included anywhere in the circuit, a wire alone, at any point on the 
line, offers the means of sounding the telephones at both stations, 
the wire being so used as to form an intermittent connection 
between the earth and the telephone line ; and this might perhaps 
be practicable even from a train in motion, the engine and rails 
taking part in the earth connection. 
2. An Account of some Experiments on the Telephone and 
Microphone. By James Blyth, M.A. 
Dr M £ Kendrick stated, that by applying the microphone or 
carbon-interrupter of Hughes to the membrane of a phonograph, he 
had succeeded in using the latter as a transmitting instrument. 
With such an arrangement, speech could be heard in the distant 
telephone even after it had become inaudible near the phonograph. 
He also mentioned that a tambour of Marey, used in physiological 
experiments, spoke distinctly when the fine point at the end of the 
lever was applied to the marks on the tinfoil of the phonograph. 
When a tube was carried from the tambour to the ear, distinct 
speech could be obtained from phonographic tracings on copper foil, 
which were scarcely perceptible to the eye. This method also got 
rid of the difficulty of having the tinfoil impressions quickly rubbed 
out, as happened when the stillette of the phonographic membrane 
