of Edinburgh , Session 187B-79. 
45 
Monday , January 1879. 
Professor KELLAND, President, in the Chair. 
The following Communications were read 
1. Notes on some Experiments with the Telephone. 
By James Blyth, M.A. 
While experimenting with an ordinary Bell telephone, of small 
resistance, I found that it was able to reveal the existence of electric 
currents produced by the mere friction between conducting substances. 
This was shown in the following way. Two files had wires firmly 
connected to them, and were thereby attached to the terminals of 
a telephone circuit in a distant room. When these files were 
rubbed against each other, a most distinct grating noise was heard in 
the receiving telephone. In order to find if this sound varied, 
when different substances were rubbed together, the following plan 
was adopted. A wire was firmly attached to a small table-vice, 
and led to one of the terminals of the telephone circuit, while the 
wire from the other terminal was attached to a clamp into which 
any substance, which it was desired to test, could be screwed. 
Different substances were then screwed into the vice and clamp, and 
rubbed against each other by an assistant, in each case, as far as 
possible, with the same pressure. By listening attentively in the 
receiving telephone, I endeavoured to detect any variation in the 
sound as the assistant passed from one substance to another. 
As far as I could judge, little or no variation was produced when 
the following substances were rubbed on themselves and on each 
other, viz. : steel, brass, iron, zinc, lead, gas carbon, copper, with 
possibly the exception of copper on iron, which, I thought, gave the 
sound a little louder. 
It was different, however, when two pieces of antimony and 
bismuth were rubbed together. In this case the sound was de- 
cidedly louder. I tried also, with a very distinct effect, antimony 
rubbing on gold, and antimony on silver. 
VOL. x. 
G 
