of Edinburgh, Session 1877-78. 
707 
Monday, 3 d June 1878. 
Sir C. WYVILLE THOMSON, Vice-President, in the Chair. 
The following Communications were read : — 
1. On the Splitting up of Electric Currents, as detected by 
the Telephone, and the founding thereon of a Sounder to 
call attention from one Telephone to another. By R. H. 
Bow, C.E. 
The telephone is of no use as a “ far-speaker,” without some 
means of calling the attention of the attendant at the distant 
station. Nothing could well he better than the “ electric-hell call,” 
and the sounder which I am about to describe makes no preten- 
sions of competing with the bell, except on the points of simplicity, 
cheapness, and facility of use ; and although its employment is 
limited to short length lines, it may be assumed that it is upon 
short length lines that the telephone will be most frequently used. 
I have had this sounder in experimental use for more than three 
months, and have shown it to many persons as a very obvious 
expedient. However, as it does not appear to have been referred 
to in any publication, I venture to bring it as a Note before the 
Society; it is of too trilling a nature to he made the subject of a 
formal paper. 
In any of the sounders I have seen described, the battery, or 
other source of electrical excitement, has been placed in simple 
circuit with the pair of telephones, or put into circuit with the 
distant one. In the proposed method of sounding, by means of a 
galvanic battery, the battery is kept separate, and, when used, the 
short wire from the one electrode is rested against one of the wires 
of the telephone, while the wire from the other electrode is slid 
with a very gentle vibrating touch upon the other wire leading from 
the telephone. On the well-known principle of derived currents , 
we know that the greater portion of the electricity will pass through 
the shorter or less resisting circuit of the nearer telephone, and yet 
that there will be a not inconsiderable portion diverted to travel round 
by the distant one ; and this, if the distance be not very great, and 
