POSSIBILITIES OF THE TELEPHONE.


The meeting of the American Association was one of unusual interest and
importance to the members of Section B. This is to be attributed not only
to the unusually large attendance of American physicists, but also to the
presence of a number of distinguished members of the British Association,
who have contributed to the success of the meetings not only by presenting
papers, but by entering freely into the discussions. In particular the
section was fortunate in having the presence of Sir William Thomson, to
whom more than to any one else we owe the successful operation of the
great ocean cables, and who stands with Helmholtz first among living
physicists. Whenever he entered any of the discussions, all were benefited
by the clearness and suggestiveness of his remarks.

Professor A. Graham Bell, the inventor of the telephone, read a paper
giving a possible method of communication between ships at sea. The simple
experiment that illustrates the method which he proposed is as follows:
Take a basin of water, introduce into it, at two widely separated points,
the two terminals of a battery circuit which contains an interrupter,
making and breaking the circuit very rapidly. Now at two other points
touch the water with the terminals of a circuit containing a telephone. A
sound will be heard, except when the two telephone terminals touch the
water at points where the potential is the same. In this way the
equipotential lines can easily be picked out. Now to apply this to the
case of a ship at sea: Suppose one ship to be provided with a dynamo