Note 8 — BATTERY TELEPHONES.

M. M. J. Page had already noticed that if a telephone is placed in the circuit of the primary helix of an induction coil, while the secondary helix of this instrument is placed in the circuit of one of M. Lippmann’s capillary electrometers, a movement of the mercurial column of the electrometer takes place at each word, and this movement is effected towards the capillary end of the tube, in whatever direction the current is sent by the telephone. This is because the mercury always tends to move more rapidly at its capillary end than at the other extremity.