Take a rod of metal, and connect the two points A and B with a galvanometer by means of non-polarisable electrodes. (Fig 1, a.) If the point O is struck, a wave of molecular disturbance will reach A and B. It will be shown that this is attended by a wave of electric disturbance. The mechanical and the attendant electrical disturbance will reach a maximum and then gradually subside. The resultant effect on the galvanometer will be due to EA - EB where EA and EB are the electric variations produced at A and B. The electric changes at
A and B will continuously balance each other, and the resultant effect on the galvanometer will be zero, (1) if the mechanical disturbance reaches A and B at the same time and with the same intensity, (2) when the molecular condition is similar at the two points, and (3) when the rate of rise and subsidence of disturbance is the same at the two
- ↑ A preliminary account of this investigation was given in a paper "On Response in Inorganic Substances," read before the Society, June 6, 1901.