Page:Proceedings of the Royal Society of London Vol 60.djvu/206

186 detected for long distances. An effect was obtained at over half a mile from the vibrator.

(3) Waves along Wires.—The uses of fine steel wires for examining the distribution of currents along wires are explained.

(4) Damping of Oscillations.—A method of determining the damping of discharge circuits is investigated. The absorption of energy in spark gaps is deduced, and the apparent resistance of the air break to the discharge determined.

(5) Resistances of Iron Wires.—Quantitative results are given for the resistance of iron wires for very rapid alternations. The value of the permeability of the different specimens is deduced, and it is shown to vary with the diameter of the wire and the intensity of the discharge.

(6) Absorption of Energy by Conductors.—The absorption of energy of iron and non-magnetic cylinders placed in solenoid through which a discharge passed were determined. Iron cylinders were found to absorb much more energy than copper ones of the same diameter, and the permeability of the iron for the discharge is deduced.

(7) Determination of the Period of Oscillation of Leyden Jar Discharges.—A method of accurately determining the period of oscillation is based on the division of rapid alternations in a multiple circuit, one arm of which is composed of a standard inductance, and the other of a variable electrolytic resistance.

The value of n, the number of oscillations per second, when the currents in the branches of the multiple circuits are equal, is, under certain conditions, given by— R 71 “ 2ttW ’

where R = resistance of electrolyte to the discharge, W = value of the standard inductance.

The value of the self-inductance and capacity of the discharge circuit for very rapid oscillations may also be experimentally deduced.

The experiments on the coefficient of magnetisation of liquids were made with a sensitive induction balance. Both circuits were commuted about sixteen times a second, so that very small inductances could be detected by the galvanometer in the secondary circuit. The principle of the method consisted in balancing the increase of the