ELECTRICITY.

New Zealand Mail, Issue 1316, 20 May 1897, Page 10

ELECTRICITY.

At the Royal Institution on a recent Saturday, Lord Eayleigh, in the course of a lecture on " Electricity and Electrical Vibrations," discussed Faraday's fundamental discovery of the inductive effects of electric currents. He showed that if two coils of wire were held parallel to each other, the starting of a current in one produced a current in the other, travelling, however, in the opposite direction, while the stoppage of the current in the first or primary coil was similarly acompanied by a current in the reverse direction in the secondary coil. It was further shown that a current was inducted in a coil appropriately moved in a magnetic field—thus any rotary motion of a coil of wire, whether near a magnet or not, gave rise to a current to be detected by a sufficiently sensitive galvanometer, owing to the coil cutting the lines of the earth's magnetic force. Lord Kayleigh pointed out the analogy between these inductive currents and effects that might bo produced mechanically. Clerk Maxwell had argued there must be some mechanical connection between the two coils, seeing that what was done in one had an effect in the other, and the lecturer exhibited an arrangement to illustrate this conception. It consisted of an endless cord stretched over two pulleys, two other weighted pulleys being hung in the dependent bights. When one of the unweighted pulleys was revolved the other unweighted one in response moved a turn or two in the opposite direction then stopped, while the stoppage of the first pulley was accompanied with a slight movement of the second one, again in a reverse direction. This device formed an exact analogue to the induction of electric currents, the same mathematic being wanted in both cases. Lord Kayloigh mentioned some of the applications of these induced currents, and explained how he had used the flame-like arc obtainable from them by means of a transformer for the oxydation of nitrogen and the isolation of argon,,at the same time describing and showing at work his apparatue for the production of the lastnamed gas. •