Elementary treatise on electricity and magnetism (1903)
Foster, George Carey, 1835-1919, Joubert, Jules François, 1834-1910. Traité élémentaire d'électricité, Porter, Alfred William, 1863- joint author · London, New York, Longmans, Green, and co. · leaf 329
magnet, suspended by a cocoon fibre, isviewed through a telescope, t. The magnet is hollow, and a scalephotographed on a glass disc inserted at the end of it furthest fromthe telescope is in the focus of a lens inserted in the other end.The case carrying the telescope and suspension tube is… … 242] DECLINATION COMPASS 307 The magnet is then inverted as in the simple compass, the telescopeis readjusted and the mean of its two directions—read on the gradu-ated circle c—is taken as the magnetic meridian. In order to obtainthe geographic meridian a mirror ni is employed which is capableof…
Electricity · Magnetism
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