Lockyer, Norman, Sir, 1836-1920, Seabroke, G. M. (George Mitchell), 1848-1918 · London, Macmillan and co. · leaf 217
r or less influence on thependulum magnet according as the pressure of the airvaries, and so adds a variable amount to the effect ofgravity and therefore to the rate of oscillation. 0 194 STARGAZING : PAST AND PRESENT. [liOUK 111. This jjiinciple is carried out as follows :—Two barmagnets, each… … Fiu. 91.—Greenwich Clock : arrangement for Comiiensation for Barometric Pressure. magnet is a south pole. Below these a horse-shoe magnet,b, having its poles precisely under those of the pendulummagnets, is carried transversely at the end of the lever c,the extremity of the opposite arm of the…
Astronomy · Telescopes
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