nd there-fore rigidly connected with the aluminium needle. (10.) A circular aperture in the case shut by a convex lens,and a long horizontal slit shut by plate glass, with its centre im-mediately above or below that of the lens, one of them above,and the other equally below the level of the centre… … XVI.] A tmosjjheric Electricity. 211 reflected out througli the plate-glass window; and three orfour fine metal wires stretched across this aperture to screenthe mirror from irregular electric influences, without sensiblydiminishing the amount of light falling on and reflected off it. 271. The…
Electricity · Magnetism
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