Ternant, A. L. (Alcide Ludovic), 1832-1884 · London ; New York : G. Routledge and Sons · leaf 284
hich is carried down into the centre of the lower coil, where it carries a second small magnet placed astatically to the former. Perpendicular to this magnet, in the horizontal axis of the lower coil two discs of mica are fixed to the aluminium rod, so that they may render the movements steady by… … apparatus. There are levelling screws in the stand, so that the magnets can be adjusted for free movement, the correct position being indicated by a spirit-level. The rays reflected from the mirror are brought to a focus either by a convex lens or by the concavity of the little mirror. These rays…
Telegraph
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