Lockyer, Norman, Sir, 1836-1920, Seabroke, G. M. (George Mitchell), 1848-1918 · London, Macmillan and co. · leaf 169
ulum stillhangs evenly supported. L 146 STARGAZING : PAST AND PRESENT. [book II. ^ As we have already seen, there is another point toconsider. Not only must we be able to support themirror when inclined to the horizon, but we mustsupport it bodily at the end of the tube when it ishorizontal. AVe… … Fig. 73.—Snpport of the mirror when vertical. * To understand it, suppose the speculum to be dividedinto forty-eight portions, as in Fig. 74, each of thembeing exactly equal in area, and consequently in weight.Now, if the centre of gravity of each of these piecesrested on points w^hicli would bear…
Astronomy · Telescopes
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