Lockyer, Norman, Sir, 1836-1920, Seabroke, G. M. (George Mitchell), 1848-1918 · London, Macmillan and co. · leaf 155
about eight strokes aminute, the length of stroke being one-third of thediameter of the speculum, and that of the side motionone-fifth. The speculum was polished on the same system of 2 132 STARGAZING : PAST AND PRESENT. [book II, levers that were afterwards to support it, in order thatno change of… … Fig. 66.—Mr. Lassells polishing machine. Bovereign standing on edge on it; this should leavethree complete impressions of the milled edge in oneminute at the ordinary temperature of the atmosphere. Fig. 66 represents the machine contrived by Mr.Lassell for his method of polishing, and shows what…
Astronomy · Telescopes
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