Lockyer, Norman, Sir, 1836-1920, Seabroke, G. M. (George Mitchell), 1848-1918 · London, Macmillan and co. · leaf 171
), the points ofwhich carry levers [primary system) supporting triangleson their extremities [secondary system), from the ver-tices of which are hung two triangles and one lever{tertiary system). All the joints of this apparatus arecapable of a small rocking motion, to enable them totake their… … Fig 75.—Primary, secondary, and tertiarysystems of levers shown separately. Complete system consolidatedinto three screws. distance from the support of the primary to the backof the speculum was about fifteen inches. This, as willbe readily seen on consideration, introduced a newstrain when the…
Astronomy · Telescopes
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