Machinery and processes of the industrial arts, and apparatus of the exact sciences (1869)
Barnard, Frederick A. P. (Frederick Augustus Porter), 1809-1889 · Washington, Govt. print. off. · leaf 618
of an observing tubeto which is attached, on the top, a small spirit level, the bubble of whichis seen by reflection, in a manner which Fig. 140 will serve to explain.The observing tube is G G, which is supported by the exterior tube C :and this in turn is secured to the sextant by the screw M.… … W, on the top of the tube, isan opening, which permits thebubble of the level S to be seenby reflection from the mirrorE, placed at an angle of forty-five degrees to the axis of the 6 tube. As the level will be too Davidsons Spirit-level Sextant. near for distinct vision, a convex lens, L, is…
Machinery · Scientific apparatus and instruments
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
