Davies, Charles, 1798-1876 · New York, Cincinnati [etc.] American book company · leaf 398
ightness of the direct and reflected images.The vernier is read with the aid of a glass G which is attached to the indexbar. The central mirror 1, or index glass, is fastened in a brass frame whichis firmly attached to the index bar by three screws. This glass is generallyset by the maker so as to… … Fig. 5. 18 ELEMENTS OF SURVEYING. [APP. B. altitudes), is specially provided with screws bv which its position with respectto the sextant plane may be rectified. At P and Q are colored glasses of different shades, which may be usedseparately or in combination, to defend the eye from the intense…
Surveying
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
