Manual of modern surveying instruments and their uses .. (1893)
Lietz, firm, math. instr. makers, San Francisco. (1893. The A. Lietz company) [from old catalog] · [San Francisco] The Company · leaf 95
it through a telescopeso as to cover the space of 2.4 feet as seen by the unaided eye,the magnifying power is 24 for the distance in focus. Thereal power is somewhat less, for as the tube of the telescope isdrawn out for near objects, the power necessarily increases.The magnifying power obtained by… … THE A. LIETZ COMPANY. 69 telescope himself, for it is to the interest of the maker to ratethis higher than it really is, for very obvious reasons. Thismethod suggests itself as perfectly practicable, and is readilytried at the time of purchase. For a very accurate determination of the magnifying…
Surveying
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