A treatise on surveying, comprising the theory and the practice (1906)
Gillespie, William Mitchell, 1816-1868, Staley, Cady, 1840- · New York D. Appleton · leaf 49
truction. All the best forms of theodolites rest upon three foot screws, andare as stable as possible. The vertical axes are as long as can be 3S GEODESY obtaiued without sacrificing the stability and symmetry of the in-strument. Tiie magnifying power of the telescope is usually equal,if not… … of the atmosphere. The magnifying powers of the telescopes ofthe larger instruments vary from about 50 to 100 diameters. Instruments with circles of 10 inches diameter, and less, arenearly always read by means of verniers. On the smaller instru- SUPPORTS OF INSTRUMENTS. 39 merits two verniers are…
Surveying
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