A treatise on levelling, topography, and higher surveying (1876)
Gillespie, W. M. (William Mitchell), 1816-1868, Staley, Cady, b. 1840, ed · New York, D. Appleton and company · leaf 34
Fig. 18 is an approved form, made by Young, of Phila-delphia. The improvement consists in the patent Lockesight, which enabies the near cross-hair to be distinctly seenat the same time as the distant object. Fig. 19. … (26.) The Telescope Level. In this the line of collimationof the telescope corresponds to the sights of Fig. 17, and ismade parallel to the level; i. e., this line is so adjusted as tobe horizontal when the bubble of its level is in the centre. There are many different forms of the Telescope Level,…
Surveying
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