The theory and practice of surveying. Designed for the use of surveyors and engineers generally, but especially for the use of students in engineering (1886)
Johnson, J. B. (John Butler), 1850-1902 · New York, J. Wiley & sons · leaf 101
re the objectivemoves. In an inverting instrument the eye-piece and reticule may move togetherin the telescope while the objective remains fixed. Here the image takes different positions in the telescope-tube, as the distances vary, and the cross-wiresare moved to suit. There is also a motion of… … Fig. 14. Fig. is. THE LEVELLING-ROD. 70. The Levelling-rod is used tomeasure the vertical distance from theline of sight down to the turning-pointor bench-mark. There are two generalclasses, Self-reading, or Speaking, andTarget Rods. A Self-reading, or Speaking, Rodisone so graduated as to enable…
Surveying
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