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 67
ce in individuals is termedtheir personal equation. To test the accuracy of your eye, turn the head so as tobring the eyes in the same vertical line, and sight to the rodheld horizontally. Note where the vertical hair strikes. Thenturn the head to the other side, so as to invert the position ofthe… … Set the instrument over A, and sight to rod at B, and notereading. The difference of the reading and of the height of LEVELLING LOCATION. 49. the cross-hairs gives a difference of height of A and B. Then setup at B, and observe to A, similarly. A new difference ofheight is obtained. . The mean of…
Surveying
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