A treatise on land-surveying; comprising the theory developed from five elementary principles; and the practice with the chain alone, the compass, the transit, the theodolite, the plane table, &c. Illustrated by four hundred engravings, and a magnetic chart (1875)
Gillespie, W. M. (William Mitchell), 1816-1868 · New York, D. Appleton · leaf 241
In the following figure, the reading is 20° 40, the index beingat a point beyond 20° 30, and the additional space being shownby the Vernier to be 10. Fig. 232. … CUAP. II.1 Verniers. 235 Sometimes 30 spaces on the Vernier are equal to 31 on the cu-cle, 31 X 30Each space on the Vernier will therefore be = ~— = 31, and will be longer than a space on the circle by 1, to which it willtherefore read, as in the last case, but the Vernier will be retro-grade. This…
Surveying
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