A treatise on surveying, comprising the theory and the practice ; (1887)
Gillespie, W. M. (William Mitchell), 1816-1868, Staley, Cady, 1840- [from old catalog] ed · New York, D. Appleton and company · leaf 221
to 3. English compasses, or circumferentors, are sometimesthus arranged. If 60 spaces on the vernier are equal to 59 on the circle, thevernier can read to one sixtieth of a division on the circle—i. e.,to 1. 312. Circle divided to 30. Such a graduation is a very com-mon one. The vernier may be… … VERMEILS. 207 Suppose 30 spaces on the vernier to be equal to 29 on the cir- 29 X 30cle. Each space on the vernier will be = —^— = 29, and will therefore be less than a space of the circle by 1, to which the ver-nier will then read. Fig. 220 shows this arrangement. The reading is 0°, or 360°. In…
Surveying
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