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 468
454 TRIANGULAR SURVEYING. flags renders them visible, when much larger motionless objects arenot; but they are useless in calm weather. A disk of sheet-iron,with a hole in it, is very conspicuous. It should be arranged soas to be turned to face each station. A barrel, formed of muslinsewed…
Surveying
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