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 134
ected from onemirror to the second, and from the second mirror to the eye.If the first mirror be moved so that the doubly-reflected imageof the second object be made to cover or coincide with theobject seen directly, then is the desired angle equal to twicethe angle which the mirrors make with each… … Let a equal the angle between the incident ray and the 116 LEVELLING, TOPOGKAPHY, AND HIGHER SURVEYING. first mirror. ]STow, suppose the first mirror to be turned n°.The incident ray now makes an angle with this mirror n°greater than before; it will therefore pass off, making an an-gle with the…
Surveying
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