A course of experiments in physical measurement (1897)
Whiting, Harold, d. 1895 · Boston, D.C. Heath and Co. · leaf 277
the angle a is adjusted so that therays of the sun ^ from the direction y may seem, afterbeing twice reflected, to come from the direction x,let us say that of the horizon; then the altitude ofthe sun is evidently 2a. The student should notethat two objects in different directions may be… … Fig. 106. of two mirrors hinged together as in Fjg. 105. Inpractice it would be necessary to remove mostof the silvering. between / and 2, since it wouldotherwise interfere with the ray yd when theangle d is very small. In an ordinary sextant, this 1 The mirror should be smoked near/and ^r before…
Physics
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