Machinery and processes of the industrial arts, and apparatus of the exact sciences (1869)
Barnard, Frederick A. P. (Frederick Augustus Porter), 1809-1889 · Washington, Govt. print. off. · leaf 608
convex band in the direction opposite tothat shown in Fig. 134, or toward the left. This system of lenticular zones is introduced into the apparatus onthe right, Fig. 130, at the point marked L. The concave band is fixed,and the eye always looks through its optical center. The convex bandis… … o 0/ / b IV—— -——-^^ ■nh-- \ ——Ipt* jji -v ■ ■■■ u 592 PAEIS UNIVERSAL EXPOSITION. they are the parallaxes. These distances may, therefore, be marked onthe scale which indicates the amount of displacement, when the lengthof the base line is fixed. Observations with this apparatus may be very…
Machinery · Scientific apparatus and instruments
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