Proctor, Richard A. (Richard Anthony), 1837-1888 · New York, A.C. Armstrong and son · leaf 289
Fig. 44. length A B. In every possible case the length of a I?is known. Take one other case in which the proportionis not quite so simple :—Suppose that D ^ is greater … than D A in the proportion of 18 to 7, as in fig. 45 ;then <^ ^ is greater than A B in the same proportion; sothat, for instance, if A B is a length of 7 inches, If a i:^a lens^th of 18 inches. ^TS transits of VENUS. We see from these simple cases how the actual size of adistant object can be…
Astronomy
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![An illustration from L'optique divisée en trois livres : ou, l'On démontre d'une maniere aisée tout ce qui regarde 1. la propagation & les proprietez de la lumiere. 2. La vision. 3. La figure & la disposition des verres qui servent à la perfefectionner [sic] (1682)](https://img.insideoutlibrary.com/img/200/ia-loptiquedivise00ango-108-12.webp)
