A treatise on surveying and navigation: uniting the theoretical, the practical, and the educational features of these subjects (1852)
Robinson, Horatio N[elson], 1806-1867. [from old catalog] · Cincinnati, J. Ernst · leaf 187
DEB. andFQQ are sectors similar to A CB. Observe that DE, FG, &c, are parallels of latitude, that is, theyare parallel to AB, the plane of the equator. The magnitude of DE is called departure, and it corresponds tothe difference of longitude AB. Also, FQ is departure corresponding to the same… … PLANE SAILING. 183 Because the two sectors A CB DEH are similar, we have theproportion. AC : DH : : AB : DE (1) Observe that A C is the radius of the sphere, DH is the sine ofthe arc PD, or the cosine of DA, which is the cosine of the lat-itude of the point D. Therefore the preceding proportion…
Surveying · Navigation
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