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 160
earth CG or CT. From G, draw GD, at right angles to AC;then the two triangles ATC, AGD, are equi-angular and similar, and give the proportionCT:TA::DG: GA. Practically. —TA is a very short distance compared to CT, forTA, the distance within which we can take observations, is nevermore than two or… … 156 SURVEYING. Now, in the preceding proportion, in the place of DG, put itsequal \TA> and we shall have, CT : TA : : \TA : GA. Whence, <^=g, ^W^m 0) That is, The square of the distance, divided by the diameter of theearth, is the distance between the apparent and the true level. We can…
Surveying · Navigation
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