Elementary astronomy; a beginner's text-book (1899)
Holden, Edward Singleton, 1846-1914 · New York, H. Holt and company · leaf 256
Surveys.—Since it is practically impossible tomeasure around or through the Earth, the figure and thesize of our planet has to be found by combining measure-ments on its surface with astronomical observations. Evena measurement on the Earths surface made in the usualway of surveyors would be… … Fig. 150.—A Part of the French Triangulation near Paris. Triangulation is executed in the following way: Two points, a andb, a few miles apart, are selected as the extremities of a base-line.They must be so chosen that their distance apart can be accuratelymeasured; the intervening ground should…
Astronomy
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