Lessons in astronomy including uranography. A brief intoductory course without mathematics (1896)
Young, Charles A. (Charles Augustus), 1834-1908 · Boston, London, Ginn and company · leaf 81
angulation. This measuring of arcs has been done on many parts of theearths surface, and the result is that the average length of adegree is found to be a little more than sixty-nine miles, andthe mean diameter of the earth about 7918 miles. The reasonwhy we say average length and mean diameter is… … Fig. 8. - ■ Measuring the EarthsDiameter. § 106] THE ROTATION OF THE EARTH. 71 106. The Rotation of the Earth. — Ptolemy understood thatthe earth was round, but he and all his successors deliberatelyrejected the theory of its rotation. Though the idea that theearth might turn upon an axis was not…
Astronomy
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