. The Adolfo Stahl lectures in astronomy, delivered in San Francisco, California, in 1916-17 and 1917-18, under the auspices of the Astronomical Society of the Pacific. In the brief time allotted for a single lecture it is impossibleto tell the whole story, so I shall confine my remarks to themost important epochs in the development of astronomy, theoldest of the sciences. In the earliest times the notions concerning the form of theEarth were as numerous and varied as were the the 6th century Pythagoras and his followerstaught that the Earth was spherical and a first advance
. The Adolfo Stahl lectures in astronomy, delivered in San Francisco, California, in 1916-17 and 1917-18, under the auspices of the Astronomical Society of the Pacific. In the brief time allotted for a single lecture it is impossibleto tell the whole story, so I shall confine my remarks to themost important epochs in the development of astronomy, theoldest of the sciences. In the earliest times the notions concerning the form of theEarth were as numerous and varied as were the the 6th century Pythagoras and his followerstaught that the Earth was spherical and a first advance seemsto have been made. Many people have the erroneous idea thatit was not known that the Earth is spherical until Magellanproved it by circumnavigating the globe. The first determination of the distance from the Earth tothe Sun was made by Aristarchus, 3d century Thisdetermination was highly ingenious, correct geometrically butyielding a very inaccurate result. This problem is so ditBcult,however, that no good determination was made until the timeof Cassini in the 17th century; so, great credit is due Ari-starchus for any determination at this early Fig. 9. Aristarchuss Method of Determining the Distance fromTHE Earth to the Sun. To Eratosthenes, 2d century , is due the first measure-ment of the size of the Earth. At noonday, at the summersolstice, the sun shone vertically down a well at Syene, inUpper Egypt, while in Alexandria, at the same time, the
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectastronomy, bookyear19
