Aristarchus of Samos, the ancient Copernicus ; a history of Greek astronomy to Aristarchus, together with Aristarchus's Treatise on the sizes and distances of the sun and moon
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Aristarchus of Samos, the ancient Copernicus ; a history of Greek astronomy to Aristarchus, together with Aristarchus's Treatise on the sizes and distances of the sun and moon : a new Greek text with translation and notes. 448 Pages.
has to 18. But it was proved that MA also has to AR a ratio less than that which 9 has to 8; therefore, ex aequali, MA will have to AB a ratio less than that which 171 has to 144, and therefore less than that which 19 has to 16 : for parts have the same ratio as the same multiples ot them: therefore, convertendo, AM has to BM a ratio greater than that which 19 has to 3. But, as AM is to MB, so is the diameter of the circle DEF to the diameter of the circle GHK; therefore the diameter of the
the moon as the older system did). Nicomachus’s order is explicable if we assume that the independent revolutions of the planets (in their orbits) was the criterion for the assignment of the notes; for the moon describes its orbit the quickest (in about a lunar month), the sun the next quickest (in a year), and so on, Saturn being the slowest in describing its orbit; these speeds are relative speeds, i.e. relative to the sphere of the fixed stars regarded as stationary. The absolute and relative
periods of revolution based on the figures attributed to Philolaus with the true periods, thus : Schiaparelli admits that the number of days for Mars (603.71) is uncertain, as it is not clear that Philolaus assumed 31 revolutions of Mars in his Great Year. But neither does there appear to be any evidence that he definitely fixed the number of revolutions made by the other planets in the Great Year. 22 Tannery, ‘La grande année d’Aristarque’, in Mémoires de la Société des sciences physiques et
of all sorts of shapes are borne into a great void, and their coming together sets up a vortex. By the usual process, in the case of our world, the earth collects at the centre. The earth is like a tambourine in shape and rides or floats by virtue of its being whirled round in the centre. The sun revolves in a circle, as does the moon; the circle of the sun is the outermost, that of the moon the nearest to the earth, and the circles of the stars are between. All the stars are set on fire because
view of the Milky Way as consisting of the stars which the sun ‘does not see’ when it is passing under the earth during the night;22 but, at the same time, he seems to have been the first to appreciate its true character as a multitude of small stars so close together that the narrow spaces between them seem even to be covered by the diffusion of their light in all directions, so that it has the appearance, almost, of a continuous body of light.23 With Anaxagoras he thought that comets were ‘a