Howe, Herbert A. (Herbert Alonzo), 1858-1926 · Meadville, Penna., Flood and Vincent · leaf 32
p across the sky each day ata perfectly regular rate, the earth must be equally dis-tant from all of them, and thus in the center of the uni-verse. What is the shape of the curve in which everyheavenly body moves? Ptolemy replies that it is acircle, the most perfect of all curves. Now an… … or of Jupiter, both of which move irregularly ? HerePtolemy had recourse to the device of the epicycle, in-troduced by Hipparchus. The word epicycle is derivedfrom two Greekwords, meaning up on and acircle. The epicyclewas a circle the centerof which moved alongthe circumference ofanother circle.…
Astronomy
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![An illustration from Vnderweysung der Messung : mit dem Zirkel vn[d] Richtscheyt in Linien, Ebnen vnnd gantzen Corporen (1525)](https://img.insideoutlibrary.com/img/200/ia-vnderweysungderm00drer-6-5.webp)
![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-242-152.webp)
