Olmsted, Denison, 1791-1859. [from old catalog] · New York, R. B. Collins · leaf 112
8. First law. The orbits of the earth and all theplanets are ellipses, having the sun in the commonfocus. In a circle all the diameters are equal to each other;but if we take a metallic wire or hoop and draw it out onopposite sides, we elongate it into an ellipse, of which thedifferent diameters… … transverse axis and CD the conjugate of the ellipse AB.By such a process of elongating the circle into an el-lipse, the center of the circle may be conceived of asdrawn opposite ways to E and F, each of which be-comes a focus, and both together are called the foci of theellipse. The distance GE or…
Astronomy
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![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-38-16.webp)
