Newton's Principia, sections I, II, III, with notes and illustrations. Also a collection of problems (1863)
Newton, Isaac, Sir, 1642-1727, Frost, Percival, 1817-1898 · Cambridge, London, Macmillan and Co · leaf 69
gles CPS, cpS, therefore thetriangles are similar (Euclid, vi. 7), and the sides about theangle CSP are proportional, that is, SP : Sp :: SO : 8c;therefore S is the center of direct similitude. Similarly, the intersection of two common tangents whichcross between the circles is a center of inverse… … focus meeting them in p, P, draw SaAD perpendicular to thedirectrix DQ of AP, PQ perpendicular to DQ, join SQ, and letpq, parallel to PQ, meet it in q, and draw qd perpendicular to SD. Then Sd : SD :: Sq : SQ :: Sp : SP;and, if the curves be similar, Sp : SP is a constant ratio. LEMMA V. 51…
Mechanics · Celestial mechanics
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