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 122
ature is the limit of the thirdproportional to the subtense perpendicular to the tangent andthe arc. 79. The chord of curvature at any point of a paraboladrawn through the focus, and in the direction of a diameter, isequal to four times the focal distance of that point. Let AP be a parabola, Pany… … 104 NEWTON. Hence, 4/SP is the limit of the third proportional to thesubtense QE and the arc PQ, and is therefore equal to the chordof curvature at P in direction of the diameter. And, since PS, PM are equally inclined to the tangents atP, the chords in those directions are equal; therefore, the…
Mechanics · Celestial mechanics
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