Note 46 — Chapter V · Sequel to the epoch of Kepler. Reception, Verification, and Extension of the Elliptical Theory.

Horrox (Horrockes as he himself spelt his name) gave a first sketch of his theory in letters to his friend Crabtree in 1638: in which the variation of the eccentricity is not alluded to. But in Crabtree’s letter to Gascoigne in 1642, he gives Horrox’s rule concerning it; and Flamsteed in his Epilogue to the Tables, published by Wallis along with Horrox’s works in 1673, gave an explanation of the theory which made it amount very nearly to a revolution of the centre of the ellipse in an epicycle. Halley afterwards made a slight alteration; but hardly, I think, enough to justify Newton’s assertion (Princip. Lib. iii. Prop. 35, Schol.), “Halleius centrum ellipseos in epicyclo locavit.” See Baily’s Flamsteed, p. 683.