William Crabtree (1610–1644) was a cloth merchant from Broughton Spout, a hamlet in the township of Broughton near Manchester, which is now part of Salford. The son of John Crabtree, a Lancashire farmer of comfortable means, and Isabel Crabtree (née Pendleton), he was educated at a grammar school in Manchester – probably the forerunner of Manchester Grammar School, which was then situated between the Collegiate Church and what is now Chetham's School of Music. He worked in Manchester, married into a wealthy family and in his spare time studied mathematics and astronomy. He carefully measured the movements of the planets, undertook precise astronomical calculations and rewrote the existing Rudolphine Tables with improved accuracy. He maintained an active correspondence, much of it now lost, with Horrocks, two other young astronomers – William Gascoigne and Christopher Towneley – and Samuel Foster, Professor of astronomy at Gresham College, London and alumnus of Emmanuel College."Crabtree, William." Complete Dictionary of Scientific Biography, 2008; Retrieved May 10, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-2830901016.html It is not known whether Horrocks and Crabtree ever met in person but from 1636 they corresponded regularly, and, because of their shared interest in the work of Johannes Kepler, referred to themselves, along with William Gascoigne, as nos Keplari (we Keplarians).
