Letter, from John Flamsteed to Henry Oldenburg, dated at Derby Concerning a scheme of the transit of Mars using Hecker's 'Ephemerides' and Streete's 'Astronomia Carolina'; calculates the distances from Mars from the earth to be expected at Mars' late September positions Original figure of transit of Mars found at LBO/5/313 Printed in 'Philosophical Transactions', vol 7, no 86, p 5040 27 July 1672