Letter, from John Flamsteed to Henry Oldenburg, dated at Derby Signed autograph Observations of Saturn with a 14 foot telescope; having found Richard Towneley's micrometer not very easy to use, Flamsteed has devised a new micrometer and will send details of it in due course; will also send calculations of the moon's transit over the star cluster Pleiades Partly printed in 'Philosophical Transactions', vol 6, no 78, p 3034 2 December 1671