London, The Royal Society, 1683. 4to (21.5 x 16.4 cm). pp. 404-415, including a three-page catalogue of the visible eclipses. Loose pages, unbound.

A rare paper by Flamsteed on the eclipses of Jupiter (the name Saturn is an editor's or printer's error). Galileo was the first who observed the moons of Jupiter. From the dance of its planetary moons, Galileo worked out a longitude solution. Eclipses of the moons of Jupiter, he claimed, occurred one thousand times annually, and so predictably that one could set a watch by them. He used his observations to create tables of each satellite's expected disappearances and reappearances over the course of several months. When Galileo died in 1642, interest in the satellites of Jupiter lived on. Flamsteed - the first Royal Astronomer of Britain - was one of those that took up the torch. Extract from the original December 1683 issue of the Philosophical Transactions. Very good copy, loose pages but these are clean and with just an occasional tiny spot. Houzeau & Lancaster, p. 1443.