The Horrocks Legacy

Abstract

During 1752, a major change took place in Mayer’s thinking about modelling of the moon’s motion, which affected the procedure to be followed when computing a lunar position from the tables. Initially the tables were applied in the single-stepped fashion (using the terminology explained in Chap. 4), but during 1752 Mayer switched to a multistepped procedure. He would basically adhere to the multistepped procedure ever after, and change only minor details later on. The purpose of the present chapter is to investigate the origin of this multistepped procedure. We will see that Mayer developed it out of a lunar theory of Newton’s, first printed in 1702, which at best has a very troublesome relation to the theory of gravitation. This dependence of Mayer’s tables on Newton’s 1702 lunar theory has never been noted before. On the contrary, it is usually said that Mayer’s tables were in some way based on Euler’s lunar theory, and that their advent made those founded on Newton’s 1702 lunar theory obsolete.1 It will here be shown that Newton’s theory exercised, through Mayer’s tables, a much more profound impact on eighteenth century positional astronomy than has hitherto been thought.