68 HISTORY OF THE [1830-40 period of stagnation. As regards astronomy of precision, this rise is more connected with the name of Airy than with any other. When Airy took charge of the Cambridge Observatory in 1828, he determined at once that the planets were to be observed as often as possible. At Greenwich they had been completely neglected by Maskelyne, who only observed the sun, the moon, and his 36 standard stars, and they had been very little looked after by Pond. Airy now began to observe them regularly at Cambridge, and also showed his interest in them in other ways ; by his suggestion that the mass of the moon might be determined by observations of Venus near inferior conjunction,* and by his new determination of the mass of Jupiter.f Having realised the value of regularly continued observations of the major planets, Airy soon saw the importance of getting the Greenwich planetary and lunar observations made since 1750 reduced and compared with the tables. These two great undertakings were not finished till the following decade. The four minor planets known at that time continued to attract very little or no attention in England, while they were, as in previous years, regularly observed and their orbits computed in Germany. The same was the case with comets ; only Halley's comet excited a great deal of interest at its return in 1835. Of researches on planetary perturbations we cannot speak here, since none were published by the Society, but it was during this period that Lubbock published a series of important memoirs on lunar and planetary theory, possessing many novel features. In order to find a more correct, value of the ellipticity of the earth by means of pendulum-observations in high southern latitudes and near the equator, the Admiralty sent out the sloop Chanticleer under Commander Henry Foster, R.N., in 1828. On several previous voyages, Foster had made pendulum experi- ments and taken other observations, for which he received the Copley Medal in 1827. He had served in the Hecla on Parry's third Arctic voyage. His work in the Chanticleer had nearly been completed when Foster was unfortunately, in 1831 February, drowned in the River Chagres. His observing books and papers were by the Admiralty handed to Baily, who had been partly responsible for Foster's outfit. In addition to two of Rater's invariable pendulums, Foster had taken with him two convertible ones furnished with two knife-edges ; these were the property of the Society ; they had been designed by Baily, and had been ad- justed and tried by him.J This led him to investigate all possible
- Memoirs, 4, part 2, p. 235 ; M.N., 1, 140.
t Memoirs, 6, 83 ; 8, 33 ; 9, 7 ; 10, 43 J M.N., 2, 171 ; 3, 36, 113 ; 4, 25. J Described in Monthly Notices, 1, 78.
