280 A Short History of Astronomy [Ca. X. 



surprising that he died comparatively early (1762) and that 

 his death was generally attributed to overwork. 



223. The monotony of Lacaille's outward life was broken 

 by the scientific expedition to the Cape of Good Hope 

 (1750-1754) organised by the Academy of Sciences and 

 placed under his direction. 



The most striking piece of work undertaken during this 

 expedition was a systematic survey of the southern skies, 

 in the course of which more than 10,000 stars were 

 observed. 



These observations, together with a carefully executed 

 catalogue of nearly 2,000 of the stars* and a star-map, were 

 published posthumously in 1763 under the title Coelum 

 Australe Stelliferum, and entirely superseded Halley's much 

 smaller and less accurate catalogue ( 199). Lacaille 

 found it necessary to make 14 new constellations (some 

 of which have since been generally abandoned), and to 

 restore to their original places the stars which the loyal 

 Halley had made into King Charles's Oak. Incidentally 

 Lacaille observed and described 42 nebulae, nebulous stars, 

 and star-clusters, objects the systematic study of which 

 was one of Herschel's great achievements (chapter xn., 

 259-261). 



He made a large number of pendulum experiments, at 

 Mauritius as well as at the Cape, with the usual object of 

 determining in a new part of the world the acceleration 

 due to gravity, and measured an arc of the meridian ex- 

 tending over rather more than a degree. He made also 

 careful observations of the positions of Mars and Venus, 

 in order that from comparison of them with simultaneous 

 observations in northern latitudes he might get the parallax 

 of the sun (chapter vm., 161). These observations ( f 

 Mars compared with some made in Europe by Bradley an- 1 

 others, and a similar treatment of Venus, both pointed to 

 a solar parallax slightly in excess of 10", a result less 

 accurate than Cassini's (chapter vui., 161), though 

 obtained by more reliable processes. 



A large number of observations of the moon, of which 



* The remaining 8,000 stars were not "reduced" by Lacaille. 

 The whole number were first published in the ''reduced" form by 

 the British Association in 1845. 



