A HISTORY OF SCIENCE 



shows that in the course of a single year he had ob- 

 served some ten thousand stars, and computed the 

 places of one thousand nine hundred and forty-two of 

 them, measured a degree of the meridian, and made 

 many observations of the moon productive industry 

 seldom equalled in a single year in any field. These 

 observations were of great service to the astronomers, 

 as they afforded the opportunity of comparing the stars 

 of the southern hemisphere with those of the northern, 

 which were being observed simultaneously by Lelande 

 at Berlin. 



Lacaille's observations followed closely upon the 

 determination of an absorbing question which oc- 

 cupied the attention of the astronomers in the 

 early part of the century. This question was as 

 to the shape of the earth whether it was actually 

 flattened at the poles. To settle this question once 

 for all the Academy of Sciences decided to make the 

 actual measurement of the length of two degrees, one 

 as near the pole as possible, the other at the equator. 

 Accordingly, three astronomers, Godin, Bouguer, and 

 La Condamine, made the journey to a spot on the 

 equator in Peru, while four astronomers, Camus, 

 Clairaut, Maupertuis, and Lemonnier, made a voyage 

 to a place selected in Lapland. The result of these 

 expeditions was the determination that the globe is 

 oblately spheroidal. 



A great contemporary and fellow-countryman of 

 Lacaille was Jean Le Rond d'Alembert (1717-1783), 

 who, although not primarily an astronomer, did so much 

 with his mathematical calculations to aid that science 

 that his name is closely connected with its progress 



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