350 . LAPLACE. 
The calculation to which I have just alluded, may be 
cited in support of considerations to which I had recourse 
when I wished to establish, that if the moon alters more 
or less the height of the barometer, according to its 
different phases, the effect is not attributable to attrac- 
tion. , | 
No person was more sagacious than Laplace in dis- 
covering intimate relations between phenomena appar- 
ently very dissimilar; no person showed himself more 
skilful in deducing important conclusions from those 
unexpected affinities. 
Towards the close of his days, for example, he over- 
threw with a stroke of the pen, by the aid of certain 
observations of the moon, the cosmogonic theories of 
Buffon and Bailly, which were so long in favour. 
According to these theories, the earth was inevitably 
advancing to a state of congelation which was close at 
hand. Laplace, who never contented himself with a 
vague statement, sought to determine in numbers the 
rapid cooling of our globe which Buffon had so elo- 
quently but so gratuitously announced. Nothing could 
be more simple, better connected, or more demonstrative, 
than the chain of deductions of the celebrated geometer. 
A body diminishes in volume when it cools. Accord- 
ing to the most elementary principles of mechanics, a 
rotating body which contracts in dimensions ought inevi- 
tably to turn upon its axis with greater and greater 
rapidity. The length of the day has been determined in 
all ages by the time of the earth’s rotation; if the earth 
is cooling, the length of the day must be continually 
shortening. Now there exists a means of ascertaining 
whether the length of the day has undergone any varia- 
tion; this consists in examining, for each century, the 
