348 "Meteorology. 



regard to its dip. The magnetic force is meafured by the 

 number of ofcillations which the needle makes in a minute. 

 The inchnation is given in degrees of the circle divided into 

 400 parts. 



He found the variation at Marfeilles on the nth of No- 

 vember 22° 55' 30"; at Madrid, in May, 22° 2'; and at 

 Aranjues, about the fame period, 21° 58'. The water of 

 the fea appeared to him to be lefs denfe under the equator 

 than at fome diftance from it. 



Buch has given fome refearches refpefting the barometer. 

 In which he examines the caufes of its variations. In his 

 opinion, the ftate of the barometer and its variations do not 

 depend on the ftate of the furface of our globe, and we muft 

 feek for the caufes beyond it. His proofs are : 



ift, That the barometer varies very little under the tropics, 

 and that its variations increafe on approaching the poles. 

 But if thefe variations defended on the ftate of the atmo- 

 fphere, they ought to be equally perceptible over the whole 

 furface of the globe. 



2d, The barometer often remains almofl; niotionlefs amidft 

 the greateft agitations of the atmofphere. Thus, in 1794, 

 when Vefuvius was in the utmoft agitation, and when the 

 air was filled with the flames, afhes, and fmoke of the vol- 

 cano, the barometer was almoft motioiriefs, 



Cotte 



