in the Mines of the Hartz. 50 1 
conclude my correction for the effects of heat upon the 
air from a mean among my numerous obfervations. 
Now this mean, reduced to the fame term of comparifon 
as above, is 1047, which is alfo a mean among thofe dif- 
ferent refults. 
Thefe differences therefore fhew us, that atmofpheri- 
cal air is not a fubflance that is homogeneous and con- 
ftantly the fame; and that next to the care of making as 
many obfervations as poflible in the mafs of air itfelf 
which it concerns us to know, the only means of deter- 
mining more exactly its various influences is to multiply 
our meteorological inftruments. 
Barometrical 
Pair, par un milieu entre mes nombreufes obfervations. Or ce milieu, reduit 
au meme terme de comparaifon ci deffus, eft 1047, qui fe trouve etre auffi le 
milieu entre ces divers refultats. 
Ces differences nous montrent done; que Fair atmofpherique n’eft pas une fub- 
ftance homogene et conftamment la meme; et qu’ apres le foin de faire autant 
qu’il eft poftible, les obfervations dans la maffe meme de Fair qu’il nous imports 
de connoitre, le feul moyen de determiner plus exa&ement fes diverfes influences, 
eftde multiplier nos inftrumens de meteorologie. 
Vot. XXIX. 
U u u 
Qbfervaikm 
