XXI. On certain Impressions of Cold transmitted from the Higher 

 Atmosphere, with the Description of an Instrument ad- 

 apted to measure them. By John Leslie, F. R. S. E. 

 and Professor of Mathematics in the University of Edin- 



burgh. 



(Read March 16. 1818J 



JL he distribution of Heat over the surface of our Globe, is a 

 capital object in the economy of Nature. The infusion of that 

 active element communicates to bodies the principle of mo- 

 tion, and quickens the ceaseless revolution of the circle of ge- 

 neration and decay. But Heat, unlike air, water, or earth, 

 appears never in a distinct and separate form : It exists only 

 in a state of combination with other tangible substances ; 

 among which, it migrates from one to another. On the re- 

 gulated tide of this transmission, depends the stability of the 

 present order of things. A very small portion of the vast scale 

 of heat is requisite and salutary for vegetable or animal life. 

 A genial warmth fosters the powers of vegetation, — but push- 

 ed farther, it soon dries up the juices, and shrivels the leaves 

 and tender shoots ; on the other side, again, when reduced to 

 a low temperature, it benumbs the energy of production, and 

 finally stifles the expansion of life. 



If the transfer of heat among bodies were much slower, 

 therefore, than what actually obtains, its inequalities would ac- 

 cumulate, and the greater part of this fair globe would be- 



Vol. VIII. P. II. 3 N come 



