r 441 J 



indicated' by the difference of the logarithms, then the mean 

 temperature was higher than 32**. If it falls fhort of the num- 

 ber indicated by the difference of the logarithms, then thte 

 mean temperature was below 32*^. 



Section, II. 



Having found and determined by its weigh't the disnfity of 

 aii- and that of its variations, as far as thefe may be occafioned 

 by the natural variations oi prejfian in the temperatiire of 32", 

 it row remains to determine howfar under each degree of 

 prefTion it is altered by variations of temperature above and' 

 below 32^. 



Ther-e are few fubjedls on wiiich the opinions of philofo- 

 phers differ fo widely as on this. The principal reafon-of 

 which variance appears to me to have been, that • the experi^ 

 ments they appeal - to were made in manomeeers of different 

 dimenfions in the bore- and. of glafs differently coittpofed and 

 differently heated during its fufion.: From this lafl circum- 

 flance its condudling power with refpeft to heat is various j 

 but in all forts of glafs veffels air adheres to them with more 

 or lefs force, according to their compofition, in low heats. 



(that 



