an Experiment on Heat. 3 1 7 
I Shall only add that, among other things which may be 
illuflrated by it, one is, that all the planets may poffibly be of 
the fame heat; lince, if the matter of which Mercury confifts 
was averfe to the generation of heat in proportion to the greater 
number of the rays of the fun it receives more than the 
Georgium Sidus, they would be both of the fame heat, not" 
withstanding their different diftances from the fun. 
I have already faid, that I was led to an enquiry into the 
fubjedt by the effedt it has on chemical operations. 
I remain, &c. 
G. FORDYCE. 
