714 Col. roy’s Experiments for 
will be nearly fifteen times that which correfponds to 
the zero of Fahrenheit. 
I am aware it will be alledged, that the proportion of 
moifture admitted into the manometer in thefe experi- 
ments, is greater than what can ever take place in nature ; 
and therefore, in order to be able to judge of the degrees 
of expanfion the medium buffers in its more or lefs denfe, 
and more or lefs moift ftates, that not only air near the 
furface of the earth, but likewife that found at the top of 
fome very high mountain, fhould have been made ufe of. 
I grant all this : but on the other hand it mult be remem- 
bered, that thefe experiments are very recently finifhed; 
that a good hygrometer (if fuch can ever be obtained) 
a great deal of lcifure time, and the vicinity of high 
mountains, were all neceffary for the carrying of fuch 
a fcheme into execution. t 
It is for thefe reafons, and in hopes that other people 
will, fooner or later, inveftigate this matter ftill farther, 
not only by experiments made on the expanfion of air, 
taken at different heights above the level of the fea in 
middle latitudes, but likewife on that appertaining to the 
humid and dry regions of the atmofphere towards the 
equator and poles, that I have been induced to haflen the 
communication of this paper. In the mean time having 
proved, beyond the poflibility of doubt, that a wonderful 
2, difference- 
