[ }J ] 
The fame Thermometer being furrounded with 
Snow, the Mercury fell down to the fame Degree as 
pounded Ice had made it do at Paris. 
Hence he concludes, that the Heavinefs of the Air 
has a fenfible Influence on boiling Water ; but that 
it in no way alters the Term of Congelation. 
All thefe Particulars may be fee n,/>. 408. of Cotes 
Experimental Lectures ; and in the Memoirs of the 
Academy of Sciences of Paris, Anno 1740. 
This is the fame Experiment which I have repeated 
on the Top of the Pic du Midy ; thinking that fo 
lingular a Fad ought to be obferved more than once. 
I carried Two Barometers, the Tubes of which the 
Reverend Father Francis had been fo good as to fill 
for me with great Care. I had likewife with meTwo 
Mercurial Thermometers, upon which I fet the De- 
grees at Bagneres : I took the fixed Terms of the Gradu- 
ation } that is to fay, that of Congelation, and that 
of boiling Water, afterwards putting nought to the 
Term of Congelation. I marked 180 9 Difference 
between this Term and that of boiling Water. 
Being come to the highefl Top of the Pic du Midy 
on the 9th of laft July , the Mercury rofe in one of 
my Barometers to 20 Inches 2 Lines; and in the 
other, to 20 Inches i-f- Line. I furrounded my Ther- 
mometer with Snow, and the Mercury fell exadly 
to the fame Degree as the Snow had made it fall to at 
Bagneres. Afterwards I plunged it into boiling 
Water; whereupon the Mercury rofe to 1650 of my 
Graduation : So that the Difference between the Heat 
of boiling Water on Pic du Midy } and that at Bag- 
neres, con filled of 15°. 
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