meafuring Heights with the Barometer . 749 
lie founded this laft deduction ; and his note on the text, 
which I apprehend, neverthelefs, conveys his true mean- 
ing, is contradictory to it : for there he fays, that the di- 
latation occafioned by the heat throughout the day, 
changed the diftribution of the weight with regard to 
all the places lituated within the Cordilleros, as well as 
on other mountains, and made the lower fections of the 
columns contain lefs and the upper fections more air, 
than they ihould have done, had it been a perfectly 
elaftic fluid. 
Having now mentioned all the barometrical obferva- 
tidns that have come to my knowledge, tending any way 
to throw light on this very intricate fubjeCt, it remains to 
ium up, from the whole, the general principles whereon 
I have proceeded in conftruCting the table of equation 
for the heat of the air. 
It will be remembered, that I have more than once re- 
marked, that in the Britilh obfervations, when the tem- 
perature was 5 2 0 , the defeCt was the lowermoft 
barometer ftanding at or near the level of the fea; but 
in the obfervations on Tinto, a confiderable hill apper- 
taining to the third clafs, whofe bafe is elevated 700 feet 
above the level of the Clyde at Glafgow, when the tem- 
perature was 5 2 0 , 1 found the equation to be little more 
than Again, thefe two faCts being compared with 
the 
2 
