. 7e5° 4 
experiment, to the numberof 105 
fub-divifions. 
Befides the fources of errors al- 
ready mentioned, there may happen 
fome others from accidental circum- 
ftancés, which may be principally 
three. 2 
I. The degree of heat of the 
common air may change during the 
time _you make. your experiment, 
and may occafion a greater or lefs 
extenfion of the column of airdn 
the great tube. 
Il. The weight of the air, or its 
preffure, may alfo change in the in- 
terval. of inftituting the experiment. 
“Hi: ‘The difference of heat com- 
municated to the tube by the body 
of the obfervator himfelf in. the 
time he is near it to eke the ob- 
fervation. oe 
Thefe 
