for adjujlhig thermometers. 829 
open, yet the water was not much expofed to the air, its 
heat then feemed fcarcely lefs than when boiled in clofed 
vefTels. 
In making thefe experiments we chiefly made ufe of 
the two fhort thermometers, in which, as the quantity of 
quickfilver contained in the tube was fmall, the error 
arifing from that part of the quickfilver being not heated 
equally with that in the ball, could be but fmall: for 
example, in the fecontl of the fhort thermometers, the, 
number of degrees contained in that part of the tube, 
between the circular plate Gg and the ball was_i8°. In, 
the experiments in fleam this part of the tube was heated 
to the fame degree as the ball. Suppofe now, that in 
open vefTels it was heated only to 122 0 , or was go° 
cooler than the ball, it is plain, that the thermometer 
would hand only or yth of a degree lower than i£- 
did in fleam, provided the heat of the quickfilver in the 
ball was the fame in both cafes. In the ether fhort ther- 
mometer, as there were only half as many degrees to an 
inch, the error was only half as great. 
In feveral of the experiments, however, we made ufe 
of the long thermometer; but then it was neceffary ta 
make an allowance on account of the quickfilver imtha 
tube being not heated equally with that in the ball. The 
better 
