Experiments upon He ah 285 
8o° to 70°, being at that time bulled in fufpending the 
inftruments. 
As it might pofiibly be objected to the conclulions drawn 
from thefe experiments that, notwithftanding all the care that 
was taken in the conftrufting of the two inftruments made 
ufe of that they fhould be perfeftly alike, yet they might 
in reality be fo far different, either in lhape or fize, as to occa- 
lion a very fenfible error in the refult of the experiments ; to 
remove thefe doubts I made the following experiments. 
In the morning towards eleven o’clock, the weather being 
remarkably fine, the mercury in the barometer Handing at 27 
inches 11 lines, Reaumur’s thermometer at 15°, and the hy- 
grometer at 47 0 , I repeated the experiment N° 3. (of heating 
the thermometer N° 1. in boiling water, &c.) and imme- 
diately afterwards opening the cylinder containing the thermo- 
meter at its upper end, where it had been fealed, and letting 
the air into it, I re-fealed it hermetically, and repeated the ex- 
periment again with the fame inftrument, the thermometer 
being now furrounded with air, like the thermometer N° 2. 
The refult of thefe experiments, which may be feen in the 
following table, Ihews evidently, that the error arifing from 
the difference of the fhapes or dimenfions of the two inftru- 
ments in queftion was inconfiderable, if not totally imper- 
ceptible. 
