for adjujling 'Thermometers* 831 
1 '.5 2 lower than it would have done if the quickfilver 
in the tube had been of the fame heat as that in the ball ; 
and, confequently, the quickfilver in the ball of the ther- 
mometer was in reality .07 cooler than when tried in 
fleam. 
We examined the boiling points of feveral thermo- 
meters, made by different artifts, by trying them in fleam 
when the barometer was at 30.1, and finding what di- 
vifion on the fcale the quickfilver flood at. The differ- 
ence of the extremes was 3°^ ; but, by a mean of all, it 
was found to Hand at e x 3 0 . 1, and confequently wmuld 
have flood at 212 0 , if the barometer had been at 29.4; 
fo that if the boiling point was to be adjufted, either in 
fleam, when the barometer is at 29.4, or with the ball 
immerfed two or three inches in water, when the baro- 
meter is at 29.1, it would agree belt with the mean of 
the abovementioned thermometers. But as it feems to be 
of no great fignification to make the boiling point agree 
very nearly with the mean of the thermometers made at 
prefent, when the extremes differ fo widely ; and as we 
apprehend that it will be more convenient to the makers 
that fome height fhould be chofen which differs lefs 
from the mean, as thereby they will more frequently^ 
have an opportunity of adj tilling the boiling point with- 
out the trouble and danger of millakes which attend the 
making 
