^22 Mr. cavallo’s Account of 
fiver in a given degree of heat, to the increafe of bulk, that 
the fame whole quantity of quickfilver acquires when heated 
of but i° ; viz. 32,0.5 grs. is.to 0,00371 gr. as 1 is to 0,001 1 -f ; 
fa that by this, experiment it appears, that i° of F ahrenheit’s 
theripometer increafes the bulk of mercury not above T ^^ B .^ths 
parts. In this procefs a fmall deviation from mathematical 
exaCt.nefs, is occafioned by the fmall difference of weight be- 
tween the quickfilver of the tube when firft weighed and when 
it is afterwards heated to i° ; but by an eafy calculation it will 
be found, that this difference is fo exceedingly fmall as not to be 
perceived by our exafteft weighing and mealuring inftruments. 
For clearnefs fake I {hall fubjoin the calculation of the above 
related experiments, difencumbered from words. Here the 
decimals are not computed to a very large number, that being 
unneceflary for this purpofe. 
Weight of theglafs, ...» 79,2 5 grs. 
Weight of fo much quickfilver as filled 4,3 inches 
length of the tube, - - 0,24 grs. 4 
Weight of the whole quantity of quickfilver con- 
tained in the thermometer, - - 32,05 grs. 
Length of the tube equal to 20°, - - 1,33 inch. 
4,3 : 0,24 :: 1,33 : 0,0742 = 20° 
20° : 0,0742 :: 1 : 0,00371 
32,05 : 0,00371 :: n 0,00011 + = to the expanfion 
occafioned by one degree of heat. 
Having repeated this experiment with other thermometers, 
and by fimilar calculations, each procefs gave a refult little dif- 
ferent from the others, which irregularity is certainly owing 
to the imperfection of my feales, which are not of the niceft 
fort : but taking a mean of various experiments it appears, 
that 
