for adjujling t thermometers . 855 
is adj ufted in fteam when the barometer is at 29 inches, 
and that the interval between the boiling and freezing 
points is 1 1 inches; the neareft number to 29 in the 
left-hand column is 29.03, and the correfponding num- 
ber in the table is 7 higher, and therefore the mark of 
212 0 rauft be placed higher than the obferved point by 
7333 of the interval between boiling and freezing, that is, 
h y S’ or *°77 of an inch. 
This method of correcting the boiling point is not 
ftriCtly juft, unlefs the tube is of an equal bore in all its 
parts ; but the tube is very feldom fo much unequal as to 
caufe any fenlible error, where the whole correction 
is fo fmall. The trouble of making the correction will 
be abridged by making a diagonal fcale fuch as is repre- 
fented in fig. 5 . 
It is not very material what kind of water is ufed for 
adjufting the boiling point, fo that it is not at all fait; 
only, if any kind of hard water is ufed, it is better that it 
fhould be kept boiling for at leaft ten minutes before it 
is ufed. But we would advife all thofe defirous of ad- 
jufting thermometers in the moft accurate manner for 
nice experiments, to employ rain or diftilled water, and 
to perform the operation in the firft mentioned manner,, 
that is, in fteam.. 
