for adjufling 'thermometer's. 833 
way below the freezing point (f> \ confequently, as Mr. 
de luc’s boiling point was adjufted when the barometer 
was at 27 Paris or 28.75 Englifh inches, it will hand 
lower than that adjufted in the manner recommended by 
us, by three-quarters of a degree of his fcale; or 8o°| 
on de luc’s thermometer, will anfwer to 212 0 on Fah- 
renheit’s adjufted in the manner propofed. 
Though the boiling point be placed fo much higher 
on fome of the thermometers now made than on others, 
yet we would not have the reader think that this can 
make any confiderable error in the obfervations of the 
weather, at leaft in this climate; for an error of i°r in 
the pofition of the boiling point will make an error of 
only half a degree in the pofition of 92 0 , and of not 
more than a quarter of a degree in the point of 62°. It 
is only in nice experiments, or in trying the heat of hot 
liquors, that this error in the boiling point can be of 
much fignification. 
(f) In order to fee how much the quickiilver in the tube of the thermometer 
would be heated in this method of adjufting the boiling point, we took the 
abovementioned tube without a ball, wrapped it round with rags, and poured 
boiling water on it as above defcribed: the heat of the quickiilver therein was 
found to be about 21 0 lefs than that of boiling water; and, therefore, the boiling 
point of a thermometer, adjufted in this manner, fuppoling the thermometer to 
be dipped into the water as far as to the point of 32 0 , fhould Hand about one- 
third of a degree lower than it would do if the quickiilver in the tube was heated 
equally with that in the ball. 
5 M 
Vol. LXVII. 
There 
