8 1 8 Report of the Committee 
preffed by more than the weight of the atmofphere, and 
on that account will be rather hotter than it ought to be. 
We are of opinion, that the quickfilver in the tube 
ought, if poffible, to be kept of the fame heat as that in 
the ball, and that the ball ought not to be immerfed deep 
in the water. Thefe two requilites may be obtained by 
ufing a veffel covered fo as to allow no more paffage than 
what is fuflicient for carrying off the fleam; for then, if 
the thermometer be inclofed in this veffel in fuch man- 
ner that the boiling point ill all rife but a little way above 
the cover, almoft all the quickfilver in the tube will be 
furrounded by the fleam of the boiling water, and con- 
fequently will be nearly of the fame heat as the water 
itfelf: we therefore made fome experiments to deter- 
mine how regular the boiling point would be when tried 
•in fuch veffels, both when the ball was immerfed in the 
water, and when it was expofed only to the fleam as re- 
commended by Mr. cavendish ft) 
The veffel ufed in thefe experiments is reprefented in 
fig. i. KB&a is the pot containing the boiling water; 
d d is the cover; e is a chimney for carrying off the 
fleam ; m m is the thermometer fattened to a brafs frame ; 
this thermometer is paffed through a hole f/ in the co- 
ver, and refts thereon by a circular brafs plate G£ fattened. 
(b) Phil, Trank vol. LXVI. p. 380. 
to 
