Mr. cavallo’s Account of 
freezing point or boiling point. Either the point of boiling 
or freezing may be found by experiment, or any other point 
may be afcertained by comparifon with another thermometer, 
and then the other degrees are nominated accordingly. 
III. Defcription of a thermometrical barometer . 
THE determination of the various degrees of heat (hewn 
by boiling water under different preffures of the atmolphere, 
has been attempted by various perfons, but it was lately com- 
pleted by the accurate and numerous experiments of Sir george 
shuckburgh, member of this Society. His valuable paper is 
iuferted in the LXIXth vol. of the Phil. Tranf. Upon confl- 
dering this paper, I thought it poflible to conftruCt a thermo- 
meter with proper apparatus, which, by means of boiling wa- 
ter, might indicate the various gravity of the atmofphere, viz. 
the height of the barometer. This thermometer, together 
with the fuitable apparatus, might, I thought, be packed into a 
fmall and very portable box, and I even flattered myfelf, that 
with fuch an inftrument the heights of mountains, &c. might 
perhaps be determined with greater facility than with the com- 
mon portable barometer. My expectations are far from having 
been difappointed, and although the inftrument which I have 
hitherto conftr acted has various defeats, I have, however, 
thought of fome expedients which will undoubtedly render it 
much more perfect ; I (hall then prefent to this Society a 
more particular account of it, and alfo cf the experiments 
which I intend to make with it. The inftrument in its prefent 
ftate confifts of a cylindrical tin veflel, about two inches in 
diameter and five inches high, in which veflel the water is 
con- 
