£24 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 companion with another thermometer, 
and then the other degrees are nominated accordingly . 
III. Defcription of a thennometrical barometer , 
THE determination of the various degrees of heat (hewn 
by boiling water under different preflu res of the atmofphere, 
has been attempted by various perfons, but it was lately com- 
pleted by the accurate and numerous experiments of Sir geqrge 
siiuckburgh, member of this Society. His valuable paper is 
inferted in the LXIXth vol. of the Phil. Tranf. Upon confi- 
dering this paper, I thought it poflible to conftrudt 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 my felf, that 
with fuch an inflrument 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 inflrument which I have 
hitherto conftrudted has various defects, I have, however, 
thought of fome expedients which will undoubtedly render it 
much more perfect ; I fhall then prefent to this Society a 
more particular account of it, and alfo of the experiments 
which I intend to make with it. The infirument in its prefent 
ftate confiffs of a cylindrical tin veflel, about two inches in 
diameter and five inches high* in which veflel the ivater is 
con- 
