[ 82 5 ] 
expanfion of fluids graduated by equal parts, is not 
a diffident flandard of heat and cold. 
Mr. Fahrenheit has flnce improved the mercurial 
thermometer to a great degree, and brought it to as 
much perfection as, perhaps, it will bear. Fie has 
remarked, that when the barometer thews a greater 
degree of preflure of the atmofphere ; the fame liquor 
will receive eight, or nine degrees of heat, more than 
when the barometer is at the lowed:. But whether 
this proceeds entirely from the liquor’s receiving a 
greater degree of heat, by the preflure of the atmo- 
fphere, may be a matter of fome doubt; as it feerns, 
by comparing the mercurial, with other thermometers; 
to be affeCted, in fome meafure, by the preflure of 
the atmofphere, in all degrees of heat and cold. 
The making of metalline thermometers has been 
hinted at by many; particularly by Mr. Smeaton, in 
his curious obfervations on the expanfion of metals, 
who recommends zink, or fpelter, as moft capable 
of expanfion, and fitted: for the purpofe. I have en- 
deavoured to make one on this principle, which I 
take the liberty of laying before this Society, with a 
defeription of its conftruCtion, and an account of the 
few obfervations I have been as yet able to make on 
it. [Vide Tab. XVIII.] 
It is compofcd of four metal bars, which aCt by a 
combination of levers, and pullies. The upper end 
of the bar A, which is 2 feet long, is oppofed by a 
flat piece of metal x, fere wed fad: to a piece of deal 
board ; y, y, y, y, and its lower end refls on a 
fmall hemifphere, placed on the fhorter arm of the 
lever B, which is fixed to the board y. 
By 
