[ iso ] 
one’s breath five or fix times on the firft bar. It 
marks the 282,000th part of an inch per foot expan- 
lion, and the powers of the levers, are fo eafily in- 
creafed, by the help of counterballance weights, that 
the millionth part of an inch expanfion, or con- 
traction, may be fhewn ; and an inftrument formed 
to point out every fiate of the cold or warmth of 
the air fo minutely, as fcarcely ever to remain fia- 
tionary. 
The bars are placed on a board of white deal, 
firaight grained, and free from knots, which was 
thoroughly well feafoned and dry. I had it varniflied 
over feveral times with firong varnilh, or japan, to 
fecure it from the moifiure of the air, which it feems 
to have done effectually. I have placed it feveral 
times in the open air, when it has rained incefiantly 
for many hours, without perceiving any difference 
in its operation. 
I found the regifiers to the thermometer fo Tatis- 
faCtory, and the operation fo light and eafy, that I 
have alfo applied them to the wheel barometer. I 
had the tube A, Fig. 3. made fomewhat above 
~ inch diameter in the hollow of the tube, with a 
ball B at the top, above 3 inches diameter, to the 
middle of which the mercury rifes at a medium. 
— 7*o inch mercury in this part of the ball, is fufii- 
cient to fill 3 inches of the tube; fo that by making 
one round of the pulley, on which the index is 
placed, T V inch lefs than 3 inches, it makes the rife 
and fall of the mercury with more exaCtnefs, than 
any barometer, where there is not an allowance made 
for the finking or rifing of the mercury in the ciffern, 
the difiance between the two furfaces being the exaCt 
height 
