C 3°3 T 
No part of the fpirit, with which the cylinder is 
filled, can get into the tube, as long as the inftrument 
is kept in an eredf poiition, or even if it is carefully laid 
down flat on a table. For tho’ in this laft cafe fome 
of the fpirits may get into the ball A, it will rife to 
that part of the ball, which is then uppermoft, and 
will not touch the orifice of the tube n ■ which was 
the reafon for adding this ball, which would be un- 
neceflary, if the inftrument was kept conftantly eredt, 
or nearly fo. If the fpirit fhould come to touch the 
orifice of the tube 77, it would work up between the 
mercury and the glafs ; which would put the in- 
ftrument out of order. 
The thermometer fig. 3. is defigned for fhewing 
the greateft cold, which happens in any place during 
the time the inftrument is left in it. The tube is 
bent into the fhape of a fyphon of unequal legs Hand- 
ing parallel to one another, the bend being at the 
bottom. The top of the fhorter leg is bent to a 
right angle, and immediately opens into a ball A, 
which, by means of a fhort bent tube on the op- 
polite fide, communicates with a cylinder Handing 
parallel to the legs of the fyphon, and pointing 
downwards.. This cylinder contains the greateft 
part of the fluid ; and is added only to make the 
thermometer more fenfible than it would be, if the 
ball A was made of a lufficient bignefs to contain the 
proper quantity of fluid. This inftrument is Ailed 
with fpirit of wine, with the addition of as much 
mercury as is fufficient to fill' both legs of tine 
fyphon, and about a fourth or fifth part of the 
ball A. 
The 
