294 57r Benjamin Thompson’s 
For this experiment I provided myfelf with a new thermo-* 
meter N° 4. the bulb of which, being of the fame form as 
thofe already defcribed ( viz. globular) was alfo of the fame fixe, 
or half an inch in diameter. To receive this thermometer 
a glafs cylinder was provided, 8 lines in diameter, and about 
14 inches long, and terminated at one end by a globe i§ inch £ 
in diameter. In the center of this globe the bulb of the ther- 
mometer was confined, by means of the ftopple which clofed the 
end of the cylinder ; which ftopple, being near 2 inches long, re- 
ceived the end of the tube of the thermometer into a hole bored 
through its center or axis, and confined the thermometer in its 
place, without the aftiftance of any other apparatus. Through 
this ftopple two other fmall holes were bored, and lined with 
thin glafs tubes, as in the thermometer N° 3. opening a paf- 
fage into the cylinder, which holes were occasionally flopped 
up with fome floppies of cork ; but to prevent accidents, fuch 
as I had before experienced from an explofion, great care was 
taken not to prefs thefe floppies into their places with any con- 
fiderable force, that they might the more eaflly be blown out 
by any confiderable effort of the confined air. 
Though in this inftrument the thermometer was not alto- 
gether fo fteady in its place as in the thermometers N° 1. N° 2. 
and N° 3. the elafticity of the tube, and the weight of the 
mercury in the bulb of the thermometer, oecafioning a fmall 
vibration or trembling of the thermometer upon any fudden 
motion or jar ; yet I preferred this method to the others, on 
account of the dower part of this thermometer being intirely 
free, or fufpended in fuch a manner as not to touch, or have 
any communication with, the lower part of the cylinder or 
the globe: for though the quantity of heat received by the 
.tube of the thermometer at its contact with the cylinder at its 
choaks, 
