78 Count Rumford’s Enquiry concerning the Nature of Heat y 
and, as a perfect knowledge of the instruments made use of, 
is indispensably necessary, in order to form distinct ideas of the 
experiments, I shall take the liberty to be very particular in 
these descriptions. 
The thermometers, four in number, which were used in these 
experiments, were constructed under my own eye, and with the 
greatest possible care ; and, after every trial I have been able to 
make with them, in order to ascertain their accuracy, they 
appear to be very perfect. 
They are mercurial thermometers, graduated according tp 
Fahrenheit : their bulbs are cylindrical, 4 inches long, and 
of an inch in diameter; and their tubes are from 15 to 16 
inches long. The mercury with which they are filled is quite 
pure ; and they are freed from air. Their scales were divided 
with the greatest care ; and, by means of a nonius, they show 
eighth parts of a degree very distinctly : they are graduated 
from about 10 degrees below the freezing point, to 5 or 6 de- 
grees above the point of boiling water. Their bulbs are quite 
naked; their scales ending about 1 inch above the junction of 
the bulb with its tube. The freezing point is situated about 5 
inches above the upper end of the bulb. The reason for placing 
it so high, will be evident, from the details of the experiments 
in which these instruments were used. 
The instrument I contrived for ascertaining the warmth of 
clothing, is extremely simple : it is merely a hollow cylindrical 
vessel, made of thin sheet brass. It is closed at both ends ; and 
has a narrow cylindrical neck, by which it is occasionally filled 
with hot water. 
This vessel, being covered with a garment made to fit it, 
