79 
and the Mode of its Communication. 
composed of any kind of cloth, or stuff, or other warm covering, 
is supported, in a vertical position, on a wooden stand, which is 
placed on a table, in a large quiet room ; and, one of the ther- 
mometers above described being placed in the axis of the vessel, 
the time employed in cooling the water, through the clothing 
with which the instrument is covered, is observed and noted 
down. 
Now, as the time of cooling through any given interval of the 
scale of the thermometer, (or from any given degree above the 
temperature of the air of the room, to any other given lower 
degree, but still above the temperature of the air of the room,) 
will be longer, or shorter, as the covering of the instrument 
is more or less adapted for confining heat, it is evident, that the 
relative warmth of clothing of different kinds, may be very accu- 
rately determined by experiments of this sort. 
I provided four instruments of this kind, all very nearly of 
the same dimensions. Their cylindrical bodies are each 4 inches 
in diameter, and 4 inches long ; and their cylindrical necks are 
about T 8 - of an inch in diameter, and 4 inches in length. This 
neck is placed in the centre of the circular flat top, or upper end, 
of the vertical cylindrical body ; and, opposite to it, in the centre 
of the flat bottom of the body, there is a hollow cylinder, T s _ of 
an inch in diameter, and 3 inches long, projecting downwards, 
into which a vertical cylinder of wood is fitted, on the top of 
which the instrument is supported, in such a manner that the 
air has free access to every part of it. This cylinder of wood 
constitutes a part of the wooden stand above-mentioned. 
As the thermometer is placed in the axis of the cylindrical 
vessel, and as its bulb is just as long as the body of this vessel, 
it is evident that it must ever indicate the mean temperature of 
