and the Mode of its Communication. 163 
on the quantity of frigorific rays which arrive at its surface, and 
on the intensity of their action ; and, as the intensity of the rays 
from the internal surface of the sphere, at its centre, is dimi- 
nished in the same proportion as the surface of the sphere is 
augmented when its diameter is increased ; it follows, that a 
hot -body placed in the centre of a hollow sphere, at any given 
constant temperature below that of the hot body, will be cooled 
in the same time, or with the same celerity, whatever may be 
the size of the sphere. 
If this conclusion be well founded, (and I see no reason to 
suspect that it is not so,) it will follow, from the principles 
assumed, that the hot body will be cooled in the same time, in 
whatever part of the hollow sphere it be situated. And, as the 
cooling of the body is not affected, that is to say, accelerated, 
or retarded, either by the greater or smaller size of the inclosed 
space in which it is confined, or by its situation in that confined 
space, so it cannot be in any manner affected, either by the form 
of that hollow space, or by the presence of a greater or less 
number of other solid bodies ; provided always, that all these sur- 
rounding bodies be at the same constant temperature. 
If, however, any of these surrounding bodies, the temperature 
of which is liable to be sensibly changed during the experiment, 
by the calorific rays emitted by the hot body, be placed very 
near that body, the cooling of that hot body will be retarded ; 
the rays from this neighbouring body, so heated, being less 
frigorific than those from other bodies at a greater distance, 
which it intercepts. 
The results of all my experiments on the cooling of bodies, 
tended uniformly to confirm the above conclusions. 
Admitting that the cooling of a hot body is effected solely by 
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