1 72 Count Romford’s Enquiry concerning the Nature of Heat, 
some of the foregoing experiments ; which, in order to their 
being more easily comprehended and examined, I shall elucidate 
by figures. 
Let the two opposite ends of the cylinders A and R (Plate V. 
Fig. 4) represent the two vertical metallic disks, of equal di- 
mensions, which were presented, at the same time, to the ball 
of the thermdscope C, in the experiment No. 23. 
In that experiment, the disk A being at the temperature of 
32 0 F. (that of freezing water,)' and the disk B at 1 12 0 F. while 
the bali of the thermoscope C, and all other surrounding bodies, 
were at 72 0 , it was found, that the temperature of the thermo- 
scope was not changed by the simultaneous actions of these two 
bodies, the one hot, and the other cold. 
In order to account for this result, on the hypothesis before 
mentioned, we must begin by supposing that the ball of the 
thermoscope gives off radiant caloric continually, in all direc- 
tions, and receives it, in return, from the surfaces of all the 
bodies by which it is surrounded. 
With regard to all these surrounding bodies, (excepting the 
disks A and B,) as they are at the same temperature as the ball 
of the thermoscope, (that of 72 0 ,) they will give continually to 
that instrument, just as much radiant caloric as they receive 
from it ; and no change of temperature will result from these 
equal interchanges. 
But, in respect to the disk A, as that is colder than the ball 
of the thermoscope, it returns to it a smaller quantity of radiant 
caloric than it receives from it ; consequently, the thermoscope 
receives continually less than it gives : it would of course be 
gradually exhausted of caloric, and become colder, were it not 
