1 22 Count Rumford’s Enquiry concerning the Nature of Heat, 
those opposite actions were in fact equal ; the’ bubble of spirit 
of wine, which, by its motion, would have indicated the smallest 
change of temperature in the ball of the thermoscope, to which 
the hot and the cold bodies were presented, remained at rest. 
On removing the cold body a little farther from the ball, to 
the distance of 3^- inches, for instance, the hot body remaining 
in its former station, at the distance of 3 inches, the bubble 
began immediately to move towards the opposite ball of the 
thermoscope, indicating an increase of heat in the ball exposed 
to the actions of the hot and the cold bodies ; but, when the 
hot body was removed to a greater distance, the cold body re- 
maining in its place, the bubble indicated an increase of cold. 
The celerity with which the ball of the thermoscope acquired 
heat, or cold, might be estimated by the velocity with which the 
bubble of spirit of wine advanced, or retired, in its tube; but, 
on the most careful and attentive observation, I could not per- 
ceive that it moved faster when the ball was acquiring heat, 
than when it was acquiring cold ; provided that the hot and the 
cold bodies, from which the calorific and frigorific rays pro- 
ceeded, were at the same relative distances. 
From these experiments, which I lately repeated at Geneva, 
in the presence of Professor Pictet, Mons. de Saussure, M. 
Senebier, and several other persons, we may venture to con- 
clude, that, at equal intervals of temperature, the rays which 
generate cold, are just as real, and just as intense, as those which 
generate heat; or, that their actions are equally powerful, in 
changing the temperatures of neighbouring bodies. 
On a superficial view of this subject, it might appear extraor- 
dinary, that so important a fact as that of the frigorific radiations 
of cold bodies should have been so long unnoticed, while the 
