in Fhdds. 283 



time, I was quite at a loss to account for. Every part 

 of the surface of the ice which had been covered by the 

 tin plate appeared to be perfect, level, and smooth, and 

 showed no signs of its having been melted or diminished, 

 excepting only in one place, where a channel, about an 

 inch v/ide and a little more than -^-^ of an inch deep, 

 which showed evident marks of having been formed by 

 a stream of warm water, led from the excavation just men- 

 tioned, in the center of the upper part of the cake of 

 ice, to its circumference. As the edge or vertical side 

 of the cake of ice was evidently worn away where this 

 stream passed, there could be no doubt with respect to 

 its direction. It certainly ran out of the circular excava- 

 tion in the middle of the ice; and though it might at 

 first appear difficult to explain the fact, and to show how 

 this hot water could arrive at that place, yet it was quite 

 evident that the immediate cause of the motion of this 

 stream of water could be no other than its specific gravity 

 being greater than that of the rest of the water at the 

 same depth ; and that this greater specific gravity was at 

 the same time accompanied by a higher degree of Heat 

 is evident from the deep channel which this stream had 

 melted in the ice, while other parts of the surface of the 

 ice, at the same level, were not melted by the water 

 which rested on it. To elucidate this point, I made the 

 following experiment : — 



Experiment No. 18. 



Thinking it probable that if the circular excavation 

 in the ice, which answered to the circular hole in the 

 middle of the tin plate which covered the ice, and also to 

 that in the second plate which was placed an inch higher, 

 had been melted by radiant Heat (as it has improperly 



