62 Inquiry concerning the Nature of Heat, 



The thermoscope was laid down on one side, so that 

 the two ends of its tube, to which its balls were attached, 

 instead of being vertical, were now in a horizontal posi- 

 tion ; and the cold body, instead of being presented 

 to the ball of the instrument on one side of it, and on 

 the same horizontal level with it, was now placed di- 

 rectly under if, and at the distance of 6 inches. 



This cold body, instead of being a metallic substance, 

 was a solid cake of ice, circular, flat, and about 3 inches 

 thick, and 8 inches in diameter. It was placed in a 

 shallow earthen dish, about 9 inches in diameter below, 

 12 inches in diameter above, at its brim, and 4 inches 

 deep. The cake of ice being laid down on the bottom 

 of the dish, the top of the dish was covered by a circu- 

 lar piece of thick paper, 14 inches in diameter, which 

 had a circular hole in its centre, just 6 inches in di- 

 ameter. 



This earthen dish, containing the ice, and thus cov- 

 ered, was placed perpendicularly under one of the balls 

 of the thermoscope, at such a distance that the centre 

 of the upper surface of the flat cake of ice was 6 inches 

 below the ball. 



The result of this experiment was just what might 

 have been expected : the ice was no sooner placed under 

 the ball of the instrument than the bubble of spirit of 

 wine began to move towards that side where the cold 

 body was placed ; and it did not remain stationary till 

 after it had advanced more than an inch in the tube. 



Experiment No. 19. Desirous of discovering whether 



, the surface of a liquid emits frigorific or calorific rays, 



as solid bodies have been found to do, I now removed 



the cake of ice from the earthen dish, and replaced it 



with an equal mass of ice-cold water. 



