on the Subject of Heat. 



'95 



and provided with a scale, and I could then scarcely 

 master my impatience and wait for the time when I 

 should satisfy myself whether heat would be able to 

 pass through this vacuum. 



I now put the apparatus into a vessel filled with 

 water at 18 Reaumur, and left it there until I was sure 

 (from the scale of the instrument) that the bulb filled 

 with mercury, which was in the centre of the vacuum, 

 had reached this temperature of 18 degrees. I then 

 took the instrument out of this vessel, and held it for 

 some minutes in another full of hot water, which was 

 kept constantly boiling by a lamp placed under it. 



Since the mercury in the tube of the thermometer 

 began to rise, although slowly, there remained no longer 

 any doubt that the heat of the boiling water really passed 

 through the vacuum into the bulb of the thermometer. 



