298 



Of the Propagation of Heat 



with a very warm covering of cotton-wool. This cov- 

 ering (which was above an inch thick) reached from the 

 surface of the melting snow in which the jar stood quite 

 to the top of the jar. The mouth of the jar was first 

 covered with a round wooden cover (from the center of 

 which a thermometer, the bulb of which reached one 

 inch below the surface of the water, was suspended), and 

 on the top of this wooden cover there was put a thick 

 covering of cotton. 



In all the experiments in the following table, except 

 the three first, the jar was exposed naked to the air, ex- 

 cept the lower part of it, which, as I have already more 

 than once observed, was always covered, as high as the 

 ice in the jar reached, with melting snow or with pounded 

 ice and water. 



In the two experiments No. 37 and No. 38, which are 

 marked with asterisks, the surface of the ice was covered 

 with ice-cold water to the depth of 0.478 of an inch 

 only ; in all the other experiments it was covered to the 

 depth of 0.956 of an inch. 



