Emission and Transmission of Heat 



and provided with a reservoir C, at its side another glass tube 

 DEF, bent over, and likewise open at both ends. The ends B 



Fig. 160. 



Fig. 161. 



Fig. i6a. 



and D are at the same level. Both tubes are inserted at their 

 lower ends in a stopper which enters freely into the tubular open- 

 ing of the vessel, this stopper bears at its upper end a plate of 

 brass of a diameter greater than the opening of the 

 vessel, which allows the stopper to be inserted al- 

 ways to the same distance. When the stopper is 

 put in , the point B is at the height which the liquid 

 should reach. To fill the vessel the stopper clos- 

 ing the opening is removed, and is replaced by 

 the stopper bearing the glass tubes ; the 

 reservoir C being full of water and the end 

 A closed by a finger. The end A is then 

 opened and the operator sucks on the 

 tube F, and evidently when water ap- 

 pears in the tube F, the water level in 

 the vessel will have reached the height 

 BD ; at this moment the extremity A 

 is again closed, the apparatus is lifted 

 out and the ordinary stopper re- 

 placed. Fig. 164. 



The mode of precedure was as follows : the vessel hav- 

 ing been filled with hot water and placed upon its support the 



