OF ARTS AND SCIENCES. 



01 



apparatus to return on the outside. When the whole of the water is 

 at a nearly uniform temperature the stirring is stopped, the valve op 

 falls into place, and the connection of the water in the outer and 

 inner vessels is practically closed as far as currents are concerned, aud 



Ik $1 



Fin. 2. 



Fig.l. 



O 



hefore the water inside can cool a little the outer water must have 

 cooled considerably. 



So effective was this arrangement that, although some of the ther- 

 mometers read to 0°.007 C, yet they would remain perfectly station- 

 ary for several minutes, even when at 40° C. At very high tempera- 

 tures, such as 80° or 90° C, the burner was kept under the vessel w 

 all the time, and supplied the loss of the outer vessel by radiation. 

 The inner vessel would under these circumstances remain at a very 



