262 The Temperature of Water 



All these pieces of ice having been fixed firmly in their 

 places by means of some little woo'den wedges, ice-cold 

 water was poured into the cylindrical vessel until the 

 surface of this liquid was an inch above the upper edge 

 of the cork cup. 



In this state of things it is evident that the two cups 

 were filled with and surrounded on all sides by water at 

 the temperature of melting ice, and that this temperature 

 was maintained constant by the pieces of ice with which 

 the water was in contact. 



After having left the apparatus in this situation for 

 about an hour, in order to satisfy myself that the tem- 

 perature of the cold water was constant and uniform 

 throughout its entire mass, I made the following experi- 

 ment. 



Experiment No. i. A solid ball of tin (F) having 

 been provided, i inches in diameter, with a cylindrical 

 projection on the lower side of it, i inch in diameter 

 and ^ of an inch long ending in a conical point which 

 projected (downwards) |- of an inch farther, and having 

 on the other side a strong iron wire 6 inches long, which 

 served as a handle, this ball, after having been im- 

 mersed for half an hour rn a considerable quantity of 

 water at the temperature of 42 F., was withdrawn from 

 the water, wiped dry with a handkerchief of the same 

 temperature, placed without loss of time above the 

 cylindrical vessel, and fixed in such a position that the 

 entire conical point of the tin ball (-J of an inch in length) 

 was submerged in the cold water contained in the vessel. 



To fix and keep the metallic ball in its place, I used a 

 strong slip of tin (GH), 6 inches long and 2j inches 

 wide, with a circular hole in the middle of it i inch 

 in diameter. This slip of tin being laid horizontally on 



