1886.] 



Observations on Pure Ice and Snow. 



545 



for this part of the operation, producing for the experiments a cylin- 

 drical mass of pure ice 2 feet 1| inches diameter, having a cubic 

 content of 8"305 feet, and weighing nearly 4 cwts. 22 lbs. A wooden 

 frame had been securely fixed in the tank to hold the necessary 

 tubes containing the thermometers. These were four in number, 

 and were placed at equal distances between the centre of the cir- 

 cular mass of ice and its circumference, the bulbs being also midway 

 between the top and bottom as indicated in fig. 1. The thermo- 



Fiq. 1. 



Sectional Elevation. 



meters were each protected by iron pipes closed with corks. The 

 bulb of each thermometer was immersed in mercury placed at the 

 bottom of the pipe, the top being also closed airtight by corks. 

 These thermometers were therefore easily removed, and replaced at 

 the stated times of observation. As the water gradually froze, the 

 arrangement became securely embedded in the ice. 



A suitable mass of pure ice having been thus obtained, and the 

 thermometers registering its temperature at 0° F. throughout, the 

 freezing mixture surrounding the tank was withdrawn and its place 

 supplied with about 15 cwt. of snow ; the gradual increase in the 



VOL. XL. 2 o 



