PHILOSOPHICAL OBSERVATIONS. 



ON COLD. 



Havixg already devoted much in Chapter XIII. of the Narrative on this subject, as it 

 regards the human body, it only remains to publish my experiments on its effect on other 

 substances. I shall begin with those on ice, wliich were repeated yearly : the thickness of 

 the ice was measured regularly, both on a lake and in the sea, everj' month, and was found 

 to increase until the end of May, when it had arrived at its maximum thickness, which in the 

 sea was ten feet, and the lake eleven ; the proportion being so much more on fresh than on 

 salt water. In the months of February and March, when the temperature of the air was at 

 fifty degrees below zero, the temperature of the ice gradually diminished between the 

 surface and the water, which was, immediately below the ice, at the temperature of twenty- 

 seven degrees ; showing that to freeze sea-water below the ice (where no air was to be 

 found) required a temperature five degrees lower than the freezing point of Fahrenheit. 

 This was done by excavating a large shaft in the ice, and, as it deepened, a horizontal 

 hole was bored large enough to admit the thermometer at every foot in depth, until we 

 arrived at the water, in which a thermometer was immediately immersed, and tlie result 

 obtained, the fiurther detail of which need not be presented. 



ITS EFFECTS ON SNOW. 



The same experiments were made on snow, with proportional results ; twelve feet dcptli 

 of snow being equal in the resistance of cold to seven feet of ice. It was from these 

 experiments that I determined on covering our miserable canvas habitation at Fury 

 beach with ice, which was accomplished by watering the snow walls as tliey were con- 

 structed, and also tlie roof; the former being made from seven to nine feet thick, and 

 the latter from four to six. Tliis we found effectual against cold until the mercury had 



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