PHYSICAL PROPERTIES OF ICE. 653 



1 1 feet in a lake of fresh water. In February and March, with the 

 air temperature at —50° F., the temperature of the ice gradually 

 diminished between the surface and the water which was imme- 

 diately below the ice at a temperature of — 27 ° F. 



The change of temperature in 12 feet depth of snow being the 

 same as in 7 feet of ice. 



Effect of Cold on Mercury. 

 '•'• Every year the mercury which had been used froze at a higher 

 temperature until it reached — 31° F., being eight degrees higher 

 than the usual point, while mercury which had not been exposed 

 retained its purity." 



English inches. 



- 6° 



•7F. 



- 0° 



•8F. 



5° 



•9F. 



13° 



•3 F. 



22° 



•6F. 



9. The Second German Expedition under M. Koldewey. 

 Temperature and Thickness of the Ice. 



Observations were made on the rate of formation and on the 

 temperature of the ice at various depths in the harbour at Sabine 

 Island, with the following results : — 



On Sept. 28 the thickness of the ice was 7 

 On Nov. 11 the thickness was 31 inches. 

 Temperature of the air — 12°'3 F. 

 Temperature of ice at the surface 

 „ ?j B inches deep 



?j » 1^ J? 



The level of the water was 3^ inches under the surface of the 

 ice, and the temp, of water +28° F. 



Nov. 24. — Thickness of ice 36 • 5 inches. 



Temperature of the air —2° '9 F. 

 Temperature of ice at tlie surface 0°*1 F. 

 „ „ ■ 7 J inches 7°-0 F. 



13 „ 12°-4F. 

 18-5 „ 16°-oF. 

 23 „ 19°-9F. 

 „ 27-5,, 21°-4F. 

 30-0,, 23°-9F. 

 The level of the water was 3 J inches under the surface of the 

 ice, and the temperature of the water was 28° * 2 F. 

 Jan. 20. — Thickness of the ice 53 inches. 

 Temperature of the air— 5° '3 F. 

 Temperature of ice at the surface — 0° • 2 F. 

 „ 10 inches 1°-2F. 

 14 „ 3°-4F. 



20-5 „ 5°-5F. 



26 „ 7°-9F. 



31 „ 11°-3F. 

 „ „ 37-5 „ 13°'3F. 



44 „ 19°-2F. 

 The level of the water was 5*5 inches under the surface of the 

 ice, and temperature of water 28° * 2. 



