72 Arctic Natural History. 



discharged by the pump at the adit (45 fathoms from the surface) is 

 only 63° 6'.* 



The Orchard, Penzance, Oct. 15, 1851. 



Arctic Natural History. 



The following interesting statements illustrative of Arctic 

 Natural History we select for the information of our 

 readers. 



1. Cause of Intense Thirst in Arctic Regions. 2. Thickness of 

 the Arctic Ice. 3. Warmth of Snow Burrows. 4. Snow a bad 

 Conductor of Sound. 5. The breaking up of an Arctic Iceberg. 

 6. Refrigerating Power of Icebergs. 7- The droppings of Eider 

 Ducks. 8. Arctic Minute Animal and Vegetable Forms, and 

 Colour of the Sea. 9. On the Flesh of Little Auks and Rotges f 

 and Sea- Fowl generally. 10. Red Snoiv. 11. On the Colour- 

 ing Matter of Marine Algce, by Dr Dickie. 12. Nostoc Arcti- 

 cum, by Dr Dickie. 13. On the Magnitude of Arctic Glaciers 

 and their advance towards and their termination in the Sea. 

 14. Ice and Sea-Water Coloured by the Diatomacece. 



1. Cause of Intense Thirst in Arctic Regions. 

 After saying farewell to Mr Mecham and his party Mr 

 Stewart returned to the ships in Assistance Bay, where he 

 arrived in the evening a little fatigued, having suffered as 

 usual from excruciating thirst. I believe the true cause of 

 such intense thirst is the extreme dryness of the air when 

 the temperature is low. In this state it abstracts a large 

 amount of moisture from the human body. The soft and 

 extensive surface which the lungs expose, twenty-five times 

 or oftener every minute, to nearly two hundred cubic inches 

 of dry air, must yield a quantity of vapour which one can 

 hardly spare with impunity. The human skin, throughout 

 its whole extent, even where it is brought to the hardness of 

 horn, as well as the softest and most delicate parts, is con- 

 tinually exhaling vapour, and this exhalation creates in due 

 proportion a demand for water. Let a person but examine 



* Observations on the temperature of other parts of the Providence Mines are 

 recorded in the Society's Transactions, vol. v., p. 390. 



