654 PHYSICAL PROPERTIES OF ICE. 



Feb. 18. — Thickness of the ice 57 inches. 

 Temperature of the air— 14° * 8. 

 Temperature of the ice at the surface — 16°* 8 F. 

 „ 14 -4 inches- 7°-l F. 

 „ 19 „ - 3°-8F. 



„ 35-9 „ - 7°-5F. 

 „ 45-6 „ 10° -OF. 

 50-6 „ 15°-8F. 

 The level of the water was 6 • 1 inches under the surface of the 

 ice. 



May 21. — Thickness of the ice 79 inches. 

 Temperature of the air 29°' 1 F. 

 Temperature of the ice at the surface 26° * 8 F. 

 ,, „ 17 inches 23°'5F. 



„ „ 26-5 „ 26°'2F. 



„ 31 „ 26°-2F. 



„ 38 „ .26°-8F. 



This was the greatest thickness of the ice. From April to May 

 the increase in thickness was at the rate of 7 inches a month, 

 whilst from January to February it was only 4 inches a month. 

 In winter the snow lying on the ice protects it, whilst in spring 

 the evaporation and the storms which sweep the surface of the ice 

 quite clear of snow keep down the mean temperature, and tend to 

 increase the rate of formation of ice. 



IV.— TIDES AND CURRENTS. 



1. Parry's First Voyage for the Discovery of North-west 

 Passage (1819-20). 



Latitude of anchorage in Melville Island - 74° 47' 19" '36 N. 



Longitude . - - . 110° 48' 29" '2 W. 



Dip of magnetic needle - - - 88° 43' 



Variation - - - - - 127° 47' 50'^ E. 



The mean time of high water on full and change days (luni-tidal 

 interval) was Ih. 29m. Usually the ice cracked from the high 

 spring tides about two days after new and full moon, but in 

 l5ecember the ice did not crack from the beach until the 22nd5 

 i.e., 5 days 8 hours after the new moon. Tliis retardation of the 

 tides may, perhaps, have arisen from the circumstance of the moon 

 and sun having both had their greatest south declination at the 

 usual time of the highest spring tide. There were also fresh gales 

 from the eastward on December 17th and 18th. During the three 

 months May, June, and July the night spring tides were higher 

 than the day spring tides, showing that the two tides in the day 

 are not equal. Tides were observed during May, June, to the 

 20th, and in July 1820. 



From this it appears that at Parry's winter quarters the tides 

 came from the east through Barrow Strait. 



