Drift Ice and Currents of the North Atlantic. 373 



Art, XV. — On the Drift Ice and Currents of the North Atlan- 

 tic, with a Chart showing the Observed Positiotis of the Ice 

 at various times ; by W". C. Redfield.* 



Of the various dangers which beset the path of the mariner, 

 perhaps there are none which excite to more vigilance than the 

 known or expected proximity of ice. In some frequented por- 

 tions of the Atlantic Ocean the ice appears almost every year, in 

 the various forms of field ice, floes and massive ice-islands, drift- 

 ed from the arctic regions by the constant action of the polar cur- 

 rents. These ice-bearing currents, in flowing tov/ards the south, 

 must necessarily incline towards the western limits of the ocean, 

 owing to the increased velocity of the diurnal rotation of the 

 earth's surface as we depart from the poles ; a law well under- 

 stood as regards the currents of air which form the trade winds. 

 Hence it is that on and near the Banks of Newfoundland these 

 ice-currents are found to cross the usual track of vessels bound 

 from the ports of Europe to northern America. 



The quantity of ice which appears on this route of navigation 

 in different years, is exceedingly various. It is sometimes seen 

 as early in the year as January, and seldom later than the month 

 of August. From March to July is its most common season. It 

 is found most frequently to the west of longitude 44°, and to the 

 eastward of longitude 52° ; but icebergs are sometimes met with 

 as far eastward as longitude 40°, and in some rare cases, even 

 still further towards Europe. 



Experience has shown that the proximity of ice is far less 

 hazardous than rocks and shoals ; and this floating danger would 

 be still less formidable were it not for the fogs and mists which it 

 often causes. The thermometer has been often held up as afford- 

 ing sure indications of an approach to ice, by the reduction of 

 temperature shown both in the air and water, and these indica- 

 tions are important and should by no means be neglected. But 

 there may be many cases of approach to ice where a reliance 

 upon the thermometer alone could not afford security. 



On the ice chart, which is annexed, we have indicated numer- 

 ous positions in which ice has been seen and reported on the 



* From the forthcoming " Memoir" of Messrs. E. & G. W. Blunt on the Dan- 

 gers and Ice of the North Atlantic Ocean. 



Vol. xLviii, No. 2.— Jan.-March, 1845. 48 



