258 THE ANTARCTIC. 



Antarctic regions into close relation with the rest of the 

 earth's surface. 



The horizontal dimensions of the icebergs vary 

 greatly ; in high latitudes a length of i J to 3 or 3I 

 miles is by no means uncommon, and, indeed, some 

 masses are greatly in excess of these measurements. 

 For example, the largest seen by Bruce was more than 

 30 miles long ; and another, seen by several ships in 

 April and May of 1892 in the South Atlantic, in lati- 

 tude 42° to 46° S. and longitude 30° to 36° W., exceeded 

 40 miles in length. As these gigantic ice masses are also 

 correspondingly broad, their surface areas must measure 

 some thousands of square miles. The years 1891 to 

 1896 were remarkable for the appearance of ice masses 

 both numerous and so enormously large that they drifted 

 far into the Atlantic and Indian Oceans. 



The drift of the icebergs and their distribution over 

 the great expanse of the southern ocean is a phenomenon 

 of supreme importance, both for the study of physical 

 geography and for the material interests of navigation. 

 After an Antarctic iceberg has been detached from its 

 native wall of ice, it may primarily be subject to the im- 

 pulse of the winds blowing from the land or from the 

 inland ice, and also to such tidal currents as may occur 

 near them. But, at some distance from the land, it is 

 swept along by the force of the true oceanic currents — a 

 force which must beyond all doubt greatly exceed that of 

 the winds, as the submerged part of the berg is larger 

 than the part above water, not only in volume but also 

 in mass. It is true that the currents of the ocean travel 

 at a slower rate than those of the air, nevertheless the 

 impetus given to the berg by a given volume of water 

 must be much greater than that imparted by a like volume 

 of air ; and as, moreover, a considerably greater mass of 

 the berg is set in motion by the water than by the air, it 

 follows that at least in the higher latitudes the path pur- 



