108 LIGHT SCIENCE FOR LEISURE HOURS. 



back by impassable barriers of land or ice, but by 

 the serious dangers to which the floating masses of ice 

 and the gradually thickening ice-fields exposed his 

 weak and ill-manned vessel. Since his time, others 

 have sailed upon the same track, and hitherto with 

 no better success. It was reserved to the Swedish 

 expedition of 1868 to gain the highest latitudes ever 

 reached in a ship in this direction. The steamship 

 * Sofia,' in which this successful voyage was made, 

 was strongly built of Swedish iron, and originally 

 intended for winter voyages in the Baltic. Owing to 

 a number of delays, it was not until September 16 

 that the ' Sofia ' reached the most northerly part of 

 her journey. This was a point some fifteen miles 

 nearer the North Pole than Hudson had reached. 

 To the north there still lay broken ice, but packed so 

 thickly that not even a boat could pass through it. 

 So late in the season, it would have been unsafe 

 to wait for a change of weather and a consequent 

 breaking-up of the ice. Already the temperature had 

 sunk sixteen degrees below the freezing-point ; and 

 the enterprising voyagers had no choice but to return. 

 They made, indeed, another push for the north a 

 fortnight later, but only to meet with a fresh repulse. 

 An ice-block with which they came into collision 

 opened a large leak in the vessel's side; and when 

 after great exertions they reached the land, the water 

 already stood two feet over the cabin floor. In the 

 course of these attempts, the depths of the Atlantic 

 were sounded, and two interesting facts were revealed. 



