182 SCIENCE IN SHORT CHAPTERS. 



As already stated, the barrier fringe that has stopped the 

 progress of Arctic explorers is a broken mountainous shore 

 down which is pouring a multitude of glaciers into the sea. 

 The ice of these glaciers is, of course, fresh-water ice. Now, 

 we know that when ice is mixed with salt water we obtain 

 what is called "a, freezing mixture" a reduction of tem- 

 perature far below the freezing point, due to the absorption 

 of heat by the liquefaction of the ice. Thus the heat of 

 the continuously shining summer sun at this particular 

 part of the Arctic region is continuously absorbed by this 

 powerful action, and a severity quite exceptional is thereby 

 produced Every observant tourist who has crossed an 

 Alpine glacier on a hot summer day has felt the sudden 

 change of climate that he encounters on stepping from 

 terra firma on to the ice, and in which he remains immersed 

 as long as he is on the glacier. How much greater must 

 be this depression of temperature where the glacier ice is 

 broken up and is floating in sea-water, to produce a vast 

 area of freezing mixture, which would speedily bring the 

 hottest blasts from the Sahara down to many degrees below 

 the freezing point. 



A similar cause retards the beginning of summer in Arctic 

 Norway and in Finland and Siberia. So long as the winter 

 snow remains unmelted, i.e., till about the middle or end 

 of June, the air is kept cold, all the solar heat being ex- 

 pended in the work of thawing. This work finished, then 

 the warming power of a non-setting sun becomes evident, 

 and the continuously accumulating heat of his rays displays 

 its remarkable effect on vegetable life, and everything cap- 

 able of being warmed. These peculiarities of Arctic climate 

 must become exaggerated as the Pole is approached, the 

 winter cold still more intense, and the accumulation of 

 summer heat still greater. In the neighborhood of the 

 North Gape, where these contrasts astonish English visitors, 

 where inland summer traveling becomes intolerable on ac- 

 count of the clouds of mosquitoes, the continuous sunshine 

 only lasts from May 11 to August 1. At the North Pole 

 the sun would visibly remain above the horizon during about 

 seven months from the first week in March to the first 

 week in October (this includes the effect of refraction and 



