Hill.— P?-o&Zc??is of Arctic Exploration. 387 



Behring Strait and the pole. This vast area has httle com- 

 munication with the warmer oceans towards the south, and, 

 enclosed as it is almost like an inland sea, there is every 

 possibility that the movements of the waters are the reverse 

 of W'hat they are in the warmer oceans, owing to the fact that 

 within the torrid and temperate zones the waters diminish in 

 temperature from the surface downwards, whilst within the 

 polar zone the reverse is the case — that is, the water increases 

 in temperature from the surface downwards. 



It is difficult to understand how the area surrounding the 

 poles can be other than the coldest portions of the earth's 

 surface, as it is there that the heat of the sun is least through- 

 out the year. At no period of the year does the sun reach an 

 elevation of more than 23|° above the horizon, and if we 

 suppose' the polar or circumpolar area to extend to latitude 

 80° N., the highest elevation of the sun, then, will not exceed 

 33^° at the time of meridian, whilst at midnight in summer 

 the elevation will be 13^° — in other words, the sun's elevation 

 during the northern summer will vary within the circumpolar 

 area between 13^° and 33-|°. 



Let us compare this with the elevation of the sun in the 

 latitude corresponding with Napier during the course of a 

 year. In summer the highest elevation is reached on the 21st 

 and 22nd December, when the sun is on the Tropic of Capri- 

 corn, or 23-|° to the south of the equator. The latitude of 

 Napier is about 39i° S., so the sun will appear to us about 16° 

 to the north of our zenith, or at an elevation above the hori- 

 zon of 74°. In winter the sun's elevation at midday will be 

 27°, or 47° lower than at midsummer. This will be on the 

 21st and 22nd June, when the sun is at the Tropic of Cancer, 

 or at the time of highest elevation over the Northern Hemi- 

 sphere. 



Now, the period of sunlight within the circumpolar area is 

 equal to that within any other similar number of degrees of 

 latitude. Everywhere there are on the average twelve hours 

 of sunlight for every day of the year ; but the question to be 

 considered is not one of light, but of heat. The earth depends 

 on the sun for its heat, and, whilst both heat and light are 

 derived from the sun, the intensity of the one and the 

 quantity of the other are very different in the different zones. 

 The heat-rays from the sun are diffused wherever light pene- 

 trates, and, as far as we know, every object in space must 

 receive some of those rays in a greater or less degree. The 

 nearer the object to the direct influence of heat and light the 

 greater we may suppose is the intensity of heat-rays and 

 light-rays upon it, but it will be manifest that the quantity of 

 heat and light received may be modified greatly by the shape 

 of the object. In any case, a source of light and heat acting 



