﻿and Fluctuations. 347 



the northern hemisphere are neither so strong nor so regular as 

 those of the southern, so that probably but little air is drawn 

 out by their friction ; but, on the other hand, the formation of 

 the land, the trend of the coast and of the mountain-ranges, 

 forces a very great deal of air from the south into the arctic 

 circle. This is notably the case on the west coast of Norway, 

 along which the atmospheric current flows into the polar regions 

 in exactly the same way as the great current of the ocean (the 

 Gulf-stream) does. Consequent on the centrifugal tendency, 

 this would naturally be ejected ; and a great part of it is ejected 

 in a succession of gales, rather than in a constant wind, which 

 find a vent on the east coast of Greenland or through Kennedy 

 Channel ; but the openings for escape are small ; and it would 

 appear that the resistance offered by the sluggish air resting 

 over the continents of Asia and America resists even a consider- 

 able pressure induced by the centrifugal tendency. The elastic 

 force of the air in the Arctic is thus kept permanently greater 

 than it would be if the area was open; and the barometer, although 

 low, has not so great a depression as would seem due to the cen- 

 trifugal tendency in such a high latitude. 



There is, however, in the neighbourhood of Iceland a small 

 area in which, especially in winter, the barometer stands 

 markedly lower than it does on its southern, eastern, or western 

 side. After what I have said as to the effect on the barometer 

 of the westerly winds circling round the antarctic regions, it 

 would be unnecessary to dwell on the depression in this very 

 small area further than to point out that the westerly winds of 

 the North Atlantic, the south-westerly and southerly winds of 

 the coast of Norway, veering, before we lose sight of them, to 

 south-east and reappearing on the coast of Greenland as north- 

 easterly gales, form a circuit round Iceland which would suffi- 

 ciently account for the existence of even a lower pressure in that 

 neighbourhood. But Professor Mohn, Mr. Buchan, and several 

 others consider that this circuit of winds is due to the low pres- 

 sure in the centre, round which they blow in a vorticose manner, 

 the air being continually drawn in towards the place of compa- 

 rative vacuum. If this is the case, what causes the low pres- 

 sure ? I have already referred at length to Mr. Buchan's opi- 

 nion that the low pressure is due to the relative heat. I have 

 shown that Iceland cannot be considered an area of relatively 

 high temperature, that areas of relatively high temperature do 

 not necessarily become areas of relatively low pressure, and that 

 the low pressure in the neighbourhood of Iceland cannot be due 

 to any such cause. On the other hand, the westerly winds of 

 temperate latitudes are incontrovertible facts. There is here no 

 question of their origin ; for, extending, as they do, right round 



