TOWARDS THE NORTH POLE. 175 



course to be pursued, therefore, is that indicated by the 

 temperature. Where the July isotherms, or lines of equal 

 summer heat, run northwards, a weak place is indicated in 

 the Arctic barrier ; where they trend southwards, that barrier 

 is strongest Now there are two longitudes in which the 

 July Arctic isotherms run far northward of their average 

 latitude. One passes through the Parry Islands, and 

 indicates the sea north-east of Bearing's Straits as a suitable 

 region for attack ; the other passes through Spitzbergen, and 

 indicates the course along which Sir E. Parry's attack was 

 made. The latter is slightly the more promising line of the 

 two, so far as temperature is concerned, the isotherm of 36 

 Fahrenheit (in July) ninning here as far north as the 77th 

 parallel, whereas its highest northerly range in the longitude 

 of the Parry Islands is but about 76. The difference, how- 

 ever, is neither great nor altogether certain ; and the fact 

 that Parry found the ice drifting southwards, suggests the 

 possibility that that may be the usual course of oceanic 

 currents in that region. North of the Parry Islands the drift 

 may be northwardly, like that which Payer and Weyprecht 

 experienced to the north of Novaia Zemlia. 



There is one great attraction for men of science in the 

 route by the Parry Islands. The magnetic pole has almost 

 certainly travelled into that region. Sir J. Ross found it, 

 indeed, to be near Boothia Gulf, far to the east of the 

 Parry Islands, in 1837. But the variations of the needle all 

 over the world since then, indicate unmistakably that the 

 magnetic poles have been travelling round towards the west, 

 and at such a rate that the northern magnetic pole has pro- 

 bably nearly reached by this time the longitude of Behring's 

 Straits. The determination of the exact present position of 

 the Pole would be a much more important achievement, so 

 far as science is concerned, than a voyage to the pole of 

 rotation. 



There is one point which suggests itself very forcibly 

 in reading the account of the sledging expedition from the 

 Alert towards the north. In his official report, Captain 



