56 POLAR PROBLEMS 



northeastern Siberia. His isogenics differ at some places considerably 

 from the published charts. The greatest discrepancy is found in the 

 vicinity of the New Siberian Islands, where according to the Maud 

 observations the declination was 2° West, whereas the charts men- 

 tioned indicate about 10° East, hence a difference of 12°. Marked 

 local magnetic disturbances were also revealed by the Maud observa- 

 tions in regions where the depth of the sea was about 40 to 70 meters. 



In the accompanying chart (Fig. i) a preliminary attempt has 

 been made to perfect Jones's chart in the regions where the additional 

 data, just described, had been obtained. 



The recent data as regards magnetic inclination (dip) and intensity 

 of the earth's magnetic field likewise show in crucial regions differences 

 from the published chart values for the Arctic of sufficient amount 

 to be taken into consideration if an analysis of the earth's magnetic 

 field is extended beyond the region of the earth included between the 

 parallels 60° N. and 60° S. 



Future polar expeditions should embrace every opportunity to 

 obtain additional magnetic data as regards distribution and secular 

 changes of the magnetic elements, both in the Arctic and the Antarctic. 



Magnetic Observatories in High Latitudes 



On account of the numerous fluctuations to which the earth's 

 magnetism is continually subject, especially in the polar regions, it 

 is highly desirable whenever conditions permit to conduct a series 

 of continuous observations for as long a period as possible, preferably 

 by photographic means, within the area of the magnetic survey. 



Thus Captain Amundsen during his Northwest Passage voyage 

 obtained photographic registration of the continual changes in the 

 magnetic elements from November, 1903, to May, 1905, at his obser- 

 vatory at Gjoa Harbor. For that period the approximate position of 

 the north magnetic pole was determined to be in latitude 70° 30' N. 

 and longitude 95° 30' W. of Greenwich.'^ (For comparison it may be 

 stated that the position determined in 1831 by Sir James Clark Ross 

 was 70° 5' N. and 96° 46' W.) It would have added greatly to our 

 knowledge of the supposed movements of the magnetic pole if similar 

 series of magnetic-observatory observations could have been obtained 

 simultaneously at several stations surrounding the magnetic pole. 



During Captain Amundsen's expeditions on the Maud, 1918-1925 — 

 the Northeast Passage voyage, 191 8-1922, and the drift in the East 

 Siberian Sea, 1922- 192 5 — the scientific personnel, under the direction 

 of Dr. H. U. Sverdrup, obtained valuable continuous records of the 

 changes in the magnetic declination at the winter quarters (77° 33' N., 

 105° 40' E.) near Cape Chelyuskin, Siberia, from October, 191 8, to 



' Graarud and Russeltvedt, op. cit., p. ii. 



