Reviews. 



The Norwegian North Polar Expedition, i8gj-i8g6. Scientific 

 Results. Vol. II. Edited by Fridtjof Nansen. Longmans, 

 Green & Co., London, New York, igoi. VI. H. Geelmuy- 

 den, Astronomical Observations, pp. 1-136, with two charts. 

 VII. Aksel S. Steen, Terrestrial Magnetism, pp. 1-196, with 

 17 plates. VIII. O. E. Schietz, Results of the Pendulum Obser- 

 vations and some Remarks on the Constitution of the Earth 's 

 Crust, pp. 1-90. 

 The astronomical observations have their chief geological value in 

 the accurate determination of localities. While they are thus funda- 

 mental and indispensable, they afford in themselves little matter of 

 note for the reviewer. The observations were chiefly made by Captain 

 Sigurd Scott-Hansen. They are abundant and bear evidence of hav- 

 ing been taken with accuracy, and they thus contribute a valuable pre- 

 cision to all other observations dependent upon locality. 



The second part of the volume is devoted to the discussion of the 

 magnetic observations of the expedition, which were also made by 

 Scott-Hansen. Concerning the value of these observations, Mr. Steen 

 remarks: "It is of especial importance to obtain determinations of 

 the magnetic elements from the polar regions, because the observations 

 have naturally hitherto been rather scarce from these deserted wastes, 

 containing large tracts where the foot of man has neveV yet trod, and 

 whose physical conditions place all kinds of difficulties in the way of 

 delicate scientific investigations. They are also important because the 

 action of the earth's magnetic forces in these very regions, judging 

 from the observations that have been obtained, presents peculiarities 

 to which there is no parallel in the temperate and torrid zones." The 

 general results are summarized in tables giving the declination, hori- 

 zontal intensity, and inclination at the numerous localities of observa- 

 tion. 



The third part, which relates to pendulum observations, has, with- 

 out doubt, the greatest interest for geologists. These pendulum 



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