Notices respecting New Books. 383 



have been known by the Chinese and early Greeks and Romans, and 

 following the course of discovery down to the present day. On 

 pp. 28 to 30 is a summary of old observations of declination, taken 

 prior to 1600 at different parts of the world, including an obser- 

 vation by Frobisher at a somewhat mysterious ' ; Fair Island (S.W. 

 of Scotland)." Dr. Bauer has many complimentary references to 

 early English observers, including Norman and Gellibrand ; but 

 he evidently thinks (cf. p. 3d) that so far as Terrestrial Magnetism 

 is concerned Gilbert's work has been overrated. The latter part 

 of the historical introduction gives tables and curves of secular 

 change in all parts of the world, also particulars as to diurnal and 

 annual inequalities of declination at various stations in America 

 and elsewhere, and includes a brief discussion of magnetic storms. 

 Under the heading of " Magnetic Observatories," pp. 56-61, we 

 have an illustrated account of the new American Magnetic Obser- 

 vatory at Cheltenham, Maryland; this includes a full description 

 of the elaborate arrangements for securing small diurnal variation 

 of the temperature. The equipment of this observatory comprises 

 magnetographs both of the Aclie (Kew) and Eschenhagen patterns. 

 Several of the photographic traces obtained at Cheltenham in 1902 

 are reproduced, including one which shows a magnetic disturbance 

 whose beginning is supposed to synchronize wdth the eruption of 

 Mt. Pelee (Martinique) on May 8th. Following this, pp. 62-65, 

 are some small scale magnetic charts, including early ones by 

 Hansteen, Halley and Duperrey, others by Neumayer, and some 

 by the British Admiralty for the epoch 1905. There is also a 

 general description of magnetic surveys, including that of the 

 United Kingdom by Riicker and Thorpe, with a reference to the 

 proposed Norwegian expedition under Amundsen during the 

 present year to the neighbourhood of the north magnetic 

 pole. 



The remainder of the volume deals more directly w 7 ith the 

 special work of the U.S. Coast and Geodetic Survey. It describes 

 the Survey's type of magnetometer-theodolite, contains instructions 

 as to the taking of observations, and gives many particulars as to 

 secular change of declination in the United States and outlying 

 territories. These secular change data are used in reducing to the 

 epoch Jan. 1, 1902, an enormous mass of observations of decli- 

 nation in America — some in British territory, — particulars of 

 which occupy pp. 117-266. Then follows a minute description 

 of the position of all stations occupied between 1881 and mid- 

 summer 1902. At the end of the book are two isogonic charts 

 for the epoch Jan. 1, 1902, one for the United States proper, 

 with adjacent regions in Canada and Mexico, the other for Alaska. 



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