DEPARTMENT OF TERRESTRIAL MAGNETISM * 



L. A. Bauer, Director. 



Alexander von Humboldt, in his Cosmos, was the first to fully grasp the 

 importance of a general magnetic survey of the globe. His words are so 

 a propos of the task set the Department of Terrestrial Magnetism that it may 

 not be amiss to quote them, italicizing those sentences of peculiar interest,! 

 viz: 



But if the laws of terrestrial magnetism are to be thoroughly investigated — that is to 

 say, if they are to be sought in the great cycle of the periodic movement in space of the 

 three varieties of magnetic curves — it is by no means sufficient that the diurnal regular 

 or disturbed course of the needle should be observed at the magnetic stations, which 

 since 1828 have begun to cover a considerable portion of the earth's surface, both in 

 northern and southern latitudes; but four times in every century an expedition of three 

 ships should he sent out, to examine as nearly as possible at the same time the state of 

 the magnetism of the earth, so far as it can be investigated in those parts which are 

 covered by the ocean. * * * Land expeditions should be combined with these voy- 

 ages, in order, where masses of land can not be entirely traversed, to determine at 

 what points of the coast-line the magnetic curves (especially those having no variation) 

 enter. * * * 



Since the memorable Antarctic expedition of Sir James Clarke Ross (1839-43), fitted 

 out with admirable instruments, has thrown so much light over the polar regions of the 

 Southern Hemisphere, and has determined empirically the position of the magnetic 

 south pole ; and since my honored friend, the great mathematician, Frederick Gauss, 

 has succeeded in establishing the first general theory of terrestrial magnetism, we need 

 not renounce the hope that the many requirements of science and navigation will lead to 

 the realization of the plan I have already proposed. May the year 1850 be marked as the 

 first normal epoch in which the materials for a magnetic chart shall be collected; and 

 may permanent scientific institutions {academies) impose upon themselves the practice 

 of reminding every tzventy-five or thirty years governments, favorable to the advance of 

 navigation, of the importance of an undertaking whose great cosmical importance 

 depends on its long continued repetition. 



This plan of Humboldt's, as well known, never came to a realization and, 

 instead, the work hitherto has consisted of more or less isolated and incom- 

 plete surveys, independently undertaken by various nations and distributed 

 over a great many years. Not even for a single epoch has it been possible to 

 construct magnetic maps on a plan of concerted action, to say nothing of the 

 impossibility of drawing them for several epochs 25 or 30 years apart. 



It was certainly high time, therefore, that a plan universally conceded to be 

 of the highest importance, which, for one reason or another, had failed of 



* Address : The Ontario, Washington, District of Columbia. Grant No. 481. $57,000 

 for investigations and maintenance. (For previous reports see Year Books Nos. 3, 4, 

 5, and 6.) 



t The quotation is taken from E. C. Otte's translation of the Cosmos, vol. 11, 1849, 

 pp. 719-720. 



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