1837.] 



Report on Terrestrial Magnetism. 



235 



one complete set of such instruments. We may, however, in the mean 

 time, offer a remark on one apparatus referred to by M. de Humboldt, 

 that of M. Gauss. However well we may consider this apparatus to be 

 adapted for the determination of the course of the regular diurnal varia- 

 tion, yet we apprehend that the great weight of the needles employed 

 would prevent their recording the sudden and extraordinary changes in 

 the direction of the magnetic forces, which are, probably, due to at- 

 mospheric changes. Another, and we conceive a very serious objection 

 to this apparatus is, that bars of the magnitude employed must have an 

 influence so widely extended, that there would be great risk of the in- 

 terference of one of these heavy needles with the direction of another, 

 especially in places where the horizontal directive force is greatly di- 

 minished, unless the rooms for observation were placed at inconvenient 

 distances from each other. 



By referring to M. de Humboldt's letter, it will be seen that the plan 

 of observation so comprehensively conceived by him, has been most 

 powerfully and liberally patronized by the Governments of France, of 

 Prussia, of Hanover, of Denmark, and of Russia : indeed, it is quite 

 manifest that a plan so extensive in its nature must be far beyond the 

 means of individuals, and even of scientific societies unaided by the 

 Governments under which they flourish. To suppose, even without the 

 example thus held out, that the Government of this, the first maritime 

 and commercial nation of the globe, should hesitate to patronize an un- 

 dertaking, which, independently of the accessions it must bring to 

 science, is intimately connected with navigation, would imply that our 

 Government is not alive either to the interests or to the scientific 

 character of the country, and would show that we had little attended tot 

 the history, even in our times, of scientific research, which has been so 

 liberally promoted by the Government. Although the investigation of 

 the phenomena of terrestrial magnetism was not the primary object of 

 the expeditions which have now, almost uninterruptedly, for twenty 

 years been fitted out by Government, — another of which, and one of 

 the highest interest, is on the point of departure,— yet a greater ac- 

 cession of observations of those phenomena has been derived from these 

 expeditions than from any other source in the same period. We there- 

 fore feel assured that, when it shall have been represented to the Go- 

 vernment, that the plan of observation advocated by the Baron de 

 Humboldt is eminently calculated to advance our knowledge of the 

 laws which govern some of the most interesting phenomena in physical 

 science ; that it appears to be perhaps the only one by which we can 

 hope ultimately to discover the cause of these phenomena ; and that, 

 from it, results highly important to navigation may be anticipated ; the 

 patronage to the undertaking which is so essential to its prosecution 

 will be most readily accorded. We beg, therefore, most respectfully, 



