Report on Tei restrlal Magnetism. 



laws, it has, in general, been doubtful whether the discrepancies 

 which have been found might not as justly be attributed to 

 errors in the observations, as to fallacies in the theory or in- 

 correctness in the laws. Under these circumstances, the Royal 

 Society, as a society for the promotion of natural knowledge, 

 cannot but hail with satisfaction a proposition for carrying on ob- 

 servations of phenomena most interesting in their nature and most 

 obscure in their laws, in a manner that shall not only give greater 

 precision to the observations, but at the same time render all the 

 results strictly comparative. 



There are, however, other grounds on which such a proposi- 

 tion as that made by M. de Humboldt should be most cordially 

 received by the Royal Society. This society is here called upon, 

 as a member of a great confederation, to co-operate with several 

 other members, already in active co-operation, for the attainment 

 of an object which ought to be common to all ; and to such a 

 call the Royal Society can never be deaf. Those who know 

 best what has been done by co-operation on a well-digested 

 system, and what remains undone in many departments of science 

 for the want of it, can best appreciate the benefits that would 

 accrue to science by the adoption of the extensive plan of co- 

 operation advocated by M. de Humboldt. Independently of our 

 acquiring a knowledge of the laws which govern the phenomena 

 here proposed to be observed, we ought to look to the effect 

 which the adoption of such a plan may have on other branches 

 of science. The example being thus once set of extensive co- 

 operation in a single department of science, we may anticipate 

 that it would be eagerly adopted in others, where, although our 

 knowledge may be in a much more advanced state than it is re- 

 garding the phenomena of terrestrial magnetism, still much re- 

 mains to be accomplished, which can scarcely be effected by any 

 other means. We might thus hope to see the united efforts of 

 all the scientific societies in Europe directed to the prosecution 

 of inquiry, in each department of science, according to the plan 

 of co-operation best adapted for its development. 



We must now, after these remarks on the general bearing of 

 M. de Humboldt's communication, go somewhat into detail on 

 points connected with it. One point of view in which we con- 

 sider the proposed plan of great importance, and to which M. 



