1837.] 



Report on Terrestrial Magnetism. 



229 



M. de Humboldt finally refers to the labours and accurate observations 

 of M. Gauss at the Observatory of Gottingen. The methods, however, 

 adopted by M. Gauss being already before the Royal Society, in a 

 memoir which has been communicated by him, renders it unnecessary 

 here to enter into the explanation given of thembyM.de Humboldt. 

 He has referred to them in order that those members of the Royal 

 Society who have most advanced the study of terrestrial magnetism, 

 and who are acquainted with the localities of colonial establish me its, 

 may take into consideration, whether, in the new stations to be esta- 

 blished, a bar of great weight furnished with a mirror should be em- 

 ployed, or whether Gambey's needle should be used : his wish is only 

 to see the lines of magnetic stations extended, by whatever means the 

 precision of the observations may be attained. 



M. de Humboldt concludes by begging His Royal Highness to ex- 

 cuse the extent of his communication. He considered it would be ad- 

 vantageous to unite under a single point of view what has been done 

 or prepared in different countries towards attaining the object of great 

 simultaneous operations for the discovery of the laws of terrestrial 

 magnetism. 



Having very fully laid before the Council the contents of M. de 

 Humboldt's letter, we have now to offer our opinion upon t he < ubject it 

 embraces. There can, we consider, be no question of the importance 

 of the plan of observation which is here proposed for the investigation 

 of the phenomena of terrestrial magnetism, or of the prospect which 

 Such a plan holds out of the ultimate discovery of the laws by which 

 those phenomena are governed. Although the most striking of these 

 phenomena have now been known for two centuries, although careful 

 observations of them have within that period been made, and that still 

 more care and attention have been bestowed upon those more recently 

 discovered, yet the accessions to our knowledge, not onlv regarding 

 the cause of the phenomena, but even with respect to the laws which 

 connect them, bears a very small proportion to the mass of observations 

 which have been made. This has arisen in a great measure, if not 

 wholly, from the imperfection of the data from which attempts have 

 been made to draw conclusions. Whatever theories may have been 

 advanced in explanation of these phenomena, or attempts made to 

 connect them by empirical laws ; still, whenever comparisons have been 

 instituted between the results of observation and such theories or 

 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 incorrectness 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 observations of phenomena most interest- 



