422 



and adds, that, perhaps, they would also previously concert upon 

 the mode of publication of partial observations and of mean re- 

 sults. 



M. de Humboldt finally refers to the labours and accurate ob- 

 servations of M. Gauss at the Observatory of Gottingen. The me- 

 thods, 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 

 them by M. 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 establishments, may take into consideration, 

 whether, in the new stations to be established, a bar of great weight 

 furnished with a mirror should be employed, 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 observa- 

 tions may be attained. 



M. de Humboldt concludes by begging His Royal Highness to 

 excuse the extent of his communication. He considered it would 

 be advantageous 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 the sub- 

 ject it embraces. There can, we consider, be no question of the im- 

 portance 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 only 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 imper- 

 fection of the data from which attempts have been made to draw 

 conclusions. Whatever theories may have been advanced in ex- 

 planation 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 promo- 

 tion of natural knowledge, cannot but hail with satisfaction a pro- 

 position for carrying on observations of phenomena most interest- 

 ing in their nature and most obscure in their laws, in a manner that 



