NOTES TO BOOK XII. 69 



magnetic stations the Russian government afterwards 

 added, Catharineburg in Russia Proper, Helsingfors in 

 Finland, Teflis in Georgia. A comparison of the results 

 obtained at four of these stations made by MM. de Hum- 

 boldt and Dove, in the year 1830, shewed that the mag- 

 netic disturbances were simultaneous, and were for the 

 most parallel in their progress. 



Important steps in the prosecution of this subject were 

 soon after made by M. Gauss, the great mathematician of 

 Gottingen. He contrived instruments and modes of ob- 

 servation far more perfect than any before employed, and 

 organized a system of comparative observations throughout 

 Europe. In 1835, stations for this purpose were esta- 

 blished at Altona, Augsburg, Berlin, Breda, Breslau, 

 Copenhagen, Dublin, Freiberg, Gottingen, Greenwich, 

 Hanover, Leipsic, Marburg, Milan, Munich, Petersburg, 

 Stockholm, and Upsala. At these places, six times in the 

 year, observations were taken simultaneously, at intervals 

 of five minutes for 24 hours. The Results of the Magnetic 

 Association (Resultaten des Magnetischen Vereins) were 

 published by MM. Gauss and Weber, beginning in 1836. 



British physicists did not at first take any leading part 

 in these plans. But in 1836, Baron Humboldt, who by 

 his long labours and important discoveries in this subject 

 might be considered as peculiarly entitled to urge its 

 claims, addressed a letter to the Duke of Sussex, then 

 President of the Royal Society, asking for the co-opera- 

 tion of this country in so large and hopeful a scheme for 

 the promotion of science. The Royal Society willingly 

 entertained this appeal ; and the progress of the cause 

 was still further promoted when it was zealously taken up 

 by the British Association for the Advancement of Science, 



