of Terrestrial Magnetism. 45 



established at Cazan, nearly the eastern limit of Europe, one 

 of Gambey's compasses, exactly similar to that employed by 

 M. Arago at Paris, the two observers were convinced by a 

 certain number of corresponding measures of horary declina- 

 tion, that, notwithstanding a difFerence of longitude of more 

 than 47°, the perturbations were isochronous. They were like 

 signals which from the interior of the earth simultaneously 

 arrived at its surface on the ^borders of the Seine and the 

 Wolga. 



When in 1827 I again fixed my residence at Berlin, my 

 first care was to renew the series of observations which I had 

 made at short intervals during the days and nights of the 

 years 1806 and 1807. I endeavoured at the same time to 

 generalize the means of simultaneous observations, the acci- 

 dental employment of which had just produced results so im- 

 portant. One of Gambey's compasses was placed in the mag- 

 netic pavilio7i, in which no portion of iron was introduced, 

 which had been erected in the middle of a garden. Regular 

 observations could not commence till the autumn of 1828. 

 Being called, in the spring of 1829, by His Majesty the Em- 

 peror of Russia, to undertake a mineralogical tour in the 

 North of Asia and on the Caspian Sea, I had an opportunity 

 rapidly to extend the line of stations towards the east. At 

 my request the Imperial Academy and the Curator of the 

 University of Cazan erected magnetic houses at St. Petersburgh 

 and Caza^n. In a committee of the Imperial Academy, at 

 which I had the honour of presiding, a discussion took place 

 on the immense advantages, with regard to our knowledge of 

 the laws of terrestrial magnetism, presented by the vast extent 

 of country limited on one side by the curve without declina- 

 tion of Doskino, (between Moscow and Cazan, or with more 

 precision, according to M. Adolphe Erman, between Osabli- 

 kowo and Doskino, in lat. 56° O', and long. 40° 36' east 

 of Paris,) and on the other, by the curve without declina- 

 tion of Arsentchewa near Lake Baikal, which is believed to 

 be identical with that of Doskino, with a difFerence of meri- 

 dians of 63^ 21'. The Imperial department for Mines having 

 generously concurred in the same object, magnetic statio?is 

 have been successively established at Moscow, Barnaoul, the 

 astronomical position of which I find to be at the foot of 

 Altai, in lat. 53^ 19' 21", long. 5^ 27' 20" east of Paris, and 

 at Nertschinsk. The Academy of St. Petersburgh has done 

 still more, and has sent a courageous and clever astronomer, 

 M. George Fuss, the brother of its perpetual secretary, to 

 Pekin, and has procured the erection there of a magnetic 

 pavilion, in the convent garden of the monks of the Greek 



