106 Discourse delivered by Baron Humboldt to the 



known, shews us that nearly all the bodies in nature are transi- 

 toiily susceptible of electro-magnetic actions. The Russian 

 empire is the only country on earth traversed by two lines with- 

 out declination, or along which the needle is directed towards 

 the poles of the earth. One of these two lines, whose position 

 and periodical motion of translation from east to west, are the 

 principal elements of a future theory of the terrestrial magnetism, 

 passes, according to the last researches of MM. Hansteen and 

 Erman, between Mourom and Nijni-Novogorod ; the second, 

 some degrees to the east of Irkoutsk between Parchnikaia and 

 Jarbinsk. Their prolongation northwards, and the rapidity of 

 their motion westward, are not yet known. The physics of the 

 globe require the complete tracing of the two lines without de- 

 clination, at equl-distant periods, for example, every ten years, — 

 the precise determination of the absolute variations of inclination 

 and intensity at all the points where MM. Hansteen, Erman, 

 and myself, have observed in Europe, between St Petersburg, 

 Cazan and Astracan, in Northern Asia between Jekaterinburg, 

 Miask, Oust-Kamenogorsk, Obdorsk, and Jakoutsk. These re- 

 sults cannot be obtained by strangers who traverse the country 

 in a single direction, and at a single period. There is required 

 a system of combined observations, carried on during a long pe- 

 riod of time, and confided to observers established in the differ- 

 ent countries. St Petersburg, Moscow, and Cazan, are fortu- 

 nately situated very near the first line of no declination, which 

 traverses European Russia. Kiachta and Verkhne-Oudinsk pre^ 

 sent advantages for the second or Siberian line. When we re- 

 flect on the comparative precision of observations made at sea 

 and on land, with the pid of the instruments of Borda, Bessel, 

 and Gambey, we may easily be persuaded that Russia, by its 

 position, is capable of forwarding the theory of magnetism in a 

 very great degree, in the space of twenty years. In speaking 

 of these matters, I am only, gentlemen, in a manner, the inter- 

 preter of your desires. The manner in which you received the 

 request which I addressed to you, seven months ago, relative to 

 the correspondent observations of Iiorary variations made at 

 Paris, at Berlin, in a mine at Freyberg, and at Cazan, by the 

 learned and laborious astronomer M. Simonoff, has proved that 

 the Imperial Academy will worthily second the other academies 



