226 



Report on Terrestrial Magnetism* 



[July 



magnetical observatories have been established at Paris, at Berlin, in 

 the mines of Freyberg, at Copenhagen, in Iceland, at Sr. Petersburgh, 

 Kasan, Moscow, Barnoul at the foot of the Altai Chain, Nertschintk 

 near the frontiers of China, even at Pekin, and at Nieolajeff in the 

 Crimea. 



M. de Humboldt states that the lines representing the horary varia- 

 tions at Berlin, Freyberg, Petersburgh, and Nicolajeff affect paral- 

 lelism, notwithstanding the great separation of the stations and the 

 influence of extraordinary perturbations; that this, however, is not 

 invariable, since even at small distances, for example, at Berlin and in 

 the mines of Freyberg, one of the needles may shew considerable per- 

 turbations, while the other continues that regular course which is a 

 function of the solar time of the place. 



The epochs at which it had been proposed that simultaneous obser- 

 vations should be made at all stations were, 

 20th and 21st of March, 



4th and 5th of May, 

 21st and22d of June, 



From 4 o'clock in the morning of 

 the first day, until midnight of the 



6th and 7th of August, } second, observing, at least hourly, 



23d and 24th of September, night and day, at each magnetic 



5th and 6th of November, station. 



21st and 22d of December, J 

 But as many observers have considered these as too near to each other, 

 the observations most to be insisted upon are those at the times of the 

 solstices and equinoxes. 



England, from the times of Gilbert, Graham, and Halley to the pre- 

 sent, observes M. de Humboldt, has afforded a copious collection of 

 materials, adapted to the discovery of the physical laws which govern 

 the changes of the variation, whether at the same place, according to 

 the hours of the day and the seasons of the year, or at different dis- 

 tances from the magnetic equator, and from the lines of no variation. 

 After adverting to the continued observations of Gilpin and of Beaufoy, 

 omitting, however, to mention the important ones by Canton, he ob- 

 serves that the arctic expeditions have furnished a rich harvest of 

 observations to Captains Sabine, Franklin, Parry, Foster, Beechey, 

 and James Ross, and Lieutenant Hood;* and that thus physical geo- 

 graphy is indebted to the attempts which have been made to discover 

 the north-west passage, and also to the explorations of the icy coast of 

 Asia, by Wrangel Lutke, and Anjou, for a considerable accession of 

 knowledge on terrestrial magnetism and meteorology. Excited, he 



* To this long list we may now add the name of Captain Bach ; nor ought the name 

 of Mr. Fisher to be omitted. 



