120 COSMOS. 



practical application of their results to the ship's reckoning, 

 and to navigation generally ; but all the cosmical phenomena 

 of magnetism, amongst which we must place those extraor- 

 dinary and most mysterious disturbances which often act 

 simultaneously at very remote distances (magnetic storms), 

 are so intimately connected with one another, that no single 

 one of them can be neglected in our attempt gradually to 

 complete the mathematical theory of terrestrial magnetism. 

 In the middle latitudes, throughout the whole northern 

 magnetic hemisphere, (the terrestrial spheroid being as- 

 sumed to be divided through the magnetic equator) the 

 north end of the magnetic needle, that is to say, the end 

 which points towards the north pole, is most closely in the 

 direction of that pole about 8h. 15m. A.M. The needle moves 

 from east to west, from this hour till about Ih. 45m. P.M., at 

 which time it attains its most westerly position. This motion 

 westward is general, and occurs at all places in the northern 

 hemisphere, whether they have a western variation, as the 

 whole of Europe, Pekin, .Nertschmsk and Toronto, or an 

 eastern variation, like Kasan, Sitka in Russian America, 

 Washington, Marmato (New Grenada), and Payta on the 

 Peruvian coast. * 2 From this most westerly point, at 

 Ih. 45m. P.M., the magnetic needle continues to retrograde 



52 Proofs of this are afforded by numerous observations of George 

 Fuss and Kowanko, at the observatory in the Greek convent at Pekin, 

 by Anikin at Nertschinsk, by Buchanan Biddell at Toronto in Canada ; 

 (all these being places of western variation); by Kupffer and Simonoff 

 at Kasan ; by Wrangel, notwithstanding the many disturbances from 

 the Aurora borealis at Sitka, on the north-west coast of America; 

 by Gilliss at Washington; by Boussingault at Marmato, in South Ame- 

 rica ; and by Duperrey at Payta, on the Peruvian shores of the Pacific ; 

 (all these being places with an eastern variation). I would here observe 

 that the mean declination was 2 15' 42" west at Pekin (Dec., 1831) 

 (Poggend. Annalen, Bd. xxxiv, s. 54); 4 1' 44 "west at Nertschinsk 

 (Sept., 1832) (Poggend. Op. Git. s. 61); 1 33' west at Toronto (Novem- 

 ber, 1847) (see Observ. at the Magnet teal and Meteorological Observatory 

 at Toronto, vol. i, p. xi, and Sabine, in the Phil. Transact, for 1851, 

 pt.ii, p. 636), 2 21' east at Kasan (August, 1828), (Kupffer, Simonoff, 

 and Erman, Reise um die Erde, Bd. ii, s. 532); 28 16' east at Sitka 

 (November, 1829) (Erman, Op. Git. s. 546); 6 33' east at Marmato 

 (August, 1828), (Humboldt, in Poggend. Annalen, Bd. xv, s. 331); 8 56' 

 east at Payta (August, 1823), (Duperrey, in the Connaissance des Temps 

 pour 1828,, p. 252). At Tiflis the declination was westerly from 7 A.M. 

 till 2 P.M. (Parrot, Reise zum Ararat, 1834, Th. ii, s. 58). 



