NOTES. 



the heat is regarded as resulting from the lono'-contiTwed chemical action of a 

 nucleus, composed of the metals of the earths and alkalies, on an already 

 oxydized external crust. In his great work, " Theorie des phenomenes electro- 

 dynamiques," 1826, p. 99, he says, " On ne peut douter qu'il existe dans 

 riuterieur du globe des courants electro-magnetiques, et que ces courants sont 

 les causes de la chaleur qui lui est propre. Us naissent d'un noyau metallique 

 central compose des metaux que Davy nous a fait connaitre, agissant sur la 

 couche oxidee qui entoure le noyau." 



( 163 ) p. 179. The remarkable resemblance between the magnetic and the 

 isothermal lines was first pointed out by Sir David Brewster in the Transac 

 tions of the Royal Society of Edinburgh, Vol. ix. 1821, p. 318, and in his 

 " Treatise on Magnetism," 1837, pp. 42, 44, 47, and 268. This distinguished 

 physicist supposes the existence of two poles of maximum cold in the northern 

 hemisphere ; one American (lat. 73, long. 100 W., near Cape Walker) ; 

 and one Asiatic (lat. 73, long. 80 E.) ; and he considers that these occasion 

 two meridians of maximum heat, and two meridians of maximum cold. In 

 the sixteenth century, however, Acosta taught the existence of four lines of 

 no declination, which he inferred from the observations of a very experienced 

 Portuguese pilot (Historia natural de las Indias, 1589, Lib. i. Cap. 17). 

 This opinion would seem to have had some influence on Halley's theory of 

 four magnetic poles, if we may judge from some discussions between Henry 

 Bond, Author of " The Longitude Found," 1676, and Beckborrow. See my 

 " Bxamen critique de 1'hist. de la Geographic," T. lii. p. 60. 



C 69 ) p. 179. Halley, in the PhiL Trans. Vol. ixix. (for 17141716), 

 No. 341. 



( 17 ) p. 180. Dove, in PoggendoriTs Annalen, Bd. xx. S. 341, Bd. xix. 

 S. 388 : " The declination needle is acted upon nearly like an atmospheric 

 electrometer, of which the divergence increases until a spark (lightning) is 

 produced." See also the ingenious comparisons of Professor Kamtz, in his 

 Lehrbuch der Meteorologie, Bd. iii. S. 531519; Sir David Brewster, 

 Treatise on Magnetism, p. 280. See also Casselmann's Observations (Mar- 

 burg, 1844), S. 56 62, on the magnetic properties of the galvanic flame, of 

 luminous arch, in a Buusen's carbon and zinc battery. 



( 1?1 ) p. 181. Argelander, in the important Memoir on the Aurora which 

 he has incorporated in the " Vortragen, gehalten in der physikalisch- 

 okonomischen Gesellschaft zu Konigsberg," Bd. 1834. S. 257264. 



f 1 ' 2 ) p. 181. On the results of the observations of Lottin, Bravais, and 

 8iV)rstrom, who passed a winter at Bosekop on the coast of Lapland (Lat. 



