TERKESTRIAL MAGNETISM. 49 



y. Magnetic Activity of the Earth in its three 

 manifestations of Force, Inclination, and Declina- 

 tion Points (termed Magnetic Poles] at which the 

 Inclination is 90 Line on which no Inclination is 

 observed (Magnetic Equator] Four Points of greatest, 

 but unequal, Intensity of the Magnetic Force Curve 

 or Line of the weakest Magnetic Force Extraor- 

 dinary Disturbances of the Declination (Magnetic 

 Storms] Polar Light. 



(Extension of the Eepresentation of Nature, in Kosmos, 

 Ed. i. S. 184208, and 427442, Anm. 1149 ; 

 Bd. ii. S. 372376, and 515, Anm. 6974; Bd. iii. 

 S. 399401, and 419, Anm. 30 : Engl. Yol. i. p. 

 167189, and 407424, Notes 141179; Vol. ii. 

 p. 331335, and cxix., Notes 509514, bis; Yol. iii. 

 p. 289290, and civ., Note 489.) 



The magnetic constitution of our planet can only be inferred 

 from those manifestations of its magnetic force which pre- 

 sent measurable relations in reference either to place or 

 time. These manifestations are characterised \yy perpetual 

 variability in the phsenomena which they present, and this 

 in a far higher degree than such other variable phenomena 

 as the temperature, aqueous vapour, and electric tension of 

 the lower strata of the atmosphere. The continual changes 

 which take place in the kindred magnetic and electric con- 

 ditions of matter, form an essential distinction between the 

 phenomena of electro-magnetism, and those which depend 

 on that primary, fundamental force of molecular and mass- 

 attraction of all matter, which, at unchanged distances, 

 VOL. TV. E 



