TERRESTRIAL MAGNETISM. 133 



in the southern hemisphere, where between those two hours 

 the direction of the movement of the needle is an opposite 

 one, its amount is greater when the Sun is in the southern 

 than when he is in the northern signs. 



The question which I touched upon seven years ago in 

 Yol. i. of this work ( 164 ) , i. e. whether there be a region of 

 the earth, perhaps between the geographical and magnetic 

 equators, in which, as a transitional region between the parts 

 of the earth in which the declination-needle moves at the 

 same hours in opposite directions, no horary variation might 

 be found ? appears from subsequent experience, and es- 

 pecially from Sabine's perspicuous discussion of the obser- 

 vations at Singapore (1 17' N. lat.), at St. "Helena 

 (15 56' S. lat.), and at the Cape of Good Hope (33 56' 

 S. lat.), to require to be answered in the negative. Hitherto 

 no place has been found at which the needle is without 

 diurnal movement (horary variation) ; and through the estab- 

 lishment of the magnetic stations we have been made aware 

 of the important ana very unexpected fact, that there are in 

 the southern magnetic hemisphere places at which the diurnal 

 variation of the magnetic needle appears to participate in the 

 phenomena, or to conform to the type, of either hemisphere 

 alternately. The Island of St. Helena is situated very near 

 to the line of weakest intensity of the earth's magnetic force, 

 in a part of the earth where that line recedes widely both 

 from the geographical equator and from the line of no 

 inclination. At St. Helena, the march of the north end of 

 the needle in the hours of the forenoon, in the months 

 from May to September, is the opposite of the march fol- 

 lowed by the same end of the needle in the corresponding 

 hours from October to February. According to five years 



