Scientific Intelligence — Meteorology, 365 



cdnstantly changing in their form and in the intensity of their light. 

 At the instants of the greatest development of light, viz., when the 

 luminous cloud was near the zenith, there was quite certainly a sound 

 heardf resembling the rustling of straw or of cloth made of silk.— 

 1840, Nov. 2lstj 5 o'clock p. m. Calm. The atmosphere had cleared 

 up, and rays of light shot simultaneously from the west and east 

 horizon with the greatest brilliancy ; at the zenith they whirled them- 

 selves round in a circle, and formed crowns of light. A soft rustling 

 was at the same time audible, Ihle makes the following general ob- 

 servations on the Aurora : — The northern lights for the most part 

 make their appearance over the western and north-western, and over 

 the eastern and north-eastern horizon, rarely in the due north, and 

 still more rarely over the southern horizon. The form of the north- 

 ern lights is sometimes in stripes, and that either with an uniform 

 division of the light or in bands with parallel streaks ; and sometimes 

 in bundles of rays, either ranged in certain lines next one another, or 

 separated into undefined groups. The boundary of the stripes of 

 light is sometimes sharp, sometimes obscure. More rarely than in 

 the form of stripes and bundles of rays, the aurora sometimes ap- 

 pears in the form of undefined luminous clouds. The black rays of 

 the northern lights, first noticed by Professor Ilanstein, i. e, sharply 

 bounded stripes, surrounded by masses of light, which, however, are 

 quite detached from them, are a not unfrequent, but extremely strik- 

 ing phenomenon. Changes of temperature in the atmosphere gene- 

 rally stand in connection with the appearance of brilliant northern 

 lights, and thus a dry cold occurs after northern lights emanating 

 from the eastern horizon, while storms and snow, with diminished 

 cold, follow the western aurora. Frequently, however, the northern 

 lights from the east and west appear simultaneously, without the one 

 or the other gaining the mastery, and then unsettled weatlier ensues. 

 A variation of the magnetic needle generally follows the appearance 

 of the aurora; in the case of the eastern aurora the North Pole of 

 the needle is turned eastwards, and in that of the western westwards. 

 A difference of hcijlit has been distinctly observed, although measure- 

 ments were not practicable. In M. Ihle's Journal, days are indi- 

 cated on which the rays of the aurora were visible below the clouds, 

 nay even lower than the abruptly rising acclivity of the valley. The 

 lower the aurora and the nearer the zenith, so much the more power- 

 ful was its influence on the magnetic needle in relation to declination 

 and intensity. It has also resulted from Ihle's observations, that 

 there is a certain connection between the occurrence of storms and 

 the appearance of the northern lights. In the case of violent storms 



