198 ELEMENTS OF STATIC ELECTRICITY. 



AURORAL BANDS. Sometimes a single streamer 

 spans the heavens from west to east like a band. The 

 author saw such a one at Chicago, Oct. 5, 1882. 

 Appearing at about 10.30 P. M., near the horizon, a 

 little north of west, it extended, within ten minutes, 

 to the eastern horizon, passing near the zenith : and 

 remained visible for more than half an hour. Its 

 apparent width was about four degrees, and its color a 

 light red. 



The signal service record, for the same date, de- 

 scribes an aurora, "seen generally throughout New 

 England, as far south as Washington, and, in the 

 northwest, from 10 30 p. M. till after midnight ; reach- 

 ing an altitude of 90, and covering 90 of the horizon." 

 Its different colors, in different localities, were "white, 

 blue, yellow, and crimson. Beams, arches, waves, stream- 

 ers, and patches of light were visible ; and, at Wash- 

 ington, frequent flashes of lightning, at the edge of the 

 dark segment." 



HEIGHT OF THE AURORA. Great diversity of opin- 

 ion has existed in regard to the height of the aurora 

 above the earth. A great altitude has been assigned 

 to it by some, who argue that the same aurora could 

 not otherwise be visible to observers thousands of miles 

 apart : while others assign to it a low altitude ; main- 

 taining that these different observers do not see the same 

 aurora, but different ones, occurring at the same time: 

 since the appearance seen by one, often differs greatly 

 from that seen by another. But, since differentials 

 of the same aurora may be visible to different observ- 

 ers, it is evident, that one of low altitude, and great 

 extent, might be seen at points as widely remote from 

 each other as the eastern and western continents ; the 



