14 NATURE-STUDY REVIEW 



correspondingly more magnificent. On this occasion, the se- 

 quence of forms differed from that just described. The first 

 manifestations were curtain forms, hung low in the south-eastern 

 sky, resembling in appearance great palisades of vertical golden 

 bars. These rapidly rose in the sky, increasing in size and brillian- 

 cy, swinging and writhing, till they swung across straight overhead, 

 revealing themselves as thin, almost vertical, films. Throughout 

 the earlier part of the evening they swayed back and forth, 

 seeming to hang suspended from long, pale, threads that reached 

 upwards to a point near the zenith. Observers from such distant 

 points as Alabama and California saw these rays, and all de- 

 scribed them as proceeding from near the zenith. Now, if the 

 aurora is a purely atmospheric phenomenon, with the greatest 

 recorded height about 140 miles, how could observers in Northern 

 Canada and Southern States all see the same point from which the 

 rays appeared to proceed? Must we not again explain this 

 appearance of radiation by the simple explanation of perspective 

 illusion? Could the distant observers see the same rays? Ap- 

 parently not. In different places different sets of curtains were 

 seen and as the rays were nearly parallel and vertical, following 

 the earth's lines of magnetic force, these rays appeared to converge 

 towards their upper extremities. If the lower edges of the curtains 

 were one mile high, for example, and the upper one hundred 

 miles high, the upper ends of two rays would appear almost to 

 meet, since they would seem only one one-hundredth as far apart 

 as at the lower ends. It would be interesting if a number of 

 observers would report on displays such as the one mentioned, 

 so that data might be obtained as to the rate of travel, the differ- 

 ences in appearance of a given part from different view-points, 

 and the distance at which particular parts can be seen. 



I have never heard any sound from the aurora, but have heard 

 one whom I regarded as a fairly reliable observer claim to have 

 heard it, described as resembling the swishing of a whip-lash 

 through the air. Note Service's reference to "a soundless sound 

 like softly bruised silk." I should like to hear from others who 

 have noticed it; also from anyone who has personally seen an 

 aurora between himself and any terrestrial object, such as a 

 building or hill. 



A common error that casual observers make about the Northern 

 Lights is to assume that the displays are centered about the North 



