Beam of November 17, 1882. 333 



referred to, speaks of a number of arches parallel to the usual 

 one being seen at Bournemouth, one across the zenith which 

 changed in position but slowly. Other observers speak of such 

 arches as distinguished from the usual forms of arch in the north; 

 and the evidence generally tends to the probability that the 

 beam itself may have been the transient lighting-up by a pass- 

 ing glow of an otherwise invisible arc. As regards the beam's 

 apparent course among the stars the observations are not 

 numerous. The Astronomer Royal (obs. 3) speaks of its 

 passing " nearly along a parallel of declination." Mr. Dobson 

 (obs. 5) states that it rose a little south of Aldebaran, slid 

 along at the same N.P.D., and disappeared under Altair. Mr. 

 Worthington (obs. 15) describes it as rising below and to the 

 right of Saturn, but does not trace it further. Mr. Munro 

 (obs. 9) mentions that it rose vertically below the Pleiades. 

 Mr. Saxby (obs. 11) assigns to it a trajectory much flatter 

 than the stars. 



For foreign positions we find Prof. Oudemans (obs. 24) 

 at Utrecht giving a precise description, viz. that it rose just 

 above Aldebaran, passed above Saturn, went through the 

 Pegasus quadrant, and sank south of the three Eagle stars. 

 Prof. Zeeman at Zonnemaire (obs. 25) traced it through Alde- 

 baran and « Pegasi. And, lastly, the Editor of del et Terre 

 (obs. 28) at Bruxelles says it appeared between i Aurigse and 

 a Tauri, and descended between (3 and % Ophiuchi. In fig. 7 

 I have constructed a star-map for the evening in question at 

 Guildown ; and on this are traced two dotted lines showing 

 the home and foreign apparent tracks of the "beam." It 

 will be seen that these are in the main conformable to the 

 general tenor of the descriptions, and are in fact portions of 

 circles struck from the equivalent to the magnetic pole as then 

 situate. Circles struck from the magnetic pole on the terres- 

 trial globe will in like manner be found fairly to correspond 

 with Prof. Herschel's assigned paths. 



In fig. 6 is found a diagram drawing (with the stars ap- 

 proximately fixed in their apparent places) showing the 

 " beam " as it appeared from Guildown Observatory during 

 the culminating portion of its passage. 



Having thus traced the " beam " to be truly part of the 

 aurora, and also having deduced as near as may be from the 

 collected observations the duration and direction of its flight 

 above the earth's surface and its approximate height, it re- 

 mains to say something of its physical character. This 

 question becomes interesting from the fact that several cor- 

 respondents to scientific journals and papers have attributed 

 to the phenomenon some sort of " meteoric " character, while 



Phil. Mag. S. 5. Vol. 15. No. 95. May 1883. 2 B 



