328 Mr. J. Rand Capron on the Auroral 



which disappeared in a few seconds." (3) Mr. Dobson (obs. 5) 

 says it was preceded and followed by "a strong black margin.'" 

 I saw nothing like any of these myself, though I had an impres- 

 sion the beam was following some definite path. Other obser- 

 vations (if made) would be interesting on the point whether 

 these appearances were real or subjective impressions. 



Turning our attention now to the combined questions of the 

 object's position, direction of flight, and height above the 

 earth's surface, we already find in print some opinions regard- 

 ing these. Mr. Saxby (obs. 11) considers: — 



1st. The direction must have been S. 70° W., probably 

 71° 45', being the complement of magnetic declination. 



2nd. The proper motion to have been over a mile a minute. 



3rd. The path was vertically over a line on the earth's sur- 

 face at a least distance from Greenwich of 72 miles, with a 

 height of 44 miles. 



4th. The object must have been in the zenith over North 

 Belgium, the Boulogne district, Cherbourg, and the north 

 coasts of Brittany. 



This was before the foreign observations were reported ; 

 and subsequently Mr. Saxby, after stating that the beam 

 passed in the zenith at Bruxelles (M. Moutigny), and at Laon 

 was seen to northward of the zenith gliding round the upper 

 edge of the great main arch of the aurora, puts the actual 

 elevation " without risk of error " as between 40 and 45 miles. 

 Mr. Taylor (obs. 14), using the observations at York and 

 Woodbridge, deduces a height of 212 miles ; and, using those 

 at Hungerford and York, finds 192 miles for height. He con- 

 siders the beam must have passed overhead in the north of 

 Italy and south of France, and must have been 200 miles in 

 length. Subsequently (upon receipt of the foreign observa- 

 tions) he makes it 70 miles in height when over Belgium, 

 but considers it must have been 150 miles high during the 

 latter part of its course. As to the York observation, it 

 seems desirable to notice that Mr. Taylor does not seem to 

 have much confidence in his own estimate of the beam's appa- 

 rent distance below the moon ; and this estimate is dissented 

 from by a relative who was watching the phenomenon at the 

 same time. Mr. Backhouse ('Nature,' pp. 141 & 315) at first 

 considered the height very considerable; and both he and Mr. 

 Taylor thought Mr. Saxby's estimate of 44 miles too low, 

 probably from near stations being used in the calculations. 

 Later on Mr. Backhouse wrote me he thought 200 miles not 

 an improbable height. 



I may here mention that I have not heard of any observa- 

 tions north of York. I made inquiries at Liverpool of the 



