RECORD OF AURORAL PHENOMENA. 25 



I have been anxious to confine myself to a mere detail of facts, without venturing upon any theory. 



My notes upon the appearances of the Aurora coincide with those of Dr. Richardson in proving 

 that the phenomenon is frequently seated within the region of the clouds, and that it is depend- 

 ent, in some degree, upon the cloudy state of the atmosphere. 



The manner in which the needle was affected by the Aurora will need some description. The 

 motion communicated to it was neither sudden nor vibratory. Sometimes it was simultaneous 

 with the formation of arches, prolongation of beams, or certain other changes of form, or of 

 activity of the Aurora; but generally the effect of these phenomena upon the needle was not 

 visible immediately, but in about half an hour, or an hour, the needle had attained its maximum 

 of deviation. Its return to its former position was very gradual, seldom regaining it before the 

 following morning, and frequently not until the afternoon, unless it was expedited by another 

 arch of the Aurora operating in a direction different from the former one. 



The bearings of the terminations of the arches are to be taken with considerable allowance. 

 They were estimated by the position of the Aurora, with respect to the sides of the house, the 

 angles of which had been previously determined. The bearings given in the whole of my 

 observations refer to the magnetic meridian, and are reckoned from the magnetic North, towards 

 the East, round the whole circle, which it is conceived will afford a means of more readily com- 

 puting the horizontal extent of the arches. 



It is to be noticed, that the bearings given by Dr. Richardson and Lieutenant Hood are true, 

 and not magnetic." — 1 Franklin, 539. 



N. B. — 1. Altitude of Aurora far inferior to that assigned to it by former observers. 



2. Action of the Aurora on the compass needle. 



3. Aurora an electrical phenomenon. 



4. Aurora formed at no great elevation; dependent on formation of cirro stratus. 



Fort Enterprise.— Lat. G4° 28' 24" N. Long. 113° 6' W. January— May, 1821. Franklin. 



" Observations on the Aurora at Fort Enterprise, extracted from the Journal of Captain Franklin. — 

 The forms of the Aurora Borealis, during the winter, have been so various and fleeting, that it 

 is impossible to comprehend them in a general outline; and the inferences I have drawn on a 

 subject, respecting which I had not prepared my mind by previous study, are offered with diffi- 

 dence." — 1 Franklin, 549. 



"Before adverting to the effect of the Aurora on the needle, I must premise that the arch-like ap- 

 pearance of the Aurora, noted in the daily remarks, did not always resemble a portion of a great 

 circle; but, on the contrary, frequently crossed the zenith, without originating and terminating 

 in opposite points of the horizon ; and although the general arrangement of the parts gave the 

 idea of an arch, yet this arch was frequently broken, and its portions disconnected. 



The color of these arches varied from gray to a lively yellow, and in clear weather the light emitted 

 was generally observed to be more brilliant and dense than when an opposite state of the 

 atmosphere existed. 



The horizontal bands or masses of light mentioned in the notes, appeared indiscriminately in every 

 quarter of the sky, and at different elevations ; they more frequently originated or terminated in 

 the magnetic east or west, but not invariably so ; and we have seen them on more than one 

 occasion begin and end in the magnetic meridian. Their light varied much in density, and was 

 generally of a yellowish hue. 



The arches and horizontal bands of Aurora occasionally separated into parts or beams, which had 

 a quick lateral motion. At such times the colors were generally most vivid, and now and then 

 prismatic. The extremities of these beams did not appear to point uniformly to any particular 

 part of the sky, but to depend entirely upon the direction of the arch which they composed. 



The term 'beam,' used in the notes, does not always allude to the appearances just mentioned, bnt 

 is also applied to the commencement of an arch when it appears in an uniform stream of light, 

 4 



