540 



APPENDIX. 



[No. II. 



I have been anxious to confine myself to a mere detail of facts, without ventur- 

 ing upon any theory. My notes upon the appearances of the Aurora coincide 

 with those of Dr. Richardson, in proving, that that phenomenon is frequently 

 seated within the region of the clouds, and that it is dependent, 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 vibra- 

 tory. Sometimes it was simultaneous with the formation of arches, prolonga- 

 tion of beams, or certain other changes of form, or of activity of the Au- 

 rora ; but generally the effect of these phenomena upon the needle, was not vi- 

 sible immediately, but in about half an hour or an hour, the needle had at- 

 tained its maximum of deviation. 



From this, its return to its former position was very gradual, seldom regain- 

 ing it before the following morning, and frequently not until the afternoon, un- 

 less 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 consi- 

 derable 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 de- 

 termined. 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 computing the horizontal extent of the arches. 



It is to be noticed, that the bearings given by Dr. Richardson and Lieu- 

 tenant Hood are true, and not magnetic. 



