622 APPENDIX. 



make a difference of 36° between the thermometer at 

 the north and south sides of the observatory. At 7 h 

 p.m. there was a faint diffusion of aurora, apparently 

 high, the needle was tremulous — 0° 02' W., but at 10 h 

 p.m. the thermometer had sunk to — 50f°, and the aurora 

 presented the most brilliant appearance I ever saw at so 

 low a temperature : the main stream rose in a narrow 

 but vivid column at E.b.N., and after making a zig-zag 

 bend to E., pursued a direction to W. in an undulating 

 arch 70° N. ; but from the westward there were no less 

 than seven distinct parts of arcs, issuing from another 

 condensed column, of a dull red and orange mixed with 

 yellow. These arcs had an altitude from 20° to 50°, 

 stretching towards the S.E., where I observed several 

 bright rays : all of those E. and W. were more or less 

 tinged with the colour I have mentioned, but beyond, or 

 what I should denominate higher, were many white 

 filmy rays or bands. On examination I found the 

 needle strangely acted on, which was shown by the 

 quickness and sudden checks or dead stops it exhibited, 

 according to the current and counter-current of the pre- 

 valent band or stream. One fact I was glad to ascertain, 

 viz. that the marked end of the needle was at 1° 20' W., 

 when the most powerfully concentrated aurora was at 

 E.b.N. and E.b.S., both rising into arcs, the former 

 (northerly) to W. at an angle of 60°, the latter 

 (southerly) faintly to S.W. Finding that the needle 

 only vibrated at different arcs between 0° 50' and 1° 20' 

 W., I went out to watch the motion of the aurora, when 

 it underwent transitions of form, from streaming arches 

 to spirals, zig-zag'd, convoluted, and indescribable bands 

 of rays, and beams altogether so eccentric and beautiful, 

 as to exceed the visions of the most exuberant imagin- 

 ation. Coronas were frequent, and as every part was in 

 rapid motion, it will be readily conceived to be no easy 



