RECORD OF AURORAL PHENOMENA. 51 



that the eye could only trace its progress partially ; and its dissolution and reappearance were 

 equally sudden. 

 At 2h. p. m., the moon arose. A clear sky. The Aurora fainter and further to the southward 

 than before."— Ibid., p. 620. 



December 28, 1820. Temp. —49°. 



"At Gh. p. m., the Aurora, in an arched form, extended from the S. E. horizon to the N. W., across 

 the zenith. This arch was at one time composed of a bright homogeneous stream of light 

 about 8° broad; at other times, it split into parallel beams, their ends directed to the east and 

 west. These beams receded from each other laterally, until they were separated by a space of 

 clear blue sky more than twice their breadth, speedily reuniting again, however, to form the unin- 

 terrupted arch. A fainter arch appeared to the northward of the other, springing from, and ter- 

 minating at, the same points in the horizon, but having an apparent curvature so much greater 

 as to keep their centres 5° or 6° apart. 



At 8h., the low fog to the southward had increased, and minute crystals of snow were falling, but 

 the zenith remained clear. 



At this time, there existed a zone of light in the north, about 20° high, whose extremities, united 

 with those of a similar zone in the south, dipped suddenly down to the horizon in the S. E. and 

 N. W. points. 



At 9h., in a calm and clear atmosphere, there were five arches, each about 4° broad; one crossed 

 the zenith, another was elevated about GO above the northern horizon, and there were three in 

 the southern half of the sky, at elevations of 45°, 6 P , and 80°. Their light was faint, and their 

 extremities converged so as to terminate conjointly in the N. W. by N. and S. E. by S. points. 



At lOh. 30m., columns of faint light rose perpendicularly from the horizon in the N., S. E., and 

 S. W. points, to the height of 20°. 



At midnight, there was an arch of light in the south, about 15° high, having its lower edge, 

 throughout its whole length, resting upon a fog-bank ; and there were also two or three faiut 

 beams rising from the horizon in the S. E., across a portion of clear sky, and a beam lying mid- 

 way between the zenith and horizon, about 20° long, and pointing north and south. 



At lh., the sky in the zenith was clear, and was occupied by an arch tending from N. W. to S. E." 

 —Ibid., p. 622. 



December 29, 1820. Temp. —52°. 



"At 6h. p. m., there appeared an arch of yellowish-gray and pretty dense light, about 10° broad 

 and 25° high, which in a few minutes began to increase in breadth, and at length separated into 

 two parallel arches, whilst at the same time a fainter beam sprung from its northern end, taking 

 a direction towards the S. by E., but, becoming more diffuse as it rose, it disappeared in the 

 zenith. The brighter part of the light obscured the stars. The united limbs of the two arches 

 in the N. by W. were divided by perpendicular dark spaces so as to appear to be composed of 

 oblique bars. 



About 10m. after these appearances were noted down, the sky was occupied, for about 70° to the 

 northward of the zenith, by large masses of light, arranged so as to converge towards the N. W. 

 by N. and S. E. by S. points of the horizon. Near these points, long slender processes of light 

 descended, and united so as to form a common stem on each side similar to the limbs of an arch 

 of the common dimensions of 2° or 3° in breadth. The internal movements of the Aurora at 

 this time were sluggish, but large masses of light were frequently generated almost instantaneously. 



At lh. 30m., a number of arches sprung from the horizon in the N. W. by N., and, sweeping 

 across the sky in various directions, suddenly curved in to terminate in the S. E. by S. The 

 arches were in general about 6° broad, and their middles were distant enough from each other 

 to spread on each side of the zenith to the distance of 50°. 



From 9h. to midnight, the Aurora formed many arches of light, very various in breadth and 

 density, all having a common origin and termination in the N. W. and S. E., but crossing the 

 heavens in a variety of directions, so as to occupy about three-fourths of the space on each side 

 of the zenith. 



