No. III.] 



Dr. RICHARDSON ON THE AURORA. 



615 



was not sufficiently dense to hide the larger stars. Its motions were in 

 general slow, and unattended by flashes. 



At 1 lh., a bright arch extended across the zenith, from E. b. S. to N. W. b. W. 

 The S. W. quarter of the sky being at the time occupied by a homogeneous 

 mass of light, which had a crescentic edge turned towards the east, and there 

 was a similar mass in the north concave towards the south. The arch 

 at first exhibited a vermicular motion from east to west, then split into 

 parallel beams, possessing, as usual, a rapid lateral motion ; and in a short 

 time, the Aurora in every part of the sky began to move with such velocity, 

 and to assume such a variety of forms, as to defy description. The central 

 arch more than once exhibited two distinct currents, or motions of its parts, 

 flowing from one end to the other in opposite directions at the same instant ; 

 and at one time all the detached parts of the Aurora appeared to collect toge- 

 ther, to form a beautiful circle or corona, which surrounded the zenith at the 

 distance of 45°, and in which the rapid lateral motion of the beams was very 

 apparent, having a direction from north, round by the south, west and east. 

 The beams, in this case, were apparently perpendicular to the earth's surface 

 in every part of the luminous ring which they formed. In a half-arch, which 

 rose immediately afterwards from the northern horizon to the zenith, the 

 extremities of the beams were directed from east to west, and the ranges of 

 beams which formed, in rapid succession, masses of light, of various shapes, 

 in every part of the sky, had no certain direction. The general colour of 

 the Aurora was a pale yellowish-gray; but when the beams moved with a 

 rapidity that could scarcely be followed with the eye, they emitted a pale, 

 but bright red light, slightly tinged with purple or violet. These beams 

 sometimes lengthened and shortened themselves with extreme rapidity, and 

 the prolonged extremities emitted a light equally brilliant, and of the same 

 hue with the rest of the beam. In about 15m. the whole of these beautiful 

 phenomena vanished, leaving behind only a few faint masses of light. The 

 moon was still surrounded by a slight bur, and the wind had changed to the 

 west. c ; * 



At midnight, the southern quarter of the sky was occupied by a broad hori- 

 zontal mass of light. At lh. there was no appearance of the Aurora whatever. 

 Sky cloudless, but rather hazy ; minute crystals of snow falling. During the 

 evening the wind was very variable, but light. 



