6l9 PHILOSOPHICAL TRANSACTIONS. [aNNO 1790. 



In the evening of March 21, 1783, between 8 and g o'clock, Mr. H. observed 

 something like a bright cloud in the eastern part of the hemisphere, and also a 

 similar appearance in the opposite part of the heavens. These luminous parts, 

 which appeared in the eastern and western parts of the horizon, were connected 

 by an arch of a fainter light. 



It reached the horizon in the w.s.w. point. In its course it passed about 12° 

 to the south of the zenith. Its breadth was about Q or 10°. It remained visible 

 about 10 or 12 minutes after he first discovered it, and then vanished gradually 

 and irregularly. He observed no coruscations, nor any motion in this arch. A 

 few minutes after another, and still more beautiful, arch made its appearance. It 

 arose a point or 2 nearer the n.e. than the former had done. Its southern edge 

 passed up a little to the north of the tail of the Great Bear, which was then in a 

 vertical position. Its northern edge appeared at first a little to the south of the 

 polar star ; but, during the continuance of the phenomenon, it gradually receded 

 about 10° to the south. The arch descended about the w.n.w. ; but neither the 

 eastern nor western extremities reached the horizon ; each of them ending in a 

 point gradually formed a little above the horizon. This arch might be about 10 

 or 12° at its vertex. It continued visible for half an hour; and though he 

 could not discover any coruscations, or quick motion, in any part, yet the differ- 

 ent portions of it were perpetually varying in the density of their light, and the 

 whole arch, or at least its vertex, made a slow and equable motion towards the 

 south. Where the light was the most dense, the smaller stars were rendered in- 

 visible by the arch, but stars of the 2d magnitude were not totally eclipsed by it. 

 This arch disappeared, as the former, by patches ; the light gradually becoming 

 less intense. The colour of both these arches was white. Before the latter arch 

 had entirely disappeared, a small one, not quite so broad as the rainbow, arose 

 from its eastern leg, and ascending in a curvilineal direction to the polar star, 

 terminated there. Its light was more faint than that of the other 2 arches ; and 

 it continued visible about a quarter of an hour. The evening was very fine 

 when he saw these beautiful phenomena ; the stars were bright, and there was 

 not a cloud to be seen except in the horizon. There was a steady light in the 

 north, without the least coruscation, extending from the n. e. to n. w. The 

 wind blew from the n. e. 



March 26, about the same time in the evening, Mr. H. was entertained with 

 a similar appearance. He first observed 2 or 3 columns of aurora borealis 

 shooting upwards in the north ; and in a short time after a complete arch, like 

 those already described, though somewhat different in its position. It arose be- 

 tween the E. and n. and n. e. points, passed obliquely to the south below Arc- 

 turus, and descended in the west through Orion, having almost the same direc- 

 tion through that constellation which the equator has. Its light was the most 



