214 PHILOSOPHICAL TRANSACTIONS. [aNNO 1? l6. 



SO much resembled the long tails of comets, that at first sight they might well 

 be taken for such. Again, some of these rays would continue visible for several 

 minutes; when others, and those the much greater part, just showed them- 

 selves, and died away. Some seemed to have little motion, and to stand as it 

 were fixed among the stars, while others with a very perceptible translation 

 moved from east to west under the pole, contrary to the motion of the heavens; 

 by which means they would sometimes seem to run together, and at other 

 times to fly one another, affording a surprising spectacle to the beholders. 



After this sight had continued about an hour and a half, the beams began to 

 rise much fewer in number, and not near so high, and gradually that diffused 

 light, which had illustrated the northern parts of the hemisphere, seemed to 

 subside, and settling on the horizon formed the resemblance of a very bright 

 crepusculum. On the first information of the thing, I immediately ran to the 

 windows, which happened to look to the south and south west quarter; and 

 soon perceived, that though the sky was very clear, yet it was tinged with a 

 strange sort of light; so that the smaller stars were scarcely to be seen, and 

 much as it is when the moon of 4 days old appears after twilight. We per- 

 ceived a very thin vapour pass before us, which arose from the precise east part 

 of the horizon, ascending obliquely, so as to leave the zenith about 15 or 20 

 degrees to the northward. But the swiftness with which it proceeded was 

 scarcely to be believed, seeming not inferior to that of lightning ; and exhibit- 

 ing as it passed on a sort of momentaneous nubecula, which discovered itself 

 by a very diluted and faint whiteness; and was no sooner formed, but before 

 the eye could well take it, it was gone, and left no signs behind it. Nor was 

 this a single appearance; but for several minutes, about 6 or 7 times in a 

 minute, it was again and again repeated; these waves of vapour, if I may so 

 call it, regularly succeeding one another, and nearly at equal intervals; all of 

 them in their ascent producing a like transient nubecula. 



By this particular we were first assured, that the vapour we saw, whatever it 

 was, became conspicuous by its own proper light, without help of the sun's 

 beams; for these nubecula did not discover themselves in any other part of their 

 passage, but only between the south east, and south, where being opposite to 

 the sun they were deepest immersed in the cone of the earth's shadow, nor were 

 they visible before or after. Whereas the contrary must have happened, had 

 they borrowed their light from the sun. 



A little after 10 o'clock, we found, on the western side, viz. between the 

 W. and N. W. the representation of a very bright twilight, contiguous to the 

 horizon; out of which there arose very long beams of light, not exactly erect 

 toward the vertex, but something declining to the south, which ascending by a 



