« ZurückWeiter »
hazy, and full of vapours, especially towards the sub-set. The moon and stars were bearded at that time, and succeeded with a halo about the moon afterwards. Which disposition of the air was probably the cause of the phenomenon. But the pyramid was doubtless imprinted on the far distant vapoors of the atmosphere, it being manifestly far off, or laying beyond some small thin clouds (C. L, C, L,) that intercepted it, and in those parts covered and hid it. I do not remember I ever saw any thing like it, except the white pyramidal glade, which is now called the aurora borealis. And it being, except in colour and length, so like that, I have thought it may perchance in some measure con. duce to the solution of that old phenomenon, the aurora borealis.
Parhelia at Sudbury, Suffolk.
By Mr. Petto. August 28, 1698, about eight o'clock in the morning, there was seen the appearance of three suns, which were at the brightest then, or a little after. About half an hour after eight I saw it, when there was in the east a dark, dusky, watery cloud; and be. low it towards the middle, was the true sun, shioing with such strong beams, that persons could not look upon it; on each side were the reflections, with the true sun in the middle. Elsewhere much of the firmament was of an azure light bloe colour. The circles which I saw were not of rainbow colours, but white; there was also higher in the firmament, more over our heads, and towards the south, at the same time, at a considerable distance from the other, the form of a half moon; but I think it was more than double the size of a half moon, with the horns turned upwards, and within of a fiery red colour, and more like a rainbow colour; these all faded gradually, after having continued about two hours.
[Phil. Trans. 1699.
Two Mock-Suns, and an Arc of a Rain.bow_inverted, with a
By the Rev. William Whiston.
A Bout ten o'clock in the morning, on Sunday Oct. 22, 1721, being at Lyndon, in the county of Rutland, after aurora borealis the night before, wind W.S.W. I saw an attempt towards two mock. suns, as I had done sometimes formerly. About half or three quarters of an hour after, I found the appearance complete ; when two plain parhelia, or mock suns, appeared tolerably bright and distinct; and that in the usual places, viz. in the two intersections of a strong and large portion of a halo, with an imaginary circle, parallel to the horizon, passing through the true sun. This circle I call imaginary, because it was not itself visible, as it sometimes has been at such appearances. Each parhelion had its tail of a white colour, and in direct opposition to the true sun; that to. wards the east was 20 or 250 long; that towards the west about ten or twelve degrees; but both narrowest at the remote ends. The mock-suns were evidently red towards the sun, but pale or whitish at the opposite sides, as was the halo also. Looking upward, we saw an arc of a curious inverted rainbow, about the middle of the distance between the top of the halo and the vertex. This arc was as distinct in its colours as the common rainbow; and of the same breadth. The red colour was on the convex, and the blue on the concave of the arc ; which seemed to be about 90° long : its centre in or near the vertex. On the top of the halo was a kind of in. verted bright arc, though its bend was not plain. The lower part of the halo was among the vapours of the horizon, and not visible. The angles, as more exactly measured on Monday, near noon, when the same appearance returned again, but more faintly, were as follow: the sun's altitude 22°; perpendicular semidiameter of the halo 23} ; distance of the rainbow from the top of the halo 23°; semidiameter of the arc of the rainbow, if our vertex be gupposed its centre, 21°. The phenomenon lasted each day for an hour and a half, or two hours. What was most remarkable op *Monday was, that the wind, which on Sunday bad been almost in.
sensible, was now become sensible, and changed to N.N.E. that the halo was sensibly become oval; its shorter axis parallel to the horizon; and the two mock-suns, which were then but just visible, especially that on the east, were not in the halo, but a degree or two without it, which I ascribe to the unusual shortness of the ho. rizontal diameter; which position of the mock-suns does not appear to have been hitherto taken notice of by any, though it was now very sensible.
October 26, about nine in the morning, as I was coming in the Northampton coach towards London, the halo returned larger and clearer than before ; and the two mock-suns jast attempted an appearance, as on Sunday ; but the air becoming thicker and thicker towards rain, I saw them no more. I add nothing to this account, but only, that August 30, before, I saw at the same place, Rutland, a remarkable halo, whose upper part had its inverted arc reddish within, and pale without, but brighter and more vivid than ever I saw before. That we had there, September 11, in the evening, the lightest and most remarkable aurora borealis, with its unaccountable motions and removals, that ever I saw, excepting that original one, March 6, 1711: that it was seen in Northamptonshire, at the Bath, and elsewhere : that the vertex of the co. lumns which shot upwards, was not our vertex, but evidently fifteen or twenty degrees distant towards the south; and that the wind was in Rutland north, as I observed myself; at the Bath west; and in Northamptonshire south; all at the same time, which deserves particular reflection.
JANUARY 13, 1768, between nine and ten in the morning, being on an eminence that overlooked some low meadow ground, Mr. Cochin observed, in a direction opposite to that of the sun, which shone very bright, and in a mist which covered the said ioclosures, an unusual meteor, which, without attempting to name it, he describes by help of the above figure. At about the distance of half a mile, and incurvated towards each other, like the lower ends of the common rainbow, there appeared in the mist two places of a peculiar brightness, as represented at A A. They seemed, as is common, to rest on the ground, were continued as high as the mist, and in breadth near half as much more as that of the iris. In the middle, between these two places, on the same horizontal line, was a coloured appearance like dcb, a, bcd, whose base could not at most subtend an angle of above ten or twelve degrees, and whose interior parts were thus variegated. The centre a was dark and irregularly terminated, as if made by the shadow of some object not larger than an ordinary sheal of corn. Next this centre was a curved space b b, of a yellowish flame colour. To this succeeded another curved space of nearly the same dark cast as the centre, seemingly tinged with a faint blue green, and very evenly bounded on each side, as at cc. After these came on the terminating ring, which was coloured very much in the manner of the common rainbow, except that the tiots were not quite so vivid (as if owing to the effect of a yellowish tinge, which seemiagly entered into the composition of all the colours) nor their boundaries so well defined. The centre of the image appeared to be exactly in the line of aspect, as it is called, or one conceived to be drawn from the sun through the eye of the spectator: and it may be observed from the figure, that these curve spaces were not segments of perfect circles, but formed like the ends of concentric ellipses, whose transverse axes were perpendicular to the horizon.
To the above description of the image it may be necessary to add the following particulars which attended it. The mist was very thick near the surface of the meadows, though rarer upwards, and chiefly, if not solely, on the side of the hill opposite to the sun. The place where Mr.C. stood was just on its confines; and as he advanced into it, the object became gradually fainter and fainter. As the sun dispersed the vapour, the appearance faded propor. tionably; and about half an hour after he first saw it, it was scarcely visible. The evening before was wet; but the drops on the hedges were congealed by frost. Where the sun shone, the bushes were each invested with a mist, as if owing to the vapours exhaled from them by the sun's warmth ; and, on a nearer inspec. tion, he could clearly discern the little humid particles which occa. sioned it, and which were floating around the bushes at about half an inch distance from each other.