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 inclosures, 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 dc b, a, b cd, 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 sheaf 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 c c. After these came on the terminating ring, which was coloured very much in the manner of the common rainbow, except that the tints were not quite so vivid (as if owing to the effect of a yellowish tinge, which seem ingly 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 proportionably; 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. [Id. 1780. SECTION X. Peculiar solar and lunar Irises seen in South America. To the before-mentioned particulars of the mountainous deserts, I shall subjoin the phænomena seen there, as subjects equally meriting the curiosity of a rational reader. At first we were greatly surprised with two, on account of their novelty; but frequent observations rendered them familiar. One we saw in Pambamarca, on our first ascent thither; it was a triple circular iris. At break of day the whole mountain was encompassed with very thick clouds, which the rising of the sun dispersed so far as to leave only some vapours of a tenuity not cognizable by the sight: on the opposite side to that where the sun rose, and about ten toises distant from the place where we were standing, we saw, as in a looking-glass, the image of each of us, the head being as it were the centre of the three concentric irises: the last or most external colours of one touched the first of the following; and at some distance from them all, was a fourth arch entirely white. These were perpendicular to the horizon; and as the person moved, the phenomenon moved also in the same disposition and order. But what was most remarkable, though we were six or seven together, every one saw the phenome. non with regard to himself, and not that relating to others. The diameter of the arches gradually altered with the ascent of the sun above the horizon; and the phenomenon itself, after continuing a long time, insensibly vanished. In the beginning, the diameter of |
