Page:Philosophical Transactions - Volume 029.djvu/421

 Light which is caſt against a Ceiling by the Beams of the Sun, reflected from the Surface of Water in a Baſon that's a little ſhaken; whoſe reciprocal vibrating Motion it very much imitated. But all agree that this Spectrum laſted only a few Minutes, and ſhow'd it ſelf variously tinged with Colours, Yellow, Red and a dusky Green: Nor did it keep in the ſame Place; for when firſt it began to appear, it was ſeen a little to the Northwards of the Zenith, but by degrees declining towards the South, the long Stri of Light, which arose from all Parts of the Northern Semicircle of the Horizon, ſeemed to meet together, not much above the Head of Caſtor or the Northern Twin, and there ſoon diſappeared.

After the firſt Impetus of this aſcending Vapour was over the Corona we have been deſcribing appeared no more; but ſtill, without any order as to Time, or Place, or Size, luminous Radii like the former continued to ariſe perpendicularly, now oftner and again ſeldomer, now here, now there, now longer, now ſhorter. Nor did they proceed at first: out of a Cloud, but oftner would emerge at once out of the pure Sky, which was at that time more than ordinary ſerene and ſtill. Nor were they all of the ſame Form. Moſt of them ſeemed to end in a Point upwards, like erect Cones; others like truncate Cones or Cylinders, ſo much reſembled the long Tails of Comets, that at firſt light they might well betaken for ſuch. Again, ſome of theſe Rays would continue viſible for ſeveral Minutes; when others, and thoſe the much greater part, juſt ſhew'd themſelves and died away. Some ſeem'd to have little Motion, and to ſtand as it were fix'd among the Stars, whilſt other 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