VOL. XXIX.] PHILOSOPHICAL TRANSACTIONS. 213 



The times by the clock were 17"" 45' sooner than the apparent time, as was 

 found by the observations of Cor Leonis and Arcturus. 



The latitude of Wansted is 51° 34'. Its longitude is 8^ in time eastward 

 from the Observatory at Greenwich. 



The Account given of this eclipse by the reverend Mr. William Derham, 

 who observed it at Upminster, is agreeable to this, as far as clouds would permit 

 him to observe. 



j4n Account of the late surprising appearance of the Lights see?! in the Air, on 

 the 6ih oj" March last; with an Attempt to explain their Principal Phcenomena, 

 By Edmund Halley, J. V. D, Savilian Professor of Geom. Oxon, and Reg, 

 Soc. Seer. N° 347, p. 406. 



On Tuesday, March 6, O. S. 17 16, the afternoon having been very serene 

 and calm, and somewhat warmer than ordinary, about 7 o'clock, out of what 

 seemed a dusky cloud, in the N. E. parts of the heaven, and scarcely 10° high, 

 the edges of which were tinged with a reddish yellow, as if the moon had been 

 hid behind it, there arose very long luminous rays or streaks, perpendicular to 

 the horizon, some of which seemed nearly to ascend to the zenith. Presently 

 after, that reddish cloud was swiftly propagated along the northern horizon, 

 into the N. W. and still farther westerly; and immediately sent forth its rays 

 after the same manner from all parts, now here, now there, observing no rule 

 or order in their rising. Many of these rays seeming to concur near the zenith, 

 formed there a corona, or image, \yhich drew the attention of all spectators, 

 who according to their several conceptions made very differing resemblances of 

 it; but by which compared together, those that saw it not, may well compre- 

 hend after what manner it appeared. All agree that this spectrum lasted only 

 a few minutes, and showed itself 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 northward of the zenith, but gradually declin- 

 ing toward the south, the long striae 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. 

 Nor did they proceed as at first, out of a cloud, but oftener 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 truncated cones or cylinders. 



