Intelligence and Miscellaneous Articles, SS9 



ON THE ZODIACAL LIGHT OF THE 29TH OF SEPTEMBER, AS IT 

 APPEARED FROM CHELMSFORD. BY DR. FORSTER,.F.L.S.&C. 



To the Editors of the Philosophical Magazine and Annals, 

 Gentlemen, 

 I hasten to communicate to you a succinct account of a remark- 

 able luminous appearance in the heavens on Monday evening last, 

 the 29th of September. About eight o'clock on that evening, going 

 out of doors, my attention was drawn towards a bright band of light 

 extending from the western horizon to the zenith or rather beyond 

 it. It appeared to me to be a portion of an arc which had extended 

 quite across the sky from west to east, as I could trace the faint re- 

 mains of it almost to the eastern point. By half past eight however 

 it was reduced to an arc of about 90°, beginning abruptly at about 

 five degrees above the horizon at the point W.S.W. by W., and, 

 after bending a little toward the south, extending itself across the 

 zenith, and terminating at about 5° east of it, fading into a sort of 

 smoky appearance. This remarkable band of light was brightest 

 at its lower or western part, and at above the middle, that is 45° 

 of altitude, began to diminish in lustre; its average breadth was 

 above three degrees; its colour a sort of reddish, giving the ap- 

 pearance of a column of brightly ignited smoke, or as if the reflected 

 light of a great distant fire could be supposed carried in a circum- 

 scribed column into the air. It was brighter than any aurora borealis 

 that I ever saw, and considerably excelled in brilliancy the light of 

 some faint coruscations of that phenomenon which I observed at the 

 same time in the north. Its duration was from eight to nine o'clock, 

 when fading away and getting whiter as to colour, it disappeared. 

 The thermometer standing at 57° .Barometer 29*55. Wind West. 

 — Such was the appearance in this neighbourhood of this remarkable 

 phenomenon; and it should be accurately recorded, and compared 

 with distant observations. For I have received some accounts of it 

 from observers in other parts of England, who discerned at first, 

 the whole arc extending across the heavens: others made its situa- 

 tion rather more south-west, while in some places it seemed to rise, 

 by the gradual elevation of its western termination above the horizon. 

 Probably you will have other accounts to compare and to record 

 collaterally with this, from a comparison of which its actual place in 

 the regions immediately above our atmosphere may be ascertain- 

 ed. To me it seems that its elevation must have been very great ; 

 as the distance of a hundred miles, according to my comparison of 

 observations, gave it no sensibly different apparent place. It must 

 have been one of very unusual electrical communications which 

 take place parallel to the earth's convexity through the rare air of 

 a region much above our more dense atmosphere, and which from 

 cutting the horizon just above the place of the recently set sun, 

 and occurring about the period of either equinox, has been called 

 the zodiacal light, and vainly imagined to be a real emanation from 

 the sun's light. It is in fact more allied to the northern lights than 

 to any other phenomenon, and like those beautiful illuminations must 



be 



