G, Jones on the Zodiacal Light. S77 



this arose from tlie great difference in color between the light 

 near the horizon adjoining the sun^ whether in the evening or 

 morning, and in the other portions of the arch: and also from 

 the most decided manner in Avhich the former, which was evi- 

 dently reflected light, usually turned towards me, wdiatever mj 

 position might be^ but especially when I was farthest from the 

 ecliptic: while the other portions of the Luminous Arch, though 

 siding over towards me at my farthest removes, were influcDced 

 in a far inferior degree by my change of place. The light at the 

 horizon next the sun, except in the middle hours of the night, 

 was always a warm yellow light, such as it ordinarily has in our 

 own latitudes : while in all other parts of the arch it was a cold, 

 white light, exactly like that of the Milky Way. Indeed not 

 only was this arch in color like the galaxy, but its brightness was 

 often so great that the notes to my observations in the deep hours 

 of the night several times say that it looked much like another 

 Milky Way stretched across the sky. 



One evening, while I was standing on the hill Ychinbia near 

 Quito, at the summit of which my observations were made, I 

 watched the sun's last rays on the snow-covered top of the dis- 

 tant Cayambi, a mountain scarcely inferior in elevation or grand- 

 eur to Chimborazo itself All around me had, for a long wliile, 

 been in shadow: the sun had set to the lofty peaks of Pichincha 

 opposite to me, but still lingered on Caj^ambi, lighting it up with , 

 a yellowish hue : suddenly, the yellow light ceased, and the sqow 

 of Cayambi took a white color that chilled me to look at, I was 

 struck with the great resemblance of this yellowish hue to that 

 of the Zodiacal Light as seen over the horizons just after night- 

 fall or before daybreak: while the subsequent white color ex- 

 actly resembled that of the other portions of the Luminous Arch ; 

 or, in the dark hours of the night, of the whole of it, stretched 



across the sky. 



The question agitating my mind in all these observations was 

 an interesting one : for, if this white liglit \vas not reflected light 

 but was an independent light, then we have ascertained a most 

 important quality of nebulous matter: it must be self luminous. 



I could not, at any time, discover an interruption or break in 

 the light of this luminous arch, such as might be produced by 

 the shadow of our globe. I tried, first, without having ascer- 

 tained exactly where such a shadow ought to fall, so as to avoid 

 any self-deception on the subject; but I could see no shadow : 

 then I noted, carefully, on the charts where the sun's opposition 

 ^ould fall, but still there was no shadow to be made out. A 

 German observer— I believe it is Theodore J. C. A. Brorsen,— 

 ^vho has seen this luminous arch repeatedly in Germany, says 

 tliat the place opposite the sun was ahvays brighter than any 



tl 



SECOND SERIES, VOL- XXIV, NO. 72. — SEPT., 1857 



48 



