38 1 G. Jones on the Zodiacal Light. 



15tli, 1857 to May 23dj sTiow me, by tlie diurnal revolution of 

 tlie earth, in positions at the times of observation, from 23*^ 15^ 

 N. to 19"^ 45' south of the ecliptic, making a distance of 2580 

 miles. Taking all my observations daring this period, north of 

 18^ N. of the ecliptic, and noting the average of the positions of 

 the central line for these observations : and then all south of 18^ 

 S. of the ecliptic, with also the average of the positions of the 

 central line for these, I find that the central line is affected to the 

 extent of 1° 45' by these my changes of place : that is, supposing 

 the average of the northern positions to have been 20'^ N. of 

 the ecliptic, and those of the southern 20° S. of it, my change 

 from one to the other, amounting to 2400 miles, produced a 

 change in the central line of 1^45'; not a parallax, but towards 

 me as my place was changed. In my obser\^ation of the 7th 

 March at"4 50 A. m. I was 19*" 30' N. of the ecliptic : in another 

 at 9 P. M. of the 19th of that month I was 20"" S. of that line, 

 making a difference of 2370 miles between these two positions: 

 the central line of the Luminous Arch shows a change in these 

 two observations of 2^ degrees ; that is, as I went from north to 

 south 2370 miles, the central line went with me southwardly 2^ 

 degrees. I should however prefer the former result of 1° 45' for 

 2400 miles, the average of many results being more reliable than 

 that of a i^^. From this, calculations may perhaps be made that 

 will give us the proximate distance of this ring from the earth- 



Another observation bearing on this was the one I had of a 

 moon's Zodiacal Light on the 14th October, 185G— one day after 

 the moon had become full. I have not the slightest doubt that 

 it was Zodiacal Light produced by the moon. It was a strong, 

 full light, with all the characteristics of this light when produced 

 by the sun, except that this was white, and wanted the warm 

 tinge of the Zodiacal Light from the sun. I took outlines of it, 

 commencing at 6^ 40"^ mean time and ending at 6^541*"; the 

 moon being hid, for a while, by a cloud on the horizon. This 

 light, pale and strong below, was merged above in that of the 

 Luminous Arch. If the full moon gives us a Zodiacal Light, 

 then the ring must obviously lie between that satellite and our 

 earth. 



_ 5. The toidlh of this ring. My observations on this subject 

 also show discrepancies which it is not easy to reconcile. During 

 the first two months of mv residence on the Cordilleras, the 

 width of the Luminous Arch as recorded on my charts is about 



the average of widths is 33° 58 



May 



> 



amount 



of my observations is 25° 56' for the width. At anj^ one night 

 it had a uniform width quite across, except at the horizons. The 

 increase of width in the whole number of observations is proba- 

 blj owing to the fact that mv eve. becominer more experienced m 



