IV APPENDIX. 



shower, are sending off from each drop reflections of light in all 

 directions, and the universal atmosphere about us is full of these 

 brilliant, variously-colored rays; but only that portion which to 

 us forms the rainbow arch, can reach our eye, and all the rest is 

 lost to our sight." 



"So it is also with the zodiacal light; and the proof that we 

 never see the whole extent at once, is manifest in the following 

 facts : — 



" 1. That when I was in a position north of the ecliptic, the 

 main body of the zodiacal light was on the northern side of that 

 line. 



" 2. When I was south of the ecliptic, the main body of the 

 zodiacal light was on its southern side. 



" 3. When my position was near or on the ecliptic, the light 

 was equally divided by the ecliptic, or nearly so. 



" 4. When, by the earth's rotation on its axis, I was, during 

 the night, carried rapidly to or from the ecliptic, the change of 

 the apex, and of the direction of the boundary lines, was equally- 

 great, and corresponded to my change of place. 



" 5. That as the ecliptic changed its position, as respects the 

 horizon, the entire shape of the zodiacal light became changed, 

 which would result from new positions of the nebulous matter 

 coming into position to give visible reflection; while portions 

 lately visible were no longer giving us such a reflection. 



" The first four of these results were not always uniform ; but 

 the exceptions were few, and were probably occasioned by the 

 nebulous rings not being exactly in the plane of the ecliptic." — 

 (Introduction to Mr. Jones's Report, pp. 16 and IT.) 



Mr. Jones in his § x adds to this: "From the deductions 

 made in § i, it is apparent that we cannot expect to get a parallax 

 of this ring ; and that we can hope for only approximations ta 

 its width." 



The partial illumination on the side toward the observer was 

 indeed a negative to parallax in excess; somewhat as aberration 

 is in its effect on the annual parallax of the stars, though not in 

 the same way. 



Mr. Jones might have added, that the circumstances which he 

 mentions would also be in the way of ascertaining the node of 

 the nebulous band, and must render questionable any supposed 

 determination of that. 



The light, as we have said, being from particles which are 

 molecular, and the whole material from which the light comes to 

 us remarkably transparent, the light itself cannot be regarded as 

 being a mere reflection;* but the result of the more comjjlicated 



* Mr. Proctor also seem? inclined to admit the possibility of a more 

 intense illumination in special directions; though not decided as to its 

 canse, when he says : '-If some solar action, for example, powerful lumi- 

 nosity in certain definite directions — as, for instance, near the plane of the 



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