G. Jones on the Zodiacal Light 383 



soutli of the ecliptic, it is obvious tliat to get the jDOsition of this 

 central line correctly, it ouglit to be observed onJj when it is 

 nearly or quite vertical to the spectator. The average of all my 

 observations, when I was at 2° or less from it, place it at its 

 furthest extent on the south at 3° 10' from the ecliptic. On the 

 northern side I had but one observation of this kind, which 

 made it S"" 80' from the ecliptic. From this we may conclude 

 that this central line ; and therefore, as the outer boundaries 

 always kept pace with it, that this great nebulous circle, makes 

 an angle of 3° 20' with the ecliptic. 



My first observations of this central line placed the ascending 

 node in longitude 62° ; but subsequent ones made it vary from 

 this down even to 42^ of longitude: and the place of this cross- 

 ing of the ecliptic seemed always to me to be verj uncertain. 

 But it was not so with the descending node, which every night's 

 observation of that part of the sky showed at once to be near 

 /? Scorpii, in longitude 242°. All the three observers already 

 adverted to, dictated this line to me as passing b3^ the twin stars 

 at that place, and I think we may accordingly consider the Ion- 

 gitude of the nodes as at 62^ and 242°. 



4. The distance from the earth and the width of this ring. The 

 manner in which that portion of the Zodiacal Light which was 

 obviously reflected light, was turned in my direction when I was 

 at my farthest removes from the echptic, was, on most occasions, 

 very remarkable. Sometimes it appeared to have little affinity 

 with my change of position; but at others this warm, yellow 

 light over the horizon was deflected towards me in a most deci- 

 ded manner, showing that the substance from which it was re- 

 flected could not be at any vast distance, most certainly not at 

 the distance which a heliocentric ring would require it to be. 

 ^or, my removes from the ecliptic could never be greater than 

 1421 miles : and a lidit affected so decidedly by so small a 

 change in the observers place could obviously not come reflected 

 from a medium at twice the distance of the sun. 



Some approximations towards the actual distance of the ring 

 rnay perhaps be gained by noticing how the central line of 

 strongest light was affected by my changes of place. This line 

 alwa}-s changed with me, going in the direction in which 1 was 

 carried, which of course is the very opposite of parallax: and 

 We must despair of having any parallax m Zodiacal Light. This 

 central line varies very much on my charts, even when I was in 

 the same positions; for it was extremely difficult to mark accu- 

 rately an object oftentimes so uncertain ; and my aim was, not 

 Tiniformity, but to record facts as they appeared to my eyes. 

 There are, in consequence, discrepancies among my lines. But 

 still these facts admit of classifications, from which general de- 

 ductions may be drawn. For example^ my records from Feb. 



