OF THE ZODIACAL LIGHT. 441 



in tlie Milky Way. The mass of tlie light, however, 

 appears to be to the north of the ecliptic. The observation 

 was made in 28° 5' N., 164° 24' W. Mr. Jones states, as 

 part of his results, that when he was north of the ecliptic 

 the main body of the light was on the north side of that 

 line, and vice versa. Now, of eleven observations by Cas- 

 sini, which he gives, all apparently made at Paris, seven 

 show the main body of the light on the north side of the 

 ecliptic and four do not ; and there are many exceptions to 

 the supposed rule in Mr. Joneses own work. Three of the 

 observations by Cassini have already been compared with 

 Mr. Joneses results. The others show the following re- 

 sults. The positions of Cassini and Mr. Jones were, 

 during all the observations compared, north of the ecliptic. 

 The signs -h or — mean that the body of the light was 

 observed to lie north or south of the ecliptic. 



Cassini. Jones. Cassini. Jones. 



February — + November -j- 4- 



March — + December -j- -|- 



September — — December -\- + 



September + — March — — 



November + 4- 



Surely these results look more like a change of position 

 depending on the time of year than on the place of ob- 

 servation. My own observations, so far as the position of 

 the axis implies the position of the main body of light, go 

 to this view of the case, although not as distinctly as might 

 be wished. The gradual diminution of the latitude until 

 July is remarkable ; but I am at present unable to account 

 for the subsequent increase being of the same sign, espe- 

 cially as the observations made in the Mediterranean in 

 1863, tabulated hereafter, have an opposite sign. 



Table I. contains the observed lengths and positions of 

 the apex of what I shall hereafter call, for the sake of distinc- 

 tion, the inner cone. On the 1 6th June 1862 traces of a much 

 fainter envelope surrounding the inner cone, and extending 



2 g2 



