148 THE APPARENT POSITION OF THE ZODIACAL LIGHT. 



it will become more practicable to compute the theoretical amounts of light at 

 various elongations which would result from any given hypothesis with regard to 

 the distribution of meteors in the Solar System. 



In any such computation, it will probably be found that between the vertex 

 of the ordinary zodiacal light and the region at the elongation 180° the light 

 will remain nearly constant for a considerable arc of longitude. This, at least, 

 was the result of some unpublished computations, made a few years ago upon 

 various hypotheses of the distribution of the meteors and the effect of their 

 phases. The existence of the zodiacal band, reported by Brorsen, Schmidt, and 

 other observers, would be wholly consistent with this conclusion ; but it is still a Httle 

 uncertain whether the observed zodiacal bands may not be due to faint streams 

 of stars. It rather singularly happens that on both sides of the Milky Way the 

 existence of such streams is indicated by the Durchmusteritng. The narrow band 

 from the Pleiades has been fully discussed elsewhere,^ and on recent, examination 

 it appeared that a similar stream of Durchmusterung stars extends along the 

 ecliptic from e Cancri to /8 Virghm. The region examined was that portion of 

 the Durchmusterung from S*" 0° to 13'' Q° in right ascension, and from — 2° to 

 -|-28° in declination. Within this region, the number of stars in each 4" of right 

 ascension was counted for each degree of declination, and, north of -)-12', these 

 numbers were multiplied by the secants of the corresponding declinations. The 

 numbers thus corrected represent observed stellar densities, the imit of area being 

 the square degree, but the corrections are everywhere small. With the aid of 

 Dien's Atlas, the epoch of which, 1860, is sufficiently near that of the Durch- 

 musterung for the present purpose, a line was laid down through the region along 

 the middle of the assumed course of a permanent band of faint light, which ap- 

 pears to me to be visible there.^ Several other lines were drawn at distances of 

 two and a half degrees apart, on either side of the principal line. For each 

 hour of right ascension, the corrected number of Durchmusterung stars in each 

 square degree intersected by the lines was taken fi-om the list previously pre- 

 pared, and the mean result was found for each line. These means, which are 

 given in Table V., do not support the hypothesis that the observed band is due 

 to an accumulation of stars, except in the first part of its course, where it is 

 obliquely intersected by the ecliptic. The first column of Table Y. gives a num- 

 ber for the designation of each line ; the principal line is No. 5, and is drawn 

 through e Cancri to o Leonis, thence south of the ecliptic so as to pass about 



^ Astronomische Nachrichten, XCIX. 91, 369. * Astronomische Nachrichten, CII. 265. 



