146 THE APPARENT POSITION OF THE ZODIACAL LIGHT. 



cannot well be determined without the aid of observers stationed in the southern 

 hemisphere, while hitherto the light has been seen only at northern stations. 

 From some observations collected upon a former occasion, however, it appears 

 that, near the vernal equinox, the observed position of the light is occasionally 

 south of the ecliptic, while between the longitudes 140' and 220' it often attains 

 a greater north latitude than elsewhere. It was the conclusion thus reached 

 that led to the present inquiry with regard to the position of the zodiacal light 

 according to the observations of Jones. The agreement of the two results may 

 make it worth while to repeat in a condensed form a list of mean positions for 

 " Gegenschein " given in the article just mentioned.^ The headings X and y8 indi- 

 cate approximate longitudes and latitudes. The mean result for each column is 

 given at its foot. 



137 +2 160+2 188+3 213 +3 341 10 -3 



150+4 170+1 197+1 221 350 19-1 



If any corrections for absorption could be applied to these latitudes, they 

 would presumably all be negative, and numerically smaller in the first, second, 

 and sixth columns than in the others, since the observations were all made near 

 the meridian. Hence the difference between the first column and the rest would 

 rather be increased than diminished by the corrections. There is accordingly no 

 similarity in detail between these results and those of Table II., while their gen- 

 eral resemblance is obvious. It will afford an additional reason for regarding the 

 latitude of the zodiacal light as actually variable in accordance with its longi- 

 tude. The strength of this reason will depend upon the degree of confidence 

 which may be felt in the actual appearance of part of the zodiacal light in the 

 form of "Gegenschein." 



Although this faint light in opposition to the Sun has been seen by very few 

 observers, some of them have expressed great confidence in its existence, and it 

 has been three times independently discovered, — by Brorsen,'^ Backhouse,^ and 



1 AstroDomische Nachrichten, CIX. 259. ^ Astronomische Nachrichten, XLII. 219. 



' Monthly Notices of the Koyal Astronomical Society, XXXVI. 46. 



