ASTRONOMY. 119 



reduces the time of the sun's rotation on his axis 

 to 25 d 9 h 36>, All the observations do not agree 

 exactly in bringing out this conclusion. LA 

 LANDE, J 3276., &c. 



The problem, From three positions of a spot on the 

 sun's disk, in respect of the ecliptic, to find the 

 position of his equator, and of his axis of rotation, 

 is of considerable difficulty. It was first directly 

 resolved by BOSCOVICH in 1737. See LA LANDE, 

 f 3257, who has also given a solution. Dr HER- 

 SCHEL has made many important observations on 

 the solar spots. Phil. Trans. 1794, 1801. 



118. A phenomenon, from which ho informa- 

 tion concerning the motion of the sun has yet 

 been obtained, though, from some circum* 

 stances, it appears to be connected with his ro* 

 tation, is the Zodiacal Light ; a luminous ap- 

 pearance, seen after sun-set, or before sun-rise, 

 somewhat similar to the milky way, but of a 

 fainter light, in the figure of an inverted cone 

 or pyramid, with its base toward the sun ; ha* 

 ving its axis inclined to the horizon, and nearly 

 in the plane of the ecliptic* 



The Zodiacal Light was discovered by CASSINI in 

 1683 ; but there is reason to think, that it had 

 been remarked before that period. 



The 



