120 OUTLINES OF NATURAL PHILOSOPHY. 



The length of the Zodiacal Light, taken from the 

 sun upwards to its vertex, is various, from 45 to 

 100, and even 120. 



The season most favourable for observing this phe- 

 nomenon, is about the beginning of March, after 

 sun-set : the axis extends toward Aldebaran, and 

 makes, with the horizon, an angle nearly of 64? 

 degrees. 



The aspect of the Zodiacal Light is by no means 

 uniform ; it is much brighter in some years than 

 others. A remarkably brilliant appearance of it 

 was observed at Paris, 16th February 1769. 



The Zodiacal Light appears to be inclined to the 

 ecliptic at an angle of 7, and to cut it in the 18th 

 of Gemini; so that it is in the plane of the sun's 

 equator, or perpendicular to his axis of rotation. 

 LA LANDE, Astron. 84-7. 



As the decisive facts have not yet occurred, which 

 are to determine whether or not the apparent motion 

 of the sun is to be explained by the real motion of the 

 earth, the language hitherto employed is entirely that 

 suggested by the appearances. The lower apsis of the 

 elliptic orbit, or that nearest to the focus in which ei- 

 ther 



