450 



COSMOS. 



add to the same table, the inclinations of the axes of rotation 

 of the planets towards their own orbits, so far as they are 

 determined with any certainty. 



The small planets are omitted here, because they will be 

 treated of further on as a separate distinct group. If we except 

 Mercury, situated near the Sun, and the inclination of whose 

 axis towards the ecliptic (7 0' 5"'9) approaches very near to 

 that of the solar equator (7 30') the inclinations of the other 

 seven planets will be seen to oscillate between Of and 3^. 

 Jupiter exhibits, in the position of the axis of rotation with 

 reference to its own orbit, the closest approximation to the 

 extreme of perpendicularity. On the contrary, the axis of 

 rotation of Uranus, to conclude from the inclination of the 

 orbits of its satellites, very nearly coincides with the plane of 

 the planet's orbit. 



Since the division and duration of the seasons, the solar 

 altitudes under various latitudes, and the length of the days, 

 depend upon the amount of the inclination of the Earth's axis 

 towards the plane of its orbit, as well as upon the obliquity of 

 the ecliptic (i. e. upon the angle which the apparent course 

 of the Sun makes with the equator at their point of inter- 

 section), this element is of the most extreme importance as 

 regards the astronomical climate, i. e. the temperature of the 



