198 DAY AND NIGHT. 



moved from the stem which nourished it, wanders afar to 

 diffuse and perfect its species. Our planet, of an ochreous 

 yellow, relieved with green and white, possesses no special 

 privileges; it shares in the ponderated movements of the 

 spheres ; it is neither the largest, nor the smallest, nor the 

 heaviest, nor the lightest, nor the nearest to, nor the farthest 

 from, the sun. And shall Earth alone, of all the planets, 

 nourish that kind of " thinking seed " which we name the 

 human race ? It seems improbable. 



But let us return to the great orb of light. It illuminates 

 exactly one half of our earth \ the other half lies in shade. 

 And as the earth rotates upon its own axis, every point of 

 its surface is necessarily exposed to the action of the solar 

 rays. This action varies in duration and intensity. 



All this I was taught, when I was still at school on our re- 

 volving planet. I remember, too, as a lesson learned by heart, 

 that, under the Equator, or, more exactly, in o o' latitude, as 

 well as at the Poles, or under 90 latitude ; the duration of 

 the day is equal to that of the night, with this difference, that, 

 while under the Equator, a day of twelve hours alternates 

 invariably with a night of the same duration, at the Poles a 

 day of six months succeeds continually to a night of six 

 months. I also recollect that, at a given moment, namely, 

 at the spring and autumn equinoxes, the duration of the day, 

 over all the terrestrial surface, is equal to that of the night, 

 just as under the Equator ; and that, after these two epochs, 

 under the intermediary latitudes, between the Equator and 



