40 FORMATION OF THE EARTH 



subsist, the animals owe to the sun their very power of move- 

 ment. The rustling of the leaves as they are stirred by the 

 wind, the devastations that follow in the wake of cyclones ; 

 the gentle ripples formed by light breezes on the surface of 

 placid waters, like the colossal waves raised by tempests ; 

 the tranquil course of rivers, like the impetuous violence of 

 torrents — all are the sun's work, just as is the clumsy progress 

 of the earth-worm, the fleetness of the gazelle or the bold 

 flight of the eagle. The song of the elves in The Midsummer 

 Night's Dream, as they pray that "never harm, nor spell, 

 nor charm " may disturb the slumbers of their queen is 

 a prayer to the sun, which causes both thunder and the song of 

 birds, and all the sounds to be heard on earth. In the opinion of 

 meteorologists even the spots on the sun's surface influence our 

 atmosphere ; the dry and rainy periods being supposed to 

 vary with the number of spots observed. These spots reach a 

 maximum every eleven years, which thus corresponds exactly 

 to our rainy cycles, and it has been even assumed, perhaps too 

 rashly, that this maximum also coincides with a period of 

 frequent earthquakes. 



Night and day and the periodic recurrence of the seasons 

 depend equally upon the sun, just as does the existence of 

 diurnal and nocturnal animals, which pass the day or the night, 

 as the case may be, in periods of alternating rest and 

 activity. To the sun, finally, is due the increase of life through- 

 out all Nature in the spring, and the tendency of all organisms 

 to multiply, each according to its kind. The sun, then, governs 

 all activity on our globe ; and, in accordance with the 

 distribution of its heat and light, all the movement that 

 animates the atmosphere and the seas, all the phenomena of 

 life, are regulated. We must, therefore, examine in detail the 

 various relations that unite us to the sun, and the way in which 

 these relations have been modified in the course of centuries, as 

 well as the changes which the sun itself has undergone. 



The earth exhibits numerous types of motion ; it turns on 

 its own axis, and the duration of that rotation is called by 

 astronomers a day ; the axis upon which it revolves is a straight 

 line fixed with reference to the earth, and the stationary points 

 on its surface which represent the extremities of this imaginary 

 line are known as the Poles ; the plane perpendicular to this 

 axis, which passes through the centre of the earth and which 



