156 PLANETARY FORCES EXCITE WIND-POWER. 



ing body begins to vibrate also, it occupies more 

 space than other surrounding particles of air. 

 Thus rendered specifically lighter, it ascends 

 buoyantly against the action of gravitation. In 

 this simple movement the orbital force predomi- 

 nates. The axial force propels other particles of 

 air into the places left by the ascending particles ; 

 and the particles of air thus put in motion impinge 

 against the outspread sails on the water and on 

 the land, and render their impulses available as 

 WIND-POWER. 



Beneath the earth's transparent atmosphere, 

 nearly four-fifths of the planet is covered by seas 

 and lakes, composed of eight-ninth parts of mole- 

 cules of oxygen and one-ninth part of molecules 

 of hydrogen. Particles of water are readily vi- 

 brated by sunshine, and, expanded into steamy 

 vapors, they occupy more space than the particles 

 of air. Rendered specifically lighter than the air 

 above them, they buoyantly ascend and are wafted 

 by the winds over the dry lands. After ascending 

 to the cold upper regions of the sky, their vibra- 

 tion being diminished, they become polarized, as 

 minute electro-magnets ; with the result of a recip- 

 rocal attraction between them, and union in falling 

 rain-drops, which descend from mountains and hill- 

 sides, and flow through the vales on- their return 

 to the sea, and are utilized on their way as WATER- 

 POWER. 



