22 



Introduction. 



the water, and much as the earth is warmed by waves sent 

 out through the ether of space from the surface of the sun. 

 The rapid and intense molecular motion at the surface 

 of the sun is transformed into wave motions in the sur- 

 rounding ether of space, as the motions of the imaginary 

 man were changed into waves in the water, and these ether 

 waves travel away from the sun's surface in all directions 

 at the rate of 186,680 miles per second. So many of these 

 waves as the size of the earth permits it to stop are arrested 

 and transformed into the various forms of motion which 

 are manifested at its surface. 



26. Amount of Energy Developed at the Sun's Surface. 

 Careful measurements and calculations have shown that 

 the energy developed second by second at the sun's surface, 

 amounts, according to Lord Kelvin, to not less than 

 133,000 horse power on each square meter or 1.09 square 

 yards of its surface. 



27. Kate at Which Solar Energy Reaches the Earth's 

 Surface. As the intense energy developed at the surface of 

 the sun spreads away from it, it becomes weaker and 

 weaker in the ratio that the square of the distance of the 

 waves from the sun increases, as represented in Fig. 2, and 





\ 



\ 

 \ 



\ 

 \ 

 \ 

 \ 



FIG. 2. 



so at the earth's surface the amount of energy has become 

 so much reduced that Lord Kelvin places it at only a little 

 more than 1.3 horse power per each square yard of surface. 



