34 



NATURE FOR ITS OWN SAKE 



is not seen ; but just as soon as a flash from the 

 sun breaks through a torn portion of the 

 cloud, the shaft falls to earth and is apparent 

 from its shadowy envelope. It appears to fall 

 earthward in a straight line, but, like all sun- 

 beams, it in reality describes a curve through 

 the lower atmosphere, especially if the sun is 

 low in the heavens. The trajectory is not 

 point-blank, but falls short like a spent rifle 

 ball. Yet this is not seen by the eye and is 

 known only to scientific calculation. To all 

 appearances the shaft falls straight and remains 

 fixed. It is the shadow of the cloud that glides 

 across the meadows, up the valleys, and over the 

 mountains ; the sun-shaft does not shift except 

 where it falls more obliquely as the earth rotates 

 from west to east, or its direction is changed 

 by cloud breaks. 



The sun-burst is perhaps seen more frequently 

 during showery weather or with thunder-storms 

 than at other times, and it is usually more lumi- 

 nous after than before a rainfall. As the first- 

 comers of the storm-clouds begin to cover the 

 sun, the shaft is often seen in a yellow beam 

 falling diagonally toward the earth. When the 

 shower is passing and the sunlight begins to 

 show again, the shaft reappears frequently in 



