THE NEW AGRICULTURE. 97 



were in winter, but still with ample flow. What keeps them full ? 

 If you remember what you have already been told about under- 

 ground water, you will answer that rivers are fed by springs as 

 well as by rains. 



" Though the weather may be rainless, the springs continue to 

 give out their supplies of water, and these keep the rivers going. 

 But if great drought conies, many of the springs, particularly the 

 shallow ones, cease to flow, and the rivers fed \>y them shrink up 

 or get dry altogether. The great rivers of the globe, such as the 

 Mississippi, drain such vast territories, that any mere local rain or 

 drought makes no sensible difference in their mass of water. 



" In some parts of the world, however, the rivers are larger in 

 summer and autumn than they are in winter and spring. The 

 Rhine, for instance, begins to rise as the heat of summer increases, 

 and to fall as the cold of winter comes on. This happens because 

 the river has its source among snowy mountains. Snow melts 

 rapidly in summer, and the water which streams from it finds its 

 way into the brooks and rivers, which are thereby greatly swollen. 

 In winter, on the other hand, the snow remains unmelted ; the 

 moisture which falls from the air upon the mountains is chiefly 

 snow ; and the cold is such as to freeze the brooks. Hence the 

 supplies of water at the source of these rivers are, in winter, 

 greatly diminished, and the rivers themselves become proportion- 

 ately smaller." 



In conclusion of this chapter, and by way of complete demon- 

 stration of the wonderful effects of subsurface irrigation, we quote 

 from an article telling a story which, read by the average farmer 

 and gardener, cannot fail to prove convincing. These surely will 

 be glad to know that the way has been found to escape the calam- 

 ities to which producers have been hitherto subjected on account 

 of frosts, floods and droughts. Nor will it become necessary to 



