496 



NATURE'S TEACHINGS. 



with moisture to one where it is needed. Wet clay lands, for 

 example, which were unproductive in point of crops, and 

 injurious in point of human health, have been converted by 

 judicious drainage into fertile and healthy grounds. 



This, as it will be seen, is a very different business from 

 removing from the soil the elements which rightly belong to 

 it, and which sooner or later, in some form or another, it will 

 claim and recapture. 



Still, it is evident that in the progress of civilisation there 

 must be accumulations of all kinds of refuse, which savages 

 utterly disregard. Then we come to the question of the Drain 

 combined with the Sewer, and are enabled to see how the hand 

 of man, if properly directed, only follows the course of Nature. 



So we undermine our towns with a complex system of drains 

 which are understood by only a very few people. For example, 



TUNNEL OP MOLE. 



just as a tree is only half visible, the roots being about equiva- 

 lent to the branches, London is only half visible, the subter- 

 ranean architecture being little, if at all, inferior to that of the 

 surface. 



Here, again, we are met by Nature. Yery few of us can 

 appreciate the extensive subterranean works which underlie 

 us, even where the hand of man has never been placed. Putting 

 aside a multitude of tiny creatures, there are, in our own country, 

 the earth-worms which pierce the ground in all directions, at the 

 same time draining and manuring it. They penetrate it with 

 their little burrows, thus admitting the air, which the earth 

 needs as much as we do and allowing moisture to take its right 

 place. Then there are the moles, that are perpetually travelling 

 after the earth-worms, and making drainage galleries of wonder- 



