through rapidly are said to be permeable, and those which do not 

 allow it to pass through are called impermeable. Now what happens 

 to the water which sinks through permeable material? Some part of 

 it no doubt does not get to any great depth. After mixing with the 

 earth and taking out of it certain substances which it can hold as 

 water holds a spoonful of salt, it is sucked up by the roots of plants 

 and yields to the plants the materials it has washed out of the earth. 

 This assistance that it gives to growing plants is one of the most 

 important of the many useful duties discharged by water, for animals 

 live on plants and without water it would be safe to say that neither 

 plants nor animals would exist. 



But what becomes of the water that sinks still deeper down? We 

 could learn a great deal about it if we could follow a miner as he digs 

 the shaft of a mine, or even by going down a newly dug well, the sides 

 of which had not been walled up. Probably you can learn a good 

 deal about the matter at the nearest railway cut, where, to get a level 

 track, a road had to be made through a hill. There are, it is true, 

 many different kinds of such cuts, and the one you inspect may not be 

 exactly like the one we are going to describe. Examine all within 

 your reach and you may find one such as the following. You may 

 discover that it consists of sand or a permeable soil above, but at a 

 certain depth down you come to clay. Usually the line of division 

 between the two slopes in some direction. If the main slope is in the 

 direction of the track you will see that the rain which soaks down 

 through the sand can not get through the clay; and so runs down 

 along the surface of the clay and where the cut has been made the 

 water oozes out between the sand and the clay. But if the main 

 slope be across the direction of the track, the water runs down hill 

 away from the track on one side and toward the track on the other 

 side, and more water flows into the cut on one side than the other. 

 Now, if the cut be a long one and you follow it you may be able to 

 find where the sand stops and only the clay is left. This will, of 

 course, be on a side hill. If you leave the track where the sand or soil 

 ceases you will be able to follow along the side of the hill the line 

 that divides the soil above from the clay or, perhaps, rocks below. 

 You will then probably be able to see what becomes of the water that 

 sinks through the soil. If, in leaving the track, you have taken the 

 direction in which the surface of the clay slopes you will find springs 

 or wet places, showing where the water runs out between the soil or 

 sand and clay. This is one of the simplest ways in which springs are 

 termed. If you know of any springs in your ^acinity you should see 

 if they can be explained in this way. If not you may find that they 



