30 Some experiments vnth the sand 



pour water on. The water stays in the sand, because it 

 cannot pass through the clay. A sandy field saturated 

 like this will therefore not be dry, but wet, and will not 

 make a good position for a house. We must therefore 

 distinguish the two cases illustrated in Fig. 17. A shows 

 sand on a hill, dry because the water runs through until 

 it comes to clay or rock, when it stops and breaks out 

 as a spring, a tiny stream, or pond ; this is a good 

 building site and you may expect to find large houses 

 there. B shows the sand in a basin of clay, where the 

 water cannot get away : here the cellars and downstairs 

 rooms are liable to be wet, and in a village the wells 

 give impure water. Matters could be improved if a way 

 out were cut for the water, but then the foundations of 

 the buildings might move a little. 



It often happens that villages are situated at the 

 junction of sand and clay, or chalk and clay, because the 

 springs furnish forth a good water supply. 



On the other hand large tracts of clay which remain 

 wet and sticky during a good part of the year are not 

 very attractive to live in, and even near London they 

 were the last to be populated : Hither Green in the 

 south-east and the clay districts of the north-west 

 have only of late years been built on ; while the sands 

 and gravels of Highgate, Chiswick, Brentford and other 

 places had long been occupied. Elsewhere, villages on 

 the clay do not grow quickly unless thci'e is much 

 manufacturing or mining ; the parishes are large, the 

 roads even now are not good while they used to be 

 very bad indeed. Macaulay tells us that at the end of 

 the seventeenth century in some parts of Kent and 

 Sussex "none but the strongest horses could in winter 

 get through the bog, in which at every step they sank 



