292 



Water Supply and Small Holdings, [july, 



gradients and other conditions are favourable, the stream 

 may be impounded and the water fed to the various water- 

 points by gravitation through pipes. In the case of lakes 

 whose level is not higher than that of the area to be served, 

 borrowed power must, of course, be used for pumping. 



Wells. — The most common and dependable source of 

 supply to the average farm is, of course, the well. Now, 

 wells may be broadly divided under two heads, viz., the shallow 

 or "surface " well, which is usually sunk to a depth sufficient 

 to tap the nearest underground water-source, known as a 

 "land-spring"; and the deep well, which is sunk and bored 

 sufficiently deep to reach the more permanent earth reservoirs, 

 called "deep-seated springs." As the land-spring is fed by 

 percolation from the surface, mo're or less in the immediate 

 neighbourhood in which it is found, it is obvious that the 

 efficiency of the wells which are sunk into it must depend 

 upon the sufficiency of the local rainfall. Deep-seated springs, 

 on the other hand, are fed from the permeable rocks whose 

 outcrops are exposed over wide areas, and whose "dip" may 

 carry them and their contained water at considerable depths 

 beneath many miles of country. It is, then, from porous 

 rocks of the older formations, such as Chalk, Greensand, 

 Oolites, and New Red Sandstone, as distinguished from 

 "drift" and "alluvium," that the more permanent subter- 

 ranean water supplies are derived, and, however little desir- 

 able it may be that the farmer should be at the mercy of the 

 local meteorological conditions for his water supply, it is 

 not rare to find, during a summer which follows upon an 

 exceptionally dry winter, that many farms and other rural 

 dwellings are practically waterless, and that this state of 

 things is the natural sequence of their reliance upon "surface " 

 wells. 



Rain-water. — In places where wells are not quite depend- 

 able and from which permanent streams are absent, rain- 

 water catchment comes next in importance as a means of 

 supply, but as the water-butt is replenished at the same time 

 and by the same influence as the shallow well both must 

 suffer after a period of drought. 



Purity of the Supply. — The average case, then, is one 



