36 SMALL WATER SUPPLIES. 



the lines so worked and finally fastened together. At 

 the points D, D, taper pieces of the ring are sawn 

 out. Their size would be 6 in. wide at the inner 

 circle and $-J in. at the outer. Finally around the 

 circumference of the frame would be fastened the 

 boards E, E, each 2 in. thick and 4 ft. long. The 

 concrete lining rests on the rock at the bottom of 

 the well, which has been previously levelled to re- 

 ceive it. Care must be taken to keep the rods in 

 position while filling in the concrete, and also to cut 

 the rock so that the frame will rest nicely upon it 

 for the first " lift ". It requires very careful ramming 

 when placing the concrete, so as to properly consoli- 

 date it and cover the rods well, and a wet mixture is 

 advisable for this particular class of work. The 

 frame should be left in for 24 hours before it is raised 

 for another lift. The lining would be plastered after- 

 wards in neat cement if required. On the whole the 

 latter method of steining wells is strongly to be 

 advised. 



We now pass on to another system of gaining 

 water from subterranean sources, namely that of 

 Boring. When a well has to be sunk of considerable 

 depth in rock, it will be found cheaper to bore it 

 than excavate it in the old way. Borings up to 15 

 ft. in diameter CAN be executed when a small hole, 

 say 6 ft. in diameter, is driven first. It is an operation 

 which demands skill, care, and specialized experience, 

 besides special plant, and is best entrusted to special- 

 ists, although a system known as the Chinese system 

 can be practised by any ordinary intelligent con- 

 tractor. The tools consist of a boring head and a 

 cutting chisel. The method is shown by fig. 17, in 



