600 



PROTECTION AGAINST SWAMPS. 



The proper interval between the feeders depends on the 

 quantity of water to be drained away, the configuration of the 

 ground and the nature of the soil. The interval between 

 any two feeders will be inversely as the quantity of water in 

 the soil. The looser the soil, the more easily is it drained. 

 On the average, according to circumstances, intervals of 16 to 



Fig. 274. 

 Plans of drainage. 



22 yards may be chosen. In very wet land, the interval 

 between the feeders may be reduced to 10 yards, whilst on 

 drier land it may be extended to 30 yards. 



A practical method of determining this interval is given by 

 Heyer, as shown in Fig. 275. Cut a feeder A, and another B 

 at different distances from A till the water in the soil at the 

 middle point C between the two feeders falls to the depth C D, 

 to which it is required to drain. 



