62 THE RUBBER TREE BOOK 



apart depend entirely upon the nature of the soil to be drained. 

 Heavy, water-retaining soils require far more drains than 

 lighter soils do. The drains, of course, need not be all of the 

 same depth. Main drains to carry away large volumes of water 

 should be always deeper than cross-section drains. For a 

 main drain a depth of from 6 to 10 feet is common, whereas 

 cross-section drains are seldom more than 5 feet and often but 

 3 feet in depth. 



The planning-out of drains ought to be done before the estate 

 is planted so as not to interfere with and interrupt the passage 

 to rows of trees, or, at all events, to do this as little as possible. 

 Where drains do cross inconveniently they can and should 

 be bridged over with slabs of cement. The cost is slight. Such 

 small bridges are permanent. This method is a great improve- 

 ment on the rotting and slippery logs in such general use in the 

 Federated Malay States and Java. Many a dangerous fall is 

 sustained through the use of these logs, and their use as bridges 

 does not reflect credit on the management of the estates. To 

 have a tidy estate and everything in good order should always 

 be the endeavour of every manager. Details should not be 

 despised. 



It is of little use to excavate drains and allow them to become 

 silted up. Drains should always be kept clear to the same 

 depth if water is to run off freely. A good method to ensure 

 this is to have cement slabs embedded in the bottom of the 

 drains at convenient distances. When the bottom of the drains 

 is seen to be level with the surface of the slabs, then the manager 

 may know that the water will run off freely and the estate be 

 well drained. If, however, the slabs are buried under soil, 

 then they should be cleared and the bottom of the drains dug 

 out again till they are level with the slabs. As it is often very 

 difficult to find the position of these slabs when they are buried, 

 a small slab of cement at the side of the bank just above the 

 buried levels is a convenience. In hilly country, where there 

 is a very heavy rainfall and the rush of waters into the drains 

 is sometimes furious, it has occasionally been found necessary 

 to cement both the bottom and the sides of the main drain, 

 especially when there is a considerable fall to a lower level. 

 This, although involving much expense, has been found to be a 

 cheaper course than continually digging the drains clear. 



