38 MANUAL FOR SUGAR GROWERS. 



trench, to prevent the surface water converting the 

 trench into an open channel, whereby the drain is 

 injured. Proper precautions must be taken to 

 23revent the access of rats and other small animals 

 to the drains. The danger of the drain silting up is 

 avoided by a careful adjustment of levels, so that 

 the water runs with equal velocity throughout the 

 length of the drain, or perhaps, with advantage, 

 with slightly increased velocity near the outlet. 

 Silting up depends to a great extent on the relation 

 of the size of pipe to the water flowing through it ; 

 a small pipe running nearly full not silting so much 

 as a large one carrying only a small quantity of 

 water. For details respecting tile draining the 

 reader is referred to special works on the subject. 

 For sugar-cane the author would suggest that the 

 drains be laid about thirty to forty feet apart and 

 four feet deep. This system of draining is some- 

 what costly, requiring a large outlay at first, and up 

 to the present time it has been but little practised 

 in the West Indies ; in the sugar-growing districts 

 of the United States it is being adopted ^dth suc- 

 cess, an example which should be followed by West 

 Indian sugar growers ; it is doubtless the way of 

 preventing losses from short crops dimng droughts. 

 It is diflicult, in the absence of actual trials, to state 

 the cost of such a system of draining in the West 

 Indies, but there is little reason to doubt that it 

 would prove remimerative, as it would increase the 

 crop and at the same time decrease the cost of work- 

 ing the land ; for the surface trenches would only 

 require to be deep enough to deal with the surface 



