42 Subtropical Vegetable-Gardening 



moss which occurs abundantly in tropical and subtropical 

 regions, cypress shingle tow, or other organic matter of a 

 lasting quality. This strains out the sand and other 

 material that is likely to filter into the tile between the 

 joints and clog the system. 



At the point where the laterals join the main distributing 

 pipe, specially prepared boxes are inserted. These boxes 

 may be made of cement, earthenware, or even of durable 

 lumber. These head-boxes are usually about 14 by 18 

 inches and long enough to reach below the depth of the 

 tile and still protrude several inches above the ground. 

 About midway of these boxes is a partition running from 

 the bottom to the top. Two holes are made through this 

 partition, one even with the holes that receive the ends of 

 the main line and the other as high as the level of the 

 ground. The holes in the head-boxes which receive the 

 laterals are placed on the same side of the partition as 

 the inlet of the main. When the lower hole in the partition 

 is opened, the water flows freely from the end of the main 

 entering the box through the hole in the middle and out of 

 the exit end of the main. When the lower hole in the 

 middle of the box is closed, the water flowing through the 

 main fills the box and runs out into the laterals. This 

 continues until the soil supplied by the laterals is thoroughly 

 saturated. When any surplus water is applied after this, 

 the water continues to flow through the upper hole in the 

 partition in the middle of the box. 



As soon as the field has been sufficiently irrigated to suit 

 the operator, the flow of water is stopped in the main and 

 the stopper taken out of the lower hole and the water 

 run off. (See bottom figure, Plate I.) 



