SOIL, MANURES AND ■WATEEIUQ. 375 



oo shakes or loose knots. These are laid so as to nearly 

 touch, and battened with lath, after which a coating of 

 thin cement makes a water-tight bottom. Matched 

 lumber, laid in white lead, answers the same purpose, 

 but costs more. The best bottom is made of tile, either 

 hexagonal, octagonal or flat, and covered with cement. 

 Ordinary hexagonal (six-sided) tile laid on iron supports 

 makes a very satisfactory bottom, and is as cheap as 

 anything in the shape of tile. "When cemented prop- 

 erly, this makes a durable and satisfactory bottom. 

 Lumber may be used for the sides, but is not satisfac- 

 tory, as it warps and springs away from the tile, caiising 

 leakage. Slate, seven or eight inches wide, is the best 

 material, and this is held in place by galvanized iron 

 strips at the top and bottom. These strips are cut two 

 inches wide, and bent in the form of U-shaped troughs. 

 The slate sets into the bottom trough, while the upper 

 trough fits over the top of the slate, holding them 

 together firmly. These slate sides rest on the iron sup- 

 ports to the tile, and are fastened to the iron gas pipes 

 which support the purlins. 



Thus it will be seen that to construct a bench for 

 sub-irrigation adds but little to the cost over one equally, 

 durable made in the ordinary manner for surface water- 

 ing. Where beds are on the ground, it might be neces- 

 sary, in some cases, to make a water-tight bottom with 

 cement, but not so if the subsoil is sufficiently retentive. 



In conclusion, it might not be out of place to answer 

 some theoretical objections urged against the plan be- 

 cause drainage is not provided for, and humidity of the 

 air is not taken into account, but it is proposed to let 

 facts stand in the place of arguments, and to place 

 the whole matter in the hands of practical men for 

 confirmation. 



