70 MANAGEMENT OF THE FORCING-HOUSE. 



they will spring away and cause leakage. To obviate this 

 the cement needs to be put on more thickly at the sides, 

 bringing it up against the side boards two or three inches 

 high, and from one to two inches thick. In fact the 

 office of the cement is to hold the water, while the side 

 boards protect the cement and retain the soil. 



" In case it is desired to make a bed on the ground, 

 the bottom may be constructed in the same manner as 

 an ordinary cellar bottom, except that the cement need 

 not be as thick. Sometimes the bottom may be made 

 directly on the clay sub-soil, or clay may be brought in 

 for the purpose and no cement used. There may be some 

 leakage in a clay bottom, but not sufficient to do any 

 harm. In all cases there must be a level bottom, or at 

 least the slope must be slight, and all in one direction. 

 Inequalities in the bottom will prevent the proper working 

 of the irrigating tile and result in unequal distribution of 

 the water, hence a perfect grade is essential. In case 

 benches are constructed, the best plan is to use indestruc- 

 tible material altogether. 



" The irrigating tiles [common drain tile] may be laid 

 lengthwise or crosswise the beds, but about fifty feet is 

 the greatest length of tile that will work satisfactorily on 

 a level, and if the runs are to be longer than this, there 

 should be one or two inches fall to each fifty feet. It will 

 be necessary, however, in case there is a fall, to check 

 the water at intervals in order to prevent a too rapid 

 flow towards the lower end. This may be easily done 

 by inserting strips of tin into the joints as often as need 

 be, so as to partially intercept the flow, and to cause the 

 water to run out at the joints wherever needed. When 

 properly laid, rows of tile several hundred feet in length 

 could be made to work satisfactorily, but we have had 

 the best success with short runs of tile, laid crosswise the 

 benches. Instead of using elbows of sewer pipe, a 

 cheaper plan is to employ common tile altogether. In 

 this case, the end of the outer tile is raised so as to 



