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 
