Bench Construction 



variations of heat and cold in about the same proportion that iron will con- 

 tract and expand. If the contraction and expansion are not provided for by 

 means of expansion joints, many cracks will come into the benches at various 

 points, proving a great annoyance and detriment to the successful working 

 of sub-irrigation. By means of these expansion joints the cracks are avoided, 

 and the bench can be maintained perfectly tight. The sides of the bench arc 

 composed of cypress strips one and one-quarter inches in thickness, and six 

 inches wide, which are fastened firmly to the iron knees by means of round- 

 headed tinned screws. (See drawing, Avhich shows the construction of the 



Sub-Irrigation Bench 

 Tiles in place ready for cementing 



sub-irrigation bench better than any description can convey.) It is our prac- 

 tice to build these benches in sections about fifty feet in length, the ends of the 

 benches, and the division between the sections, being made by filling in with 

 hard brick, set in the same cement as is used for the bottom. In the center 

 of each division an inch pipe is fitted in the bottom of the bench by means of 

 a collar. This pipe is dropped through a hole made in the terra cotta, and is 

 held firmly in place by short lugs. In making a bench, a wooden plug is 

 put into the end of the pipe and the cement is run around the plug and over 

 the iron collar. When the cement hardens, this holds the pipe firmly. The 

 wooden plug is then removed, and in troweling down, the cement is finished 

 with a slope toward the hole, so that w^ater will naturally drain off the bottom 

 of the bench through the pipe. All sub-irrigation benches should be built 



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