Forcing-Pit heated by hot Water. 

 30 



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Ground Plan, 

 pp. Hollow pilasters; c c, air-chamber, or flue for the pipes. 



coarse dry rubbish. The heating-pipes, which should be not less 

 than a pair of 4-inch pipes for a pit whose lights are 6 ft, long, 

 are to be laid as usual, on small piers about 9 in. above the floor 

 of the flue, which should be paved with bricks or tiles, or else 

 trodden very firm. The flue is then to be covered in with 

 |-inch slate (Valencia slate is best and strongest) in slabs. The 

 apertures of the flues leading to the back pilasters must be 3 in. 

 below the top of the flue, to retain a stratum of heated air in 

 contact with the slate; and the pilasters should correspond with 

 the rafters of the pit, thus interfering least with the general ar- 

 rangement. The boiler, for which purpose one of the conical 

 boilers described p. 132, is admirably adapted, must be placed in 

 an ash-pit, sunk at one end of the pit ; unless, indeed, hot water 

 can be laid on from some existing apparatus near at hand. 



In finally preparing the pit for the operations of culture, the space 

 between the ilue and the front of the pit is to be filled, and the 

 whole surface of the pit over the flue is to be covered, with stones 

 or brickbats free from dirt, and coarse gravel, diminishing in size 

 upwards till they be of the size of pigeon's eggs or rather less. 

 The depth of this layer over the flue should not exceed a foot; 



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