i7i Pits heated hy hot Water. 263 



heated by one boiler upon the siphon principle, with cisterns at 

 the farther end, and lids on them to put water in when necessary. 

 In the one row the pipes go and return along the front, and a 

 flue along the back. In the other row, which is the one appro- 

 priated for winter and early forcing, a flue goes along the back, 

 covered with paneled squares, ancl painted : the top pipe goes 

 along the front, and the bottom pipe returns in a channel in the 

 bottom of a tank in the bottom of the pit. The smoke is 

 turned along these back flues, when required, by dampers in 

 the fireplace, and when not wanted there is a third flue on the 

 outside of the pits for it to go along ; and all these flues are 

 continued across a walk at the end of the pits into a chimney at 

 the end of a Calcutta pit. When I first began, I had a chimney 

 over the boiler to turn the smoke up when I did not want it to 

 run along either of the pits ; but this covered the lights so with 

 blacks that I was obliged to have it taken down, and a flue run 

 along the outside, as before stated. Stop-cocks are placed in 

 the pipes, so that either row may be worked separately, or both 

 together. The tank in the early-forcing row extends the whole 

 length, and nearly the whole breadth, of the pit ; and is supplied 

 with water by a small pipe from a main, with a cock to regulate 

 the supply. At the opposite end there is a large pipe, with an 

 elbow joint, which communicates with the tank, and shows the 

 quantity of water that is in it. Below the large pipe there is a 

 small one with a cock, which empties into a drain, to draw off" 

 the water from the tank when repairs are necessary. The tank 

 is made with bricks and mortar, and cemented ; the channel in 

 the bottom for the return-pipe is 1 ft. wide and 6 in. deep : on 

 each side of this channel there is a brick flat, pigeon-holed and 

 covered with flag-stones, to protect the pipe. The pit is divided 

 into four compartments, of two lights each : in each of these 

 divisions there are two cross-drains communicating with the 

 return-pipe, and covered with oak planks. These oak planks 

 have circular holes cut at each end, and upon these circular 

 upright pipes ai'e placed, 6 in. wide at bottom and 3 in. wide at 

 top. By these steam is admitted into the divisions, and air is 

 circulated : when not wanted, they are covered with pieces of 

 slate. The pit is filled with leaves nearly up to the glass, to 

 allow for sinking; and, when they have sunk sufiiciently low, the 

 hillocks of soil are put in, and the plants are planted as soon as 

 the soil is warm. As long as the leaves contain sufficient 

 moisture, the water in the tank is confined to the channel for 

 the hot-water pipe ; but when the leaves begin to get dry, the 

 water is turned in, so as to fill the tank, and then allowed to 

 evaporate into its usual channel. By this simple process I can 

 always keep a proper moisture in the pits, highly conducive to 

 the growth of cucumbers and melons. When I first began 



