506 CULTURE OF THE CUCUMBER IN PITS. 



the flues to have gutters for the pipes from a boiler, with a power of 

 filling and emptying the gutters at pleasure ; so as to have a command 

 of either dry or moist air, as either may be wanted. The floor of the 

 pit may be supported on arches, or it may be made of planks, or of 

 slates or tiles resting on joists. The pit to be filled with mould, sand, 

 or sawdust, according as it may be desired to grow the plants in pots 

 or in the free soil. A trellis may be made to hook on the rafters, on 

 which to train the plants. The upper surface of the pit to be two 

 feet from the glass, and the trellis to be one foot from the glass. 



Corbett's cucumber -pit (fig. 352) is heated with hot water circulated 

 in open troughs, which, however, have covers for being put on when 

 a dry heat is wanted. The mode of heating by water in open gutters, 

 as we have seen, is strongly recommended by Mr. Glendinning, as it 

 is by Mr. Lymburn, on account of the great radiating powers of 

 water, which are equal to those of lampblack, which is to polished 

 iron as 100 is to 15. Mr. Duncan, from whose ' Treatise on Cucum- 

 ber Culture ' the section (fig. 352) is taken, also says Corbett's mode is 

 " the most economical plan of heating yet discovered, and deserving 

 the support of every one interested in horticulture, especially the 

 cucumber-grower." This seems to have been the parent of what has 

 long been known as Rendle's system of tank heating which has been 

 extensively used in cucumber, melon, and plant-houses, and for many 

 purposes is still equal, if not superior, to hot- water pipes. 



The troughs are arranged so as to produce both bottom and top 

 heat, accompanied with proper moisture, or a dry air at pleasure, by 

 putting on the covers to the troughs. The air in the confined chamber 

 under the bed is always at the point of saturation, and a circulatory 

 movement of the air of the pit, exterior to the chamber, is always 

 maintained by drains, passing from the front path, under the troughs 

 in the chamber, to the troughs in the back path, at the bottom of the 

 back wall, as shown in the section. 



Green's cucumber-pit is thus described by himself: " The walls 

 are built of nine-inch brickwork, five feet high in the back, and two feet 

 and a half in front, and the space enclosed is five feet wide in the clear, 

 and thirty-six feet long, covered with nine lights, and divided into three 

 compartments. A trough of brickwork is carried along the middle of 

 the bottom from end to end. This trough is constructed by first lay- 

 ing a bottom of two bricks thick, one foot wide, and then forming the 

 two sides of the trough with bricks on edge; the whole being so 

 cemented as to hold water. The pit is heated with hot water by 

 means of a branch of two-and-a-half-inch pipes proceeding from the 

 boiler which heats a stove at a short distance. The hot water flows 

 along the back and front of the pit, above the level of the bed of soil, 

 but the return pipes are placed beneath the bed in the trough just 

 described, which is filled with water, or partly so, as circumstances 

 may require, by means of a small pipe that leads to the outside. 

 Another small pipe is laid in the bottom of the trough for letting off 

 the stagnant water, and for emptying the trough occasionally ; for in 

 very dark damp weather, a drier heat is required. In order to have 



