CULTURE OF THE CUCUMBER IN PITS. 503 



SUBSECT. 111. Culture of the Cucumber in pits heated by dung linings, flues or 



hot water. 



1070. Of pits heated wholly or in part by dung linings, there are a great 

 variety of forms, chiefly differing in the construction of the exterior wall 

 through which the heat is communicated to the bed of soil or fermenting ma- 

 terial within. One of the most common, and most generally useful, is that 

 known as M'Phail's pit, already figured and described (843). The prin- 

 cipal advantage of these pits is, that dung casings may be applied with little 

 or no previous preparation, and thus much heat, that in the preparation of 

 dung for common hotbeds is lost, is here turned to account. The treatment 

 of the plants within the bed is exactly the same as that described in the pre- 

 ceding subsection, and no better directions can be given for managing the 

 linings than those of Mr. Mills (1061). 



1071. Pits to be heated by flues or hot-water, are as various in their con- 

 struction as those to be heated by dung linings ; some forms have already 

 been given (515, 935, and 047), and we shall in this subsection describe 

 three other forms. 



1072. A pit to be heated by a flue built by the late eminent horticulturist, 

 Mr. Knight, is thus described. The back wall is nearly 9 feet high, and 

 the front wall nearly 6 feet high, inclosing a horizontal space of 9 feet wide ; 

 and the house is 30 feet long. The fireplace is at the east end, very near 

 the front wall, and the flue passes to the other end of the house within 4 

 inches of the front wall, and returns back again, leaving a space of 8 inches 

 only between the advancing and returning course of it ; and the smoke 

 escapes at the north-east corner of the building. The front flue is composed 

 of bricks laid flat, as I wished to have a temperate permanent heat, and the 

 returning flue of bricks standing on their edges, as is usual; the space 

 between the flues is filled with fragments of burned bricks, which absorb 

 much water, and gradually give out moisture to the air of the house. Air 

 is admitted through apertures in the front wall, which are 4 inches wide, 

 and nearly 3 inches in height ; and which are situated level with the top of 

 the flues, and are 18 inches distant from each other. The air escapes 

 through similar apertures near the top of the back wall. These apertures 

 are left open, or partially or wholly closed, as circumstances require. 

 Thirty-two pots are placed upon the flues described above, each being 16 

 inches wide at least, and 14 inches deep ; but they are raised by an inter- 

 vening piece of stone and brick out of actual contact with the flues. Into 

 each of these pots one melon plant is put, which in its subsequent growth 

 is trained upon a trellis, placed about 14 inches distant from the glass, and 

 each plant is permitted to bear one melon only. Each might be made to 

 bear more, but if they should be as large as Ispahan melons when perfect 

 are, they would certainly be of inferior quality. The height from the 

 ground, at which the trellis is placed, is such that I can with convenience 

 walk under it, and of course discover, without difficulty, the first appear- 

 ance of red spiders, or other noxious insects. (Hort. Trans, vol. i. Second 

 Series, p. 86.) This pit was used by Mr. Knight for the culture of Persian 

 melons, but it is evidently well adapted for the culture of cucumbers, under- 

 neath which sea-kale, rhubarb, or various other articles, might be forced. 



1073. A pit to be heated by hot water and by a flue from the fire which heats 

 the boiler, is thus described by Mr. Torbron. It is almost unnecessary to 

 add that it will answer as well for melons as for cucumbers, and indeed if 



