Boosl. CONSTRUCTION OF CULINARY HOT-HOUSES. 511 



young 



452 



2680. The jjit for forcing herbaceous vegetables may be in all respects of the same di- 

 mensions as above, but with the angle of the glass not more than 15°. On this plan and 

 angle, the back of the pit will be two feet higher than the front : but the simplest plan 

 is to omit the passage, and lessen the width of the pit two feet, retaining the slope of 15°, 

 and the compound, or double sashes, between each rafter. 



•2681. Pits without fire heat, to be worked by that arising from the bed of bark or 

 dung, may be of any length, six or seven feet wide within, and with the glass at an 

 angle of fifteen degrees. 



2682. M^PhaiVs pit is approved of by many gardeners for growing cucumbers and 

 melons, and may be considered as coming into general use. Abercrombie, after de- 

 scribing it as a " flued pit without a furnace," says, " some persons approve of this kind 

 of frame, and others disapprove of it ; but when the management of the air-chamber is 

 understood, it may be applied very successfully to the forcing of early melons and choice 

 esculents. It allows new stable-dung, even before any of the fiery particles are exhaled, 

 to be used without any danger of burning tlie roots of the plants." (Pr. Gard. 

 p. 662.) 



2683. Other jnts and fixed frames. West's pit {fig. 1547.) and the Alderstone fixed 

 frame {fig. 1549.) are both structures deserving introduction where neatness is an object, 

 and it is to be hoped that these and similar structures (see Hort. Trans, vol. iv. and v.) 

 will soon come into more general use, and elevate tlie melon-ground from a disorderly 

 dung-yard, to a scene fit for general inspection. 



2684. KnishVs melon-pit {fig. 452.), and which may also be applied to the culture of cucumbers, 

 pines, or other low vegetables, is surrounded by a cellular 

 wall, (see 1561.) The front wall is four feet, and the back 

 wall five feet six inches high, enclosing a space of six feet 

 wide, and fifteen feet long, and the walls are covered with 

 a wall-plate, and with sliding lights, as in ordinary ho't- 

 beds. The space included may be filled to a proper 

 depth with leaves or tan, where it is wished to promote the 

 rapid growth of plants ; Knight, however, did not use dung 

 internally, but grew the melon-plants in large pots, and 

 trained them on a trellis at a proper distance from the 

 glass. The wall is externally surrounded by a hot-bed 

 composed of leaves and horse-dung, by which it is kept 

 warm, and the warm air contained in its cavity is per- 

 mitted to pass into the enclosed space through many small 

 perforations in the bricks. At each of the lower corners is 

 a passage (a), which extends along the surface of the 

 ground, under the fermenting material, and communicates 

 with the cavity of the wall, into which it admits the ex- 

 ternal air, to occupy the place Of that which has become 

 v/arm and passed into the pit. The entrances into these 

 passages are furnished with grates, to prevent the ingress of 



vermin of every kind. The hot-bed is moved and renewed in small successive portions, so that the 

 temperature may be permanently preserved, the ground being made to descend a little towards the wall 

 on every side, that the bed in shrinking may rather fall towards than from the walls ; and Knight enter- 

 tains " no doubt, but that the perpetual ingress of warm air, even without an internal leaf-bed, will 

 prove suliicient to preserve pine-apple plants without the protection of mats, except in very severe 

 weather." {Hort. Trans, v. 224.) 



2685. The Edmonstone pine or melon 

 pif (fig- 453.) is eighteen and a half 

 feet long, by six feet in breadth ; the 

 heiglit of the back is five feet, the 

 height of the front three feet nine 

 inches ; the declivity for the glass one 

 foot three inches. The pits for the 

 dung are on the outside of the frames, 

 and sunk level with the surface of 

 the earth, or gravel, on the outside. 

 The height of these pits is three feet, 

 their breadth two feet. The outside 

 of the pits for the dung is built with 

 a nine-inch wall up to the surface, 

 with one course of hewn stone on the 

 top. One inch is cut out for the 

 boards that cover the space allotted 

 for the linings to rest upon : that appearance of litter and dung, which is so offensive in ordinary hot- 

 beds is thus prevented. The boards that cover the dung are one inch thick, by two feet two inches in 

 l)readth. They are of the length of the pit, and have rings at each end for lifting them with. The 

 pits should be well drained, to carry off the under water, and a small grate should be made at the end of 

 the drains. The kind of matter which is generally employed to fill these pits, is a mixture of new horse and 

 cow dung : sometimes we use tree leaves and short grass, which do very well, provided they be duly pre- 

 pared, by throwing them up in a high heap, to remain eight or ten days, that they may ferment to an 

 equal temperature. To maintain seventy degrees of heat with horse and cow dung, or leaves of trees is 

 no difficult matter, and it is easy to preserve the plants in health, and in a fruitful state during the 

 severest winter, by covering the pits with mats in time of frost. {Caled. Hort. Mem. iii. 336.) 



2686. The common hot-bed frame is generally from four to five feet wide within, and 

 from nine to twelve feet long, divided into three or four lights or sashes. The back is 

 generally double the height of the front, so that the slope of the glass is seldom more 

 than ten degrees. Knight, with great correctness of principle, considers this as too flat 

 to admit the sun's rays in the winter season, and recommends a basis of earth sloped to 



