394 



ACCELERATING VEGETATION. 



be, in a high degree, in the case of the culture of the cucumber and melons, 

 as well as in forcing flowers. Sometimes a stratum of faggots or billet 

 wood is placed on the ground as a foundation for the dung, which keeps it 

 from being chilled ; and if here and there the stratum is carried up vertically 

 for a foot in width and 18 inches in height, it will facilitate the entrance of 

 heat when casings are applied, or of cold air, if the heat of the bed should be 

 found too great. The ends of these vertical strata, when not to be used, 

 should be covered with litter to prevent the escape of heat by them. 



845. Ashes, tan, and leaves. — Ashes are often mixed with the dung of 

 hotbeds, and are supposed to promote the steadiness and duration of their 

 heat, and to revive it if somewhat decayed. Tan and leaves have also been 

 used for the same purpose ; and it is generally found that about one-third 

 of tan and two-thirds of dung will form a more durable and less violent 

 heat than a bed wholly of dung. The heat of dung-beds is revived by 

 linings, or collateral and surrounding walls, or banks of fresh dung, the old 

 dung of the bed being previously cut down close to the frames. These 

 linings, as before observedj require less preparation than the dung for the 

 beds. The dung-bed being formed, and havmg stood two or three days with 

 the frame and lights placed over it to protect it from rain, is next to be 

 covered with earth, of quality and in quantity according to the purpose to 

 which it is to be applied. In severe weather, the sides of the bed are often 

 protected by hurdles of straw or faggots, which tend to prevent the escape 

 of heat. 



846. The nightly cam'wg to hotbeds and pits may be of boards, or of 



and the following mode of retaining the 



Three pieces of iron of 

 a, are screwed on to the end of the frame, one piece at 



^ the top, another at 



bast-mats, or reed or straw mats 

 covering will be found neat as well as economical 



the form of fig. 328, 



0 



.0 



the bottom, and 

 the other in the 

 middle, so that the 

 top of the iron is 

 about two inches 

 above the light; on 

 the opposite end 

 three pieces of the 



Fig. 328. Details of wire fastening mats on frames, one-sixth of the full size, forni of C, are 



screwed on at the same distances as a / 6 is a side view of a, and d is b. side 

 view of c. A wire, three-eighths of an inch in diameter, and rather longer 

 than the frame it is intended for, must be made with a loop at one end (/), 

 to place over the iron d ; the other end must be fitted with a thumb-screw 

 (e), to screw up the wire when it is placed in the notch which should 

 be counter-sunk m the centre. Small hooks should be driven in the frames, 

 either front or back, to lay the wires in when not m use. (G. ikf., 1842, p.l09) . 



847. Management of hotbeds and pits heated by dung.— As the body of 

 air inclosed is small, its temperature is easily raised too high by the sun, 

 and depressed too much by high winds or very cold nights. The artificial 

 supply of heat from the fermenting material not being under control is 

 another cause of overheating, and hence the constant attention required to 

 give or take away air during the day, and to regulate the coverings put on 

 at night. Much mischief, as has been already observed, is produced by 



