ACCELERATING VEGETATION, 



361 



interstices in the layer of billet-wood ; <?, the bed of soil ; A, a trellis 

 for vines, melons, or other plants, at one foot from the glass ; i, a gutter 

 for receiving the water from the glass, and which should conduct 

 it through a small pipe, either at one end or in the middle, to a barrel, 



Fig. 328. 



Cross section of a pit on AfPhaiFs principle, with variations. 



or to a cistern of slate or of other material sunk in the soil of the pit in 

 front. The preferable situation is midway between either end, in 

 order that the vapour of the water may be equally diffused in the 

 atmosphere of the pit. By keeping the upper surface of the dung in 

 the form shown in the figure, it will throw olf the rain, which may be 

 conducted away in small surface gutters. 



The formation of common hotbeds is effected by first marking out the 

 dimensions of the bed, which should be six inches wider on all sides 

 than that of the frame to be placed over it, and then, by successive 

 layers of dung laid on by the fork, raising it to the desired height, 

 pressing it gently and equally throughout. In general such beds are 

 built on a level surface ; but Mr. Knight forms a surface of earth as 

 a basis, which shall incline to the horizon to the extent of 15; on this 

 he forms the dung-bed to the same inclination ; and finally the frame, 

 when placed on such a bed, if, as is usual, it be deepest behind, will 

 present its glass at an angle of 20 instead of six or eight, which is 

 undoubtedly of great advantage in the winter season. This seems a 

 very desirable improvement where light is an object, which it must 

 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 eighteen 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 through them. 



