122 Mode qfnsoarming and ventilating Hot-houses 



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extra-moisture is wanted, water is poured through the grating 

 (c), so as to cover the bottom of the drain. In Mr. Penn's 

 hot-house, in which he grows orchidaceous plants, the drains 

 are about 6 ft. apart, about 18 in. deep, and ] ft. wide; in his 

 green-house, they are about 12 ft. apart; and in his pine-pit, 

 the pines being plunged in tan, they are about 7 ft. apart. In a 

 span-roofed hot-house for botanic or stove plants, the hot-water 

 pipes are ranged along the centre of the house ; and the tubes in 

 which the hot air ascends from the pipes are of boards, and fixed 

 immediately over them, under the ridge of the roof, with their 

 tops reaching to within 2 ft. of the glass. In the pine-stove, 

 the hot-water pipes are under the back path, and the tubes, 

 which are of boards about 18 in. broad, by 9 in. deep, are 

 placed against the back wall in the inside of the house, each 

 having a cover that takes off by the hand. In those houses 

 that have back sheds, the tubes are in the outside of the back 

 wall, as shown inj/%-. 19. ate. The shed has a double roof 

 to retain the heat; and the border, shown atyj is used for 

 forcing sea-kale, rhubarb, &c., and for raising small salading. 

 Care is taken in forming the drains that they shall open to the 

 pipes, not directly under the upright tubes, but in the space 

 between them, as shown in Jig. 20., in which ggBxe the drains; 

 //, the situation of the gratings over them ; z, the situation of the 

 tubes ; and /f, the hot-water pipes. The object of this arrange- 

 ment is, to allow the air from the drains to pass a short distance 

 along the hot-water pipes, so as to be reheated before it ascends 

 to enter by the openings b. When it appears desirable to change 

 the air of the house, this is not done by opening the sashes in 

 the usual way, but by taking the stoppers out of two open- 

 ings into the back drain which contains the hot-water pipes, one 

 at each end, and communicating with the open air. These open- 

 ings are so small, that each may be filled up with a brick, and 

 made air-tight by a little clay. It ought to be observed, that the 

 wooden tubes by which the hot air ascends are all made perfectly 



