Book III. DETAILS FOR WATER, AIR, &c. 331 



1686. Shelves, excepting such as are placed near the ground, or almost close under the 

 upper angle of the roof, are extremely injurious to the vegetation going forward in the 

 body of the house by the exclusion of light. This consideration, therefore, must be 

 kept in view in placing them ; in some cases they are inadmissible, as in conservatories ; 

 in others, as in propagating-houses, the light they exclude can better be spared, than in 

 fruiting or flowering departments. For forcing strawberries, they may be introduced 

 under the roof in vine and peach-houses, and removed when their shade proves inju- 

 rious, &c. The ordinary form is that of a flat board ; but an improvement consists in 

 nailing two fillets along its edges, and covering the board with a thin layer of small 

 gravel or scoria. This preserves a cool genial moisture which keeps the earthen pot 

 moist, and lessens the effect on the earth of alternate dryings and waterings ; and it also 

 admits the more ready escape of water from the orifices in the bottoms of the pots. Some, 

 in the case of forcing strawberries and French beans, have the fillets or ledges of the 

 shelves so high as to contain two or three inches of water, by which means whole rows of 

 pots can be inundated at one operation ; but this is too indiscriminate an application of 

 a material on which so much in the growth of plants depends. 



1687. Stages are shelves in series rising above each other, and falling back so as their 

 general surface may form a slope. They vary in form according to that of the house. 

 The houses with shed roofs and opaque ends have merely a series of steps reaching from 

 one end to the other ; but wherever the ends are of glass, by returning each 

 shelf to the back wall, due advantage is obtained from the light furnished by the glass 

 ends. The addition of lodgement, or turned-up edges to each shelf, and the covering 

 them with gravel, is, of course, as advantageous as in separate shelves, and surely 

 more consonant with natural appearances, than leaving them naked like household, or 

 book shelves. Shelves and platforms of stone are now very general, and found more 

 congenial to the plants than dry painted boards. 



Subsect. 10. Details for Water, Wind, and Reneival of Air. 



1688. The reservoirs of water in hot-houses are commonly cisterns of stone or timber, 

 lined with lead, or cast-iron troughs or basins. Sometimes, also, tanks are built in the 

 ground, and lined with lead or cement. The cistern is sometimes placed in an angle, or 

 other spare part of the house, and the water lifted from it at once with the watering-pots ; 

 but a more complete plan is to build it in an elevated part of the back wall, where it may 

 have the benefit of the heat of the house, and whence pipes may branch off to different 

 parts of the house with cocks, every 30 or 40 feet, for drawing supplies. Tanks and 

 cisterns below the level of the front gutter may be supplied great part of the year from 

 the water which falls on the roof; but more elevated cisterns must either be supplied by 

 pumps, or elevated springs. The sources of supply, and the quality of the water must 

 be taken into consideration before the situation of the cisterns are determined on. In all 

 cases, there must be waste-boxes at the cocks, and waste-pipes from the cistern, to coun- 

 teract the bad effects of leakage. 



1689. Artificial rain. A very elegant plan has been invented and executed by Messrs. 

 Loddiges, for producing an artificial shower of very fine rain in hot-houses, by conduct- 

 ing pipes horizontally along the roof, at the distance of six or eight feet, and having these 

 pipes very finely perforated by a needle. According to the power of the supply, one or 

 more pipes may be set to work at a time, and a very fine shower thrown down on the 

 leaves of the plants with the greatest regularity. This has been done in one of the 

 palm-houses of these spirited cultivators at Hackney, and for which a medal was voted 

 to them by the Horticultural Society, in 1817. The following is a particular account of 

 this apparatus. (Hort. Trans, vol. iii. p. 15.) 



A leaden pipe of half an inch bore is introduced into one end of the house, in such a situation that the 

 stop-cock, which is fixed in it, and which is used for turning on the supply of water, may be within 

 reach : it is then carried either to the upper part, or the back of the house, or to the inside of the ridge 

 of the glass frame-work, being continued horizontally, and in a straight direction, the whole extent of the 

 house, and fastened to the wall or rafters, by iron staples, at convenient distances. From the point where 

 the pipe commences its horizontal direction, it is perforated with minute holes, through each of which 

 the water, when turned on, issues in a fine stream, and, in descending, is broken, and falls on the plants, 

 in a manner resembling a gentle summer shower. The holes are perforated in the pipe with a needle, 

 fixed into a handle like that of an awl; it being impossible to have the holes too fine, very small needles 

 are necessarily used for the purpose, and in the operation great numbers are of course broken. The 

 situation of the holes in the pipe must be such as to disperse the water in every direction that may 

 be required, and in this particular the relative position of the pipe, and of the stations of the plants to be 

 watered, must be considered, in making the perforations. The holes are made, on an average, at about 

 two inches' distance from each other, horizontally, but are somewhat more distant near the commence- 

 ment, and rather closer towards the termination of the pipe, allowing thereby for the relative excess and 

 diminution of pressure, to give an equal supply of water to each end of the house. A single pipe is 

 sufficient for a house of moderate length : one house of Messrs. Loddiges, which is thus watered, is sixty 

 feet long, and the only difference to be made in adapting the plan to a longer range, is to have the pipe 

 larger. The reservoir to supplv the pipe, must of course be so much above the level, as to exert a 

 sufficient force on the water in tlie pipe, to make it flow with rapidity, as it will otherwise escape only in 

 drops ; and as too strong a power may be readily controlled by the stop-cock, the essential point to be 

 attended to, in this particular, is to secure force enough. From the above details it will be observed, that 



