2176. Artificial rain. A very elegant plan has been invented and executed by Messrs. Loddiges, for producing an artificial shower of very fine rain in hothouses, by conducting pipes horizontally along the roof, at the distance of 6 or 8 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 stopcock, 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 framework, 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 commencement, 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 60 ft. 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 supply the pipe, must of course be so much above the level, as to exert a sufficient force on the water in the 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 stopcock, the essential point to be attended to, in this particular, is to secure force enough. From the above details it will be observed, that some nicety is required in the arrangement and formation of the machinery; but it is only necessary to view the operation in Messrs. Loddiges' house to be convinced of the extreme advantage and utility of the invention, when it is properly executed. (Sabine, in Hort. Trans., vol. iii. p. 15.)
