214 FIXED STRUCTURES FOR GROWING 



a sufficient quantity was once added for the purpose required, the waste 

 which takes place can be supplied by fresh water. (Hood's Treatise, p. 167.) 

 507. Open gutters have been employed, either partially or wholly, instead 

 of closed pipes, for circulating hot water in hothouses, and by a number of 

 gardeners this is considered a very superior mode where great atmospheric 

 moisture is required. The earliest apparatus of this kind is one which was 

 put up in Knight's Exotic Nursery, Chelsea, in 1830, and described in the 

 Gardener s Magazine for that year, pp. 374 to 376. It has since been 

 erected by Mr. VTeekes at several places, and a patent was taken out for 

 some modifications of it by Mr. Corbett in 1838. Instead of the upper or 

 flow-pipe, an open gutter of iron, wood, slate, or stone, is employed ; it is 

 placed on a level, from the boiler to the furthest point where it is carried, 

 and it commonly returns to the boiler in a closed pipe. It can be carried 

 over doors or similar interruptions by syphons, and under them by inverted 

 syphons ; and the open gutter has covers which can be taken off and on 

 at pleasure to diminish or increase the quantity of vapour admitted to the 

 atmosphere of the house. (Gard. Mag. 1838.) There is an apparatus of 

 this kind in Pontey's Nursery, Plymouth ; the boiler is one of Shewin's (Ro- 

 gers's, 604) largest-sized conical ones, which appears to answer admirably. 

 From the boiler the water flows in an open gutter, formed of slabs of slate, 

 (jointed very neatly together), to the further end of the house, from which 

 point it returns in a four-inch iron pipe back to the boiler. From having 

 the gutter open they have a very humid heat, but by the use of slate covers 

 they can regulate it so as to have little or much vapour, as circumstances 

 may require. (Gard. Chron. Jan. 2, p. 6.) At Cowley, near Exeter, Mr. 

 Corbett's open system has been put up, and the gardener there finds it the 

 most simple and efficacious means of heating that he has tried. For orchida- 

 ceous houses he particularly recommends it, and he has found it far superior 

 to close pipes in the pine stove. Mr. Glendinning also considers it the best of 

 all systems. It combines, he says, the simplicity of the good old level system 

 with the grand advantage of diffusing through the house, without trouble, any 

 quantity of moisture required, or entirely withholding it. The circulation 

 of the water in the gutters is quite as rapid as by any other system, if not 

 more so, even when left entirely open. The invention is divested of all 

 intricacy, as the water may be exposed to full view from its leaving the 

 boiler until its return, and the apparatus is not liable to go out of repair. 

 Its effectual application to every description of forcing-house is at present 

 without a parallel ; as, by the partial or entire removal of any number of 

 covers, an unvarying degree of moisture, always governed by the tempera- 

 ture maintained, can, with the greatest ease and accuracy, be communicated. 

 This alone, to practical men, will secure to it a decided preference. Red 

 spiders, thrips, and all other insects, will be readily subdued ; and an atmo- 

 sphere, at once invigorating and refreshing, at all times maintained. (Gard. 

 Mag. 1841, p. 57.) The opinion of Mr. Rogers is thus expressed : " For 

 Orchideae, melons, and cucumbers, I .should think it excellent ; for stove- 

 plants, at certain seasons, equally so ; but, for other garden purposes, its 

 utility must depend upon the power of completely covering the troughs, and 

 regulating the escape of moisture. For greenhouses, as well as for forcing 

 grapes and pines, it would require two or three years' experience to satisfy 

 me of its advantages ; especially for the two latter purposes. Heat is often 

 employed in gardens more to dry than to warm buildings ; as, in greenhouses 



