152 



HEATING AS APPLIED IN HORTICULTURE. 



allow it to escape at the chimney is a 

 waste of fuel, and a convincing proof of 

 the insufficiency of the system. The 

 flue must be had recourse to in some 

 shape or other, and be so conducted as 

 to allow the heat in it to find its way 

 either into the house heated by the 

 pipes, or into some other attached to it. 

 We have, in the case of pine stoves, and 

 other houses requiring the greatest 

 amount of constant heat, placed a flue 

 along the back wall, with openings over 

 it, so that the side and greatest part of 

 the top may radiate heat into the house ; 

 and as such houses have, or ought to 

 have, enclosed sheds behind them, the 

 other side of the flue heats them at the 

 same time, and thus renders them dry 

 and fit for store-rooms, for forcing sea- 

 kale, rhubarb, chicory, &c. In some 

 cases we have turned the heat, after 

 passing the boiler, into the pit or vault 

 under the pine bed, dividing it longitu- 

 dinally into two, by carrying a 9-inch 

 wall up the centre, leaving a space of 

 1 8 inches in width at both ends to admit 

 of the circulation — the smoke travelling 

 along the front flue first, and returning 

 by the back one, and escaping by the 

 chimney over the boiler. Such flues 

 being of a large size — say, for a pine pit, 

 8 feet wide within — they may be each 

 3 feet wide and 2 feet in depth. To 

 render them perfectly smoke-tight, they 

 are well parged within. The pavement 

 forming the floor of the beds, on which 

 the pots are plunged, or the border 

 formed, if the planting-out system is 

 adopted, forms the roof, which is sup- 

 ported on a scarcement at both sides, 

 and the 9-inch wall in the middle. This 

 pavement is closely jointed, and over it 

 is 6 inches of drainage, upon which the 

 pots or soil are set. Earthenware tubes 

 are set at intervals upright through the 

 bed, resting on the drainage and upon 

 the top, through which liquid manure — 

 chiefly diluted cow or other urine — is 

 poured, for the purpose of affording those 

 ammoniacal gases which the old dung-beds 

 supply in so eminent a degree, and for 

 which they, so far as this is concerned, 

 are so superior to all other modes of 

 heating whatever. These tubes also 

 enable the cultivator to keep the bottom 

 of the bed, or the bottoms of the pots, 

 in a proper state as regards moisture, 



which, without such a provision, would 

 be apt to become dried up, from the 

 drying properties of the flues under- 

 neath. By these means we think we 

 obtain all the heat the fire is capable of 

 affording, always deducting that amount 

 necessary for carrying the smoke out at 

 the chimney-top. The flues, being large, 

 are not speedily choked with soot; the 

 draught is moderated, and time given 

 to the heat to ascend through the top, 

 and to warm the whole mass of building 

 constituting the sides of the pits, which, 

 when once heated, continue to give it 

 out, even long after the fires may be 

 extinguished. Sufficient bottom-heat will 

 be obtained by this means to render the 

 application of tanks or hot-water pipes 

 unnecessary. Flues of the ordinary 

 dimensions will not do for this purpose, 

 as they so soon become choked with 

 soot. These heated pits, we need scarcely 

 remark, should be cleared of soot at such 

 times as the plants are about being 

 arranged, or fresh beds formed for them ; 

 and this is easily effected by lifting a 

 piece of pavement at both ends, when 

 the accumulated soot will be found an 

 excellent manure, as it will be arrested 

 in its progress, little of either it or of 

 smoke passing out at the chimney. 

 Indeed, were there no other advantage 

 attending this plan than the absence of 

 smoke, it would amply repay the ex- 

 pense. 



The heating capabilities of flues have 

 been variously estimated ; but as much 

 depends on the construction of the 

 house to be heated, mode of glazing, &c, 

 no very correct data can be laid down. 

 It has, however, been stated as nearly 

 approaching the true amount, that one 

 fire will heat 3000 feet to a stove tem- 

 perature, if the structure be span-roofed 

 or curvilinear, having all its sides of 

 glass ; while, in the case of lean-to houses, 

 one fire will heat 5000 cubic feet to that 

 temperature for the former, and 3000 feet 

 for the latter form. 



With regard to size, the average may 

 be taken at 10 inches in breadth, and 

 15 inches in height internally; and the 

 furnace for such a flue, at 2 feet in 

 length, 18 inches wide, and the same 

 in height. 



We have just been favoured with draw- 

 ings of a highly ornamental fire-clay flue, 



