186 



HEATING AS APPLIED IN HORTICULTURE. 



and those destined to the cultivation of 

 tropical plants, a still greater surface of 

 water is desirable ; and, for this purpose, 

 slate cisterns placed immediately over 

 the heating-pipes, as broad as the front 

 shelves, and from 1 foot to 15 inches 

 deep, may be advantageously employed. 

 Their temperature will always exceed 

 that of the house by a few degrees; and 

 the great surface affords an abundant 

 though gradual supply of moisture; — they 

 act also as partial reservoirs of heat, and 

 afford the only efficient means of culti- 

 vating the beautiful but much-neglected 

 tribe of stove aquatics. 



" In the few houses where cisterns are 

 introduced, they are in general provided 

 more for ornament than use : the posi- 

 tion in which they are placed, and the 

 materials of which they are constructed, 

 forbid their being warmed ; and, in fact, 

 the temperature of the water contained 

 in them is always some degrees below 

 that of the house. It may be observed, 

 that this arrangement meets the necessity 

 of the case with exceeding accuracy ; for 

 condensation is greatest, and consequently 

 the atmosphere is most rapidly dried, 

 when the external air is coldest, and a 

 great artificial heat is maintained ; — and 

 at this very time the increased heat of 

 the pipes increases the evaporation from 

 the cisterns. But to insure this result, 

 the cisterns employed must be above the 

 level of the heating-pipes, and, if possible, 

 directly over them." 



There is, we think, one objection to 

 Mr Rogers' plan of placing the troughs 

 or cisterns over the hot-water pipes — 

 namely, their preventing the radiation 

 of the heat upwards. So far, therefore, 

 as providing a humid atmosphere is 

 concerned, we would prefer having the 

 troughs under the return-pipes, as already 

 stated ; and as for obtaining a supply 

 from cisterns in which tropical aquatics 

 are cultivated, it would be better to con- 

 duct a small branch-pipe from the main 

 ones into such cisterns; — for it is an 

 admitted fact, that the water in such 

 cisterns is never sufficiently heated to 

 suit the nature of the plants cultivated 

 in them. A still better plan would be to 

 place an open gutter or evaporating cast- 

 iron pan along the top of the kerbs or 

 parapets — or, indeed, in any part of the 

 house most convenient ; and into it 



lead a small pipe of hot water, either 

 from the main pipes or direct from the 

 boiler. This pipe should be furnished 

 with a cock, to let in the hot water when 

 evaporation is required ; a return-pipe of 

 the same dimension, attached to the same 

 end of the gutter at which the supply is 

 admitted, will draw it off and return it 

 to the source from whence it came. 



The following very judicious remarks 

 on heating by hot water form part of an 

 excellent paper read before the * Horti- 

 cultural Society of London," by John 

 Rogers, Esq. After alluding to the 

 various methods adopted, acknowledging 

 the great advantages of hot water over all 

 other modes of heating, and stating the 

 saving in fuel to be equal to twenty-five 

 per cent, in well -arranged apparatuses 

 over well - arranged and well-managed 

 flues — observing, however, at the same 

 time, that many of the modes even at 

 present in use are so defective as to be 

 actually consuming a greater amount of 

 fuel than ordinary furnaces — he pro- 

 ceeds to say : " This remark applies not 

 merely to the earlier apparatus, where 

 the power was inadequate to the work 

 required, but even to the best-constructed 

 modern ones ; and the waste of fuel 

 arises from a misunderstanding of the 

 nature of a hot-water apparatus, and from 

 an attempt to make it do that which, if 

 it be properly constructed, it is impos- 

 sible that it should do. 



" It is a great desideratum with gar- 

 deners, as far at least as my experience 

 goes, to get up heat in a short time ; and 

 their ordinary test of the excellence of a 

 hot-water apparatus is, how speedily they 

 can get the water to boil. Where an 

 apparatus is properly constructed, this 

 can seldom be^ effected without a most 

 extravagant waste of fuel. The water in 

 a hot-water apparatus, constructed on the 

 most perfect principles, will take as many 

 hours to heat to the boiling point as the 

 pipes which contain it are inches in 

 diameter, — and it will also cool in the 

 same ratio. Four-inch pipes will accord- 

 ingly take four hours to reach the tem- 

 perature of 200° ; and they can be heated 

 to the boiling point in one hour, only by 

 the consumption of four times as much 

 fuel as would suffice if properly applied; — ■ 

 or, in fact, allowing for the waste of heat 

 by the chimney, which increases under 



