164 



HEATING AS APPLIED IN HORTICULTURE. 



the whole may be removed in a few 

 minutes should any repair be necessary." 



This furnace, " though well adapted for 

 burning coke, cinders, or dry wood, would 

 perhaps not answer well for coal, as the 

 smoke would be so much chilled, by con- 

 tact with the metallic surface of the fire- 

 place, that the flue would be liable to 

 become foul. This might be prevented 

 by constructing the furnace as in fig. 180, 

 lining it throughout with fire-brick : s is 

 an inclined plane of fire tiles, on which 

 the fuel is to be spread when first put 

 into the furnace : t are air-passages, 

 between the fire-bricks and the case of 

 the furnace, leading from the front, and 

 having openings, u u, into the fire-place, 

 at the joints of the bricks, above the in- 

 clined plane. A regulated supply of air 

 being admitted through these openings, 

 would mix with the vapours rising from 

 the coal, and in a great measure effect the 

 combustion of the smoke in passing over 

 the fire, and through the heated passage m. 

 The boiler should be placed within the 

 house, either under the plant stage, or in a 

 pit sunk below the level of the floor; the 

 end only being built into an opening in 

 the wall, for the purpose of supplying the 

 fire with fuel from the back sheds." 



Sir Joseph Paxton, in reviewing the 

 preceding plan of heating, with his usual 

 intelligence and good sense offers the 

 following remarks, which are in accord- 

 ance with our own opinion. Although 

 we have not had any opportunity of see- 

 ing the apparatus in operation, we per- 

 fectly comprehend the advantages likely 

 to arise from its use ; the principle of 

 which is, that heat would be thrown 

 much sooner into a greenhouse, upon 

 the approach of a sharp frost, for ex- 

 ample, by this means, than by those in 

 more general use ; and if this can be 

 effected, it will render heating by hot 

 water perfect. The following are the 

 remarks to which we have referred : — 

 " Mr Cruikshanks seems confident that 

 on this principle a much greater pro- 

 portion of the heat generated by the 

 combustion of the fuel may be com- 

 municated to the atmosphere of the 

 house, and that with less loss of time 

 than by any of the methods now in use. 

 The flue, or flues, surrounded with water, 

 may doubtless be constructed in such a 

 manner, that the heated air and vapours 



passing through them may be so far de- 

 prived of their caloric as to enter the 

 chimney at a temperature little above 

 that of the water ; and beyond this point 

 the economy of fuel cannot possibly be 

 carried. To limit the loss of heat by the 

 chimney is, of course, a desideratum in 

 any mode of warming buildings; but 

 it appears to be overlooked in many plans 

 proposed for the purpose, especially in 

 those for employing oil and other fluids, 

 at a temperature considerably above the 

 boiling point of water. As the heated air 

 and vapours must necessarily enter the 

 chimney at a higher temperature than 

 that of the fluid in the boiler, the loss of 

 heat will be greater in proportion as that 

 temperature is increased. 



" There is another circumstance con- 

 nected with the plans alluded to, that 

 does not appear to be taken into consider- 

 ation at all — the great capacity of water for 

 heat, compared with most other fluids — 

 oil, for instance, or mercury. Water, it 

 is well known, in being heated any num- 

 ber of degrees, absorbs twice as much 

 caloric as an equal bulk of oil or mercury ; 

 and, consequently, a given bulk of water 

 at 212°, in cooling down to 60° — that is, 

 in losing 152° of sensible heat — will warm 

 the surrounding atmosphere as much as 

 an equal bulk of oil or mercury would do 

 in cooling from 364° to 60°, or in losing 

 304° of sensible heat, as indicated by the 

 thermometer. Such being the case, if 

 oil or mercury, or almost any substance 

 that can be named, could be compared in 

 point of economy, safety, and cleanliness 

 as a material, with water at or under the 

 boiling point, still it would be inferior to 

 water in point of economy as regards the 

 consumption of fuel." 



The apparatus represented by fig. 178 

 is constructed of copper, and costs about 

 £9 : for a house 30 feet in length, it would 

 not cost ,£13. In the plans, figs. 179 and 

 180, the outer case or boiler is supposed 

 to be cast-iron, as well as the case of the 

 furnace in fig. 180, and all the other parts 

 in copper. The whole might be made of 

 cast-iron ; but there would be a risk of 

 its cracking in those parts exposed to the 

 fire. Plate-iron or tin-plate might be 

 employed, either wholly or in part ; but 

 cast-iron and copper would perhaps be 

 preferable materials. With respect to the 

 pipes, when made of sheet-copper, or zinc, 



