226 



HEATING AS APPLIED IN HORTICULTURE. 



set." Again, on the top of this is built 

 one more course of brickwork simi- 

 lar to the others. This is closed in 

 with slates, and forms a third chamber 

 unconnected with the others, having a 

 distinct opening for the cold air of the 

 house to flow into, as shown by the black 



Fig. 308. 



square, and also a distinct outlet into the 

 house, thereby dispersing the hot air, 

 which would otherwise be only radiated 

 from the uppermost plate of the chamber. 

 The whole of the apparatus, except the 

 furnace doors, is placed within the house, 

 and occupies a space of only 7 feet by 2^ 

 feet, exhibiting the appearance represent- 

 ed by figs. 307 and 309. 



Fig. 309. 



" I am aware," says Mr Kendall, " that 

 by applying so high a heating power 

 I am laying myself open to criticism; 

 but to all who feel disposed to apply the 

 lash, my answer is, ' It is well to have a 

 giant's strength,' but yet we need not 

 ' use it like a giant.' " 



General remarks on hot-air stoves. — Among 

 the many objections we have to such 

 stoves, are their being constructed of 

 iron, — and that so thin in body that they 

 cannot retain sufficient heat in cases 

 where the fire is accidentally allowed to 

 get too low; and also that the heat 

 given out by them is much too great 

 when the fire, from acccident or careless- 

 ness, is allowed to become too great. 

 They are also soon worn out in conse- 

 quence of being exposed to damp with- 

 out and the vapours from the coal within, 

 and will therefore become expensive in 



the end in consequence of requiring fre- 

 quent renewal. And lastly, and worst of 

 all, we may mention the deleterious effects 

 they have upon the air passing through 

 them, or heated by them, which will be 

 noticed more at length hereafter. If hot- 

 air stoves are to be used at all, they should 

 be built of brick, and on the principle long 

 ago laid down by Count Rumford, with 

 probably the addition, as suggested by Dr 

 Arnott, of giving greater depth for the re- 

 ception of the fuel, so that a fire may be 

 maintained within them for eight or ten 

 hours. Count Rumford, as we have else- 

 where remarked, introduced into use 

 double doors to his furnaces and stoves, 

 with ash-pit doors fitting close to the frame, 

 and regulating the admission of fresh air, 

 for the purpose of carrying on slow and 

 progressive combustion through a well- 

 appointed register in the centre of the 

 ash-pit door. Dr Arnott carried his im- 

 provements still farther, by adding greater 

 depth to the receptacle for the fuel, as 

 well as perfecting the admission of air to 

 support a slow and steady combustion. 

 The Chunk stove varies the application of 

 this principle, but not conveniently for 

 hot or green-houses, because it is not cal- 

 culated for a perpetual fire. An anony- 

 mous correspondent in " The Chronicle," 

 on this subject remarks : "The Vesta stove 

 offers greater advantages for the purpose; 

 and, where the fire-place is required large 

 enough to become necessary to place it 

 outside the house, I think," he says, " it 

 may, with some variation, be adapted to 

 the purpose. Under these considerations, 

 and having a fire-door and ash-pit register 

 that had belonged to a Rumford roaster, 

 I fitted up a small greenhouse on the 

 plan here suggested. The cubic dimen- 

 sions of the greenhouse inside are about 

 1260 feet; the area of the glass 220 feet; 

 the back and end walls have an area of 

 about 260 feet. The fire-place, with the 

 door inside the house, is 8 inches by 9 

 inches within; the flues, passing backward 

 and forward over each other," a very bad 

 plan, " are nearly 30 feet long before en- 

 tering the chimney. As to its effects, we 

 have kept the fire in for three weeks or 

 more without re-lighting, — and have had 

 rather more than sufficient heat at times, 

 from the want of experience in the early 

 part of the experiment. I had coals 

 weighed at the most severe period of the 



