156 
ON THE AERIAL SYSTEM OF FORCING. 
use, and constant repairs ? Boilers to unset, to clean, occasionally split, pipes o|- 
dizing on the one surface, and choking up with incrustation on the other.” 
All this is true, and much more. We have within five minutes’ walk, a gent- 
man’s greenhouse, plant-house or grapery, according to the actual processes to whi 
it may he, pro tempore , devoted ; it has a capital hot-water apparatus or triple rani 
of cast-iron pipes, very conveniently fitted up ; the furnace also consuming any pc 
combustible matter, and little of it. Yet the prime cost of this machinery, we ai 
told, exceeded £60, to say nothing of the house itself. And yet, this very comple 
arrangement of pipage might, and would be exposed to the same calamity which, 
many years since, caused the loss of all the plants of a handsome conservatory, 
happened that the year 1837 terminated with a temperature so mild, (nearly 5(jj 
that the idea of fire never once occured ; the pipes were full, and all was safe ; b 
on the 3rd or 4th of January, 1838, the celebrated frost of that year set in at ora 
The whole volume of water froze, and, we believe, remained ice till destruction hi 
done its work, for the fire from behind, (vis a tergo), could produce no effect up< 
a medium so non-conductive as that of ice. As the very reverse of this fatal vis 
tation, a small vinery, furnished with an elaborate hot- water apparatus, suddenly lo 
an entire crop of fruit, by the intensely rapid heating of its tubes, which, defyii 
regulation, raised the atmosphere to 100° in January. This was the result of a co 
incurred a month or two before, and which exceeded £40 ! 
The defects, therefore, of our best machinery are manifest ; they do not equal 
heat the air of a house ; and so far as they do act by radiation, whether from hi 
brick flues, or from water tubes, or tiled channels, they render the atmosphere dr 
and so far insalubrious. Now then, in order to remedy these defects, and to iii 
duce a constant interflow of fresh, warm air, charged with aqueous vapour, an 
therefore brought, as it were, into the condition of a new gas that can flow inters! 
tially, and thus insinuate itself among the minutest particles of air already in tb 
house, we must so arrange the apparatus that no particle of its hot surface be 
exposed as to act by direct radiation. 
A considerable period must elapse ere we can hope to construct a furnace whic 
will neither cause the loss of perhaps half its fuel by the chemical formation of ca 
bonic oxide, nor the diversion of the heat actually obtained, from its proper course; 
but, notwithstanding, approaches have been made — and we had the satisfaction tj 
inspect a stove which appeared to be built upon principles that gave promise, at leas 
of great prospective improvements in the construction of forcing-houses. Thi; 
house had a span roof, with aspects to south and north ; also, corresponding frori 
and back upright lights. The quarries are far too small, and the laps are not puttie 
therefore, from the extent of the glazed surfaces, it is peculiarly exposed to atmi 
spheric influences. Yet by the situation of the furnace and its channels, all the hea 
save that which escapes by the chimney-shaft, absolutely passes into the atmospher 
of the house without any radiating surface whatsoever, and its equable diffusioi 
appeared quite astonishing. 
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