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ON THE CONSTRUCTION AND HEATING OF HOT-HOUSES. 
scale it would of course be necessary, the quantity of water being small, and there 
being- no mass of brickwork to act as a reservoir of heat ; this purpose, however, is 
evidently much better answered by a cistern of water within the house, than by a 
boiler and brickwork, from which much heat is dissipated in the back shed ; but to 
prevent loss of time in applying the heat in severe weather, it should be so con- 
nected with pipes that the water in them may be sufficiently heated to warm the 
house before it is allowed to pass into the reservoir. 
The ventilation is another subject that comes under this head. With respect 
to ornamental conservatories, or stoves of a peculiar construction, the modes of 
ventilating are various, and should always be such as will properly correspond with 
the form of the house. 
In all ordinary forcing-houses, or greenhouses, air is admitted at the back and 
front, usually by sliding the lights. Our readers may remember that in vol. 1, 
page 130, we recommended ventilators in preference to sliding the back lights : — 
Jirst, from the ease with which ventilators are opened — secondly, because when the 
lights are open, if a sudden shower of rain or snow falls, it is necessary to draw 
them up again with great speed, or much wet will be admitted, perhaps at a time 
when the cultivator was particularly anxious to keep his house dry, — and thirdly, 
because in severe and stormy weather air can be admitted by ventilators in the 
back wall (if the ventilators be properly constructed) when it could not be admitted 
safely any other way. 
It is not, however, always convenient to have ventilators fixed in the back wall 
of a forcing, or greenhouse, nor can they be made to look altogether ornamental. 
On looking over a French work on gardening, called the " Manuel du Jardinier," 
written by M. Noisette, in five vols., we observed a very simple way of elevating the 
back lights (see figures) to admit air : it is rather an old way, but we do not remember 
to have seen it figured in any work, either English or French, previously to this. 
