144 GREENHOUSE CONSTRUCTION AND HEATING. 
The first attempt at heating, in connection with horti- 
culture, in this country was made, I believe, at Belvoir 
Castle, where great fires were kept burning during the 
spring and early summer against the back wall of a lean-to 
vinery, though if I remember rightly the fires were employed 
before the glass, the latter being added afterwards. The 
wall being thus kept constantly warm induced the vines 
to break into growth and ripen their. fruit earlier and 
better than usual. This was of course a very rough and 
frightfully wasteful method of heating, but it was the first 
step in the science of 
forcing, though soon 
abandoned in favour 
of the smoke-flue. 
cease These smoke-flues, 
Ht. GE. . so-called, which may 
still be found in many 
old-fashioned vineries, etc. in country gardens, were 
constructed of brickwork, and led from a furnace built 
outside one end of the house, usually along the front 
and across one end of the structure into a stack 
or chimney at the other end, as shown in Fig. 95. 
Flues are still employed by some growers for certain 
purposes, and indeed a combination of flues and 
hot water pipes is probably the most economical of all 
methods of heating, but though by no means expensive 
to construct, flues are certainly rather extravagant in 
fuel, and moreover afford a dry and somewhat 
harsh warmth, unfavourable to the growth of delicate 
plants, especially when the brickwork becomes at all 
overheated. 
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