r 
106 GREENHOUSE CONSTRUCTION AND HEATING. 
struck, or tender seedlings raised, with great success, but 
the pipes ought to be kept constantly hot, of course. 
Where there is a flue, this may be easily utilized to 
supply bottom heat, where necessary. Indeed, I would 
rather have a flue covered in closely, in a pit, such as 
described above, than outside, or standing free in the house, 
for in case of any smoke or sulphurous fumes escaping, 
this, being confined beneath the pit, would not do nearly 
the same amount of harm to the plants, etc., as would 
otherwise be unavoidable. This will, however, be more fully 
treated on in the section devoted to heating. 
In pine houses, and occasionally elsewhere, somewhat 
similar pits to those recommended above, for cucumbers, 
are provided, but are filled with fresh tan, which affords 
a gentle warmth, and in this the pots are plunged. Such 
pine-pits are frequently furnished as well with a couple 
of rows of 4in. piping, laid near the bottom, in order to 
assist the tan in providing the mild but steady bottom heat 
which appears to be necessary to the welfare of the plants. 
Sometimes similar pits are provided in propagating houses, 
and filled simply with fermenting manure, but though 
sufficiently effective, this plan involves too much labour 
and waste in changing the material as required to be 
recommended. 
Trellises.—In structures intended for the cultivation 
of cucumbers, vines, tomatoes, etc., which require to 
be trained over the roof, a wire or other trellis of some kind 
must be provided. In small houses it will suffice to screw 
some of the small iron rods with an eye at one end 
and a thread run on the other, that are obtainable at almost 
any ironmonger’s, into the undersides of the bars at regular 
