4 GREENHOUSE CONSTRUCTION AND HEATING. 
position, and other conditions may be favourable, to the 
best of his power. 
In large and smoky towns, plants growing in a greenhouse 
are protected, to a great extent, by the glass roof, from 
the constantly falling particles of soot, dust, etc., that 
would otherwise be deposited on them, and are consequently 
both cleaner and healthier than those exposed to the 
open air. 
Greenhouses are generally supposed to be very costly 
structures, and so they frequently are, though a great deal 
depends upon the way in which one goes to work. Elaborate 
constructions, in which heavy or fancifully wrought wood 
or iron work, coloured glass, powerful and intricate heating 
apparatus, and everything of the very best materials and 
workmanship are employed, are naturally and unavoidably 
expensive. So also are too frequently those erected by a 
professional horticultural builder, especially where a fixed 
or contract price is not agreed upon previously. For, 
although these men know exactly the right way to go to 
work (or ought to do so), it should be remembered that they 
have to employ skilled and reliable workmen, who have to 
be well paid, and to find travelling and other expenses as 
well, while lastly they must have a good margin of profit 
themselves, or they could not live. In fact, it is not so 
much the actual materials that cost the money so much as 
the labour, which is always a very heavy item, particularly 
when that of a skilled description has to be employed. 
On the other side, a handy man, who can use the 
ordinary carpenter’s tools, and do most of thé wood-work, 
as well as the painting, glazing and fitting, himself, with 
perhaps the assistance of a lad, or ordinary labourer only, 
