8 GREENHOUSE CONSTRUCTION AND HEATING. 
with a view to meet the peculiar nature and requirements of 
each as nearly as possible. Orchids, in particular, usually 
thrive best in houses designed specially for them, and the 
requirements of the different classes of this wonderful order 
of plants, as to heat, moisture, ventilation, etc., vary greatly. 
And yet the best plants are frequently grown in cheaply 
constructed houses ; and most growers for market, especially 
those whose chief aim is profit, make use of such as are 
built in the simplest manner and at the least possible cost. 
The late Mr. P. Ladds, of Bexley, one of the most suc- 
cessful of all the great London market growers of greenhouse 
plants and flowers, began his career with houses of this 
description, most of those first erected at his old nursery at 
Bexley Heath being of the roughest possible character, the 
sashbars neither planed nor painted on their undersides, but 
prepared from the rough material, and the houses heated 
only by means of a single 4in. flow and return pipe running 
along the central pathway. Nevertheless, it was with such 
appliances as these that this well-known grower made the 
greater part of his ‘‘pile,” and though the houses in the 
huge nursery at Swanley, which Mr. Ladds established 
subsequently, are of more pretentious construction, neither 
are these, by any means, elaborate or costly erections. 
Another market grower, who realised a large fortune a few 
years since, employed houses built in the cheapest possible 
manner, the sides being formed of sheets of galvanized iron 
only ; and in Mr. Beckwith’s huge nurseries at Tottenham 
and Hoddesdon most of the houses were built with concrete 
walls, rafters or ‘‘bars”’ of T iron (bent to the proper 
angles and bedded in the concrete at each end), and glass, 
the squares being for the most part 24in. in width. 
