88 THE GREEN-HOUSE. [Jan. 
The better to confine the air warmed by the sun in the day time, 
and to prevent the cold air from rushing in on the approach of night, 
■when that within begins to cool and consequently to contract 
in bulk; I would advise to have all the panes in the roof-lights neat- 
ly and closely puttied, where they overlap one another; and to have 
either one, two or three of those lights, in proportion to the length 
of the house, so constructed, as to slide down and up a few feet, by 
means of pullies; in order to give vent to the foul air generated in 
the house, which naturally ascends to the upper part. The sized 
glass, recommended in page 11, for hot-bed lights, is what I would 
particularly recommend for these roof-lights, being not only the 
strongest, but by much the cheapest. 
The windows or upright front-lights, must be made with large 
panes of glass, &c. to admit the more light, as well as to give a hand- 
some appearance to the house: the upper half of each window 
must be so contrived, as to slide down, and the lower half up, 
occasionally, to admit air to the plants when necessary. 
If a spacious and ornamental window be placed in each end, (if 
the house be detached) to receive the benefit of the rising and set- 
ting sun, it will be of considerable advantage; these particularly 
should have good close shutters either inside or outside, and be kept 
shut every night during the winter, and also in the day time in very 
severe weather, except while the sun immediately shines on them. 
If the front is so contrived, that inside shutters to the windows can- 
not be conveniently hung, outside sliding shutters should be made, to 
be used only when necessity requires. 
But let it be particularly observed, that all the lights, cases, doors, 
and wood work of the house, be made of good seasoned wood, and 
well painted, to prevent either their swelling by wet, or shrinking 
by drought; that all parts be well jointed and fitted together, so as 
to be as nearly air tight as possible. 
A house constructed on this plan, will very seldom require the 
assistance of fire-heat, which ought always to be used with great 
caution in a green-house; it will admit light, collect heat, and give 
health, beauty and vigour to all the plants. 
Some green-houses for large collections of plants, have two wings 
of smaller dimensions, added to the main building, one at each end, 
in a right line, separated sometimes from it by glass partitions, and 
sliding sashes for communication, the front almost wholly of glass, 
and part glass roofs, as above observed; thus by these additional 
wings, the green- house will consist of three divisions, whereby the 
different qualities and temperatures of the various plants can. be more 
eligibly suited. The middle or main division may be for all the 
principal and more hardy, woody or shrubby kinds, which require 
protection from frost only; one of the wings may be appropriated 
for the succulent tribe, and the other for the more tender kinds that 
require occasional heat in winter, yet can live without the constant 
heat of a stove or hot-house. 
Many green-houses, as they are commonly built, serve more for 
ornament than use; their situation to receive the south sun being 
