Mr James Bewley’s Description of a Plant-house. 243 
place them to it, the warmer they are. This is curiously 
indicated by the little creeping Ficus and other plants cling- 
ing to the under size of the inner glass, and spreading over 
it, apparently in great enjoyment. Another important re- 
sult takes place from the non-radiation of heat through the 
roof. In ordinary houses, where moisture forms a requisite 
of good plant-growing, no matter how freely we use the 
syringe in the evening, we find the house dy in the morn- 
ing, arising from the great condensation of moisture on the 
roof, and running off when thus condensed. The cooled 
air having parted with its moisture in the morning when 
the temperature rises a little, it becomes absolutely dry, to 
the great detriment of the plants. With the double roof, 
there is very little condensation on the roof, the blanket of 
non-conducting air between the two roofs of glass prevent- 
ing it; and consequently, as the air cools down a little at 
night, the condensation takes place on the plants themselves, 
exactly according to nature. I have gone into my orchid- 
house, which has a double roof and sides, of a morning, and 
have seen the plants as beautifully covered with dew as a 
plot of cabbages on a May morning. Is not this nearly the 
perfection of plant-growing ? We generally commence fire 
heat in the fern-house when the cold weather sets in, in the 
latter end of October, and leave it off in March, when the 
house gets about 54. Thus we have fire for about five 
months only in the year, and during these five months, the 
consumption of fuel is not more than one-half of what it 
would be if the house had but a single roof. Now, using 
only half fuel for five months, and none during the other 
seven, causes a very large saving, and to this must be added 
the saving from no fire attendance during the same seven 
months,—no small item. These together I calculate to 
amount to about 20 per cent per annum, on the extra cost 
expended on the double roof. But this is trifling compared 
with the enhanced value of the plants grown in a double- 
roofed house. The effect is astonishing. Plants which 
with difficulty held their own, or but slowly improved in an 
ordinary house, have grown and improved with me in a way 
that would surprise plant-growers in general. I should 
add, there is one point on which great caution is requisite 
