244 Mr James Bewley’s Description of a Plant-house. 
by any one who adopts double-roofed houses: from the uni- 
formity of temperature, and the consequent non-condensation 
of moisture, very moderate waterings and syringes are suffi- 
cient to keep the plants in health. A beginner will be very 
apt to overdo it. My fern-house has nothing done to it for 
weeks together beyond a very light syringing each morning 
in summer, two or three times a week in spring and autumn, 
and once every week or ten days in winter. 
My large plant-house is about 130 feet long, 19 wide, and 
11 high. It had shelves at either side 3 feet wide, then 
paths of equal width, and a central stand 7 feet wide ; 
beneath each of the side shelves there were two 4-inch flow 
pipes and two returns, twelve pipes in all. When I double- 
roofed it, the heat was too much, so I built a low brick 
wall on either side, and also enclosed in the same way the 
central 7 feet, and filled up the spaces with gravel, &., to 
about 3 inches over the pipes; the gravel is kept damp, 
and on it the plants stand—on a hotbed, in fact, and they 
delight init. I think any one who will cover up all his 
heating power in this way will soon find that it is superior 
to exposure; the heat is so gradually diffused and the 
moisture also, the gravel beds being frequently watered. 
The peculiarity and advantage of double-roofed houses may 
be summed up thus:—Great economy of heating power, 
and great uniformity of temperature and moisture ; and con- 
sequently remarkable facility in growing plants in perfect 
health and beauty. So far as my experience has gone— 
and I have now been trying it for some years,—I can have 
no hesitation in recommending the system to every person 
for the cultivation of any description of plants. 
The Great Mixed Forests of North America in Connection 
with Climate. By J. B. Hurtsurt, LL.D.* 
This vast forest, composed principally of deciduous trees, 
covers an area of about 2,000,000 square miles, extending 
from the Gulf of Mexico to the northern boundary of 
Canada, and from the Atlantic to the prairies of the west, 
* Read at the Meeting of the British Association at Newcastle, 1863. 
