170 THE AMATEtJRls KITCHEN GARDEN. 
whence it passes through an opening, h, into the tank, and 
thus gets moistened, as well as warmed, before it enters the 
house, through the tubes, n, which are placed at intervals 
along the casing of the tank, and all of which can be closed, 
when necessary. After circulating round the house, the air 
■escapes through the back wall, at i, and at this opening, as 
well as at f the ventilation is regulated by a sliding shutter 
outside, the one in the back wall being also worked from 
within, by means of a cord over a pulley. 
The tank is of slate, encased in brickwork, with a partition 
down the middle, to regulate the circulation of the water. 
When used for cucumbers and melons, a bed is made, m, a 
good depth of loose rubble being first laid down, for drainage, 
and the soil is added as re- 
quired by the plants. Under 
the tank is an open space 
for a bed, o, and the heat, 
communicated to this, from 
the bottom of the tank, and 
the brick piers, p, suffices 
admirably for forcing mush- 
rooms, rhubarb, asparagus, 
etc., but as the latter does 
best in light, sufficiently to 
colour the shoots, we have 
not often grown it there — 
for mushrooms it is admir- 
able. From the front of the 
tank to the back wall, about 
a foot from the glass, is a 
wire trellis, to which the 
plants are trained. When 
the trellises are not all in 
use, we turn to use the 
back” wall for greenhouse 
plants, on moveable shelves, 
and the return pipe, shown 
in the section, runs along the lower part of the wall, and 
gives sufficient heat to force geraniums, camellias, rhododen- 
drons, cytisuses, etc., and beyond the tank we have eight feet 
of space, which we call the *' c cool end,” and which is heated 
only by the return pipe, which leaves the tank and passes 
