BUILDINGS FOR HORTICULTURAL PURPOSES. 
61 
and the water flow round the house in them, 
instead of in pipes. But we know of nothing 
better than pipes, and should always use them 
in preference. 
To go from the consideration of these to 
other buildings. "We have to mention that as 
the top lights constitute the principal expense 
in pits and frames, stoves, and propagating 
houses, they may be had for fetching at less 
than a shilling per foot glazed complete and 
primed. Who would be without plenty of 
glass ? The stove is important. It should, 
in a small establishment, be made to answer 
for any thing of the stove kind, though many 
people are so prejudiced against this general 
treatment of all plants. These may be con- 
trived in the same building, placed in the 
different degrees of heat that may be formed, 
or rather made, in the same house. There 
can be always found appropriate places for 
different things ; and it is worth while to keep 
also different degrees of dampness by artificial 
means. In the stove or hothouse, Mr. Penns' 
system for circulating the air is the most advi- 
sable plan for heating the house. This plan 
consists of giving off the heated air at the 
lowest portion of the house, that it may spread 
up the roof, and, as it falls, returning under 
the floor or false bottom to the place where 
the fires continue to heat it as it passes 
from time to time, by which means a rapid 
uninterrupted circulation is kept up, and 
greatly contributes to the health of the 
plants. The section of a hothouse upon 
this plan would be something like Fig. 5. 
On a large scale, this would be a most 
L_J 
Fig. 5. 
effective plan, for there is nothing more simple, 
and when one of the pits constructed on this 
plan is closed, the circulation of air is re- 
markably strong: holes are left, through which 
air may be admitted at pleasure ; but it is not 
often required. The brick-work in the stove 
is more expensive than in a greenhouse or 
conservatory, and the false bottom under 
which the cooled air passes from the back to 
the front, rather increases the labour ; but in 
houses in which the tan pits are built, they 
would form an obstacle to the free circulation 
of air, if it were not for a grating at the back 
to let it down under the floor as it cools, and 
another grating under the pipes to let the 
cooled air come up again between them to be 
warmed again. The wood-work and glazing 
of a stove is no more than that of a green- 
house, and the build is much the same, except 
that the house should be deeper from back to 
front. The operation of the boiler and pipes 
is very simple, and may be understood from 
the following diagram (Fig. 6), for, turn and 
twist the pipes as you may, all that is re- 
quired, is, that one end goes out at the 
top of the boiler, and the other end returns 
in at the bottom of the boiler. Thus the 
Fig. 6. 
Fig. 7. 
boiler is like two inverted flower-pots, one 
less than the other, and the water is between 
the inner one which holds the fire, and the 
outer one which is exposed. The fuel is put 
in at top and shut down. The flue is pro- 
vided for in the fixing. This boiler would 
feed hundreds of feet of pipe, and it is per- 
haps the simplest and best of the many plans 
for heating horticultural buildings ; due re- 
gard being had to the capacity and the eco- 
nomy of the thing, for both are objects worthy 
of attention. It is easily managed, for when 
the fire is lighted well, the aperture may be 
filled to the top and covered over, the regu- 
lator of the flue being so far closed as to allow 
of slow steady combustion. If a tank for hot 
water is preferred to tan in the interior pit, 
the tank may be made about eight inches 
deep, or from that to ten, the top must be 
closed with large slates, cemented together, 
leaving only one aperture to open at pleasure ; 
this may be heated by sending the usual iron 
pipes through the tank ; on the top of this tank 
may be placed a foot of tan or soil, or any 
other medium in which to plunge pots, or 
plant whatever is to be grown. The top of 
one (Fig. 7), is open to show the pipes, the 
