Jan.] THE HOT-HOUSE. 95 
back wall, will counterbalance the strong heat discharged by this 
first range where most wanted. 
The first range being continued round the front and ends, must 
then be carried along the back wall in four or six returns, which 
will be sufficient to expend all the heat before its discharge into the 
chimney, which must be carried up immediately from the end of 
the uppermost or last flue, either in or outside of the back wall, so 
as not to appear in the inside of the house, and particularly in the 
opposite end to the fire-place. 
The under range of flues, immediately communicating with the 
fire, ought to be four bricks on edge deep, that they may not be too 
soon stopped with the soot, and all the flues eight inches in the clear, 
and covered with broad tiles, the several returns may be made three 
bricks on edge deep; and, in the beginning of the first bottom flue, 
you may have a sliding iron regulator, to use occasionally in ad- 
mitting more or less heat, as it may seem necessary; being very 
careful, as you proceed, that the brick- work of each flue be careful- 
ly jointed with the best mortar for that purpose, and well pointed 
within, that no smoke can get out, having each return closely co- 
vered with broad tiles, well bedded and jointed with mortar, cover- 
ing the uppermost flues also v/ith broad thick tiles the whole width, 
all very closely laid and joined as above, and the said uppermost or 
last range of flues, to terminate, as before observed, in a vent of 
chimney at one end of the back wall; or, if two separate sets of 
flues, a chimney at each end, in which you may contrive an iron 
slider, near its communication with the last flue, to confine the heat 
more or less on particular occasions, or to prevent its passing off 
too quickly, or becoming of too weakly a degree. 
In very wide stoves, flues are continued immediately round the 
bark-pit, within an inch or two of the wall, to form a -vacancy for 
the heat to come up more freely, and also to prevent its drying the 
tan of the bark-bed too much, which flues may be used occasionally 
or generally, by the assistance of a sliding iron regulator, to admit 
or exclude the heat less or more as it may appear expedient. 
You should be very careful that neither the fire-place, nor flues, 
be carried too near any part of the wood-work, lest it should take 
fire. 
Proceed now to set out the cavity for the bark-pit, first allowing 
a space of eighteen inches, or rather two feet wide round the front 
and both ends, and also a walk of two feet, or two and a half, along 
the ba^k wall for the convenience of walking, watering and at- 
tending the plants; then in the middle space is formed the pit for 
the bark-bed, six, seven or eight feet wide, or whatever it may 
allow, and the whole length of the house, the end walks excepted; 
which is to be three feet deep, and surrounded with a nine inch 
brick wall, coping it all round with a timber plate, framed and mor- 
tised together, which effectually secures the brick-work: sometimes 
a four inch wall is made to do, as by such more room is gained in 
the pit; this will answer very well, but is not so permanent. 
The top of this pit ought to be exactly on a level with the front- 
