PITS AND FRAMES. 115 
as that of the roof. To carry the lights, bearing-bars 
of about 3in. by l4in. or 1}in. stuff, laid on the flat, and 
lightly dovetailed into. and nailed to the plates are fixed 
across every 4ft., or whatever the width of the lights may 
be, with a ‘parting piece” of 24in. by lin., or in. fixed 
on edge on the top of each, as shown in the sketch. A 
similar parting piece should be fixed at each end of the pit, 
to keep the end lights from slipping off sideways, and about 
din. of ‘‘ play” must be allowed to each light, so that it may 
run easily and not stick even indamp weather. Proper iron 
or brass handles must be screwed to each light, top and 
bottom, to pull or push them up and down by. 
Pits intended to contain hot-beds of manure, leaves, etc., 
must of course be sunk in the ground some distance, as 
no less a depth than 8ft. to 4ft. of such material will retain 
its heat for any length of time. The portion below the 
surface must be lined with brickwork or concrete, and as 
a rule the front, back, and end walls are carried straight 
down to the required depth, a brick or concrete bottom 
being also usually put in. All brickwork below the 
surface ought, however, to be Qin. in thickness, whatever 
the thickness of the walls above may be. This class of 
pit has, however, a certain disadvantage in that as the 
manure, etc., decays and settles down it carries with it 
any plants, in pots or otherwise, that may be plunged 
or planted in it, thus rendering it impossible to train them 
to a fixed trellis of any kind. 
An excellent type of pit in which this objection is done 
away with is constructed as follows :—In an ordinary 
deep brick pit (made, however, somewhat deeper than 
usual) a false bottom of perforated kiln tiles, or iron 
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