PITS AND FRAMES. 113 
contents to be attended to without exposing them directly 
to the outer air. 
Such a pit is illustrated in Fig. 73, and at the sacrifice 
of a small proportion of the area, enables the gardener to 
attend to his charges in any kind of weather, and, in fact, 
transforms the structure into a miniature greenhouse. 
Where economy is an object, a pit of this kind may be 
constructed very inexpensively, especially if the sides are 
formed of stout boards, or even of low banks of turf-sods. 
The cubic contents being small, such a pit may be 
efficiently heated by means of a couple of rows of 3in. or 
even 2in. piping, and a still less costly method would be 
to employ a simple smoke-flue, constructed of either 
bricks, or of 6in., or even 4in. glazed earthenware 
drain-pipes. These are very inexpensive, and when properly 
set, answer admirably, but this part of the subject 
will be dealt with more fully in the section devoted 
to heating. 
Pits, properly so-called, and as distinguished from frames, 
may be divided into two classes, viz., those built simply 
on tbe ground, or on a very shallow foundation, and in 
which the plants stand on the solid bottom, or level ground 
—with a surfacing of ashes, to exclude worms, of course— 
and secondly, those constructed with a sunk pit inside from 
2tt. to 4ft. or so in depth, which may be filled with 
fermenting manure or the like when required, and thus 
provide a more or less brisk bottom-heat. Those of the 
former class may, or may not, be heated by means of 
hot-water pipes, according to the purpose for which they 
are, intended, but where necessary the usual method is 
to run an ordinary 2in. pipe all round the pit, placing 
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