shroom-growing uncertain, and the
maggots destroy the mushrooms. This system allows each bed a bearing
period of two months. After yielding a crop for some seven to nine weeks
the beds are pretty well exhausted and hardly worth retaining longer.
They might drag along in a desultory way for weeks, but as soon as they
stop yielding a paying crop we clear them out and start afresh.

And when the mushroom season is closed we lift out and remove the
manure, clean the boards used in shelving, and give the cellar a
thorough cleaning,--whitewash its walls and paint its woodwork with
kerosene to destroy noxious insects and fungi.

[Illustration: FIG. 5. BASE-BURNING WATER HEATER.]

[Illustration: FIG. 6. VERTICAL SECTION.]

The heating apparatus consists of one of Hitchings' base-burner boilers
with a four-inch hot-water pipe that passes around inside the cellar,
and it deserves special mention because of its economy, efficiency, and
the satisfaction it gives generally. This boiler needs no deep or
spacious stoke-hole. Here it is set under the stairway in a pit four
and one-half feet long, by three feet wide, by eighteen inches deep; it
is not in the way, and there is plenty of room to attend to it. The
heater, like a common parlor stove, has a magazine for the supply of
coal. It has a double casing with the water space between and down to
the bottom of it, so that when set in a shallow pit there is no
difficulty whatever about the circulation of the water in the pipes. The
hot water passes from the boiler to an open iron tank placed two feet
above it, as shown in the engraving, and thence down through a
perpendicular pipe till it reaches and enters the horizontal pipes that
pass around the cellar and, returning, enters the boiler again near its
base. The boiler and pipes are filled from this tank, which should
always be kept at least half full of water, and looked into every day
when in use, so that when the water gets lower than half full it may be
filled up again. About 134 running feet of four-inch pipe are included
inside the cellar (sixty-four feet on each side and six feet across at
further end); this gives 134 square feet of heating surface, or a
proportion of about a square foot of heating surface for every fifteen
cubic feet of air space in the cellar. This proportion is more than
ample in the coldest weather, but beneficial in so far that there is no
need to fire hard to maintain the proper temperature. A three-inc