enough to extend around the frame three feet each way. Pack
this down well, especially around the edge, put on a second and
third layer until you have a well-trodden and compact bed of manure
at least two and one half feet in depth. Place the frame in the
center of this bed and press it down well." A two-inch layer of
decayed leaves, cut straw, or corn fodder, spread over the manure in
the frame and well packed down, will help to retain the heat.
Ventilate the bed every day to allow steam and ammonia fumes to pass
off.

"The soil inside should be equal parts of garden loam and
well-rotted barnyard manure. Tramp well the first layer of three
inches. To make it entirely safe for the plant seeds in the hotbed,
add another layer of the same depth. Use no water with garden loam
and manure if you can possibly help it."

"Before sowing any seeds put a thermometer in the bed three inches
deep in the soil. If it runs over 80 degrees Fahrenheit, do not sow.
If below 55 degrees it is too cold; you will have to fork it over
and add more manure. If the bed gets too hot, you can ventilate it
with a sharp stick by thrusting it down into the soil."

Another way that the old gardeners have to make a hot bed is with
fire. On a large scale this is cheaper, though more complicated than
the fermentation of manure. In making this kind choose your location
and build the frames as before. "Cut a trench with a slight taper
from the east end of the plot to the end of the hotbed, and on under
the ground to about four feet beyond the end of the bed. This taper
to the outlet will create a draught and so keep a better fire. Arch
this over with vitrified tile. The furnace end where the fire is
should be about six feet away from the bed. When the trenches are
completed, cover over with the dirt that was taken out of them. Two
such trenches under the frames will make a good hotbed. Anyone can
do this sort of work."

A hotbed can also be heated by running steam pipes through the
ground, but unless you happen to be where exhaust steam could be
used, this method is not economical except for big houses. The care
and expense of a separate steam plant would be too great to pay,
unless for growing winter vegetables for market or flower culture.
If you go into that on a scale large enough to pay, new problems at
once demand solution.

Vegetables under glass have kept pace with other crops. Within
fifteen miles of Boston are millions of square feet of g