in spring. The foundation is of wood, locust posts
being used, with boards nailed upon both sides and coated with coal tar.
The house is forty one feet long and sixteen feet wide, and is heated by
a tank constructed as follows: brick piers are built three feet apart on
which are laid common blue flag stones six feet long and two feet wide.
The sides and divisions of the tanks are built of brick, and cemented
inside. One of Hitchings & Co.'s boilers furnishes the heat, and is
connected with the tank by two inch iron pipe. Above the tanks are the
propagating beds as shown in figure 8. The tank, with the exception of
that part across the end of the house is covered with beds and no
provision is made for other heat than that radiated from the sides, and
that portion left uncovered at the end. In the practical working of the
house, this has been found insufficient, and pipes have been introduced
for atmospheric heat, the tanks being still retained for bottom heat.

[Illustration: FIG. 8.--_Section._]

[Illustration: FIG. 9.--_Ground Plan._]

[Illustration: FIG. 10.--_Perspective View._]

DESIGN No. 3.

The following plan is similar to the one previously given, and was
erected for the same general purposes. It has, however, been found to
answer so well for a general green-house, that there is but little
forcing or propagation carried on. At the east end is the boiler pit,
seed room, &c.; the roof of which is of tongued and grooved boards bent
to the curve of the roof and battened. The foundation is of stone, and
the whole house of a substantial character. Bottom heat is furnished by
brick tanks built in the same manner as before described, the water in
which is heated by iron pipes running through the tanks (see section
_Fig._ 12.) The pipes being also used to heat a grapery near by on a
higher level, it was necessary to carry them thus. This arrangement for
bottom heat is not as good as when the water flows directly into the
tank from the boiler. There is a large bed in centre of house in which
pots of plants are plunged, and considerable shelving at ends of house.
Bottom ventilation is obtained by six inch earthen drain pipe, placed on
a level with the floor inside and running through the wall and up to
the surface of the ground outside, where they are covered with wooden
caps for regulating the amount of air required. Ventilators are placed
over the doors and in the opposite end of house, in addition to which,
the s