94. GREENHOUSE CONSTRUCTION AND HEATING. 
of begonias, roses, bouvardias, carnations, or anything of 
the kind, in pots. The side beds, it will be seen, are 
solid, being filled up with ashes, rough soil, or the like, 
and are surfaced with ashes or sea-sand. This last, by the 
way, is a capital material for surfacing the beds or stages 
in plant houses, being at once perfectly sweet and porous, 
and a preventive of insects, while it also presents a smooth 
and, when moist, sufficiently firm surface. The middle of 
the house is shown fitted with a flat-topped raised staging, | 
and if this is constructed of flooring boards or the like and 
trestle legs, held together by means of a few screws only, so 
as to be easily removable, it can be taken down in the 
autumn and the space rendered available for standing large 
chrysanthemums in pots, or the like. A low, solid bed may 
of course be substituted, if preferred, or the space planted 
with tomatoes during the summer. This type of house, 
but with low or level beds, is indeed admirably adapted for 
the growth of tomatoes on a large scale. 
Shelves.—Shelves near the glass are extremely useful 
for certain purposes, such as for standing seed-pans, 
boxes, or'small pots on, and they are frequently fitted in 
propagating and other houses. Being usually fixed close to 
the glass, any plants placed on them cannot become drawn, and 
make a very short and sturdy growth, but as soon as they 
become tall enough to touch the glass, or nearly so, when 
the tops are liable to suffer from frost outside, as well as 
from hot sun, they must of course be removed elsewhere. 
Shelves are constructed, as a rule, of ordinary flooring 
boards, from 6in. to Yin. wide, and may be supported by 
means of iron or wooden brackets, or in any convenient 
manner. A very common position for shelves in the low 
