the glass not being lined with foliage, as in the case of graperies, the
diffusion of light would not be materially obstructed. Under some
circumstances, Green-houses may be placed east and west, as when a
portion of the house is to be devoted to the purposes of propagation.
The north side can thus be advantageously used, being less exposed to
the sun's rays. Many plants requiring partial shade, would find there,
also, the most favorable conditions for their cultivation.

Green-houses or Conservatories attached to dwellings, will answer in
almost any position that convenience may require, or the taste suggest,
as they are generally not so much intended for the growth of plants as
for their display when in bloom. The sun should shine upon them,
however, at least half the day. When they are intended for the growth of
plants, then the more sun-light they can have the better.

FORMS OF HOUSES.

Until within a few years past, the straight-pitched roof, both single
and double, has been used almost exclusively in the construction of
glass houses. That there is an advantage in this form over some others,
on the score of expense, and because there is less skill required in the
builder, we admit, but there the advantage ends. The superiority of the
curvilinear form is now beginning to be very generally acknowledged, on
account of its being more graceful and pleasing to the eye, and because
of its superior adaptability to the growth of plants. When to the curved
roof is added the further improvement of circular ends, as illustrated
in some of the designs furnished in this work, we have secured forms of
houses that will admit double the light of the old-fashioned, heavy
sliding sash structures which were built twenty-five years ago. Happily
these old glass houses are fast falling into decay, and but few new ones
are erected on their model.

Curvilinear roofs possess advantages over those of a straight pitch
which may be briefly summed up as follows:

1. A larger run of roof for a given width of house, and consequently,
more and better diffusion of light.

2. A greater power of reflecting the sun's rays, because of the
constantly varying angle at which they strike the glass.

3. A greater amount of head room within the building, without the
necessity of high parapet walls, or perpendicular sides.

4. Greater strength of the roof, enabling it to resist pressure from
accumulated snows, without the necessity of supporting co