NEW YORK: GEO. E. WOODWARD & CO., 31 BROAD STREET, and ORANGE JUDD COMPANY, 245 BROADWAY.
Entered according to Act of Congress, in the year 1865, by GEO. E. & F. W. WOODWARD, In the Clerk's Office of the District Court of the United States, for the Southern District of New York.
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[Pg 20] 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 columns under the rafters, which are indispensible under a straight roof of considerable span, to prevent its settling down, and the opening of joints in glass and wood work, admitting the cold air from without.
A good proportion for a grapery or conservatory, is twenty feet in width by fifty feet in length. We think the width should never be much less where the roof is of double pitch. Single pitched houses should not exceed sixteen feet in width.[Pg 21]
Mistakes are frequently made in the erection of structures for the growth of plants which, notwithstanding all the skill and art of experienced gardeners, render it impossible to arrive at satisfactory results. One of the most common of these is the excessive height of the roof. Men of experience in the construction and use of glass houses, have satisfied themselves that the lowest elevation which the uses and purposes of the building will admit, is the best. The difference in temperature between the floor and roof of a house twenty feet in height, will vary from ten to fifteen degrees. It is obviously desirable that there should be as little difference as possible in the temperature of the air on the ground, among the lower parts of the plants, and in the upper regions of the house. The nearer we can approach an equilibrium, the better success will attend our efforts. Nurserymen generally, and sometimes other cultivators, understand this, and they build their plant houses with roofs of low pitch, affording scarcely room to stand upright within them. Their plants are thus brought near the glass, and they grow stocky and firm, presenting quite a different appearance from the attenuated specimens frequently met with in private establishments.