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one is desired to be built, and varied to suit local circumstances. A few examples will be given. It is plain that if any one have a grapery or con servatory, a propagating house or pit can be advantageously put beside it, that shall have only half of what is represented in figs. 1 and 4. This is seen in fig. 7, where (a) is the (see fig. 7) span-roof of the grapery, (b, b) the lean-to propagating houses, (c) the walk, and (d) the table, and on the opposite side the table is reversed and placed next to the grapery, a more inconvenient form, as the glass roof is always in the way of the operator's head unless the pit be quite deep; and it leaves. a space as part of the vinery border. The hot bed form may be used as in fig. 8, where (a) is the table, (see fig. 8) heated by the hot water tank (f) supported by the joists or studs under it, and (b) is a small pit, and (c) the sash that open, the operator being on the outside. Robert B. Leuchar; in the edition of his book published in 1857, by Moore & Co., figures a double hot-bed house, the ground plot of which is seen in fig. 9, in which (a) is the heater under a cover between the two hot beds (b) and (c) (see fig. 9). The water pipes are seen heating the tanks But he figures the tanks as used for an air heater, which is a disadvantage for the equalizing material should rest on the tank as at (a) fig. 8, and not on his plan as at (g) fig. 9; and experience has shown that though water circulation is easy in pipes, it is difficult to make two tank houses circulate from one stove, therefore it is better that a broad flume or part of the tank connect at (h), the dotted lines, and the return pipe be from (i) changing the division board (j) to (k), or be by the dotted pipe lines as represented.
On a former occasion, I have said, when remarking on graperies, the theory of them should be that they are all of glass, with no opaque parts in their construction, as the dark parts, as rafters, posts, and other shadow casting parts, cut off the sunlight disadvantageously. And in the roofs already given, they have been on the same principle of having the glass on small fixed rafters, that the glass surface may be as extensive as possible. But this is not necessary in a propagating house, indeed so far from being the case, operators of such glass roofed propagating houses are obliged to be frequently adjusting the cloth shades or awnings over their glass whenever the sun shines; or for convenience they coat the glass on either the upper or under side with whitewash, or a mixture of whitewash and clay, thus making a permanent awning or shade. This suggests the use of white enamelled glass, as well as the blue glass, proven to be an aid in germination, while it excludes the intense light. Those who may take any interest in the glass used, are referred to an English publication called, The Gardener's Chronicle, of August 16th, 1848, where Mr. Hunt gives an account of experiments with different colored glass; the yellow rays of light, are shown to prevent the germination of seeds, and cause plants to die, red light will allow growth but it is sickly; while the blue light was a remarkable stimulant of germination and growth. The glass of the extensive Palm house at Kew, also an English structure, three hundred and sixty-three feet long, one hundred feet wide, and sixty-three feet high, was the subject of much scientific research, and then it was proven that a "very pale yellowish green glass" gave the greatest penetration
into the house of the rays of the sun. The latter is the glass for graperies, conservatories, and the "hardening off" stand in the propagation of grapes, while the blue shade should serve as a shade and a stimulant to the propagation table, and would be universally used, were its cost not so great. But since a shade of some kind must be used, it is apparent, that the whole roof need not be of glass. Fig. 10 represents a roof, where only that portion (a) over the propagating table is made of glass, while a somewhat broad space at the eaves marked (c) is of wood or other roofing material; and the broader space, (see fig. 10), marked (b, b) is also of wood, tin, slate or other roofing material; the several parts of the roofing lapping the one over the other, so as to shed rain. It is plain that the edge of the roof cannot be very wide, or it would cast a perfectly opaque shade over the table, while the ridge portion may cover all the walk, with no disadvantage. Thus the cost of glass, its breakage, and the radiation of heat through the glass will be lessened. Some such houses have been built with a narrow belt of glass, and have succeeded well for the early growth of vines, especially in the cold months of the year, or the very hot.
Another modification of the house is to build it above ground. Thus figs. 11 shows (see fig. 11) several forms, as (a) a house embanked and turfed, (b) a house with a sloping stone wall, (c) with a pilastered wood or brick thin wall, and (d) a hollow or chambered brick wall.
Fig. 12 shows a circular house, such as were the supposed "perfect houses" a few years ago; where (a) is the central propagating table, and (b) the outer propagating table, built of brick, with either a Polmaise apparatus, or the space beneath the table being a large flue; in either case the chimney rising at (c) the north side of the circle. At (d) is (see fig. 12) seen the curve of the roof, and without the further detail of the structure, we pass on to fig. 13, which shows an octagon shaped house with some ornaments, also entirely above ground. Fig. 14 is the ground plot of fig. 13. In fig. 13, the space (a, a, a) to the dotted lines on the glass roof, should be enameled or blue glass all around the house, except at the north end, admitting shaded light to propagating table, and (b, b, b) is the clear glass, and should be the "pale yellow green" Kew-house glass, admitting the unshaded (see fig. 13) sunlight to the "hardening off," and growing stand beneath it. And there is a door in the doorway that projects somewhat from one side of the house, while (d, d) are the capped ventilators at the top of the house, and (e) is the chimney from the pit beneath the large stair shaped hardening off table. In fig. 14, a ground plot of fig. 13 (see fig. 14), (f,f,f) is the propagating table continuous on all sides of the house, from one side of the doorway to the other side of the doorway; while (9, 9, g) is the walk and space for the work and care of the house, and the space (h, h) is the hardening table, on the stairs on which the plants, when potted, are placed to mature their roots, and may be grown the remainder of the season; and (i) is the chimney of the stove or heater beneath the hardening table.
Fig. 15 is a more elaborate, oblong structure, with a similar ground plot to that of the last fig. It will be seen by applying the scale that the panes of glass in figs. 13, 15, 34, and elsewhere, are represented as larger than they should be. Without attempting any more designs of