226 tanner s bark, but it is much more economically provided, on the score of labour at least, by hot-water pipes. Pits of many different forms have been designed, but it may be sufficient here to describe one or two which can be recommended for general purposes. Fig. 20 represents a simple and useful form of pit designed for the Chiswick garden by Mr Sibthorpe, and published by Mr R. Thompson (Gardener s Assistant, 499). It is 7 feet wide, the front wall 2 feet high, the back wall 3i feet. The walls are one brick thick, or 4J inches, with a 4-iuch pier a at every third rafter, the FIG. 20. Sibtliorpe s Plant Pit. foundations being respectively 9 and 14 inches. The wall plates both at front and back project so as to allow the drip to fall clear of the walls ; and fillets of wood fixed to their under surfaces and close up to the wall on each side serve to maintain both the wall plate and top of the wall steadily in their positions. Such a pit used for cucumbers or melons might be excavated slightly below the ground level to admit of bottom heat being supplied by a bed of fermenting dung, over which the soil should be placed in the usual way, bringing the plants up near to the glass ; or the bottom heat might be supplied by the tank system of heating or by hot- water pipes. For small store plants of any kind the interior might be filled up with any porous materials, finishing off with a surface of fine coal-ashes at a suitable height, or larger plants might be accommodated by using it as shown, without any filling up. Heat can easily be supplied by one or two 4-inch pipes, front and back, according to the temperature required ; but if fermenting material be used for this purpose, the lower portion of the walls, as far up as will be covered by the interior filling, should be pigeon-holed. An excellent pit for wintering bedding-out plants or young greenhouse stock is shown at fig. 21. It is built upon the pigeon hole principle as high astheground level a, a, and above that in 9- inch brickwork. At a distance of 9 inches retaining walls b, b are built up to the ground level, and the spaces between the two are covered by thick boarding, which is to be = ___^__ shut down as shown at c in Fig. 21. ventilated Plant Pit. cold weather to exclude frost, and opened as shown at d in mild weather to promote a free circulation of air through the pit. The height of the pit might- be reduced according to the size of the plants ; and, to secure the interior against frost, a flow and return hot-water pipe e should pass along beneath the staging, which FIG. 22. Hot-Bed Three-Light Frame. should be a strong wooden trellis supported by projections in the brickwork. The water which drains from the plants or is spilt in watering would fall on the bottom, which should be made porous to carry it away. For many plants this under current of ventila tion would be exceedingly beneficial, especially when cold winds [PITS AND FRAMES. prevented the sashes from being opened. A pit of this character may be sunk into the ground deeper than is indicated in the figure if the subsoil is dry and gravelly, but in the case of a damp subsoil it should rather be more elevated, as the soil could easily be sloped up to meet the retaining wall. For all useful purposes these two forms of pits will suffice, but Fran there will always be found occupation for some of the common hot bed frames (fig. 22). They should be made of the best red deal. 1 J inch thick. A convenient size is 6 feet wide, 24 inches high at the back and 15 in front ; and they are usually 12 feet long, which makes three lights and sashes, though they can be made with two lights or one light for particular purposes. Indeed, a one-light frame (fig. 23) is often found very ^ convenient for many purposes. The lights should be 2 inches thick, and glazed with 21 oz. sheet glass, in broad panes four or five to the breadth of a light, and of a length which will work in conveniently and economi cally, very long panes being un- desirable from the havoc clused Fia 23. -One-Light Frame, by accidents, and very short ones being objectionable as multiply ing the chances of drip ; panes of from 6 or 8 to 12 inches long are of convenient size for garden lights of this character. In all gardens the frames and lights should be of one size so as to be interchange able, and a good supply of extra lights (sashes) may always be turned to good account for various purposes. FIG. 24. Span-Roof Frame. Boulton and Paul s span-roof garden frame (fig. 24) may under some circumstances be useful as a substitute for the three-light frame. It is adapted for storing plants in winter, for nursing small plants in summer, and for the culture of melons and other crops requiring glass shelter. These frames are made 11 inches high in front, 22 at the back, and 32 at the ridge, with ends of 1^-incli red deal ; the sashes, which are 2 inches thick, open by gearing, the front and back separately. The lights are hinged so that they can be turned completely back when necessary. This more direct and ready access to the plants within is one of the principal recommendations of this form of pit. 13. Mushroom House. Mushrooms may be grown in Mus sheds and cellars, or even in protected ridges in the open roon ground, but a special structure is usually devoted to them. A lean-to against the north side of the garden wall will be found suitable for the purpose, though a span-roofed form may also be adopt ed, especially if the building stands apart. The internal ar rangement of a lean- to mushroom house is shown in "fig. 25. The length may vary from 30 feet to 60 feet ; a convenient width is 10 feet, which admits of a 3^ feet central path, and beds 3 feet wide on each side. The shelves should be of slate a, a, supported by iron uprights b, b, each half having a front ledge of bricks set on edge in cement FIG. 25. Lean-to Mushroom House. c, c. The slabs of slate forming the shelves should not be too closely fitted, as a small interval will prevent the accumulation
of moisture at the bottom of the bed. They may be supported
