2183. The German mushroom-house (figs. 654, 655, and 656.). It is a common practice with German gardeners to grow mushrooms on shelves, and in pots and boxes, placed behind stages, or other dark parts of their forcing-houses otherwise unoccupied. (Dietrich's Gartners Lexicon; Ransleben's Briefe, &c.) This practice was carried to Russia, and from Russia was brought to England by Isaac Oldaker, who thus describes the sort of house adapted for the German practice:�'The outside walls (G, H, figs. 654, 655.) should be 8.5 ft. high for four heights of beds, and 6.5 ft. high for three heights, and 10 ft. wide withinside the walls: this is the most convenient width, as it admits of a set of shelves 3.5 ft. wide on each side; and affords a space through the middle of the house 3 ft. wide for a double flue and a walk upon it. The wall should be 9 in. thick, and the length of the house as it may be judged necessary. When the outside of the house is built, make a floor or ceiling over it (as high as the top of the outside walls) of boards 1 in. thick, and plaster it on the upper side (e e) with road-sand well wrought together, 1 in. thick (this will be found superior to lime), leaving square trunks (f) in the ceiling, 9 in. in diameter, up the middle of the house, at 6 ft. distance from each other, with slides (s) under them, to admit and take off air when necessary; this being done, erect two single brick walls (v v), each 5 bricks high, at the distance of 5.5 ft. from the outside walls, to hold up the sides of the floor-beds (a a), and form one side of the air-flues (t u,t u), leaving 3 ft. up the middle (t x t) of the house for the flues. Upon these walls (v v) lay planks (t v) 4.5 in. wide, and 3 in. thick, in which to mortise the standards (t k) which support the shelves. These standards should be 3.5 in. square, and placed 4 ft 6 in. asunder, and fastened at the top (k k), through the ceiling. When the standards are set up, fix the cross bearers (i n, i n), that are to support the shelves (o o), mortising one end of each into the standards (i), the other into the walls (n). The first set of bearers should be 2 ft. from the floor, and each succeeding set 2 ft. from that below it. Having thus fixed the uprights (t k), and bearers (i n), at such a height as the building will admit, proceed to form the shelves (o o) with boards 1.5 in. thick, observing to place a board (d d) 8 in. broad and 1 in. thick, in the front of each shelf to support the front of the beds. Fasten this board on the outside of the standards, that the width of the beds may not be diminished. The shelves being complete, the next thing to be done is the construction of the flue (P, fig. 656.), which should commence at the end (L) of the house next to the door, run parallel to the shelves the whole length of the house, and return back to the fireplace, where the chimney (s) should be built: the sides of the flue inside to be the height of four bricks laid flatwise, and 6 in. wide, which will make the width of the flues 15 in. from outside to outside, and leave a cavity (t u, figs. 654, 655.) on each side, betwixt the flue and the walls that are under the shelves, and one (x y) up the middle, betwixt the flues, 2 in. wide, to admit the heat into the house from the sides of the flues. The middle cavity (x y) should be covered with tiles, leaving a space (h) of 1 in. betwixt each tile for the admission of the heat. The top of the flue, including the covering, should not be higher than the brick walls that form the front of the floor-beds. The reason why the sides of the flues are recommended to be built stronger than usual, is, because they support the walk. The walk itself is formed by three rows of tiles, the outside rows making the covering of the flues, and those of the centre row are what cover the middle cavity (x y), as above mentioned; the outside cavities (t u) of the flue are left open, the tiles which are placed over the flues being laid so as not to cover these cavities, which allows the heat of the sides of the flues to rise upwards.' (Oldaker, in Hort. Trans., vol. ii)
