m 



PITS AND FRAMES. 



division of the tank, it will be observed, 

 is placed just above the centre line of the 

 columns of support, and takes the bear- 

 ing of the top of the tank, which is also 

 the bottom of the bed, and thus affords 

 stability and strength. The iron columns 

 c c c are placed 3 feet apart. Both divi- 

 sions of the tank act as flows ; the return 

 of the water is made through the pipes 

 bb. e e is a grating footpath extending all 

 round the pit; and through it, as well as 

 from between the supporting pillars at Jc, 

 light and air are admitted into the vault 

 /below, as also through the openings at g 

 and h h. The two latter are shown as 

 shut by a contrivance for regulating the 

 admission of atmospheric air from with- 

 out. These openings, which extend all 

 along the front and back, acting as blind 

 areas, are 9 inches wide, thus keeping the 

 walls under the surface dry, and admit- 

 ting air into the bottom of the vault 

 through the drains i i. Atmospheric 

 ventilation is effected by the usual open- 

 ing of the front lights and wall ventilators 

 near the top of the back wall. 



With such a command of ventilation 

 from below, the front lights need never 

 be opened. We are not aware that such 

 a house has ever been constructed, but 

 we are preparing plans at present for a 

 house of this kind, for the purpose of 

 growing melons, the plants to be planted 

 in the bed over the tanks, and trained 

 over the roof in the manner of vines. 

 The great degree of humidity, accom- 

 panied with a high temperature, required 

 in melon and cucumber houses, calls 

 loudly for a principle of ventilation for 

 the maintenance of a healthy atmo- 

 sphere, which, we doubt not, will be 

 secured by following out the principle 

 here explained. 



§ 4. — MUSHKOOM-HOUSES. 



Although the cultivation of the mush- 

 room has long been practised in Britain, 

 it must be acknowledged that, up to the 

 year 1815, when Oldacre introduced the 

 German mushroom - house and mode 

 of cultivation, it was carried on in a 

 very slovenly, if not a very uncertain 

 manner. 



In construction, the mushroom-house 

 should be made sufficiently large, as it 



will be found the most suitable place for 

 forcing rhubarb, sea-kale, chicory, &c, in 

 winter, not only securing a constant suc- 

 cession of these invaluable winter vege- 

 tables, but doing so at much less expense 

 and trouble than the modes in general use. 

 Lily of the Valley may also be forwarded 

 in it until the flower spikes begin to 

 appear, when they will have to be re- 

 moved to a lighter abode. Hyacinths 

 and all other bulbs may be also forwarded 

 by being plunged overhead in leaf mould, 

 or other light covering. In regard to 

 situation, it matters little what the aspect 

 be ; and hence it is generally made part 

 of the arrangement in connection with 

 the offices behind the range of hothouses, 

 or in cellars under them. Indeed, the 

 latter, if not too damp, is of all others the 

 best situation for the purpose. 



The German mushroom-house, fig. 660, is 

 thus described by Mr Oldacre in " Horti- 



cultural Society's Transactions," vol. ii. : — > 

 " The outside walls should be 8^ feet high 

 for four heights of beds, and 6| feet for 

 three heights, and 10 feet wide inside 

 the walls. This is the most convenient 

 width, as it admits of a set of shelves 3^ 

 feet wide on each side, and affords a space 

 through the middle of the house 3 feet 

 wide for a double flue and a walk upon 

 it." Hot-water pipes were not in use 

 when this house was erected. " The walls 

 should be 9 inches thick, and the length 

 of the house as may be judged necessary. 

 When the outside of the house is built, 



