472 



PIT§ AND FRAMES. 



do if admitted higher up the sides. The 

 bottom of the pit is to be rendered per- 

 fectly dry, by having a drain run along 

 its whole length ; and the floor should be 

 composed of 10 or 12 inches of coarse 

 gravel or coal-ashes, to absorb the spilt 

 water that falls from the pots while 

 watering. The circulation of air passing 

 over the surface of the floor will also 

 greatly tend to keep it dry. With suffi- 

 cient coverings to the glass, many plants 

 may be wintered in such a pit, which 

 will give room in the greenhouse for the 

 larger and more delicate species. In 

 section Rafters will be shown the kind 

 of rafter we use in the gardens at Dal- 

 keith for such pits — as, from their con- 

 struction, we can cover the glass roofs 

 most conveniently with asphalt felt, or 

 wooden shutters, made exactly of the 

 same size as the glass sashes. With such 

 Covering, we require no fire heat ; and 

 were it no other than the saving of the 

 breakage in glass, such coverings are well 

 worth the expense of making and of 

 putting on. Such pits as these are in- 

 valuable to amateurs. 



Conservative pit, with bottom ventilation. — 

 The annexed cut, fig. 673, represents 



Fig. 673. 



what we think would be an excellent pit 

 for wintering bedding-out plants, young 

 heaths, or other young greenhouse stock. 

 Build the pit upon the pigeon-hole prin- 

 ciple, as high as the ground-level a a, and 

 above that in 9-inch brick-work. Build 

 retaining-walls b 6, 9 inches distant only 

 from the side walls of the pit, similar to 

 those where dung linings are used. 

 Cover the spaces thus formed with thick 

 boarding, to be shut down in cold weather 

 to exclude the frost, as shown at c, and 

 opened in mild weather, to promote a 

 free circulation of air through the pit, as 

 shown at d. The plants being set upon 

 open trellis-work, the spilt water in the 

 process of watering would fall down into 



the bottom of the pit, which ought to be 

 well drained and covered with coal-ashes. 

 To render such a pit as useful and com- 

 plete as possible, hot-water pipes 3 inches 

 in diameter may be laid, as shown at e, 

 to be used only in severe frosts, and 

 when the boarded coverings are also 

 down. Indeed, if sufficient covering be 

 laid over the roof, fire heat will be seldom 

 required. A pure and dry atmosphere 

 should be kept up in such pits, which 

 will secure the plants against both cold 

 and damp. Such a pit may, with every 

 propriety, be constructed under the sur- 

 face of the ground, when the soil is 

 quite dry and gravelly ; otherwise it 

 should stand above the ground - level, 

 with a view to secure perfect dryness 

 within. Wherever the soil is damp, or 

 the situation liable to inundation, conser- 

 vative pits should be elevated above the 

 surface rather than sunk under it : that 

 elevation may extend to the height of 

 2 feet, thus securing freedom from damp, 

 and bringing the plants, particularly if 

 small, nearer to the eye. 



Span-roofed cold pit. — The annexed fig. 

 674 shows the section, and fig. 675 the 

 Fig 674 ground-plan, ofa 



conservative pit 

 for protecting 

 half-hardy plants 

 during winter. 

 The side walls are 

 of 9-inch brick- 

 work, both for strength and for resisting 

 the cold. The roof is in the span form, for 

 convenience and 

 light. The floor 

 should be of pav- 

 ing tiles, but laid 

 open in the joints 

 for admitting the 

 air from the flues 

 below to ascend 

 amongst the 

 plants. The floor 

 is supported on 

 brick walls 9 

 inches thick, 

 and from 6 to 

 9 inches high. 

 Their position is 

 shown in the 

 ground-plan, as 

 are also the open- 

 ings cccc in the side walls for the admission 



