CONSERVATIVE PITS. 



471 



1 A shed of this description is an indis- 

 pensable adjunct to every well-ordered 

 garden, and in the present case it serves 

 as a roof to the mushroom-house. In the 

 centre of each vault, shown in fig. 670, a 



Fig. 670. 



circular ventilator, d, 9 inches in diameter, 

 will be made, having a stone or cast-iron 

 stopper, with a folding ring. The boiler 

 is placed at e on ground-plan ; the direc- 

 tion of the hot-water pipes is indicated by 

 the lines, and the whole roof of the mush- 

 room-house is covered over with pave- 

 ment, which at the same time forms the 

 floor of the shed above. Mr Forsyth 

 objects to cast-iron shelves "on account 

 of the rust — and to slate shelves, as being 

 generally cold and damp, and therefore 

 not suitable to the purpse ; but he knows 

 of no objection to shelves built of bricks 

 and mortar, and kirbed with hewn stone 

 3 inches wide, and batted together with 

 lead." "We presume, upon the same 

 ground, that he would also object to 

 stone shelves. For ourselves, we do not 

 see how such could be colder or damper 

 than bricks, in a structure kept at a 

 moderate temperature by fire heat. The 

 plan altogether deserves attention. 



§ 5. — CONSEEVATIVE PITS. 



Conservative pit with solid walls, fig. 671. 

 — The protection afforded by this pit 

 during winter will be found sufficient for 

 preserving many of what are called half- 

 hardy plants, such as ericas, many New 

 Holland plants, fuchsias, myrtles, and 

 many others. The pots should be plunged 



in finely-sifted coal ashes, to preserve 

 their roots from being frozen ; that mate- 

 rial being also, at the same time, an excel- 

 lent corrector of damp, which is the 

 greatest enemy to plants during their 



Fig. 671 



state of rest. Frost may be excluded by 

 covering the sashes with felt or canvass 

 shutters, and ventilation effected by tilt- 

 ing up the bottom and top ends of the 

 sashes alternately. Such pits should be 

 6 feet wide, 3 feet 6 inches high at back, 

 and 2 feet 6 inches in front, and the walls 

 9 inches in thickness. 



Conservative pit with hollow walls, fig. 

 672. — This is a modification of the last, 



Fig. 672. 



adapted for smaller plants. The walls 

 are all above the surface, and are built 

 hollow the more effectually to exclude 

 the frost. The plants are set on a level 

 trellis stage, with openings at least an 

 inch between the bars. This stage is 

 movable, to admit of its being lowered or 

 elevated to suit the height of the plants. 

 Ventilation is secured by openings along 

 the back and front of the pit at a a. These 

 are furnished with revolving brass regis- 

 ters, so that more or less air may be admit- 

 ted according to the state of the weather. 

 The air passes into the space b, and, 

 rising through the trellis, circulates 

 through amongst the plants, without 

 coming directly upon them, as it would 



