PLANTS, WITH GLASS ROOFS. 221 



its walls are of turf or earth ; and instead of glass sashes, frames of reeds, or 

 boards, or thatched hurdles, or other coverings, are substituted. The cold pit is 

 used for protecting plants in pots not in a growing state, or for preserving culi- 

 nary vegetables from the frost. In warm situations and dry soil, it has a thick 

 mound of earth, or thick wall of turf, which in either case should be coped 

 so as to be kept as dry as possible. Even in the case of brick pits, an outer 

 casing of dry turf prevents to a very great extent the effects of frost, and 

 sudden changes of temperature. The casing may also be made of boards, 

 where great neatness is an object, leaving a cavity to be filled with coal- 

 ashes, charcoal, dry sand, or other non-conducting materials. In pits of this 

 kind, with glass sashes instead of opaque covers, many hard-wooded green- 

 house plants, such as camellias, myrtacese, heaths, &c. may baserved through 

 the winter without any artificial heat, care being taken to adapt the nightly 

 coverings to the weather. The usual width of such pits is from six to eight 

 feet ; height of the back wall, three to five feet ; and of the front wall, two 

 to three feet. A pit to be heated by a bed of tan within, and exterior cases 

 of dung, may be of the same or larger dimensions, with the back and front 

 wall pigeon-holed or panelled, (490), and with boarded covers to protect the 

 linings from rain and wind, hinged to the wall -plate. Instead of exterior 

 linings for supplying extra heat, flues or hot- water pipes may be introduced 

 along the front and ends, or entirely round the pit ; sometimes with a plat- 

 form of boards over them for plants in pots, or even for a bed of soil, but more 

 frequently separated from the bed of tan by a narrow wall, or by a partition of 

 plates or flag-stones. The width of the bark-bed in such pits is seldom less 

 than five or six feet, and eighteen inches of additional width is necessary for 

 the front flue, or six-inch pipes ; and double these widths if the flues or pipes 

 are carried round the house. For the more convenient management of pits, 

 they are sometimes constructed sufficiently high behind to admit of walking 

 upright there ; and a passage for that purpose is left at the back, of three or 

 four feet in width, and a door made in one end. The roof over the 

 passage is generally opaque and sloping to the north, as in fig. 157. To the 



possessor of a small garden, and 

 an amateur, this is a very de- 

 sirable description of pit, as in 

 it he may grow almost every- 

 thing, provided he does not 

 attempt too many kinds of 

 culture at once. The form is 

 very economical, from there 



Fig. K6. Span-roofed pit, with the roof over the path opaque- being as IllUch SUl'faCC of pit as 



there is covering of glass ; and the interior is very comfortable to work in, as 

 the operator need not stoop. If the ends were made of glass, it would be an 

 improvement, by admitting the morning and evening sun : it would then, 

 however, be entitled to be called a small house, instead of a pit. The sashes 

 of all pits are made to slide between rafters which are fixed to the plates of 

 wood, which form, partially or wholly, the copings to the walls. There 

 should be a bolt to each sash for fixing it when shut, and also when let down 

 for giving air, in order that there may be no risk of its being blown off by 

 high winds ; and all the sashes ought to admit of being readily taken off, for 

 the purpose of taking out, and putting in dung, tan, or other materials. 

 When the pit is ten or twelve feet in width the sashes may be in two lengths, 



Q 



