336 Memoirs of the Caledonian Horticultural Society. 



than room for their expansion. These being put in, the openings left for 

 introducing the pipes are built up. 



" The section of that part of the pits to be used for the culture of pine- 

 apples is 10 in. higher, both on the south and north, than that for melons. 

 The glass roof consists of two sashes, with a ridge-tree between them If in. 

 thick, to which the rafters are fixed, and the upper ends of the sash-stiles 

 hinged. The hinge crosses the top of the ridge at the height of the sash, 

 having ajoint on each side, with movable pins ; the middle part is screwed 

 to the ridge, and the tails to the middle of the sash-stiles, before the cope 

 or upper part of the ridge-tree is fixed on. The front or south sash is 

 made more than double the length of the north one, that the influence of 

 the sun's rays may reach the back of the plant-pit. The sashes are 2 ft. 3 in. 

 broad. 



" The rafters are Hin. thick between the sashes, and continue at this 

 thickness for fully a quarter of an inch above the sides of the sashes. They 

 are then reduced on both sides three eighths of an inch, the remainder 

 being six eighths of an inch thick, and ljin. high, with a cope on the top of 

 it, which is mitred into the cope of the ridge-tree. This forms a place for 

 receiving wooden shutters to cover the glass at night in winter. To the 

 under part of the rafters, at the height of the wall-plates (which are 2 by 

 4i in.), are nailed pieces of deal If in. thick, and broader than the rafters 

 by 1 in. on each side. At the bottom these are checked into the wall- 

 plates ; and, together with the wall-plates, form the rest for the under side 

 of the ashes. On each side of the rafters, near the bottom, and to the 

 edge of the sash-rest, an iron stay is screwed, having a hook at the upper 

 end, and moving on the screw-nail with which it is fixed. An iron eye is 

 screwed into the edge of the rest for the hook to enter. On the under 

 side of each sash-stile other eyes are screwed, and so placed, that, when 

 the sashes are opened and the end hooks of the stays placed in them, the 

 gardener may have headroom to do any work in the pits. All the sashes 

 at the bottom are furnished with iron handles. Air is given by tilts in the 

 common way. 



" It will be found that there is a sufficient degree of bottom heat in the 

 plant-pits either for the culture of ananas or melons, and other plants ; the 

 flags at the bottom (r) and the sides (e e) of the plant-pits, being all in con- 

 tact with a mass of heated matter, which is excluded from the action of 

 the external air. It will also be seen that there is a sufficient degree of 

 heat for the atmosphere of the pits. Take, for instance, the end division, 

 or melon-pit : the depth of the steam-chamber is 3 ft., the plant-pit is 

 1 ft. 8 in., and the breadth of the cover of the flue is 1 ft. 2 in. ; making 

 together 5 ft. 10 in. : the length of the chamber wall on both sides is 

 9 ft. 6 in. ; together equal to 19 ft. This, multiplied by 5 ft. 10 in., gives 

 111 superficial feet nearly. The end of the chamber wall is 8ft. 4 in., 

 which, multiplied by 3 ft., the depth of the chamber, gives 25 ft; both 

 together making nearly 136 sq. ft. of surface in close contact with a mass 

 of stones heated to about 170°. But should this be found to give out too 

 little heat, a considerable increase may be obtained by making the steam- 

 flue return on each end of the pits as some of them have been built ; or, if 

 a drier and greater degree of heat be required than that given out by the 

 brick wall of the chamber, this may be easily accomplished by constructing 

 the chamber wall either of Arbroath pavement, or the kind found in the 

 neighbourhood of Dundee, which is still better adapted for the purpose, as 

 it is not only very hard, and impervious to moisture, but may be got of any 

 suitable dimensions. In constructing the chamber of these materials, two 

 flags, of 4 ft. 10 in. long and 3| in. thick, may be set up on end, the height 

 of the chamber and flue, and two others of any length laid horizontally 

 between them, and so on, till the chamber is completed. They will require 



