408 



PLANT-HOUSES. 



tors built in the front wall a. The cold air, 

 on entering, comes in immediate contact 

 with the side of the tank, and also passes 

 through under it, in openings 4 inches 



square left on purpose, thereby becoming 

 warmed before reaching the plants. The 

 back wall is built hollow, (as all our 

 brick walls are:) the cold air entering 

 near the top by openings, 4 inches square, 

 made in the north side of the wall, 

 descends through the wall, and enters the 

 house close to the floor by similar open- 

 ings inside — these remain open night and 

 day. The top ventilation is accomplished 

 by the ridge opening along its whole 

 length, as described and exemplified in 

 section Ventilation. The roof is a span 

 without rafters or framed sashes, the 

 astragals being dovetailed into the side- 

 wall plates and ridge-boards. They are 

 kept in their proper places by means of 

 an iron bar 1 inch square, extending the 

 whole length of the house, and perforated 

 under each astragal, to admit of the 

 latter being screwed down upon the bars. 

 The ridge is supported by upright wooden 

 columns, 5 inches square — their bottoms 

 being set on, not in, stone blocks a foot in 

 height. An inverted arch of iron circular 

 rod is attached to these uprights, and, 

 curving upwards, is screwed into the iron 

 bars above alluded to. This is done 

 more with a view of suspending plants 

 from, in rustic baskets or ornamental 

 earthenware pots, than for supporting the 

 roof, which would be strong enough with- 

 out such aid. It is glazed with sheet 

 glass 2 feet long and 9 inches wide, 16 

 ounces to the foot. There is no iron in 

 this house excepting the inverted arches 

 and the bar for regulating the astragals 

 — the boiler employed being of lead. 



The length is 30 feet, breadth 22 feet, 

 and the height 1 1 feet from the floor to 

 the ridge. 



From the roof were suspended many 

 species, both attached 

 to blocks of wood, 

 and also having their 

 roots enveloped in 

 balls of moss, &c. 

 Many of the orchids, 

 ferns, &c, were so 

 treated, some of 

 which require a 

 greater degree of hu- 

 midity than others, 

 particularly the lat- 

 ter. To afford them 

 this supply in a gra- 

 dual and constant 

 manner, just over them was attached to 

 the edge of the astragal a small piece of 

 putty, which intercepted the stream of 

 descending condensed steam, and caused 

 it to fall upon the moss, block of wood, 

 or whatever else the plant was attached 

 to ; and this supply of water could be 

 directed to their roots, if it was judged 

 inexpedient for it to fall on the stems or 

 foliage, by attaching a small wire to the 

 putty, and fixing the other end at that 

 point where it was wished the water 

 should be discharged. 



The centre part of this house was two 

 years ago transformed into an aqua- 

 rium, in which the Victoria Regia and 

 other aquatics are growing luxuriantly. 

 The water-tanks in front have also been 

 removed, to afford space, and a smoke-flue 

 substituted ; while the large tank in which 

 the Victoria is planted is heated by a system 

 of leaden pipes supplied from the original 

 leaden boiler, agitation being given to the 

 water by mechanical power, and a con- 

 stant supply of fresh water heated, by 

 causing it to pass through a pipe coiled 

 in the furnace, before it is discharged 

 into the tank. A waste-pipe leads the 

 overflow water into a tank in the adjoin- 

 ing house. 



Orchids are, however, still cultivated 

 in this house, and are set upon a trellis 

 placed over the flues, and suspended from 

 such parts of the roof as will not make 

 them shade the plants in the tank ; and 

 the back wall is also covered with them. 



The orchid-house at Kew is also of the 

 span-roofed form, heated by hot-water 



