VENTILATION. 



291 



along, to be fixed with a staple to an 

 upright stauncheon, n, placed at each 

 end of the pit. When the lights are to 

 be raised the reverse way, it would be 

 only hooking on the rod to the opposite 

 sides of the frames. By this simple con- 

 trivance, the frames may be all raised at 

 once, and to a pitch that the glass may 

 receive the rays of the morning and 

 evening sun perpendicularly, while it 

 catches that of the mid-day sun at an 

 angle of incidence." 



The front upright sashes of lean-to 

 houses, and also the side sashes of span- 

 roofed ones, are often opened and shut 

 p. as shown in the 



annexed dia- 

 gram, fig. 394. 

 The sash a is 

 hinged to the 

 top wall-plate b, 

 and is opened 

 to any extent, 

 by pushing out 

 the handle c, 

 which is fur- 

 nished with 

 holes, that fit 

 to an iron stud 

 fixed in the low- 

 er wall-plate d. 

 This handle is attached to the sash by 

 a universal joint, so that, when the 

 handle is drawn in on 

 shutting the sash, the 

 handle, instead of lying 

 amongst the plants, is 

 turned aside, and laid 

 upon the wall-plate, if 

 found to be more conve- 

 nient. 



Another modification 

 of this method is shown 

 by fig. 395, where the 

 handle is curved up- 

 wards, but which acts 

 upon the same principle. 



Span-roofed houses might be advan- 

 tageously ventilated as in the annexed 

 diagram, fig. 396. Let the side walls be 

 built hollow, whatever may be their 

 height ; and 4-inch square ventilators be 

 placed along both sides of the house imme- 

 diately under the wall-plate a a, and 2 feet 

 apart from each other. The hot-water 

 pipes, flues, or heated air-chamber, are to 

 be under the floor within a hollow-walled 



cavity b b, and covered with an iron- 

 grating footpath. The ridge is to be open 



Fig. 396. 



Fig. 395. 



and arranged as in fig. 389. The cold air 

 will, by entering at a, descend, or rather be 

 drawn down, the hollows in the wall, and, 

 entering the heated cavities bb, will become 

 genially warmed, and ascend into the house 

 through the gratings, not in currents, but 

 in a uniform and diffused manner, and 

 escape through the ridge at c. In winter, 

 this, or a similar mode of ventilation, is of 

 paramount importance ; as nothing is so 

 hurtful to plants placed in a warm cli- 

 mate as to be exposed to sudden draughts 

 of cold air, which in the majority of 

 houses is the case. In summer, when 

 greater ventilation is required, the side 

 sashes may be opened, or ventilators in 

 the wall of a larger size may be employed ; 

 as at that season the atmospheric air is 

 sufficiently heated to be rather beneficial 

 than the reverse to plants. Were the 

 apertures for the admission of cold air on 

 a level with the pipe or flue chamber, this 

 might be found neither advantageous to 

 plants, nor sufficient for the exclusion of 

 vermin. 



Nicol — whose ideas in horticultural 

 architecture were in general original — 

 says of ventilators that they are useful at 

 those times when it may be imprudent to 

 open the roof or front sashes, and that 

 they may be constructed in various ways, 

 and placed in different situations. " If," 

 says he, " the hothouse have a shed be- 

 hind it, they might be made to open in 

 the manner of a common window, near 

 to the top of the back wall ; and three in 

 an ordinary sized house would be enough. 

 I lately made," he continues, " four venti- 

 lators in a house that had no sheds be- 

 hind it in this manner. When the wall 



