VENTILATION. 



283 



more perpendicular to the sun's rays in 

 winter and spring ; and although it would 

 be less so in the months of June and July, 

 yet this would be rather beneficial." 



Ventilating the upper part of fixed 

 roofs, by having the openings hinged, as 

 proposed by Mr Fortune in fig. 373, is 

 extremely objectionable on account of 

 the liability of the hinges to break or get 

 out of order, and also because the wind 

 has great power upon those parts of 

 the roof so opened. Where sufficient 

 ventilation cannot be obtained by open- 

 ings in the front and back walls of lean-to 

 houses, and in the ridge of span-roofed 

 ones, or at the top of dome-shaped ones 

 —and we see no reason why this should 

 not be completely accomplished, particu- 

 larly for the greater part of the year — 

 then it would be better to adopt sliding 

 sashes, to be used only in extreme cases. 



Fig. 375 exhibits a mode of opening 

 and shutting ventilators placed at the top 

 of the back wall of houses. 

 A lever is attached to an 

 upright bar of iron, which, 

 when pulled down at one 

 end by a cord or small chain, 

 throws the ventilator out, 

 by the other end becoming 

 elevated, and keeps it at any 

 point of elevation, by the 

 cord or chain being fastened 

 to studs in the wall within. 

 When the cord or chain 

 is loosened, the lid of the 

 ventilator falls back into its 

 place, being loaded with a 

 sufficient weight of metal 

 fixed to the low T er part of 

 its external surface. 



Fig. 376 acts much in 

 the same way, the opening 

 being effected by pulling 

 down one cord or chain, 

 and the shutting of it by 

 pulling another. 



M. Noisette, in Manuel du Jardinier, 



Fig. 375. 



Fig. 376. 



Fig. 377. 



describes a mode of 

 ventilation very com- 

 mon on the Continent. 

 It consists of a bar 

 of iron made to swing 

 upon a pivot fixed in 

 the rafter, as shown in 

 the annexed cuts. Fig. 

 377 shows the sash ele- 



vated ; fig. 378 the same w r hen it is shut. 



There are many objections, however, to 



this mode, of which 

 Fig. 378. the chance of the 



wind blowing the 

 sash to pieces is not 

 the least. It is, at 

 the same time, a 

 much more ingenious 

 mode of ventilating 

 than many we have 

 seen in use on the 

 Continent. We publish it with the view 

 of its being improved upon. 



A very excellent mode of admitting 

 cold external air into a heated vault in 

 which water tanks are placed, and allow- 

 ing it to enter the atmosphere of the house 

 or pit, is shown in section Tank Heat- 

 ing, fig. 259, as exemplified in the garden 

 of the Hon. Robert Clive. By this me- 

 thod a pipe, the orifice of which is level 

 with the ground surface, is made to pass 

 under the front wall, and to discharge its 

 air into a vault heated by hot-water 

 troughs. The air thus heated, and con- 

 sequently taking with it a large portion 

 of humidity, after passing over the whole 

 vault, is admitted into the house through 

 chimneys at the back of the bark bed. 

 These chimneys, as well as the mouth of 

 the air-pipe, are furnished with stoppers, 

 so that air can be admitted or excluded 

 at pleasure. 



We have tried the following mode of 

 ventilation, which will be understood by 

 a glance at the annexed diagram, fig. 379. 



Fig. 379. 



a is the orifice of a 4-inch cast-iron pipe, 

 fitted with a stopper to be used as occa- 

 sion may require. This pipe passes down 

 outside the parapet wall, discharges its 

 air into an open chamber in which the 

 hot-water pipes are placed, and which is 



