280 



VENTILATION. 



weights are suspended by copper flexible 

 chains, by which the top ventilation goes 

 on simply, and without being seen ; while 

 the front ventilation, or supply of air, is 

 obtained by pulling down or raising up 

 the casement-windows forming the sides 

 of the house. 



Where new houses are erecting, advan- 

 tage will undoubtedly be taken of the 

 most approved modes, of which we have 

 given several examples ; and in the case 

 of houses already up, and imperfectly 

 ventilated, perhaps the simplest and 

 most effectual will be that recommended 

 by Mr Tweedie, and described in the 

 " Memoirs of the Caledonian Horticul- 

 tural Society." Fig. 366 shows a longi- 



Fig. 366. 

 k k 



tudinal section of a roof to be ventilated 

 in this way, on which, by sympathetic 

 movement, small tin, copper, or zinc 

 frames are lifted, with one or more panes 

 of glass in each, according to the opening 

 desired. In the diagram, k shows the 

 ventilators half open, and e the cord or 

 jack-line, to which the lever h is attach- 

 ed, balanced at one end by a weight g, 

 and made fast at the other by a movable 

 hand-pin. In one of the door-posts, 

 or other permanent piece of the end 

 framework, are several sockets, 6 inches 

 asunder. Into these sockets an iron 

 hand-pin is " introduced, regulating 

 the whole apparatus, by being moved 

 upwards and downwards, from socket to 

 socket, by the hand, according to the 

 various degrees of air- vent wanted. This 

 iron pin is fixed to a cord or chain c 

 passing through the stile or door-frame a, 

 over a pulley d, which cord or chain is 

 fixed to a rod or chain e e, having an 

 axle-joint at the junction of each lever. 

 The rod or chain, when the hand-pin 

 is moved up or down, moves horizontally 

 between a pulley d, and another pulley /, 

 fixed to the corresponding stile or door- 

 frame at the other end of the house, by 

 the action of a weight g attached to the 

 end of the rod by a cord or chain passing 

 over the second pulley /. This horizontal 

 rod or chain e e, in its motion thus pro- 



duced by the weight g, operates at every 

 joint, as already mentioned, on bent 

 levers h, which, being attached to hatches" 

 — that is, the openings for ventilation — 

 " k, lift or lower them so as to admit or 

 exclude the air, as circumstances may 

 require. The upper end of the lever is 

 fastened to the hatches by screw-nuts, 

 in order that, by unscrewing them, the 

 sashes may be freed from the levers, and 

 removed at pleasure for repair." 



The whole of the top sashes of a house 

 may be easily drawn up or down by 

 means of an endless screw applied to a 

 rack fixed on a circular rod of iron 

 extending the whole length of the house, 

 to which each sash is secured by a double 

 chain passing over a pulley fixed in the 

 wall. By turning the screw in one direc- 

 tion, the sashes are pulled down, and by 

 reversing the motion they are pulled up 

 again. They may also be kept stationary 

 at any point desired. The same machine, 

 slightly modified, will apply to the front 

 sashes or ventilators. The handle in 

 both cases should be acted upon at the 

 middle of the house. 



Mr G. Hurwood, of St Peter's Foundry, 

 Ipswich, has lately taken out a patent for 

 various mechanical modes of ventilating 

 both dwelling-houses and plant structures. 

 We consider his mode to possess consider- 

 able merit; and, indeed, so far as ventilating 

 hothouses is concerned, we see no difficulty 

 in applying Mr Hurwood' s principle to 

 those already built, and also to houses of 

 almost all forms. The roof-lights are 

 opened or closed by turning the handle e, 

 fig. 369, working, by means of a vertical 

 cog-wheel, in another horizontal wheel 

 placed in the back wall, and attached 

 to the lower end of a perpendicular rod 

 or axle, which is also furnished at top with 

 a similar cog-wheel, working in another 

 set obliquely, so as to suit the angle of 

 the roof — the latter wheel being attached 

 to the spiral screws, k in figs. 368 and 

 369, working in a toothed rack or plate 

 of iron, I in figs. 369 and 371, which is 

 attached to the side-rail of the sash to be 

 acted upon. From this it will readily be 

 seen that, by turning the handle e, fig. 

 369, the spiral screw, k, lets down or 

 draws up the sash to any extent of venti- 

 lation required, and keeps it steadily in 

 its place. In fig. 369 part of the wall is 

 broken away, to show the arrangement of 



