354 



FRUIT-HOUSES. 



transverse section, showing the founda- 

 Fig. 482. tions of back 



wall a, piers for 

 supporting the 

 slate pavement 

 forming the 

 passage b, as 

 well as that of 

 the piers c, up- 

 on which the 

 iron plate or 

 plinth a, fig. 

 484, reposes. 

 These latter 

 piers are placed 

 at equal dis- 

 tances, each 

 space being equal to the breadth of two 

 of the front sashes^ one of which is a fix- 

 Fig, 483, turerf, while 

 the other is 

 movable, as 

 shown at 

 e, fig. 484. 

 The mov- 

 ing sashes, 

 working on 

 two iron 

 wheels, one 

 of which is 

 shown at 

 b, fig. 484, 

 screwed to 

 the side 

 rails of the 

 sash c, and 

 running up- 

 on the se- 

 micircular 

 bead /, for- 

 ming part of the iron plate or plinth. 

 In the transverse section, fig. 483, d shows 



Fig. 484. 



the handle of a lever 

 placed in the centre 

 of each compart- 

 ment, which, work- 

 ing in an iron socket, 

 fixed in the back 

 wall, throws up the 

 back half of the roof, 

 for the purpose of 

 top ventilation. This 

 is, however, better 

 seen in fig. 485, 

 where the spiral 

 screw is shown at a, 

 working in a cog-wheel, b, which gives 



the required movement; and in fig. 

 486, the toothed quadrant a is shown, 

 which regulates the amount of ven- 

 tilation, as well as maintains it in its 

 Fig. 485. 



proper place. These cog-wheels, which 

 are acted upon by the spiral screws at 

 the centre, are all fixed to a longitu- 

 dinal axle of iron bar, extending the 

 Fig. 486. 



whole length of each compartment : one 

 of each is attached to the centre of each 

 movable roof- sash, so that, by the 

 operator turning the lever handle at the 



Fig. 487. 



centre of the structure, each of the 

 movable roof-sashes is acted upon either 

 for depression or elevation, thus venti- 

 lating the whole in about the space of a 

 j,. 4gg minute. Fig. 487 shows the 

 ' rafter, with the orifice a 

 for the longitudinal axle to 

 work into. Fig. 488 is a 

 section of the rafter, half 

 size. Fig. 489 shows the back 

 gutter, with the movable sash 

 attached to it by a hinge at a. 

 This gutter receives the water 

 of the back part of the roof, 

 as seen in the end elevation and transverse 



