GREENHOUSES, HOTHOUSES, FORCING-PlTS. 251 



8 inches, and a ventilator, is laid out, allowing space for an iron bar gauge, wliich 

 connects eacli sash with the other, and receives the ventilating-sash between, 

 for which nine inches are required. Having marked the space required for each 

 sash, gauge-bar, and ventilator, proceed to transfer corresponding marks to 

 the ground : the marks thus made are the centre of a series of piers of brick 

 or stone, each 14 inches square, and equidistant, if a lean-to house, from 

 the back wall : if a span-roofed structure, the same is to be done for the oppo- 

 site side. 



679. These piers, if for 16-foot sashes, will be better if made 18 inches 

 thick, and built buttress-fashion ; that is, sloping outward to their base, so as 

 to bear better the thrust of the sashes. When the piers have settled suffi- 

 cient!}', the saddles are fixed on them, in a bed of cement. 



680. The saddle consists of a block of wood fitting on the piers, the upper 

 surface of which is cut to an angle according with the angle of the house. 

 Upon this saddle another angular frame of wood is placed, which fits the angle 

 of tlie saddle, and runs along the whole range of piers, performing at once the 

 office of wall-plate, gutter, and support to the sashes : for the upper surface 

 is a hollow angle, receiving the lower ends or horns of the sashes, while it is 

 so set on the piers as to have just sufficient inclination to carry off the water 

 to a pipe at the lower end. All the lengths necessary to connect this gutter 

 are joined over the saddles, the joints being made water-tight either by putty 

 or cement, and pitched inside and out. 



68 r. In lean-to houses, the top of the sash simply leans against the wall, 

 being bevilled to fit it : they may be covered with cement, or not ; but in span- 

 roofed houses the sashes are bevilled so as to support each other at the proper 

 angle, and a pair of strong iron hinges sunk into the wood, and screwed firmly 

 to the styles of each sash, keep them in their proper place : while a ridge or 

 coping of wood, fitting them exactly, covers the whole, and is screwed on to 

 the top rail of the sashes, fitting closely to the upper ends of the ventilators 

 when closed ; for these, like the cap, are raised above the surface of the 

 sashes. 



682. The ventilators, consisting, as we have already explained, of two 

 smaller sashes, each one half the length of the lights, and nine inches wide, 

 are hooked on to the left-hand style of each sash by two hinges, the hook 

 being screwed into the style, and the eyes into the lower part of the ventilator, 

 lapping over the right-hand style of the adjoining sash. A stay opens 

 both ventilators at once when required, or the upper ventilator alone may be 

 opened. The upper ventilator falls into the lower by a sloping bevilled edge, 

 and both are hooked together by a hook-and-eye on the lower surface. A small 

 piece of wood sliding in a groove made in the side-styles of the sashes, protects 

 the house from drip, and the water is carried off into the gutter below by grooves 

 on the upper surface of the styles of the sashes. The ends are fixed under the 

 styles of the outside roof-sashes, and secured to each other by means of cross- 

 plates let into each, and firmly screwed up ; the doors being hung in the usual 

 manner, and opening to the right or left, or inside, as may be desired. 



