36 



THE AMATEUR S GREENHOUSE 



heated with a flow-and-return four-inch pipe on each side, and 

 openings in each wall must be provided to allow the heat to 

 escape into the pits to keep the inmates safe. There is no ob- 

 jection to the pits being heated with a separate system of 

 pipes, from the same boiler, of course. Two-inch pipes will 

 be large enough for the pits ; and one passing down one pit 

 and up the other will be quite sufficient for ordinary purposes, 

 especially as the lights can be covered with mats in severe 

 weather. The greenhouse floor should be laid with white and 

 black tiles, unless stone can be procured at a cheap rate ; but 

 for the floor of the pits a bed of ashes will suffice. The open- 

 ings in the wall should be provided with shutters, in case the 

 frames should be occupied with hardy plants, that merely re- 

 quire protection from too much moisture ; if side-lights are 

 adopted, they should be made to elide, instead of pushing out, 

 and, of course, be made to slide from the inside. 



The next example is an improvement on the foregoing. 

 The pits are removed, the space is wider, and the angle at ridge 

 more sharp, and more ample staging is provided, the centre 

 stage having the advantage of a course of pipes on each side, 

 connected with the flow near the boiler. The width is seven- 

 teen feet, the height to the ridge nine feet. This would make 

 a good vinery, and a number of plants could be grown beneath 

 the vines, though, to be sure, some caution would be required 

 in selecting them, and it would not be prudent to clothe the 

 roof densely with the ample foliage of the vine?. 



aECTIOX OF SPAN-EOOF GEEEXHOrSE WITH STAGING AND HOT WAT1,E 

 PIPES. 



Now, we propose to go to work and build a cheap span-roof 



