PLANTS, WITH GLASS ROOFS. 



161 



means of a mechanical contrivance that opens or shuts a part or the 

 whole of the ventilating space at once with the utmost ease. These 



houses, as will be seen, 

 admit a maximum amount 

 of light, as those slim but 

 strong rafters produce 

 scarcely any shade. Num- 

 bers of them have recently 

 been erected throughout 

 the country, and cultiva- 

 tors speak highly of their 

 cultural merits. The ma- 

 terials used in the interior 

 of plant-houses, such as 

 shelves for supporting 

 pots of plants, pathways 

 for walking on, walls for 

 enclosing tan or other fer- 

 menting matter in pits, are 

 bricks, flagstones, slates, 

 wood, and cast iron. The 

 paths are sometimes co- 



Fig. 132. 



Patent sash-bar. 



vered with open gratings of cast iron, which admit of the soil under 



Fig. 133. 



Lean-to house (Beard's patent}. 



