FORCING DEPARTMENT. 313 



is required, are of cast metal : the lights are com- 

 posed of wood rims, and copper bars ; over the rafters 

 is a wood coping, which prevents the wet getting 

 in between the tiles and rafters, and, likewise, 

 lessens the external action of the atmosphere : the 

 same effect is produced within, by the new con- 

 trivance of a safety water gutter, composed of wood, 

 and lined with lead, and screwed on the lower part 

 of the rafters, which is an invention of Mr. Jones, 

 and of real importance, as it prevents any of the 

 water that collects on the lower part of the rafters 

 from falling on the foliage, at the same time, that 

 it gives them a neat appearance. 



The sash bars, or astragals of the lights, Fig. 3, 

 consist of sheet copper, the lower side of which is 

 hollow ; a circumstance which, as Mr. Atkinson has 

 justly observed, obviates every objection that at- 

 taches to wrought iron, or cast metal ones, of being- 

 conductors of heat and cold. This tube, by being 

 always full of air, transforms the bars into non-con- 

 ductors. 



Hot-Houses, constructed with these materials, 

 and in this manner, I consider preferable for every 

 practicable purpose, for durability, neatness, admis- 

 sion of sun and light, and as non-conductors, to any 

 other description of house that I have yet seen. 



The lights of the forcing range are all glazed with 

 crown glass, seven by seven inch squares. See Fig 2. 

 There is one improvement of peculiar importance, 

 introduced by Mr. Jones in the glazing of these 

 houses, which deserves to be more generally adopted 

 than it has yet been, as it is the most effectual pre- 

 2 s 



