GREEN-HOUSE STRUCTURES. 51 



is shut clown, the bar is hooked on to a pin that secures it 

 ID place, so that the sash cannot be moved by wind. I 

 am particular to describe this method of airing, as it is, as 

 far as our experience has gone, the best method we have 

 ever seen used. The ridge-poles are cut out exactly as is 

 shown at J, and the sash lays on the shoulder, braced by 

 the angle shown in the cut. The interior arrangements 

 are shown by the end section. G shows the bench, or 

 table, as it is completed. The space beneath the bench, 

 if bottom heat is required for propagating or other pur- 

 poses, should be boarded up below the bottom of the 

 pipes, the lower board being hinged, so that, in cold nights, 

 additional heat can be given to the atmosphere of the 

 house, if required. But for the general uses of growing 

 plants, the benches must be left open below, so that the 

 heat given out by the pipes will pass freely to all parts of 

 the house. If one house is wanted at a higher tempera- 

 ture than the others, it will be necessary to board up 

 along the posts from the ground to the top of the posts, 

 and by wholly or partially shutting the valves in the pipes 

 of the other houses, throw a greater heat into the one in 

 which the high temperature is wanted. The walks 

 through the house (K) are 2 feet wide, which leaves 4-J feet 

 on each side for bench room. These widths we find to 

 be the most convenient for the working of the plants ; 

 if narrower, too much space would be lost ; if wider, the 

 further side of tho benches could not be reached easily. 



The width of walk, however, must be determined by 

 what the green-houses are designed for : if for workmen 

 merely, 2 feet, or even less room, will do for the walk ; 

 but if visitors are to be accommodated, it should be at 

 least 2J feet in width. 



A brick shed (A) covers the boiler pit (F), and is 

 attached to the north end of the pits, the back wall 

 being about 12 feet high, the front 8 feet, width 16 feet ; 

 besides breaking off the north wind from the green-houses, 



