£88 



ON THE CULTURE 



much importance should hitherto have been so little 

 attended to. 



The water which falls on the roof of a hot-house 

 is in most seasons sufficient at least for the Pine- 

 plants contained in it : I say in most seasons, for 

 the quantity collected from the dews in dry weather 

 is almost incredible : whether it proceeds from the 

 exhalation arising from the frequent waterings in 

 the hot-house, in which case the same water may 

 possibly be used several times over, or whether the 

 great heat in the hot-house attracts the watery 

 particles floating in the open air during the night, 

 are points that I shall not take upon me to de- 

 termine. 



When a hot-house is building, by bestowing a 

 very trifling additional expense, (which will save 

 a continual one afterwards,) the rain that falls on 

 the roof may be brought into a cistern placed in 

 any part of the building. 



When this is intended, it will be necessary to 

 have a course of stone project in front nine inches 

 beyond the wood plate that supports the roof ; 

 which stone should have a groove cut in the middle, 

 five inches in breadth, and the depth of the groove 

 at the beginning should be half an inch, increasing 

 one-eighth of an inch in every yard in length. 

 This is a good proportion. The groove will receive 

 the water that falls on the roof, and if worked in 

 the above manner, the water will descend to one 

 end of the stove if small ; but if the hot-house be 

 large, it will be more convenient to descend from 



