GREEN-HOUSE STRUCTURES. 107 



it should only be given just enough to cover the edge of 

 the pane, (from one-eighth to one-fourth of an inch.) If 

 given too much, the water gets in, and when it freezes it 

 cracks the glass. 



GROUND GLASS. 



The use. of ground glass is gradually becoming greater 

 every season. I confess to having had a prejudice against 

 it, thinking that it obscured the sun's rays too much, and 

 was apprehensive that, for that reason, it would not be 

 so well suited for plants in winter ; but from an examina- 

 tion last season of a large lot of green-houses glazed with 

 such glass, and used for various purposes, I am convinced 

 that it obscures the light only in a very small degree, if at 

 all ; for in the green-houses referred to, plants of all de- 

 scriptions, both for foliage and for fruit, as well as for 

 producing flowers in winter, were under culture, and they 

 could not have been in better condition than they were. 

 The advantage of the ground glass is, that it entirely 

 prevents the burning of the foliage, which is a source of 

 great annoyance in the cultivation of plants and fruits. 

 I am so convinced of the utility of it, that whenever I 

 again construct more green-houses for my own use I 

 shall use it. It costs but little more than the glass in 

 common use, and must be a great saving, as it does 

 away with the necessity for shading during the summer 

 months, shading being mainly used to prevent the burn- 

 ing or blistering of the leaves. 



HEATING BY HOT WATER. 



The mode of heating in general use is by hot water, 

 though many beginners with limited means still use smoke 



