MODES OF HEATING. 61 



measuring about 7,000 square feet of glass, are copiously 

 drenched with water in one hour. If watered in the usual 

 way by watering-pots, the same number of hands would 

 not do the work as well in six hours. 



Of all labor-saving apparatuses yet introduced into our 

 gardens, this force pump is the most valued. 



As a green-house of this description is built for the pur- 

 pose of growing winter flowers, ample provision is made 

 for heating ; eight 4-inch pipes run its entire length, which 

 is about one square foot of heating surface to three square 

 feet of glass, or, in other words, one foot of 4-inch pipe to 

 three square feet of glass. This is the necessary quantity 

 when a night temperatare of 60 degrees is required in sec- 

 tions where the thermometer runs down to 10 or 15 be- 

 low zero. "When a temperature of 40 or 45 only is 

 necessary at night, one foot of heating surface to four feet 

 of glass is the rule. But, of course, much depends on ex- 

 posure, style of green-house, etc., so that no infallible 

 rule can be applied. 



CHAPTER XI 



MODES OF HEATIN G. 



Although I have incidentally alluded to the different 

 modes of heating in some other parts of the work, the 

 matter is one of so much importance, and one in deciding 

 about which the beginner is so often puzzled, that I will 

 again briefly refer to it a little more directly. 



The horizontal smoke flue is, we presume, the original 

 mode of heating green-houses, and where but one build- 

 ing is erected, with not more than 1,000 square feet of 

 glass surface, or where the beginner is limited in means, it 



