78 How to Make the Garden Pay. 



ground terra-cotta flue C, 10 inch diameter, which runs from the 

 boiler room to the smoke stack B at the north end. The steam 

 pipes are placed from 18 inches to 6 inches under the centre 

 of each bench, as shown in D D D D, resting on a concrete and 

 covered with a 5 -inch horse-shoe tile. The concrete is made 

 of one part Portland cement and 5 parts gravel, laid two feet 

 wide and two inches in thickness. Two lines of I- or i^-inch 

 pipe under each bench would be an improvement, but the heat 

 radiation is good, and the surface of the benches warmed pretty 

 uniformly, certainly much more so than by Mr. Baker's plan of 

 simply encasing the 2-inch pipe with a 3-inch tile. With the 

 hot-water system the distance of underground pipes from the 

 surface should be more uniform, but a double line of pipes in 

 this case is still more desirable. 



While theory and the opinion of expert growers gives 

 preference to heating from above ground for forcing purposes, 

 Mr. Bingham has, practically, most excellent success with the 

 underground system. "The ground is thoroughly warmed 

 several inches deep," says Mr. B., " and retains the heat much 

 better than the air, which comes in contact with the cold glass. 

 By keeping our source of heat lower, we get a much larger per 

 cent, of its value than by air-heating systems. Theoretically we 

 claim to save 50 per cent, of heat which is wasted by other plans, 

 and our trial has practically proved it." This is a matter yet 

 open for investigation ; but in the meantime it will be advisable 

 to place the pipes in the cheaper, handier and entirely safe way 

 in use in Mr. Baker's forcing houses, when the house is 

 intended chiefly or wholly for forcing vegetables. There is no 

 objection, however, to introducing the underground system for one 

 of the benches, as shown at D, page 74, mainly for plant growing 

 and propagating purposes, as also to try forcing for the com- 

 parison of results between the two systems. 



Provision has to be made for ventilation. The simplest 

 method consists in hinging every alternate outside sash, so that it 

 can be lifted, or in arranging it as explained for the cold plant 

 house, allowing every alternate outside sash to slide down or be 

 removed entirely. Mr. Bingham's house is also constructed in 

 such a way that the caps, rafters and sashes can be entirely taken 

 off* during the warm season, and stored in a convenient place 

 under shelter. At the approach of another forcing season, the 

 benches can thus be enriched and otherwise prepared for 

 cropping as easily and conveniently as beds in the open ground. 



I do not think that a simpler, cheaper, and safer forcing house 

 could be conceived than one built on the same general principles 

 here described. It combines the best features of the hot-bed and 

 the greenhouse, and will tend to elevate the undertaking of 

 growing vegetables and plants during the winter and early spring 



