DETACHED GREENHOUSES, ETC. 181 



same scale) is a section, showing the arrangement of the 

 benches, etc. 



In constructing the furnace for flue heating, the size 

 of the furnace doors should be, for a greenhouse twenty 

 by fifty, about fourteen inches square, and the length of 

 the furnace bars thirty inches. The furnace should be 

 arched over, and the top of the inside of the arch should 

 be about twenty inches from the bars. The flue will 

 always "draw" better if slightly on the ascent through- 

 out its entire length. It should be elevated in all cases 

 from the ground, on flags or bricks, so that its heat may 

 be given out on all sides. The inside measure of the 

 brick flue should not be less than eight by fourteen 

 inches. If tiles can be conveniently procured, they are 

 best to cover with ; but, if not, the top of the flue may 

 be contracted to six inches, and covered with bricks. 



After the flue has been built of brick to twenty-five or 

 thirty feet from the furnace, cement or vitrified drain 

 pipe, eight or nine inches in diameter, should be used, as 

 they are not only cheaper, but radiate the heat quicker 

 than the bricks ; they are also much easier constructed 

 and cleaned. Care should be taken that no wood work is 

 in contact with the flue at any place. It should be taken 

 as a safe rule, that wood work should in no case be nearer 

 the flue or furnace than eight inches. In constructing, 

 do not be influenced by what the mechanics will tell you, 

 as few of them have any experience in such matters, and 

 are not able to judge of the dangers resulting from wood 

 work being in close contact with the heated bricks. 

 There are scores of greenhouses burned every year owing 

 to carelessness or ignorance in allowing the brick work 

 to be too close to the wood. The cost of such a green- 

 house (twenty by fifty feet), at present prices, heated by 

 flue, would be about six hundred dollars, or about sixty 

 cents per square foot covered by the greenhouse. 



