88 GARDENING FOR PROFIT. 



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 may 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 had 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. 



The cost of such a greenhouse, twenty by fifty feet, 

 heated by flue, when built alone, would be, at present 

 prices in this vicinity, about $12 per running foot, or 

 $600 ; but if three were built together, connected at the 

 gutters, and thus save the outer walls, as shown in the 

 chapter on Forcing Pits and Greenhouses in another part 

 of this book, the cost of construction for three houses 

 heated by smoke flues would not exceed $10 per running 

 foot, or $1,500 for three houses each twenty by fifty feet. 



