174 



2rAXUAL OF GARDENING 



smoke and hot air, instead of being carried directly upwards, is 

 carried through a shghtly rising horizontal pipe that runs 

 underneath the beds. For some distance from the furnace, 

 this flue may be made of brick or unvitrified sevrcr pipe, but 

 stove-pipe msij be used for the greater part of the run. The 

 chimney is ordinarily at the farther end of the run of beds. It 

 should be high, in order to provide a good draft. If the run of 

 beds is long, there should be a rise in the underlying pipe of at 

 least one foot in twenty-five. The greater the rise in this pipe, 



the more perfect 

 will be the draft. 

 If the runs are 

 not too long, the 

 underlying pipe 

 ma}^ return un- 

 derneath the 

 beds and enter a 

 chimney directly 

 over the back 

 end of the fur- 

 nace, and such a 

 chimne}^, being 

 warmed from the furnace, will ordinarily have an excellent 

 draft. The underlying pij^e should occupy a free space 

 or pit beneath the beds, and w^henever it lies near to the_ 

 floor of the bed or is very hot, it should be covered with 

 asbestos cloth. While such flue-heated hotbeds may be 

 eminently successful with a grower or builder of experience, it 

 may nevertheless be said, as a general statement, that when- 

 ever such trouble and expense are incurred, it is better to make 

 a forcing-house. The subject of forcing-houses and green- 

 houses is not discussed in this book. 



The most satisfactory material for use in hotbed and cold- 

 frame sash is double-thick, second-quality glass ; and panes 



209. Useful kinds of waterins-pots. These are adai:)ted 

 to different uses, as are different forms of hoes or 

 pruning tools. 



