WARMING OF GLASS-HOUSES. 



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(fig. 98). This plan should never be used unless it is imperatively 

 necessary, for the rule to be observed in arranging all hot-water pipes 



FIG. 97. 



is for the water continually to rise till it has done its work, and then 

 to fall to the stove to be re-warmed. 



At the highest part of the pipes a small cistern is generally 

 placed. At my garden, in all my systems of warming I have 

 cisterns holding hundreds of gallons of water, so that the gardener 

 has always the command of warm water to water his plants. 



Hitherto hot-water systems have always been arranged by a flow 

 and a return pipe ; however, I conceived the idea of using a single 

 pipe arranged with a gradual rise. I have a frame heated with a 

 single pipe ; the hot water flows along the top of the pipe and returns 

 along its lower surface, thus having two currents in an opposite 

 direction traversing the pipe at the same time (fig. 99). The 



FIG. 99. 



circulation proves excellent and rapid, and answers most efficiently, 

 I can strongly recommend its adoption in every case where a single 

 pipe is competent to communicate sufficient heat. 



In warming any house, it is desirable to have an excess rather 

 than a deficiency of heating surface, and the pipes should be placed 

 in those situations where the cold air can be immediately brought in 



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