MARKET GARDENING UNDER GLASS. 105 



and boiler in a pit in the center of the house, so that all 

 radiated heat may be utilized. 



Third Carrying the smoke flues from the furnace 

 the entire length of the house, and beneath one of the 

 beds if the house be a double one ; then carrying the 

 smoke beneath the middle sill, provided the length is 

 not more than one hundred feet in each direction, so as 

 to get all the heat out of the smoke which otherwise 

 would pass out of the stack. 



Fourth By keeping the glass down near the beds 

 the volume of air to be heated may be reduced to a 

 minimum. 



Fifth By carrying hot water pipes, in large air 

 flues, twelve or fourteen inches below the surface of the 

 plant beds, the tops of the flues planked over with open 

 joints, so that a large volume of warmed air may pass 

 upward through the soil. By the several plans of under- 

 ground heating Mr. Bingham claims that fifty per cent, 

 of the heat wasted in other houses is saved, and in the 

 health of the plant is found a practical application of 

 the rule relating to human hygiene that to most fully 

 preserve health it is best to keep the "feet warm and 

 the head cool." 



For ventilation, one or all the outside sashes may be 

 pulled down, or off, that on warm days the plants may 

 be literally turned out of doors to free air and direct 

 sunshine. The rafters and caps are of original design, 

 and the entire arrangement is claimed as a combination 

 of many of the best principles of forcing house construc- 

 tion. The joints are so made as to be very thoroughly 

 air tight. The surface of the beds is nearer the glass 

 than in other plant houses, the roof structure being set 

 down upon the natural surface of the earth ; the house, 

 in fact, being nothing but a roof or combination of 

 roofs, the paths under the ridge being excavated twenty- 

 four inches deep in the solid earth, the plant beds being 



