126 



GLASS HOUSES FOR VEGETABLE CROPS 



Benches and beds. 



In the narrow houses it has been customary 

 to have raised benches three or four feet in 

 width along the walls, with one or more others 

 six or eight feet in width in the middle of the 

 houses, the walks being eighteen to twenty-four 

 inches in width between the benches, or the walks 

 placed along the walls, and all of the benches have 

 a width of seven or eight feet. In some cases, the 

 gutters are supported by means of arches so as 

 to permit the placing of walks under the gutters, 

 where the space is less useful than in the center 

 of the houses. The raised benches are often built 

 entirely of wood, or with wooden bottoms and some 



fGflBLE mETER 



in five feet in the width of the house. This some- 

 times hastens development 10 to 25 per cent. 



Heating by means of flues. 



Various methods are used for heating vegetable 

 houses and all have their merits under certain con- 

 ditions. The old-fashioned flue answers very well 

 for small houses in sections where wood can be ob- 

 tained cheaply for fuel, but it is not very reliable 

 in the colder climates, except after severe cold 

 weather is over. A brick furnace is constructed at 

 one end of the house, with a length of three to 

 five feet according to the length of the wood. An 

 opening can be left at one end near the bottom to 



■Glass gable 



Fig. 183. Details o( construction of a long-slope greenhouse. 



less destructible materials such as gas-pipe or 

 cement for the supports. In some cases, cement 

 has been used with good satisfaction for construct- 

 ing the bottoms of raised benches. The practice is 

 becoming more common in the construction of 

 houses designed entirely for vegetable forcing, to 

 do away with raised benches. Sometimes the 

 ground is handled exactly as in a garden, all of the 

 ground being covered with the crop with the ex- 

 ception of a narrow space every fifteen or twenty 

 feet for use when watering or ventilating. It is 

 more common, however, to keep the surface soil a 

 foot or more above the level of the walks. This 

 certainly helps in the drainage of the soil. If the 

 soil is inclined to be heavy, it is an excellent plan 

 to sink the walks or to fill up the beds so as to 

 make the surface at least eighteen inches above 

 the walks. The soil can be held in place by cement 

 walls that need not be more than two inches thick 

 at the top. If drain tiles are run about a foot be- 

 low the surface, either across or lengthwise of the 

 beds, it will aid both in the drainage and the aera- 

 tion of the soil. Even better results can be secured 

 by running one of the heating pipes in a tile once 



serve for a draft, and a tile or iron smoke-pipe 

 should lead from near the top of the other end, 

 with a slight ascent, to a smoke-stack at the far- 

 ther end of the house. There should be a door for 

 putting in the fuel in the end or top of the furnace. 

 In addition to the increased danger from fire when 

 a flue is used, these furnaces give more or lefs 

 trouble with smoke and do not work well when the 

 flue is more than fifty feet long. For use in fire hot- 

 beds, which are really low and narrow greenhouses 

 used for starting lettuce and similar crops in the 

 spring, a flue with a tile running through the soil 

 at the depth of a foot answers very well. 



Heating with hot water. 



For greenhouses with less than 5,000 square feet 

 of glass, a hot water heating system will be more 

 satisfactory than either a flue or steam system, as, 

 although it will cost nearly 50 per cent more to 

 install, it will be more economical in fuel and will 

 require less attention than a steam-heating plant, 

 besides giving a more regular heat if run without 

 a regular night flreman. 



In a hot-water system the water is heated in 



