106 VEGETABLE GARDENING 



The total length of the houses here described may vary 

 according to circumstances. The house from which this 

 plan is taken was 100 feet long. It was heated with a second 

 -hand tubular steam boiler, which at an outside tempera- 

 ture of zero has to carry about five pounds pressure to 

 maintain a temperature of 65 or 70 F. Two inch pipes 



conduct the heat from 

 the boiler, one line of 

 pipe running up each 

 side of the house and 

 both returning through 

 the center at B, back to 

 the boiler. The furnace 

 room is an excavation 

 10x12 feet and six feet 

 deep at the north end of 



Fig. 41. Valley in market gardener's green- 



house, showing the way the sashbars are at- the HOUSC, built With 3. 

 tached to the plate. 



good wall and roof. The 



length of pipe required is 450 feet. In the extreme north- 

 ern states, more pipe radiating surface would perhaps be 

 required for best results . 



The entire cost of material for a structure of these 

 dimensions, boiler and pipes included, amounts to about 

 $450. The cost of steam fitting will have to be added to 

 this, but the rest of the work can be done by any man of 

 ordinary intelligence. Mr. Greiner, whose description 

 has been largely followed in the above, says that he likes the 

 pipes all above ground, as here recommended, for forcing 

 vegetables; but if wanted for starting seedlings and for 

 general propagating purposes the pipe had better be placed 

 ten to twelve inches under the surface, and encased in an 

 ordinary three-inch drain tile as shown at D, Fig. 40. In 



