102 MARKET GARDENING. 



center posts, the side sills by heavy posts four feet high 

 and five feet apart. These posts rest on brick founda- 

 tions. At one end of the line of houses is a glass-roofed 

 cross-section covering a footwalk of thirty inches, and 

 covering also a plant bench forty inches wide set against 

 the wall ; on this bench may be raised any of the small 

 crops. Under the bench mushrooms are successfully 

 grown, the light being excluded by cloths hanging in 

 front and reaching to the ground, the mushroom spawn 

 pricked out on a level surface, the earth and manure 

 mixture being first properly compounded, and upon the 

 degree of its proper preparation much depends the 

 measure of success. 



The ventilation is, of course, a most important sub- 

 ject. As a rule, plants do not get enough of it, but of 

 this experience alone can be the only guide. The glass 

 is thick, 10x12, put on with oil and lead mixture, the 

 panes lapping and fixed in place by S hooks. The glass 

 selected is free from blisters. The cost of such houses is 

 estimated at three dollars per running foot. 



For houses where the operations are sufficiently ex- 

 tensive to warrant the employment of a night engineer, 

 steam, as the heating agent, is found to be more efficient 

 than hot water, as by steam perfect control of the tem- 

 perature can be had, but, in houses so small as not to 

 profitably sustain the expense of a night engineer, hot 

 water is recommended ; as the water well heated up at 

 bed-time may, with banked fires in the furnace, be relied 

 upon to sustain a safe temperature till morning. 



The heating system in the houses under considera- 

 tion is by four six-inch steam pipes passing through each 

 house, of sixteen feet in width, such pipes carried about 

 eight inches above the level of the surface beds. Pro- 

 tection from wind is a valuable factor in the economical 

 heating of a forcing house, as in bleak situations more 

 than double the coal is required than is consumed in shel- 



