VAEIOUS FORCING METHODS. 83 



covered with five or six inches of horse manure. This 

 covering was to prevent the heat from escaping from 

 the soil too rapidly. It was then ready for the steam 

 to be turned into the tunnels. In the illustration one 

 of the tunnels has been uncovered to show its construc- 

 tion. 



To conduct the steam a one and one half inch pipe 

 was carried above ground from the boiler to one end 

 of the central tunnel, a distance of 185 feet. A steam 

 hose long enough to reach each tunnel was attached 

 to this pipe through which to blow steam into the 

 tunnels. It was not the idea to give a constant supply 

 of steam, but to discharge a little into the tunnels each 

 afternoon, or as often as was necessary to maintain 

 sufficient warmth. A piece of tile was inserted into the 

 mouth of each tunnel to prevent the discharging steam 

 from tearing away the earth. 



The first steam was turned into the tunnels on 

 November 14. Steam was discharged into each tunnel, 

 not to exceed five minutes at a time, in order not to heat 

 the earth too hot in any single place. It required about 

 one hour of steaming the first day to bring the bed up 

 to the required temperature of 60 degrees. The dis- 

 tribution of heat throughout the bed was very uniform 

 and satisfactory. The moist steam seemed to permeate 

 the soil equally in all directions. 



After the first day, very little steaming was neces- 

 sary until the crop began to be produced. On an average 

 the bed was steamed about twice in three days and then 

 only for about five minutes for each tunnel. The soil 

 and horse manure mulch seemed to hold the heat very 

 well, the frequent steamings keeping up fermentation 

 in the mulch. 



The first picking was made in ten days. When steam 

 was not turned on until the last of December, the crop 

 was not ready until the middle of January. The results 

 are thus summarized by Horticulturist Whitten : — 



The steam, coming in direct contact with the soil. 



