HUMIDITY-REGULATED AND RECIRCULATING DRY KILE". 
11 
spray. This spray completely saturates the air in the flue B at what- 
ever predetermined temperature is required. The baffle plates D D 
are to separate all entrained particles of water from the air, so that 
it is delivered to the heaters in a saturated condition at the required 
temperature. This temperature is, therefore, the dew point of the 
air when heated above, and the method of humidity control may 
therefore be called the dew-point method. It is a very simple matter 
by means of the humidity diagram, 1 or by a hydrodeik, to determine 
what dew-point temperature is needed for any desired humidity 
above the heaters. 
flfliff 
Fig. 1. — Diagrammatic section of improved dry kiln with spray chambers in center. 
Double-truck form. 
Besides regulating the humidity the spray F also acts as an ejector 
and forces a circulation of air through the flue B. The heating sys- 
tem H is concentrated near the outer walls, so as to heat the rising 
column of air. The temperature within the drying chamber is con- 
trolled by means of any suitable thermostat, actuating a valve on the 
main steam line. The lumber is piled in such a way that the 
stickers slope downward toward the center. 
M is an auxiliary steam spray pointing downward for use at very 
high temperatures. C is a gutter to catch the precipitation and 
1 Forest Service Bulletin 104, " Principles of Drying Lumber at Atmospheric Pressure 
and Humidity Diagram," Superintendent of Documents, Government Printing Office, 
Washington, D. C. Price, 5 cents. Lumber World Review, Feb. 10. 1915, 
