KILN DRYING HANDBOCK Va 
the fresh air is usually brought in at the bottom and distributed 
throughout the length of the kiln by means of ducts under the 
charge of lumber. Vertical ventilating flues, with the outlets to 
them leaving the kiln at various heights and in various ways, are 
commonly provided at intervals along both sides of the kiln. All 
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Hicurr 10.—Cross section of a natural-circulation compartment kiln. 'The arrows indicate 
the direction of the main circulation, which is crosswise. Air, heated by the coils, 
passes up through the central chimney and sidewise through the end-piled stock, accu- 
mulating moisture in its movement through the lumber pile. Most of the moisture-laden 
air drops down between the walls and the baffles, returning then to the heating coils, 
but some of it is discharged through the outiet flues. FHresh, comparatively dry air, 
drawn through the inlet duct, replaces the moist air discharged. Continuous recircula- 
win ad outside circulation of this nature are essential to gatisfactory operation of 
the kiln 
parts of the flue arrangement, however, depend upon the diverse 
ideas of the individual manufacturers; commercial practice includes, 
for instance, the entire possible range of locations for the outlets, at 
