﻿54 



BULLETIN 1136, U. S. DErxVKTxMLAT 01 AGRICULTURE. 



furnish support to the lumber during (Irving so that it will be as 

 straight as possible when dry. 



For drying in a progressive kiln, the lumber is always loaded on 

 trucks or bunks and run through the kiln on rails, which are usually 

 pitched down toward the dry end, so that gravity will assist in mov- 

 ing the trucks. Large compartment kilns are usually provided 



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Fig. 11. — Cross section of superheated-steam compartment kiln. 



with rails, so that the lumber can be run in on trucks; but many 

 small kilns have no such provisions, and the lumber is piled on 

 horses or other supports. 



The two general kinds of piling used for lumber are vertical or 

 edge piling, and horizontal or flat piling Each of these may be 

 divided into cross and end piling. In cross piling, the boards run 

 crosswise of the kiln, and in end piling thev run lengthwise of the 

 kiln. 



