398 



THE TIMBERS OF THE WORLD 



be advantageous, as the thermal kiln would need some means such as 

 steam jets or exhaust fans to assist in the circulation ; but as a rule, for 



Green Tunoer 

 Err^crrrce. 



B. F. STURTEVANT FAN OPEPATED 



Diagram of Fan-operated Progressive Kilx. 



progressive dryers the thermal circulation shows to most advantage as 

 regards ease of working, while it produces excellent results. 



Sturtevaxt Progressive Kilx. 

 Beech trees were felled and sawn, the timber dried and then planed in less than three weeks. 



If a compartment kiln is ver}' long and has doors at both ends, it 

 can be operated in a semi-progressive manner. This is done by piling 



