14 



BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 



wood-rotting fungi, which cast off innumerable viable spores to be 

 carried about by air currents to sound lumber. The elevated posi- 

 tion of these fruit bodies on high tramways gives much greater 

 facility to the wide distribution of their spores. 



Since the tramways require large amounts of timber in their con- 

 struction, the use of wood preservatives in protecting them from 

 decay is worth careful consideration. This w^ould effect a direct 

 saving both by prolonging the life of the timber and by preventing 



the dcA'elopment of 



the fungous fruit 

 bodies. 



In only one part 

 of the tramway 

 structure is decay 

 secondary to other 

 deteriorating f a c - 

 tors, and this is in 

 the planking. Where 

 the trucks or "bug- 

 gies " operate con- 

 stantly, the wear at 

 the center very often 

 nicely balances the 

 decay at the ends, 

 but even here, from 

 the standpoint of 

 sanitation alone, a 

 light preservati ve 

 treatment sufficient 

 to immunize the tim- 

 ber so that fungous 

 fruit bodies can not 

 develop is strongly 

 recommended. 

 The initial cost of constructing extensive tramways from 10 to 25 

 feet high reaches a considerable figure, even at the actual mill cost of 

 the timber. In the upkeep of these structures replacements are 

 necessary as rapidly as the timbers fail, the resulting maintenance 

 charges being a considerable item of expense. In none of the mills 

 visited had thorough wood preservative treatments been applied. 

 Partial attempts were noted in several instances, where brush treat- 

 ments, usually of some patented coal-tar compound, had been applied 

 at the joints. Ordinarily it is the more widely advertised trade prod- 

 ucts which reach the attention of millmen. The cheaper preserva- 



FiG. 10. — Partially rotted hardwood boards piled against a 

 lumber stack. Infection will spread by contact to the 

 sound lumber. 



