14 
BULLETIN 510, II. 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 would effect a direct 
saving both by prolonging the life of the timber and by preventing 
the development 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 preservative 
treatment sufficient 
to immunize the tim- 
ber so that fungous 
fruit bodies can not 
develop is strongly 
recommended. 
The initial cost of constructing extensh T e 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- 
P75F 
Fig. 10. — Partially rotted hardwood boards piled against a 
lumber stack. Infection will spread by contact to the 
sound lumber. 
