FELLING AND LOG-MAKING 99 
for the spores of certain funji,!^ which cause a discoloration. The 
fungi develop most rapidly during warm, sultry weather. Sum- 
mer-felled timber may be very seriously damaged by insects 
and fungi in from two to four weeks. 
The felling time of trees, such as oak, is sometimes restricted 
to the late summer and early fall if the timber is to be trans- 
ported by water because heavy species cut at this season and 
allowed to dry for from sixty to ninety days become more buoyant. 
The logging of hemlock often is restricted to the period between 
May and August, during which time the bark will peel.^ As it 
is a valuable by-product, used for tanning purposes, the logger 
seldom cuts the timber without saving the bark. 
Tanbarks are also secured from chestnut oak (Quercus prinus) 
and from the tanbark oak of California {Quercus densi flora). 
The season for peeling chestnut oak is from early April until 
the end of June, and for tanbark oak, from the middle of May to 
the middle of July. The timber in both cases is now used for com- 
mercial purposes, although the bark often is the more valuable 
product. 
Coppice fellings should be made during the winter and early 
spring because the sprouts are then more thrifty than those from 
trees cut during the growing period.^ Late winter felling is 
preferred because there is less chance for the bark to be loosened 
from the stool by the collection and freezing of moisture. 
The season of the year in which timber is cut does not, so far 
as known, influence its strength, although it may afl^ect its dura- 
bility. Hardwoods are more complex in structure and are more 
easily damaged in seasoning than are softwoods. Winter-felled 
hardwood timber air dries more satisfactorily than summer-felled 
timber because the water content evaporates slowly and the 
^ There are several genera of fungi which attack the sapwood of deciduous 
and coniferous woods, causing a bluish, blackish or reddish discoloration. 
The infection takes place largely through spores carried into the galleries 
made by ambrosia beetles, sawyers and other borers. 
^ Bark from hemlock logs cut in December or later may be successfully 
peeled from May to July inclusive, provided they are properly decked. The 
quality of bark is said to be equal to that peeled in the usual manner during 
the summer months. Bark from logs that have been in the water is valueless. 
See American Lumberman, July 21, 1900, p. 18; Dec. 30, 1916, p. 31. 
3 See Chestnut in Southern Maryland, by Raphael Zon. Bulletin No. 53, 
U. S. Bureau of Forestry, 1903, pp. 14-17. 
