66 ELEMENTARY WOODWORKING 
kinds of wood. If we say that the strength of white 
pine is one half, we mean one half that of white oak, 
and in all timber calculations white oak is the standard, 
just as the yard and mile are standards of length. In 
work which requires strength, such as carriage making, 
shipbuilding, and _ cooperage, 
white oak is used very exten- 
sively. 
The quartered oak used so 
rouch for furniture is obtained 
by cutting the logs in a special 
manner. The method of cut- 
/ ting gives a beautiful mottled 
effect with the silver rays 
spread out in irregular white 
splashes on a dark background. 
We might separate the oak 
into two distinct groups: (1) 
Fic. 79. Typical Leaf of the those trees whose acorns ripen 
eae in one season ; (2) those which 
require two years. The acorns of this latter group re- 
main on the tree throughout the first winter and ripen 
the second summer. 
To the first class belong the white oak just men- 
tioned, the post oak, chestnut oaks, mossy-cup oak, and 
live oak. 
