168 FORESTS, WOODS, AND TREES 
by cuttings, and the expense is slight. The wood of both 
white willow and crack willow is tough, and indents with- 
out splintering from blows or hard usage. It can be used 
for brakes, carts, hurdles, roofing, and flooring. 
4. Cricket-bat willow or blue willow (Salix coerulea). 
This is a hybrid between Salix fragilis and Salix alba, 
occurring only in the female sex, and invariably propagated 
by sets or cuttings. It is grown in the eastern counties of 
England, mainly in Essex, Hertford, Suffolk, Norfolk, and 
Cambridgeshire. Remarkably fast in growth, it produces a 
wide-ringed timber, light in weight and of great elasticity, 
which is used for making cricket bats, and sells at a high 
price. Trees often attain, in thirteen to fifteen years after 
planting, 40 to 50 feet in height and 13 to 15 inches in 
diameter. Cricket-bat willow should be planted only in 
good sites, such as rich alluvial lands by the side of a 
running stream, or fertile loam where there is a good supply 
of moisture. Ground of any kind sodden with stagnant 
water, and clay, gravel, and peat soils are quite unsuitable. 
Large sets, 6 to 10 feet long, should be used for planting. 
As this willow requires much light and space, and the 
object is to produce as quickly as possible a short stem, 
clear of branches for about 12 to 15 feet, the part utilisable 
by the bat-maker, a good crown of foliage must be preserved 
from the start, and the trees should be planted wide apart, 
the distance between them being not less than 30 feet. A 
full account of the cultivation of this tree was given by the 
writer in TZrees of Great Britain and Ireland, vii. 1763- 
1769 (1913), of which an abstract by A. P. Long was 
published in Journ. Board of Agriculture, xxi. 289 (1914). 
Black Walnut (Juglans nigra).—tIt has been proposed to 
grow this American species in our woods, as the timber is 
very valuable, and splendid single trees are known to occur 
in many parks in the south of England. The tree is, how- 
ever, exacting as regards soil and climate. It is sensitive 
to frost when young, but afterwards becomes perfectly 
hardy. It requires for its good development a considerable 
