212 Agricultural Education and Forestry Exhibition , 1906. 
(d) Other hardwood trees for returns during rotation. 
(e) Sprinkling of larch for early returns. 
(f) Shade-bearers,, such as spruce, silver fir, and beech, for soil production 
and stimulation of the main crop. 
Inside the building an exhibit illustrated the economic 
differences between dense and thin crops of trees. Thus, 
where only 2,722 trees per acre were planted four feet apart, 
there was not only less timber, but the numerous branches 
depreciated the value of the wood. A crop of 4,840 trees to 
the acre planted three feet apart gives a larger crop and also 
superior straight timber owing to the suppression of branches 
through density of growth, although the girth of the trees 
is somewhat less than the girth of trees planted wider apart. 
Another example from Alnwick illustrated cases of severe - 
pruning. The cuts would be dressed with a mixture of one 
gallon of tar and about one quart of paraffin oil. 
The evil effect of not pruning close to the stem was shown 
by a specimen. In this case decay had set in down the 
stem. When live boughs are cut close to the stem, healing 
takes place before the decay sets in. In plantations of conifers, 
when left alone, the natural pruning caused by thick planting 
takes place. 
A portion of a stem taken from the centre of a poor Scotch 
fir wood, seventy years old, showed the effects of thinning too 
early. The clean portion at the base of the trunk was due to 
the original thick planting, and the thick branches at the top 
appeared in consequence of the plantation, when young, having 
been thinned too soon. The commercial value of the crop 
had therefore been greatly depreciated in consequence of this 
mistake. 
On the other hand, a section of a spruce tree illustrated the 
advantage of deferred thinning. The section was taken from a 
portion of a forty-five-year-old pure wood containing 632 trees 
to the acre, with cubic contents (true measure) of 6,000 ft. 
The section was taken ten feet from the base ; the total height 
of the tree was fifty-three feet and the cubic contents were ten 
feet. The increment amounts to 133^ cubic feet per annum. 
The average increment of the whole wood — about 100 acres on 
moorland peaty soil — is over 100 cubic feet per acre per annum. 
It is therefore a very valuable crop for estate purposes. 
The Royal Agricultural College also showed specimens 
illustrating the evil effect of natural or incorrect pruning, 
the results of both being similar. Healing by occlusion is 
rendered impossible by the presence of the stump, which, as 
it dies, serves as a channel for the conveyance of water to the 
trunk. In a specimen shown, decay had already set in, and 
the planks when sawn out would be blemished. 
