186 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
part which faced the north contracted. The writer has not enough 
scientific knowledge to explain this as he would like, but we know 
from practical experience that the trees cut from a thick wood 
where there is enough leaf canopy overhead to prevent the sun’s 
rays striking the stems, will saw into anything required without 
warping ; whereas trees that have had their stems exposed to the 
sun for any length of time are very difficult to saw straight, and 
very difficult to season without warping; this applies to conifers, 
and more especially to larch, Scots fir, and spruce. 
A large quantity of small-sized spruce is used in the Harz 
district for making pulp for paper-making; one factory which we 
visited was said to have sent in one year over £30,000 worth of 
pulp to a single firm in England. We are convinced that the 
great bulk of our home-grown spruce would not be so suitable 
for pulping as the German spruce, on account of the large branch 
knots which it possesses, caused by the trees being too thinly grown. 
We understand that where the branch knots are large, they are 
cut out with a gouge before the wood is put into the pulping- 
machine; but the billets of spruce we saw ready to go into the 
machines in Germany had very small branch knots, and there was 
no appearance of any having been cut out, but otherwise the billets 
were very particularly cleared of bark. 
The spruce is said to be by far the best paying crop in the Harz 
district. We were told that an acre of their best wood would pro- 
duce at the final clean cut from 6000 to 7000 cubic feet of timber. 
This is a long way ahead of anything we have seen produced at home, 
from either spruce, Scots fir, or larch; in fact, it is considered a heavy 
crop if we get from 4000 to 6000 cubic feet per acré at the final 
clean cut; and the writer has oftener seen 2000 than 6000 cubic 
feet per acre from the last clear felling of fir woods in Scotland. 
We were always under the impression that we over-thinned our 
woods, and since seeing the German method we are certain that this 
is the case. We cannot, however, always blame the foresters for 
over-thinning. In many cases a proprietor wants to have money 
out of a wood, and the thinning process goes on until there is only 
a skeleton wood left. 
Something may also be said for the advocates of thinning, if it is 
only timber suited for the rougher and cheaper class of goods that 
is wanted, as for instance railway and other sleepers. By thinning 
early, Scots firs can be got up to a size suitable for cutting into 
sleepers much sooner than is the case under the German system, 
