172 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
elevation, and other considerations, which operate against free 
growth, the outturn of timber is decidedly lower than that 
obtained by the even-aged high forest system. 
As a rule, spruce, as well as other woods, receive no thinning 
until about the thirtieth year after their formation, It will, how- 
ever, be understood that on favourable situations it may take place 
earlier, and on unfavourable somewhat later. The first thinning 
is generally a light one, but it is repeated every fifth or sixth 
year until the end of the rotation. By that means the trees, as 
may be imagined, are, when thinning begins, tall and spindly, and 
probably not a third of the size of those of a similar age in this 
country. After thinning, the stems lay on an enhanced increment, 
which is stimulated by each of these operations, and in order to 
prevent soil exhaustion, the overhead canopy is, as far as possible, 
kept unbroken, As has already been remarked, tall clean trunks 
with little taper are the result. Such timber finds a ready market, 
and is used for structural, pulping, and mining purposes, there 
being numerous mines and pulp-mills in the vicinity of the forest. 
The latter manufacture the pulp by a purely mechanical process, 
and in the form of cardboard large quantities of it are annually 
imported to this country, the price received by the manufacturers 
being at the rate of £8 per ton. 
The woods, on the whole, are comparatively free from diseare, 
but considerable damage to their stems is occasioned by the deer, 
either by nibbling with their teeth or tearing the bark with their 
horns. Perhaps the fumes from smelting-works that are situated 
in the forest do greater damage to vegetation than all other 
agencies combined. Near Altenau a large area, which at one 
time was covered with thriving spruce woods, is now quite 
depleted owing to this cause. During the process of smelting 
silver, copper, and lead, which are combined in the form of 
sulphides, sulphur dioxide is given off in large quantities, and 
here, as well as in other districts where such works are located, 
it has, during the last fifty or sixty years, proved extremely 
hurtful to tree growth. Efforts have been made to convert that 
gas into sulphuric acid, and so retain it, but only with slight 
success, so that the fumes given off are practically as injurious 
as in their original form. 
Large masses of Scots pine have usually a rather sombre 
appearance, but those on the German plains, as viewed from an 
elevated position, contrasted favourably with the lighter greenery 
