176 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
but some of those made under older systems (which are really 
much the same in the main for practical purposes, though not 
so finical and would-be highly scientific—perhaps, however, it is 
heresy to express such an opinion); but somé interesting details 
concerning the latter were given at a Forest Conference held in 
Constance, in which the comparative results of (a) sight, 
(b) moderate, and (c) heavy thinnings were given in the ratio of 
the results of the moderate thinning (100). They may be 
tabulated as follows :— 
Percentage of Total Increment in Cubic Contents | 
| ‘Timber-Crop Age Period of in the Thinnings that were 
; ’ | Observation. | 
{ 
(a) Slight. | (b) Moderate. (c) Heavy. 
& 
| 
Years. | Years. | 
HScots pine, /2)|) 137 17 96 100 / III 
Wiseech.) 5.0 75) 1)) 50 21 88 100 te) 
Beech, ce nd 7 aT 99 100 | 108 
Silver fir, . 49 15 93 100 | IOI | 
| Oak.) 2 1+ 38 | Not stated oa | 100 | 110 | 
} 
In considering these figures, it should, however, be borne in 
mind that what the German forester calls a heavy thinning is 
something quite different from the wholesale slaughter of the 
innocents that so often takes place in our British plantations under 
this name. And the same caution must be intoned before 
summarising an article by Professor Schwappach on the thinning 
of young spruce-woods. Commencing with the statement that in 
Germany the general principle acted on is to form spruce-woods 
so that they may close up as quickly as possible, to begin to thin 
at about thirty to forty years of age, and to make the thinnings 
heavier as the woods grow older—an opinion he has hitherto 
shared and has advocated in his published works, and which has 
received support from the experiments made by the Investi- 
gation Committees in Prussia, Bavaria, and Wurtemberg—his 
attention was recently drawn to the somewhat different results of 
similar experiments made by the Austrian Committee at Maria- 
brunn, and in Prince Schwarzenberg’s woods in Bohemia. He 
therefore obtained official permission to make a “tour of study” 
in 1904, visited the centres in question, and drew his own con- 
clusions, which he has now published. Without attempting to 
