152 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
which are sufficient in themselves to preclude the possibility of 
success. ‘Their size is too small to enable the trees to derive any 
benefit from mutual shelter, and this is often aggravated by their 
occupying exposed points and ridges, while they frequently 
consist of species which are not adapted for timber production 
at all, and no use can be made of them. 
In larger plantations, which might be expected to provide 
valuable material, the most frequent causes of bad condition are 
met with in badly drained soils, early and excessive thinnings for 
the sake of fencing materials, the use of the plantations for graz- 
ing purposes, and a general absence of systematic management 
from the time of planting onwards, chiefly due to their distance 
from headquarters. Add to these the fact that pure plantations 
are the exception rather than the rule, and it can be understood 
how difficult it is to find material of a suitable character. Yet 
if searched for, material does exist which is worth making use 
of, as I hope to show presently. 
During the time I have been in the North of England, I have 
made a modest attempt to get together data of a character which 
would bear some resemblance to the results already obtained in 
Germany and elsewhere. As yet, the actual results are so 
insignificant as to hardly deserve mentioning, but a brief 
description of the more important might be of interest to some 
of you. 
Up to date, sample plots of Scots pine, spruce, larch, and Corsican 
pine have been measured in three centres, Dipton, Healey and 
Ashgill. Of these plots, five are Scots pine, six spruce, two larch 
and one Corsican pine, while other centres have been selected for 
future work. The following description of these centres will enable 
an opinion to be formed of the classes of soil and situation in each, 
the figures relating to the plots being given in the Appendix 
(see pages 166 and 167). 
Dipton CENTRE. 
Dipton, and the immediately adjoining woods, are the property of 
the Duke of Northumberland, the executors of the late Mrs Back- 
house, and Mr W. C. B. Beaumont, M.P. The total area is about 
1500 to 2000 acres, the greater part of which occupies land which 
was enclosed a little over one hundred years back, and planted by 
the Governors of Greenwich Hospital, then the owners of the land. 
The soil varies from clay to fine sand and coarse gravel resting on 
the Millstone Grit, having an unimproved agricultural value of 2s. 
to 3s. per acre. The elevation varies from 300 to 600 feet above sea- 
level, and the general slope of the ground is towards the north, 
north-west, and north-east. The natural surface vegetation is 
heather or coarse grass, birch being the predominant indigenous 
