I50 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY: 
which any given crop is likely to reach maturity predicted. In 
Great Britain no reliable records of this kind have been made, 
and it is almost impossible to say what our soil is capable of © 
producing if managed on proper lines. Most British measure- 
ments of tree-growth have hitherto been confined to individual 
trees, remarkable either for their exceptional size, rarity, or some 
historic interest attaching to them. ‘These records, although 
highly interesting up to a certain point, rarely enable the forester 
to arrive at any conclusion as to the normal or abnormal 
character of the growth of the trees in question. In the case of 
common forest trees of the country, it is, of course, not difficult 
to recognise the relative size of any given individual of known 
dimensions, provided the soil, situation and age are given, and 
compare it with the general average of the species throughout 
the country. But it is impossible to tell whether such an 
individual is a normal or abnormal specimen for that particular 
district, unless the information is supplemented by further 
particulars regarding those round about it. With old trees, again, 
the age is often difficult to ascertain, while the dimensions of the 
tree at eighty or a hundred years, the ages at which most forest 
crops are cut, are unknown, and the rate of what may be termed 
their economic growth cannot be ascertained. Measurements of 
ornamental trees, such as conifers, are usually accompanied by 
particulars of age, soil and situation, so that it is often possible 
to obtain some idea of their rate of growth within a given time. 
But unless such trees are sufficiently numerous to enable an 
average rate of growth over a definite area to be struck, they 
rarely justify any reliable conclusions being arrived at. Take, 
for instance, the case of a certain species being represented by a 
single individual, or by eight or ten widely separated trees. The 
rate of growth of the one, or the average rates of growth of the 
whole, do not afford any clear indication of what might be expected 
from a forest crop of that species, covering, say, 5 or 10 acres of 
ground, The single individual may possibly be growing on a 
spot which is not typical of the surrounding soil, while the 
widely separated trees may respectively be growing on soils 
and situations varying in different directions, and effectively 
preventing any connection being traced between their conditions 
and the average rate of growth of the trees. But when a 
sufficient number of trees of one species are found on a definite 
area, all being of the same age, and all growing on the same 
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