EXACT PROGEESSIVE MEASUREMENT OF TREES. 271 



and then found to be 13-5 and 16-45 inches at very nearly the 

 same elevation, have since added, during the last two unfavour- 

 able years, one of them 1*10 and 1-55, and the other I'lO and 

 1*75, to their girth — a great iu crease at their age — I cannot but 

 conclude that this beautiful oak is the hardiest of our leaf- 

 vsheddinf:f trees, whether native or acclimatised, so far as I have 

 yet examined them. 



I have also made observations on twenty-nine evergreen trees 

 — yew, ilex, pinus, picea, araucaria, deodar, sequoia, and cypress. 

 But the details are so vitiated by collateral influences, such as 

 injury from storms, peculiar locality, and undiscoverable causes 

 of failure, that it is not possible to attach confidence to the 

 results. I have been surprised, however, to find that numerous 

 specimens of sequoia, araucaria, and deodar have suffered little 

 injury during the last three years, and very much less than they 

 appear to have sustained in other parts of Scotland. On the 

 other hand, the Scotch fir has been a great sufferer. One tree in 

 the Botanic Garden, two on the high east ground of the Arbo- 

 retum, a fine one, nearly 8 feet in trunk girth, on the low south- 

 west ground, and one (the finest of all I have seen around 

 Edinburgh), on the lawn of Cammo House, near Cramond Bridge, 

 have ceased entirely, or nearly so, to make wood for three years 

 past, and their heads have shown every successive year more 

 and more failure in foliage. 



8. When trees are grown for profit, and doubts are entertained 

 whether certain of them have not ceased to add to their wood, 

 the point may be settled wnth precision by an exact measurement 

 at the beginning and end of a single growing season of three or 

 four months. 



Since these results, expressed numerically, have been so easily 

 obtained, simply by patient observation, — results which are un- 

 attainable Ijy any other method yet known, — it follows that 

 by the same means information of greater value in a practical 

 point of view may be arrived at in regard to the influence of 

 soil, subsoil, altitude, exposure, climate (as constituted mainly by 

 heat, cold, sunsliine, and rain), transplanting, thinning, pruning, 

 and especially manuring. Tliis wrirk, however, must be con- 

 signed to forest owners, who alone can conduct it; and they will 

 meet with their reward if they will combine, form themselves 

 into a committee of this Society, teach and encourage their 

 foresters to observe, and offer prizes for the ablest reports. 



I mention manuring i)articularly, because the subject has been 

 hitherto almost entirely neglected. But from imjuiry it will 

 appear tliat a forest does not differ in tliis respect from a farm. 

 If we examine the section of the tnink of a tree some ninety 

 years old, reared in a liill forest with tliin soil, we find that for 



