314 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
paribus, by the largest logs, and the weight, for instance, of the 
cubic foot will, in some woods at any rate, be very much larger in 
the case of the log than in that of scantlings. The following results, 
for example, were obtained from beams of the Indian teak tree, 
Tectona grandis, which were 10 feet long by 4 inches by 6 inches. 
Weight per cubic foot, 45 to 50 lbs. 
Value of P=600. 
Modulus of elasticity = 5000.1 
To illustrate what I have above said regarding the power results 
obtained from scantlings, | may mention that in the professional 
papers published at Roorkee, the actual weight of the teak in log 
was given at 50 lbs. per cubic foot, and in scantlings at only 
35 lbs.—the latter having probably lost the essential oil which 
would be retained in the former. 
ILLUSTRATION OF RATE oF GROWTH. 
I am now brought to a consideration of the use of specimens in 
ascertaining the rate of growth, which is not the least interesting 
and instructive of their uses. For this purpose the kind of 
specimens I have commended, varying of course in size according 
to age, seems to lend itself most naturally to this part of my 
subject. Here again, however, we shall require explanatory tables. 
For we want to know the kind of soil in which the various 
specimens have been reared—the height above the sea-level of the 
forests or plantations whence they have been taken—the increment 
of annual growth, in fact everything that can tell us anything of 
the history and nature of the tree which is represented by its 
section. This is especially useful to the planter, whether repre- 
sented by an individual or by a government, who wishes to raise 
trees, not merely for ornament and use, but for pecuniary profit. 
I would make special reference in this regard to the specimens of 
oak shown by Sir James Campbell in 1884 as the products of the 
1 Pj sult of f lay 
P is the result o ormula 5p: 
W is the weight which causes the beam to break. 
L = length of beam in feet between the supports. 
3 = breadth of beam in inches, 
D = thickness of beam in inches. 
P being generally adopted to express the power of the beam to resist 
superimposed pressure. 
