16 TIMBER AND TIMBER TREES. [CHAP. 
tions that the largest he measured of this species was 
about 36 feet in diameter. 
Decandolle gives the following list of the ascertained 
ages of the undermentioned species of trees :— 
Elm . ts C + 335 years. | Lime . ‘ ‘ 1,147 years. 
Cypress. - - 350 ,, Oak . . 810toI,500 ,, 
Larch . A 7 - 576 4, Yew . » 1,214 to 2,820 ,, 
Cedar. y ‘ . 800 ,, Adansonia . 3 5,000 ,, 
These figures have, doubtless, been based and com- 
puted upon the supposition I have advanced of there 
being one concentric circle for each year of growth ; 
but, as they do not serve us for any practical purpose, 
we must look to those trees of moderate dimensions, 
which attain to maturity in a shorter time, rather than 
to those I have enumerated, for the timber we may 
wish to employ for architectural works. The record, 
however, which these circles afford of the duration of 
life in trees possesses a value of which we cannot but 
feel the importance. 
~ | have carefully examined and counted the annual 
layers of a great many specimens—taking generally 
an average of ten trees—with the view to show the 
common and comparative rates of growth, and have 
tabulated them to afford an opportunity of noticing any 
variations there may have been in the time required to 
form the wood in each of the several given\diameters 
of 6, 12, 18 inches, &c. This evidence of the ordinary 
rate of growth, and the time which it takes to bring 
the various descriptions of timber trees to maturity, 
will be of value to us when considered in connection 
with the properties and characteristics of the timber 
employed for architectural works. 
The number of concentric circles, or woody layers, 
found in various timber trees, within a radius of 3, 6, 9, 
