PATTERSON v. M'CAUSLAND.—3 BLAND. 71

pseudo acacia,) is finer in its grain than any of the oaks, and much
harder, when seasoned, than any of them, except the live oak.
The locust converts its sap into perfect wood every third year;
which is not done by oaks in less than every tenth or fifteenth
year; and at twenty-five years of age it yields twice the mass of
wood of any other tree. 2 Midi. Am. Sylra. 11.

The eminent botanist who has given us the most full, accurate,
and instructive account of all our forest trees, appears to have
frequently adverted to this general opinion, that the concentrical
layers in the wood of such trees afforded evidence as well of their
progress in vegetation as of their age. In speaking of the white
cedar, (cupressus thyoides,) he says, that " the concentrical circles
are always perfectly distinct, even in stocks of considerable size,
but their number and compactness prove that the tree arrives at
its full growth only after a long lapse of years. I have counted
two hundred and twenty-seven annual layers in a trunk twenty-one
inches in diameter, and five feet from the ground; and forty-seven
in a plant only eight inches thick at the surface, which proved it
* to be already fifty years old. I was told that the swamp
in which it grew had been burnt at least half a century be 87
fore, and had been re-peopled from a few stocks that escaped the
conflagration, or perhaps by the seeds of the preceding year. " 2
Mich. Am. Sylra. 341. From which it would seem, that the num-
ber of the concentrical circles in the young cedar being found to
correspond so nearly with the known lapse of time within which
it must have grown, after all the old ones had been destroyed,
might have induced this botanist to speak of this fact as a corrobo-
ration of the general opinion; yet he merely states the circumstance
and leaves the matter to the judgment of the reader. But in
another place he has distinctly given us to understand, that how-
ever disposed to treat this opinion with respect, he himself had no
great confidence in its correctness. In treating of the hemlock
spruce, (abies canademis,) he says, "The hemlock spruce is always
larger and taller than the black spruce; it attains the height of
seventy or eighty feet, with a circumference from six to nine feet,
and uniform for two-thirds of its length. But if the number and
distance of the concentric circles afford any certain criterion of the
longevity of trees, and the rapidity of their vegetation, it must be
nearly two centuries in acquiring such dimensions" 2 Mich. Am.
Sylva. 318. (e)

The inferences deducible from the apparent number of concen
trical layers found in the trunk of a tree, upon an inspection of a

(e) " In a field of and sandy loam, long under the usual cultivation, a piece
of five or six acres was covered by a second growth of pines thirty-nine years
old, as supposed from, that number of rings being counted on some of the
stumps. The largest trees were eighteen or twenty inches through." Ruffin
on Calcarious Manures, chap. 13.