born; hence, pregnant slaves, when offered for sale,
are not warranted sound, because the fetus as it grows within the body
takes to itself as nourishment all the best qualities of the mother's
food, and so the stronger it becomes as the full time for birth
approaches, the less compact it allows that body to be from which it is
produced. After the birth of the child, what was heretofore taken to
promote the growth of another creature is now set free by the delivery
of the newborn, and the channels being now empty and open, the body will
take it in by lapping up its juices, and thus becomes compact and
returns to the natural strength which it had before.

2. On the same principle, with the ripening of the fruits in Autumn the
leaves begin to wither and the trees, taking up their sap from the earth
through the roots, recover themselves and are restored to their former
solid texture. But the strong air of winter compresses and solidifies
them during the time above mentioned. Consequently, if the timber is
felled on the principle and at the time above mentioned, it will be
felled at the proper season.

3. In felling a tree we should cut into the trunk of it to the very
heart, and then leave it standing so that the sap may drain out drop by
drop throughout the whole of it. In this way the useless liquid which is
within will run out through the sapwood instead of having to die in a
mass of decay, thus spoiling the quality of the timber. Then and not
till then, the tree being drained dry and the sap no longer dripping,
let it be felled and it will be in the highest state of usefulness.

4. That this is so may be seen in the case of fruit trees. When these
are tapped at the base and pruned, each at the proper time, they pour
out from the heart through the tapholes all the superfluous and
corrupting fluid which they contain, and thus the draining process makes
them durable. But when the juices of trees have no means of escape, they
clot and rot in them, making the trees hollow and good for nothing.
Therefore, if the draining process does not exhaust them while they are
still alive, there is no doubt that, if the same principle is followed
in felling them for timber, they will last a long time and be very
useful in buildings.

5. Trees vary and are unlike one another in their qualities. Thus it is
with the oak, elm, poplar, cypress, fir, and the others which are most
suitable to use in buildings. The oak, for instance, has no