and cheap. They may, without much departure from the truth, be said to
be Thames mud and chalk; but the process of manufacture requires care
and thoroughness. The article supplied, when of the best quality, has
great strength, and is quick setting, and is far better than what was
manufactured from stones in which the ingredients existed in a state of
nature. In England we slake our lime and make use of it while it is
fresh; but it may interest you to know that the custom in Italy and
parts of France is different. There it is customary to slake the lime
long before it is wanted, and to deposit it in a pit and cover it up
with earth. In this condition it is left for months--I believe in Italy
for a year--and when taken out it is stiff, but still a pasty substance.
It is beaten, and more water added, and it is then made into mortar with
sand. It is claimed for mortar made in this way that is exceptionally
strong.

Now that we have considered bricks and partly considered mortar, it
remains to pay some attention to brickwork. The simplest and most
familiar work for a bricklayer to do is to build a wall. In doing this
his object should be to make it as stout as possible for the thickness,
and this stoutness can only be obtained by interlacing the bricks. If
they were simply laid on the top of each other, the wall would be no
more than a row of disconnected piles of bricks liable to tumble down.
When the whole is so adjusted that throughout the entire wall the joints
in one course shall rest on solid bricks and shall be covered by solid
bricks again--in short, when the whole shall break joint--then this wall
is said to be properly bonded, and has as much stability given to it as
it can possibly possess. There are two systems of bonding in use in
London, know as English bond and Flemish bond. English bond is the
method which we find followed in ancient brickwork in this country.