Tons per
foot. 
Best stocks, set in Portland cement and
sand 1 to 1, and three months old. 40
Ordinary good stocks, three months old. 30
Hard stocks, Roman cement and sand 1 to 1,
three months old. 28
Hard stocks, lias lime, and sand 1 to 2,
and six months old. 24
Hard stocks, gray chalk lime, and sand,
six months old. 12

The rule given in popular handbook, that brickwork in mortar should not have to carry more than three tons per superficial foot, and in cement more than five tons, is probably sound, as in no building ought the load to approach the crushing point, and, indeed, there are many sorts of foundations on which such a load as five tons per foot would be too great to be advisable.

It is a rather interesting inquiry, whenever we are dealing with a building material, if we ask what can we best do with it, and for what is it ill fitted.  The purposes for which brick can be best used depend, of course, upon its qualities.  Speaking generally, such purposes are very numerous and very various, especially the utilitarian purposes, though rich and varied ornamental work can also be executed in brickwork.

Perhaps the most remarkable quality of brickwork is that it can be thrown into almost any shape.  It is in this respect almost like a plastic material, and this peculiarity it owes chiefly to the very small size of each brick as compared with the large masses of the brickwork of most buildings.  Stone is far less easily dealt with than brick in this respect.  Think for a moment of the great variety of walls, footings, piers, pilasters, openings, recesses, flues, chimney breasts, chimney shafts, vaults, arches, domes, fireproof floors, corbels, strings, cappings, panels, cornices, plinths, and other features met with in constant use, and all formed by the bricklayer with little trouble out of the one material—­brickwork!  A little consideration will convince you that if the same material furnishes all these, it must be very plastic.  As a limitation we ought to note that this almost plastic material cannot be suddenly and violently dealt with—­that is to say, with the exception of some sorts of arches, you cannot form any abrupt or startling feature in brickwork, and you are especially limited as to projections.

If you wish to throw out any bold projection, you may support it on a long and sloping corbel of brickwork.  But if there is not room for that, you must call in some other material, and form the actual support in stone, or terra cotta, or iron, and when you have gained your projection, you may then go on in brickwork if you like.

Brick cornices should be steep, but cannot be bold, and so with other ornamental and structural features.  A noteworthy property of brickwork, and one of immense value, is that it is thoroughly fireproof; in fact, almost the only perfectly fireproof material.  There is an interesting account of the great fire of London by one of the eye witnesses, and among the striking phenomena of that awful time he notes that the few brick buildings which existed were the only ones able to withstand the raging fire when it reached them.