They are most commonly square, or nearly so; but occasionally the shape more resembles that of the ancient Egyptian and modern English brick, the width being about half the length, and the thickness half or two-thirds of the width.

The greatest size to which the square bricks attain is a length and width of about two feet.

From this maximum they descend by manifold gradations to a minimum of one foot.

The oblong bricks are smaller; they seldom much exceed a foot in length, and in width vary from six to seven and a half inches.

Whatever the shape and size of the bricks, their thickness is nearly uniform, the thinnest being as much as three inches in thickness, and the thickest not more than four inches or four and a half.