The intaglio is not very deep but all the details are beautifully sharp and distinct, while they are on so small a scale that it requires a magnifying glass to distinguish them. The material of the cylinder is translucent green felspar, or amazon-stone, one of the hardest substances known to the lapidary. [Illustration: PLATE 81] The fictile art of the Assyrians in its higher branches, as employed for directly artistic purposes, has been already considered; but a few pages may be now devoted to the humbler divisions of the subject, where the useful preponderates over the ornamental. The pottery of Assyria bears a general resemblance in shape, form, and use to that of Egypt; but still it has certain specific differences. According to Mr. Birch, it is, generally speaking, “finer in its paste, brighter in its color, employed in thinner masses, and for purposes not known in Egypt.” Abundant and excellent clay is furnished by the valley of the Tigris, more especially by those parts of it which are subject to the annual inundation. The chief employment of this material by the Assyrians was for bricks, which were either simply dried in the sun, or exposed to the action of fire in a kiln. In this latter case they seem to have been uniformly slack-baked; they are light for their size, and are of a pale-red color. The clay of which the bricks were composed was mixed with stubble or vegetable fibre, for the purpose of holding it together--a practice common to the Assyrians with the Egyptians and the Babylonians. This fibre still appears in the sun-dried bricks, but has been destroyed by the heat of the kiln in the case of the baked bricks, leaving behind it, however, in the clay traces of the stalks or stems. The size and shape of the bricks vary. 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. Each brick was made in a wooden frame or mould. Most of the baked bricks were inscribed, not however like the Chaldaean, the Egyptian, and the Babylonian, with an inscription in a small square or oval depression near the centre of one of the broad faces, but with one which either covered the whole of one such face, or else ran along the edge. It is uncertain whether the inscription was stamped upon the bricks by a single impression, or