Among the technical peculiarities of Han pottery, the marks--usually three in number--of small, oblong rectangular kiln supports will often be noticed under the base or on the mouth of the wares. These so-called "spur-marks" were made by the supports or rests on which the ware was placed when in the kiln. In many cases, too, large drops of glaze have formed on the mouth of the piece, proving that the vessel was fired in an inverted position, which directed the down flow of the glaze as it melted towards the mouth. This is by no means universal. Indeed, the glaze drops on other pieces are found on the base even when the "spur-marks" appear on the mouth. The explanation of these apparently contradictory phenomena is that to economise space one piece was sometimes placed on top of another in the kiln. The ornamentation of Han pottery was accomplished in several ways: by pressing the ware in moulds with incuse designs, which produced a low relief on the surface of the pottery; by the use of stamps or dies[21]; and more especially by applying strips of ornament which had been separately formed in moulds. All these ornaments were covered by the glaze when glaze was used. Laufer has made an exhaustive study of Han decoration in his book, and it will be sufficient here to give a few typical examples. On Plate 2, Fig. 1 is a green-glazed vase of typical Han form with two handles representing rings attached to tiger masks which are borrowed, like the general form of the piece, from a contemporary bronze. This vase, formerly in the Dana Collection and now in the Fine Arts Museum at Boston, has a posthumous date[22] incised on the neck corresponding to the year 133 B.C. Fig. 2 is a rare specimen with reddish body and polished black surface in which are incised designs of birds, dragons and fish, and bands of vandykes, lozenges and pointed quatrefoil ornaments. It has the usual mask handles, and stands 16 inches high. On Plate 3, Fig. 1, is a "hill jar" with brown glaze, standing on three feet which are moulded with bear forms. On the side is a frieze in strong relief with hunting scenes of animals, such as the tiger, boar, monkey, deer, hydra and demon figures, spaced out by conventional waves. This kind of frieze is frequently found ornamenting the shoulders of vases such as Fig. 1 of Plate 2, and the animals are usually represented in vigorous movement, often with fore and hind legs outstretched in a "flying gallop." The cover is moulded to suggest mountains rising from sea waves (the sea-girt isles of the Taoist Immortals), peopled with animals. Fig. 2 is a green-glazed box or covered bowl of elegant form, the cover moulded in low relief with a quatrefoil design surrounded by a frieze of animals.