orbiculus known as the orbiculus; apart from this its object is uncertain. In later stamps the inscription often reads backwards, or certain letters are reversed. The letters were cut straight in a mould and lie in the plane of the surface, being of rectangular section, not wedge-shaped, as in inscriptions on marble. During the Republican period and the first century of the Empire a plain “block” type is used; then the letters become smaller and more elegant, with bars at the ends of the hastae, as 20
E, M etc. Finally they show a tendency about A.D. 200 to become broader and shorter: 20
E, M, S At and after the time of Diocletian the forms become very varied. Punctuation in the best period takes the form of a 15
triangle afterwards the mark becomes vague in form. Ligatured letters are rarely found after the time of Diocletian, but are common in the best period; sometimes more than two are combined.[[2506]] The stamps with which the letters were made were usually of wood or bronze, but have not been preserved.
In the centre of the stamp it was customary to place an emblem or device of some kind, perhaps in view of a law which obliged brick and tile makers to affix distinctive marks or emblems on their bricks; but the devices are not peculiar to individual workshops, and some potteries, such as the Terentian (see below), used several. They may be compared with the countermarks or small adjuncts on the coins of the Republic, and the seals and stamps on the wine-amphorae of Thasos (Vol. I. p. [158]). Figures of gods, such as Mars, Cupid, and Victory, animals, and even groups of figures, occur, and after the third century Christian emblems are often found. It is most probable that they were merely ornamental and without significance, except in certain cases of canting or punning allusions. Thus M. Rutilius Lupus has a wolf; Flavius Aper a boar; Aquilia an eagle; C. Julius Stephanus a wreath; and Aelius Asclepiades a serpent, with reference to the god Asklepios.[[2507]]
FIG. 194. STAMPED TILE (BRITISH MUSEUM).