separately, and most likely from a mould of sand, was known to the Romans, is evident from the names of the emperors Domitian and Hadrian on some pigs of lead in the British Museum; and that it was practised during the middle and succeeding ages, we have ample testimony from the inscriptions on our ancient bells.[I-27] [Footnote I-27: The small and thick brass coins, struck by Grecian cities under the Roman emperors, and known to collectors as “colonial Greek,” appear to have been cast, and moulds for such a purpose have been discovered in our own country.] In the century immediately preceding 1423, the date of the wood-cut of St. Christopher, the use of seals, for the purpose of authenticating documents by their impression on wax, was general throughout Europe; kings, nobles, bishops, abbots, and all who “came of _gentle_ blood,” with corporations, lay and clerical, all had seals. They were mostly of brass, for the art of engraving on precious stones does not appear to have been at that time revived, with the letters and device cut or cast in hollow--_en creux_--on the face of the seal, in order that the impression might appear raised. The workmanship of many of those seals, and more especially of some of the conventional ones, where figures of saints and a view of the abbey are introduced, displays no mean degree of skill. Looking on such specimens of the graver’s art, and bearing in mind the character of many of the drawings which are to be seen in the missals and other manuscripts of the fourteenth century and of the early part of the fifteenth, we need no longer be surprised that the cuts of the earliest block-books should be so well executed.