Page:De Vinne, Invention of Printing (1876).djvu/284

274 for the purpose of testing its agreement or disagreement with letters of the same kind on other pages, and the comparison establishes the fact that the letters are founded types.

The errors of the Speculum are those of types. They show the inversion of letters in positions which preclude the possibility that they could have been formed upon engraved blocks. The occasional occurrence of a c for an e, of an n for a u, of an  for an f, and the "turning upside down" of other letters, are examples of errors which can be made only by compositors.

The unequal perspicuity of the letters in the Speculum is that of unequally worn types. Of two adjoining letters, one will be distinct, black, and deeply indented in the paper; the other will be of dull color, and of indistinct outlines. The distinct letter is a new and high type, which has received the full force of impression; the indistinct letter is an old and worn type which has been touched but feebly by impression. If all the letters had been engraved on one plate, they would have been of equal height, and should have been equally legible, or nearly so, under impression.

The four editions of the Speculum are, of themselves, presumptive evidence that each edition was printed from types. It is improbable that the printer would re-engrave blocks for a second edition when those of the first were in existence. If the first edition had been printed from types, and the types had been distributed, as is customary, the printer was obliged to reset them in order to make the second edition.

These four editions were certainly the work of the same printing office, and, without doubt, of the same printer, for