Page:De Vinne, Invention of Printing (1876).djvu/65

Rh will reproduce all its peculiarities, whether of merit or defect. The steel of the punch is then hardened until it has sufficient strength to penetrate prepared copper. It is then punched, by quick and strong pressure, on the flat side of a narrow bar of cold rolled copper. This operation makes a reversed or sunken imprint of the letter on the punch. In this condition, the punched copper bar is known among type-founders as a Drive, or a Strike, or an Unjustified Matrix. It becomes the Matrix proper, only after it has been carefully fitted-up to suit the mould. The exterior surface of the drive must be made truly flat, and this flatness must be parallel with the face of the stamped or sunken letter in the interior. The sides of the drive must be squared, so that the interior letter shall be at a fixed distance from the sides. The depth of the stamped letter, and its distance from the sides, must be made absolutely uniform in all the matrices required for a font or a complete assortment of letters. The object of this nicety is to secure a uniform height to all the types, and to facilitate the frequent changes of matrix on the mould. The justifying and fitting of matrices to moulds is one of the most exact operations in the art of type-founding.

For every character or letter really required in a full working assortment of types, the type-founder cuts a separate punch and fits up a separate matrix; but for all the characters or letters which are made to be used together, there is but one mould. Types are of no use, as has been shown, if they cannot be arranged and handled with facility, and printed in lines that are truly parallel. However unlike they may be in face, they must be exactly alike in body. This uniformity of body, which is as