As regards the production of stamps, it must be premised that two qualities were indispensable; first, cheapness; secondly, security against imitation. To obtain this latter quality, it was necessary to have excellence both of design and of workmanship, together with exact uniformity in the whole number issued—requirements which made extreme cheapness difficult. The Queen’s head was first engraved by hand on a single matrix; the effigy being encompassed with lines too fine for any hand, or even any but the most delicate machinery to engrave. The matrix being subsequently hardened, was employed to produce impressions on a soft steel roller of sufficient circumference to receive twelve; and this being hardened in turn, was used, under very heavy pressure, to produce and repeat its counterpart on a steel-plate, to such extent that this, when used in printing, produced at each impression two hundred and forty stamps; all this being of course done, as machinists will at once perceive, according to the process invented by the late Mr. Perkins. In this manner there were produced in the first fifteen years more than three thousand millions of stamps; all, as being derived from the same matrix, of course absolutely uniform. At the end of that time it was thought desirable to create a second matrix, but as this was obtained by transfer from the first—save that the lines were deepened by hand—the deviation from identity was at most very slight. With plates procured from this, the process, however, being somewhat modified, there had been printed, up to July, 1867, more than seven thousand millions of stamps; thus making up a total of considerably more than ten thousand millions, in all of which the impression is, for all practical purposes, absolutely uniform.[301] Now it will easily be perceived that, if imitation cannot be effected without resort to the means described above, as used in the production of the stamps, forgery is in effect impracticable; since no forger can have the command of very powerful, delicate, and therefore costly machinery, requiring for its management skilful, and therefore highly-paid, workmen. If the Queen’s head alone constituted the effigy, something in imitation might be done by the aid of lithography, or some other such copying process; but this fails when applied to the extremely delicate lines already mentioned as constituting the background; which in the lithographer’s hands do but smirch the paper.