To become a financial success it was necessary that the stamps should be produced cheaply, yet of workmanship so excellent that imitation could be easily detected. Now there is one art which we unconsciously practise from infancy to old age—that of tracing differences in the human faces we meet with. It is this art or instinct which enables us to distinguish our friends from strangers; and it was, perhaps, recognition of this fact that long ago led to the placing on the coinage of the portrait of the reigning monarch because it was familiar to the public eye, and therefore less likely than any other face to be counterfeited. In an engraving of some well-known countenance, any thickening or misplacing of the facial lines makes so great an alteration in features and expression that forgery is far more easily detected than when the device is only a coat-of-arms or other fanciful ornament.[166] For this reason, therefore, it was decided in 1839 to reproduce on the postage stamp the youthful Queen's head in profile designed by Wyon for the money of the then new reign, daily use of which coinage was making her face familiar to all her people. The head is also identical with that on the medal—likewise by Wyon—which was struck to commemorate her first State visit to the city in November 1837. The stamp then being difficult to counterfeit, and worth but little in itself, while the machinery employed to produce it was costly, the reason is obvious why, so far as is known, only two attempts, and those so clumsy that one wonders who could have wasted time in forging the things, were made to imitate the finely executed, earliest “Queen's head.”[167] The design was engraved by hand on a single steel matrix, the head, through the agency of this costly machinery, being encompassed by many fine, delicately-wrought lines. The matrix was then hardened, and used to produce impressions on a soft steel roller of sufficient circumference to receive twelve repetitions, the beautiful work of the original matrix being therefore repeated, line for line, in every stamp printed. The roller, being in turn hardened, reproduced, under very heavy pressure, its counterpart on a steel plate a score of times, thus making up the requisite 240 impressions which cause each sheet to be of the value of one sovereign.[168]