Then lithography made its appearance, and in no great while was applied to the production of drawing-copies, once the monopoly of crayon engraving. Nor was this the only quarter from which the method of François and Demarteau was assailed. By degrees it fell out of use for the production not only of drawing-copies, but of fac-similes of drawings by the masters for artists and amateurs; or, if occasionally practised, it was--as in the subjects engraved some thirty years back from drawings in the Louvre and the Musée de Lille--with so many modifications, and in combination with such a number of other processes, as reduced it from supremacy to the rank, till worse should befall, of a mere auxiliary. In our own time it has had its death-blow in the advance of photography; and as, after all, its one object was the presentation of an exact likeness, the absolute effigy, of its original, the preference of a purely mechanical process of reproduction is, if we consider the certainty of the results, no more than natural. In proportion as, by its very nature, photography is powerless to take the place of engraving, when the work to be reproduced, be it picture or mural decoration, presupposes in the interpreter, in whatsoever degree, the power of translating what is before him, just so far is it capable of fulfilling the one condition imposed upon the copyist of a drawing or an engraving--that of perfect fidelity in imitation. The object attempted by François, Demarteau, Bonnet, and others--the production by engraving of a sort of optical illusion, the exact fac-simile of a drawing--had been started before them by Jean Christophe Leblond, an artist born of French parents at Frankfort, who, moreover, had sought to extend to the imitation of colour what his successors were content to restrict to the imitation of monochrome. Very early in the eighteenth century, Leblond succeeded in producing prints in several tints, by a method which he called "pastel engraving," and to which custom has given the more general name of "colour engraving." For the second half of this title, it might, perhaps, have been better to use the word "printing." What is called "colour engraving" is not really a special engraving process. Its whole originality consists in the production of a single proof from several plates (generally four), in the preparation of which the rocker, the roulette, and sometimes even the burin, have been used. From these plates, each inked with a single colour, the effect of which is relieved or modified by the subsequent addition of those tints with which the other three are covered, there results in the proof, by the use of points of correspondence, an _ensemble_ in colour which is similar in appearance to that of painting in pastel, in water-colour, or in gouache. This was pretty much the process, and the results were in some sort comparable with those obtained by chromo-lithography. The