There is no more troubled story in the history of glass-making than that of the manufacture of MIRRORS at Murano from the fourteenth to the eighteenth century. We have seen in the early days, when these mirrors were backed with lead (p. 138), that the Germans had already become experts in this department. More than once in the Venetian archives there are references to the secret methods of these _Todeschi_. In a petition of 1503 there is mention of a plan for making good and perfect mirrors, a precious secret unknown except to certain Germans. It is impossible to resist the suspicion that there is here a reference to the cylinder process, which, as we have seen, was already known to Theophilus (p. 129); by this process it would have been possible to produce a fairly large and comparatively flat sheet of glass. The Venetians, on the other hand, probably continued to a late period to use the old method of ‘spinning’ or ‘flashing.’[156] It was only after the middle of the sixteenth century that the mirror-makers, the _specchiai_, formed themselves into a separate corporation; but in this guild were included, it would seem, the makers of the so-called mirrors of steel.[157] Thus we find that in 1574, one Francesco Zamberlan, who only two years before had taken out a patent for his ‘_specchi d’acciaio_,’ was admitted to the new guild on the ground of his special knowledge. Those engaged in the polishing—the _lustratura_ and _spianatura_—of both materials, glass and metal, were also members of the guild. For us the interest in these mirrors lies rather in the framing. We find the new corporation early engaged in quarrels with the painters and with the workers in tarsia, mother-of-pearl, and coral (_i miniatori_, _i marangoni_, _e muschieri_), who found employment in decorating the frames. For a time, no doubt, the Venetian mirrors held their own, but before the end of the seventeenth century the French, thanks to the energy of Colbert, had not only learned all their secrets, but by an entirely new method—namely by a process of casting or founding, and subsequent rolling and polishing of the glass plates—were able to meet the demand for the large mirrors that were now regarded as indispensable in a Louis-Quatorze salon. But these ‘_glaces de St. Gobain_’ are of an entirely different nature from the exquisitely framed little _lustri_ with which we are now concerned. Unfortunately, as far as I know, there are no characteristic specimens of these _cinquecento_ mirrors—at least of those in which glass forms an important element in the frame as well—in any of our public collections. For fine examples of such work we must go to the Louvre or the Hôtel de Cluny. It will be noticed that the margin of the glass is invariably bevelled, thus forming a transition to the elaborate framing. These _cinquecento_ Italian mirrors were extensively copied, and this at an early date, both in France and at Nuremberg.