In one application of glass the Germans appear early to have acquired some skill. We may perhaps regard the thirteenth century as the time when the use of glass for mirrors of any size first became general; this may account for the frequent references to them in the literature of the time. As far back as 1250, the great Dominican encyclopædist, Vincent de Beauvais, states that the best mirrors are made from glass and lead (_ex vitro et plumbo_). A _spiegel-glas_ is mentioned by a German writer as early as the end of the twelfth century, and by the end of the next century the mirror provided a frequent metaphor for the poets of the time. Thus Dante, in two passages in the _Divina Commedia_, speaks of ‘a leaded mirror.’ In the _Paradiso_ (ii. 89) Beatrice declares that the rays of the sun are reflected from the moon— ‘_Come color torna per vetro Lo qual diretro a sè piombo nasconde_’; and in the twenty-third book of the _Inferno_ (25-26) Virgil says to the poet, ‘_S’io fossi d’impiombato vetro_—I should not more quickly receive your image than now my mind receives your thoughts.’ This double reference would seem to point to a recent discovery that had attracted Dante’s attention. In the thirteenth and fourteenth centuries it would appear that although the German mirror-makers had to import the clear crystalline ‘metal’ from Venice, the Venetians attempted in vain to make mirrors on the German system. The difficulty, perhaps, was to prepare flat and even sheets of glass of any size, and this difficulty the Germans may have surmounted by means of the cylinder process described by Theophilus. The Nuremberg mirrors, however, so famous at a later time, were of a different type. They were of spherical outline, cut directly from the _paraison_ of the glass-blower; into this _paraison_ a mixture of ‘_piombo, stagno, marchesita d’argento e tartaro_’ had been introduced before the vesicle was quite cool—so at least a contemporary Italian writer asserts. Such mirrors were set in painted wooden frames with broad margins. An example of one of these may perhaps be seen in Jan van Eyck’s famous interior in the National Gallery. If now we turn to England, the record is even more meagre. Mr. Hartshorne, who has industriously brought together every reference he could find to glass[99] in this country during the Middle Ages, is fain to confess that he cannot point to a single example of what is undoubtedly English glass made between the Norman Conquest and the time of our Tudor kings. References to its use in contemporary writers are much rarer than in France. The _cuppa vitrea_, which in 1244 Henry III. sent to his goldsmith, Edward of Westminster, directing him to remove the glass foot, to replace it by one of silver, and to mount the whole in silver-gilt, was probably of Oriental origin; nor can we even claim for certain as English the two humbler vessels belonging at a later time to his son, Edward I.[100]