Here at the beginning I am confronted with a difficulty of a class only too often met with when treating of the technique of the minor arts—the difficulty of finding in our language suitable words to express, without danger of misconception and confusion, the practical details of the matter in hand. I have now to deal with the methods by which the surface of glass may be cut, polished, scraped, or eaten away, so as to form an artistic design. This, I may say at once, can be effected by any one of the following methods:— 1. By _scratching_ with a diamond. I can find no other word; the term ‘engraving’ is vague and ambiguous; to use the word ‘etching’ is still worse, for though the result resembles in a measure the etched line on copper, this expression should be reserved for the process by which the surface is eaten away (the German _ätzen_) by acid. 2. By removing the surface by means of a small revolving wheel, or more rarely, of a cutting-tool, with the aid of emery or other hard powdered stone. The term ‘engraving’ may well be used here, if it is understood in the sense in which we speak of an ‘engraved gem,’ for small hard stones have been cut in this way from ancient times. 3. When, however, by means of a large wheel, the surface is deeply cut away, we may better use the words ‘cutting’ or ‘carving.’ The grinding down of the surface and subsequent polishing, as in the case of glass cut into facets, would fall into this division. It is, however, often difficult to say which of these terms—engraving, cutting, or grinding—it is preferable to use; nor is the use of the German words ‘_schleifen_’ and ‘_schneiden_’ much more definite. 4. By exposing parts of the surface to the fumes of hydrofluoric acid, the only acid that will attack glass. This process may well be called etching. We have already spoken of the use of the diamond by the Venetians for scratching lace-like designs upon the surface of their thin glass, so unsuitable for other forms of engraving. The diamond point was early used in a similar way in Germany. Mathesius, after speaking of the imitations of the _vetro di trina_, made in his day in Silesia, proceeds to say that it is also the practice to draw (_reissen_) ‘_auf die schönen und glatten Venedischen gleser mit demand_ [diamond] _allerley laubwerck und schöne züge_.’ This decoration with the diamond point was carried to great perfection in Silesia. Herr von Czihak has reproduced in his work on the glass of that country (p. 122) two tall cylinders of this ‘_gerissene glas_’ (so it is called in contemporary inventories), which cannot be later than the sixteenth century. So, again, much of the glass of _cristallo_ type made at Hall in the Tyrol was thus decorated.