That even before the end of the sixteenth century there were engravers of glass in other parts of Germany, above all in Silesia, is very probable, but there can be no doubt that it was the connection of Lehmann and of the Schwanharts with the Imperial Court that first brought this style of decoration into favour with people in high station. In fact, for some time this engraved glass was made for the most part to the order of wealthy patrons. Besides those named by Sandrart, the Archbishop-Elector of Mainz and the Bishops of Würzburg and Bamberg are mentioned as patrons of the new art, and large prices were given for fine specimens of engraving.[214] One immediate consequence of the new fashion was to cause a demand for an absolutely clear white glass, and this led to such improvements in the manufacture that the glass of Silesia and Bohemia was soon recognised as the best in Europe. [Illustration: _PLATE XLII_ ENGRAVED BEAKER. THE COVER WITH ENAMELLED METAL KNOB GERMAN, EARLY EIGHTEENTH CENTURY] From other sources we hear that George Schwanhart the elder had three daughters, Sophia, Maria, and Suzanna, who devoted themselves to the engraving on glass of flowers and ornaments, and especially of those examples of calligraphy then so much in fashion. Sandrart, most ungallantly, fails to mention these ladies, who were his contemporaries. Many other names of engravers on glass have been handed down to us,[215] but I will only mention Hermann Schwinger (1640-83), who was also a wood-carver and engraver on copper. We have in the British Museum (Slade, No. 883) a tall cup of thin white glass elaborately engraved with a Bacchic subject. Below, scratched by the diamond in small characters, may be read ‘_Herman Schwinger, cristall schnider zu Nürnberg_.’ There has been much discussion as to the nature of the improvements effected by the Schwanharts in the glass-cutting machinery. But before the end of the seventeenth century the arrangement of the wheels and the division of labour were probably on the whole established much in the manner that we find in local works in Bohemia at the present day. In a general way we may say that there has always been a distinction between the mechanical processes of grinding and polishing and the more delicate and artistic work of the engraver. In the latter case the work is done by pressing the glass against the edge of a minute copper wheel. On the other hand, the glass is ground down on a wheel of iron from three to eighteen inches in diameter, it is smoothed upon a stone wheel and finally polished upon one of wood, with the assistance in each case of suitable abrading mediums, whether emery, quartz sand, tripoli, or putty-powder.