There is little or no ornament in the latter, and perhaps there was never much, though it may have once had simple borders between the panels and a rich border like that at Poitiers (not shown in the drawing) surrounding the whole. The technique followed in the painting is precisely that which obtained for nearly three hundred years after. That is to say, as far as possible the effect is obtained by glazing, and the features and folds of drapery are put in with strong, dark, sweeping lines of enamel. The style of the drawing, however, both in the figures and the drapery, is perhaps more purely Byzantine than any later work. The sweeping lines of the drapery are graceful and decorative, but the action of the figures is absolutely conventional. There is none of that feeling for motion which, expressed in line, gives so much vigour and animation to the subject windows of the thirteenth century. In colour, however, which after all is the most important thing in a window, this glass is splendid, and for the quality of the material and the way in which it has resisted the attacks of time it is superior to much glass of a later date. FOOTNOTES: [1] Pliny's word "nitrum" does not mean what we call nitre, which is potassium nitrate, but natron, or natural carbonate of soda, of which deposits are found in the Nile Delta. It is this that is meant in the passage in Jeremiah: "Though thou wash thee with nitre, and take thee much sope...." [2] These panes are, I believe, of cast glass; but I have seen Roman window glass found at Silchester that was obviously "blown" glass and of very good quality. [3] By some writers it has been claimed that the whole idea of stained-glass work was derived from cloisonné enamel; but from the fact that the glazing of windows in glass and metal had been known long before, I think the course of events I have suggested above to have been more probable. [4] There is some at Augsburg and at Tegernsee in Bavaria which may perhaps be a little earlier, but it is not certain. III THE STYLE OF THE FIRST PERIOD [Sidenote: The three periods.] Stained glass from its birth to the Renaissance has been divided by Winston into three main periods, each having broad characteristics peculiar to itself, and which he named after the corresponding architectural styles, Early English, Decorated, and Perpendicular. As, however, these terms only apply to English work, and as the architectural styles do not altogether correspond in date with those of the glass, I prefer to speak simply of the First, Second, and Third Period. The First lasts from the earliest examples almost to the end of the thirteenth century, and might be subdivided again into twelfth and thirteenth century work, between which there is a distinct difference. The Second covers nearly the whole of the fourteenth century.