details, and the consideration of internal evidence, be found more important than in this. It is seldom that the age of a glass painting is determined by the direct testimony of a date affixed to it, or of written documents; nor can a safe conclusion always be drawn from the situation which it occupies. It might at first be supposed that the glass would not be older than the window in which it is found, especially when the principal divisions of the picture or pattern coincide with the apertures of the window; but the inference from this circumstance cannot be relied upon, since instances are known in which windows have been constructed for the reception of glass older than themselves. It is therefore only from the internal evidence afforded by the work itself, that the date of a glass painting can in general be ascertained; and this evidence is not, as in a Gothic building, presented by a few prominent features, the contour of a moulding for instance, or the form of a window, but by a variety of minute particulars, no one of which is perhaps adequate of itself to decide the question.
"Some of these tests are peculiar to glass paintings, such as those afforded by the nature and texture of the material, its colour, and the mode of painting it. Some, again, it has in common with other objects; such as the character of the drawing, the form of the letters, the architectural details, the costume of the figures, the heraldic decorations, &c. All these features are not equally trustworthy; those derived from the general practice of the day, as regards the manufacture of the glass, and mode of painting it, are more to be relied on than those afforded by the nature of the particular subjects represented.
"Each period of medieval glass painting has its distinctive style of execution, but artists were at all tunes prone to copy the designs of their predecessors. This may serve to account for the occasional representation in a glass painting, of the armour, costume, and architectural features of a period anterior to that of the work itself.
"I shall now endeavour to shew more particularly the value of certain tests of date.
"Mere general arrangement affords scarcely any criterion of date. The "medallion window" is perhaps confined to the Early English period; and designs extending themselves into more than one lower light of a window, can hardly be said to be earlier than the Decorated. But with these exceptions, almost every late arrangement is to be found more or less developed in the earlier styles.
"The general appearance or effect of a glass painting is a feature deserving the utmost attention; but taken alone, it affords only a sure proof that the work belongs to some general period, without conveying a more definite idea of its date. The general effect of a glass painting depends indeed almost entirely on the quality and texture of the glass employed in it. Hence it varies according to the progressive changes in the manufacture of that material. These, as might be expected, were so slow and gradual as to be hardly perceptible; and glass, apparently of the same quality, was therefore employed during long periods of time. Owing to this circumstance, it becomes impossible to pronounce with certainty whether, for
