14. Aix-la-Chapelle.
It will be observed that in the marginal lines which frame this window, and again in the white bands in two out of the three patterns from Salisbury, leads are introduced which have only a constructional use, and rather confuse the design. That they do not absolutely destroy it is due to its marked simplicity, and to the proportion of the narrow bands to the broad spaces. This is yet more clearly marked in the very satisfactory glazing designs from S. Serge at Angers. The fact is, there is a limit to the possibilities of design, such as that from Sens ([page 96]), in which literally only four leads (viz., those from the points of the central diamond shape) are introduced wholly and solely for strength; and when it comes to windows of any considerable size, such as clerestory windows, to which plain glazing is peculiarly suited, leads which merely strengthen become absolutely necessary. The art of the designer consists in so scheming them that they shall not seriously interfere with the pattern.
15. South Transept, Salisbury.
Were the pattern in lines of colour upon white, the crosslines strengthening them would of course be lost in the darker tint; but, as it happens, we do not find in the earliest glazing lines of interlacing colour, though they occur by way of border lines, as at S. Serge ([below]), where a marginal line of yellow is enclosed between strips of white.
