dates, I suppose, from about A.D. 1300, but it was soon found to be inconvenient to have open traceries for the upper corridor, and the arches on the other two sides were filled in before the middle of the fourteenth century with very good two-light windows. Fortunately the whole of this work is still in very excellent preservation, and deserves much more notice and study than it has ever, I believe, received.[65] The ordinary bricks used here measure 10½ in. × 5 in. and are 3 in. high, whilst in San Pantaleone they are 3½ in. high and as much as 15 in. long. Here (as generally in the centre of Italy) the bricks have all been dressed with a chisel, with which diagonal lines have been marked all over the face. I can only assume that this has been done to improve the texture [Illustration: 48. CASTLE. PAVIA. p. 278.] [Illustration: 49.--WEST FRONT, S. PANTALEONE, PAVIA. Page 279.] of the bricks in appearance, and, perhaps where two bricks are side by side on the same plane, to make a little distinction between them by tooling the bricks in opposite directions. Two other features of Pavian brickwork may also here be mentioned: one, that the depth of the arch-bricks is almost always increased from the springing line to the centre--the intrados and extrados not being concentric; the other, that the arch-bricks do not radiate from a centre, but are arranged so as to obtain a vertical joint in the centre. The first is a very defensible practice, the second seems to me to be the contrary.