Sec. 74. The work done at Grantham in the fourteenth and fifteenth centuries illustrates the purely natural development of the ordinary aisled church into the aisled rectangle. We have seen, in an earlier chapter, that, soon after 1300, the church consisted of an aisleless chancel, which was, however, overlapped at the west end by the north aisle of the nave; a nave, the north and south aisles of which followed different systems of spacing; a western tower and spire, engaged within the aisles; and north and south porches. Several chantries were founded in the church during the fourteenth century. Not long after the Black Death of 1349, the south aisle was extended eastward to the whole length of the chancel. The south wall of the chancel was pierced by an arcade; and the lady chapel thus formed was raised upon a double crypt. It was not until more than a century later that the east wall of the north aisle was taken down, and the "Corpus Christi chancel" built out, continuing the north aisle without a break, and completely flanking the north wall of the chancel, through which an arcade was made. Here the reason of expansion was obviously the growth of chantry chapels; and the expansion follows the simplest course. The last addition to the fabric was the present vestry, in which was a chantry founded by the Hall family. This was built out at right angles to the north aisle, at the point where the old work was met by the later extension. Not until the church had been fully aisled, and afforded no further room for new altars, were chantry chapels usually added in the shape of excrescences from the fabric. [Illustration: Fig. 16. Plans of Grantham church: (3) about 1350; (4) present day.]