The water from the gutter behind the parapet is carried out on to the
backs of the flying-buttresses by means of holes cut through the
stonework. Into these pipes are passed which convey the water through
to the open gutter channels of the buttresses. The backs of the raking
buttresses, though they are sharply weathered to throw the water from
them quickly, are also covered with lead as a further protection.
These buttresses have carried the thrust of the vaults down-wards with
safety for about six hundred years. But the presence of two distinct
arches under each of them indicates that they have been altered a
little since first they were put up. This was done when it became
necessary to carry their thrust farther out because of the new chapels
that were added long after the vaults were built over the nave. At the
foot of each raking slope is a horizontal piece which runs out until
it comes in contact with the octagon pinnacles of the vertical
exterior buttresses. It should be noted that where the
flying-buttresses meet the vertical wall of the clerestory there is in
some cases a portion of the flat buttressing of the twelfth century
visible.

Between the buttresses of the chapels are four two-light windows, The
outer arch of each of these windows is a beautiful example of late
thirteenth-century moulded detail. The main line of the arch curve is
excellent, and the whole opening between the head, jambs, and sill is
beautifully proportioned. Some fifteenth century tracery remained in
these windows until it was replaced by the present modern work. The
outer arch is in two orders, which are carried by slight attached
shafts, some of which are renewals. The capitals to these are carved,
and have square abaci, rounded at the angle, as they pass over the
capitals. These abaci, which are finely moulded, are not more than
about two and a half inches in depth. The bases of the jamb-shafts are