l tower, and the
substitution of a lighter lantern. When this was done, the great round
arches east and west of the tower were changed into pointed arches, but
those north and south were left unaltered. There is every probability
that some signs of insecurity had made themselves evident. We have seen
that three stages of the Norman tower were erected by Abbot William of
Waterville. Though not so stated we infer from this that at least one
more stage was afterwards added. In any case the tower must have been a
very massive structure, considerably higher than the present one. In the
early part of this century, in 1321, the great tower of Ely had fallen;
and its fate may have warned the monks of Peterborough to see that the
disaster was not repeated here. This alteration must have been made,
judging by the details of the architecture, in the second quarter of the
century. Above the lantern was a wooden octagon. The views that are
given of this hardly warrant the admiration that has been sometimes
expressed, or the regrets that have been uttered at its removal. It may
have been designed to carry a wooden spire, such as was afterwards
erected on the bell-tower. But most will agree with the criticism that
it was "a low and unsightly structure." It hardly rose more than eight
or ten feet above the top of the lantern, and the whole height of the
central tower, including the octagon, was less than the height of the
south-western spire of the front.

To this century belongs the transformation of the triforium windows all
through the nave and choir. Parapets were at the same time added above
the Norman corbel tables. The change effected in the apse was the most
noticeable; not only were the two upper tiers of Norman windows replaced
by Decorated ones of larger size, but the three lowest ones in the
centre were altogether removed, and their place taken by lofty archways,
when the new building was built. But we can judge of their appearance
from the two side windows which still remain; these, being not now
external, have had all the glass removed; but the mullions and tracery
are perfect, and even the iron-bars across are still there. At the inner
surface of the wall the five lower windows have very good hanging
tracery, of different designs.

The south-western spire of the west front is also of this period,
probably a little earlier in date than the lantern. This is of very
remarkable beauty, and very much more elegant than the co