chapel. Formerly
used as a prison, it must have subjected its miserable inmates to even
more trying variations of heat and cold than the famous "_Piombi_" of
Venice.

With the exception of the chapel, its crypt, and sub-crypt, which were
vaulted throughout, all the floors were originally of wood, and were
supported on double rows of stout oak posts, which in their turn
sustained the massive oak main floor beams.

The forebuilding, on the south face of the keep, was probably added by
Henry II. It survived until 1666, as it is shown in a view of the Tower
executed by Hollar about that date; but it appears to have been removed
prior to 1681.

The chapel of St. John is a fine example of early Norman ecclesiastical
architecture. It consists of a nave, with vaulted aisles, having an
apsidal eastern termination. It is covered by a plain barrel vault, and
on the fourth floor level has a triforial gallery, also vaulted. It is
connected by two doors with the gallery in the thickness of the wall
that surrounds this floor, from one of the windows of which it is said
that Bishop Ralph Flambard effected his remarkable escape.

It is probable that at first (except the chapel, which was covered by
its own independent roof) there were two separate high-pitched roofs,
one covering each division, and not rising above the battlements, the
wall gallery serving as a kind of additional fighting deck, for which
reason it was carried round the triforium of the chapel. As the need for
this diminished, two large additional rooms were gained by raising the
central wall a story, and superposing a flat, lead roof.

The absence of privacy, fireplaces, and sanitary accommodation on this
fourth floor, with the cold draughts from the stairways and windows of
the wall-gallery, must have been well-nigh intolerable; nor could wooden
screens, hangings, or charcoal brasiers have rendered it endurable. It
is not surprising, therefore, that under Henry III. the palace was
considerably enlarged, or that these chambers were abandoned by him for
warmer quarters below, in the Lanthorn Tower "k," and its new turret
"J" although the chapel and council chamber continued to be used down to
a much later date.

After the siege of Rochester by William Rufus in 1088, Gundulf had built
a _stone_ wall round the new castle of Rochester. This probably moved
the King to enclose the Tower of London with a similar wall, for the
_Saxon Chronicle_ tells us that in 1091 "a s