"the summit of an old machicolated square tower"
A machicolated tower
Creative Commons Attribution Share AlikeA machicolated tower - Credit: Ilario
Illustration of machicolations in use
Public DomainIllustration of machicolations in use - Credit: Pearson Scott Foresman

Machicolations are projecting galleries on top of a castle wall. The floors are perforated with holes through which defenders could drop missiles or boiling liquid on attackers below.

By equipping Bly with such features, James establishes it as a scene of deadly conflict.