[MR] wheel-stair?

[Robert Dawson, PA-C]

Violante doth ask:

> A mundane acquaintance today asked me what a
> wheel-stair was.  As in "Fyvie Castle has the finest
> wheel-stair in all of Scotland".  I couldn't answer
> him, so I turn to you all.  Help?

A "wheel stair" is what americans would usually refer to as a spiral stair.
It is a stair in which the treads issue from a (narrow) central column.

regards,

McKenna