Bruce Clark stated:

> Reed pipes are notorious for going out of tune at a moments notice,
> and are very susceptible to temperature changes.

Actually, reed pipes are not as susceptible as flue pipes.  They may go
out of tune because of loose tuning springs, but then flues could have
loose tuning slides.  This is partly due to the resonators maintaining
stability to a certain extent.

The reason that reeds seem to go out of tune more readily is the fact
that there are usually many more flue ranks than reeds in an organ,
and so when the flues go out of tune their weight of numbers gives the
impression that it is the reeds that are out.  Clarinet and saxophone
pipes usually have half-length resonators, and these _do_ go out of tune
more.

Jim Quashnock stated:

> I am not aware of any "reed" ranks which are totally made with
> flue pipes.  Maybe someone else can shed light on this.

Cornet stops in church organs are predominantly flue pipes, made up
of several ranks, sounding together remarkably like a well-regulated
reed.  A 5-rank cornet is usually made up of wide-scaled pipes in the
following configuration :

     8-foot (unison)
     4-foot (octave)
     2 2/3-foot (quint)
     2-foot (super-octave)
     1 3/5-foot (tierce)

They usually run from middle "C" to the top of the keyboard, with their
pipes mounted on a raised board because of the room they take up, hence
they are sometimes labelled "mounted cornet".

To my knowledge there are no mechanical organs with this type of
register, although some German organs such as Ruth have tierce mixtures
which go some way to providing a reedy type of sound in forte.  But
then, someone out there may know better.

John Page, UK

 [ The big Mortier organs have a 'mixtur' of five pipes for each note
 [ of the 12-key bass division, configured for strong energy in the
 [ octaves above the fundamental.  The sound produced reminds me of
 [ several bowed bass viols in unison.  -- Robbie