The Gavioli frein: an invention from Gavioli.  About 1920 almost every
organ have a stop "violin", a flute.  This stop mostly was used for
"zang", this means it was playing the main melody.  The open pipes from
the "viool" were made of wood, with a rather narrow pipe-scale.  The
"frein" is a small metal sheet, fitted near the flue of the pipe, which
resulted in a remarkable round, violin-like tone.  Gavioli got this
invention patented in 1878 under the name of "frein harmonique".

Frein indeed comes from the French, since Gavioli was living in France
when he patented his frein-invention, using the French language.  Frein
is a good word to describe what this adjustment is doing.  I do not know
the German word for it, but I would not be surprised if it would be
"Frein".  After all, in Holland it's called a "frein" as well.

The sound of the pipe is modified by the frein.  Normally we have a
stopped pipe with a tube in the stop.  This causes the doubling of the
period of the pipe, as written before.  The frein however is not
mounted on top of the pipe, but next to the flue (Kernspalte)

          |           |
          |           | <-pipe
          |           |
          |           |
           \          |
             ---------| <- the horizontal part is the "kern" (languid)
    A---> /           |
          \          /      A is the "onderlabium" (lower lip)
           \        /
            \      /
             \    /        The gap between languid and lower lip
              \  /         is the glue.


Remember: the book "Orgelbouwkunde" is completely in Dutch, but it does
have a list of organ terms in the four languages, to avoid misunder-
standings and disappointments.

Jan Kijlstra