I wonder if Mrs. Gashinski has any pictures of the Gavioli? In the
archives of the Kring van Draaiorgelvrienden (KDV) we have a lot of
pictures made in the Gavioli factory around 1906.
110-key models were always built in Paris, never in Waldkirch, Germany.
Some examples had a box with additional pipework on top of the main
chest. I can imagine that Mr. Williams organ was built like that, and,
in that case, it was not a dummy organ but just a part of it.
Many big organs by Gavioli's descendant, Marenghi (and later on,
Mortier), built the same type of instruments. Gavioli & Cie have built
tens of this type, of which only a few survive.
Best regards from Holland,
Hans van Oost, KDV