When I was in college I had the opportunity to explore and
photograph a Link Unit Orchestra at the State Theater in Ithaca,
New York.  I was amazed at two things: how an 8-rank 3-manual organ
could have 186 stop tabs, and how compact the relay and tuned
percussion units were compared to other theater organs I had seen.

I later found out that the reason for the extensive unification was
that this instrument was a touring demonstrator organ played by Mr.
C. Sharpe Minor himself.  It had every option, including four tuned
percussion instruments and an extensive toy counter.  The reason
for the compact construction was the use of a 1 horsepower Spencer
blower to create vacuum for the operation of these devices, in
addition to the 5 HP Spencer Orgoblo for wind.

Vacuum lines were run to the relay room and the pipe chambers to
activate simple pneumatics to operate the relay switches and the
strikers on the instruments.  The relay had pizzicato and sostenuto
functions in addition to all of the switches for the extensive
unification, and was only about 18" deep by 72" wide by 78" tall,
so it was quite compact by Wurlitzer relay standards.

After college I got involved with flying and in the corner of the
hanger at many small county airports you would see a Spencer
centrifugal vacuum unit.  I puzzled over this, wondering why I was
seeing so many of them. Then someone told me that the Spencer vacuum
was all that was left of an old Link flight trainer.

There must have been a lot of them out there around WW2.  Even today
you can still see a few of those Spencer units lurking in the corner.
So the vacuum-operated pneumatics from the orchestrions were adapted
for the pipe organs and then for the flight trainers.  Very clever
re-use of a simple technology.

I had the privilege of meeting Ed Link, Jr., in Binghamton when one of
the other 3-manual Link theater organs was restored for the Roberson
Center.  He was six years old in 1910 when the family moved from
Indiana to Binghamton, and he died in 1981.

Larry Kerecman

 [ Larry at the Link 3/8 C. Sharpe Minor Unit Organ at the State Theater, Ithaca (~1967)
 [ http://www.mmdigest.com/Attachments/14/12/29/141229_164454_Larry%20at%20the%20Link-r-c-10.jpg