After Bruce Miller read of the other two acrylic tracker bars that
exist besides his own, which he thought was unique, he wrote me
wondering if they were all made by the same person.  In 090113
MMDigest Les Higger reported the fourth acrylic tracker bar and
says that it was made by Herbert Vincent.

I knew Herbert N. Vincent as Ross R. Davis's band organ repairman.
I am willing to bet that all four acrylic tracker bars were made by
him.  I never knew Herb Vincent personally, although we had exchanged
letters once years ago.  He died in 1966.  Pictures and a biography
of Mr. Vincent are on this web page:

http://www.mechanicalmusicpress.com/history/articles/hnv.htm 

Matthew Caulfield
Irondequoit, New York