Ian Gillis: You ask for "definitive" information.  Of that I can't
provide any; however, I might be able to add something that could
lead to some.

The boxes appear to be ones used by the late Richard Tonnesen of
Richardson, Texas [Custom Music Rolls].  The label work I absolutely
cannot place, although I can say that it was uncharacteristically
fine, whoever may have produced it.

Certain of the titles shown are distinguished; some especially-so.
The Horowitz ones certainly are distinguished, as is the Gieseking,
but the two composer-played selections -- the Pensée à Schumann of
Sapellnikoff's and the Klavierstücke of Rehberg's -- are standouts.

The first because it is one of the finest poetical utterances to
be found in the entire of the German Welte-Mignon catalog and the
Rehberg on account of it's being one of the rarest.  (Over a period
of some fifty-plus years I never ran across a copy.  Welte had a very
bad habit of holding back exquisite titles to be released only during
Depression times, and thus their resulting extreme rarity.)

Also, the Helene Leon performance of Seguidillas by Albéniz there
(along with the gigantic "La Vega," part of the unfinished Alhambra
suite) must count as outstanding examples of Spanish piano mastery,
both compositionally as well as pianistically.

As for the roll productions themselves, I'd at least guess that they
were of that batch rumored to have been made from a T-100 tracker bar
that Richard Tonnesen had (or, was loaned to him), that was then used
to transcribe various of titles from Ken Caswell's collection.

I was not present during this Gryphon/Caswell/Tonnesen Era excitement
and activity then on-going in Texas.  Fellow MMD contributor and
subscriber John (Gryphon) McClelland however I believe was, and if-so
I am sure he will be able to supply solidity where I have only surmise.

Jim Miller
Las Vegas, Nevada