The clear description Spencer Chase gives in his quest to identify
a box pump leads me to believe he has found an early Ampico pump.
The internal flap valve scheme using a slotted aluminum base was
used by Ampico and was phased out around 1919-1920.  Some leeway on
these dates is necessary as my recollection could be off a bit; the
dates aren't important.  What is important is that Spencer is correct
in assuming this pump would make for a great flap valve tester.

Two words of caution, since the pump is destined for a Duo-Art
application.  First, the 15 pump size is indeed found in some Duo-Art
pianos and it usually is inadequate.  Additionally, the Ampico pump has
less capacity then the Duo-Art pump because of the design differences
already mentioned by Spencer.

Secondly, if it is an Ampico pump and it is coupled with a Duo-Art
motor, the rotation will cause the pump pulley to unscrew from its
shaft.  Duo-Art motors and pumps run counter-clockwise.  Ampico pumps
and motors run clockwise.

Of course, Spencer will deal with these issues.  I await his findings.
It sounds like a good project.

Bob Taylor