[ Ref. John Dewey in 190925 MMDigest ]

The photo suggests to me that the box is a Recordo 'A' type box.
A leaker type of box has a port to atmosphere and this box does not
have such a damped, padded labyrinth type of structure.

Also, the main pneumatic with the spring attached, and the large
nipple nearby, suggests the pneumatic is the choking element.  Also
again, the smaller pneumatics above the large pneumatic with the
spring, are different sizes, and they all pull together against the
spring.

I did model a Recordo type 'A' box.  The model was scaled up from
a picture supplied by John Tuttle.  The model gave close to the
vacuum steps required.  The ports used were

  none, 1, 2, 3, 1+2, 1+3, 4, 1+4, 2+3, 1+2+3 = 2+4, 3+4.

Actually, quite a nice design concept.

Paul Rumpf
Melbourne, Australia