Bob Cain wrote:
Laurence Payne wrote:

On Tue, 17 Aug 2004 11:25:12 -0700, Bob Cain
wrote:

Because there is a real difference. Air can't carry the DC
component of velocity but it can carry any time varying
component.


I guess DC offset in air is barometric pressure?

Right, and a constrained piston can't change it.

No, it should change it a little bit. Of course, the ratio between the
volume of the box behind the piston and the volume of the earth's atmosphere
is very small. But it's nonzero!
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."