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.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein