On Sat, 09 Sep 2006 11:32:14 +0100, Eiron wrote:

Measure it yourself. Get a straw and blow through it. Feel the airflow
or hold a strip of paper. You can see how directional it is. Then suck.

That's measuring the effect some distance from the orifice. Aren't we
interested in the effect AT the orifice? Unless the wall is very
close.