MIT demonstation of pull vs push
 

MIT -- where is the guy who hijacked the MIT professor's email addy? -- has a
permanent display showing what happens when fluid is pulled rather than pushed.
To those who don't wish to hit the site, it shows that nothing happens under
pull, while something does happen under push.

[sher, you chance to tell us once again how much more you know than a Nobel
physicist.]

http://web.mit.edu/Edgerton/www/FeynmanSprinkler.html