'(<a href="http://www.j-archive.com/media/2006-07-25_DJ_24.wmv">Kelly of the Clue Crew reports from the Exploratorium, San Francisco, CA.</a>)  Pressure from both sides on this vital piece is what holds up a catenary arch'
the keystone
SCIENCE AT THE EXPLORATORIUM: Pressure from both sides on this vital piece is what holds up a catenary arch
Pressure from both sides on this vital piece is what holds up a catenary arch
Pressure from both sides on this vital piece is what holds up a catenary arch
SCIENCE AT THE EXPLORATORIUM
the keystone
SCIENCE AT THE EXPLORATORIUM