Irene Stamm encouraged her husband, Jason, to wander off to look at the nuclear stuff for a while so she could play with the da Vinci toys. She had a lot to choose from: The National Museum of Nuclear Science and History has about 30 of the Italian Renaissance artist's machines on display as part of a traveling interactive exhibition that runs through mid-May.

There were gadgets with pulleys and weights and balls that could be cranked up. There was a robotic drummer whose beat sounded like that guy who sits on a ship and plays drums to keep the oarsmen rowing in rhythm.