Foucault pendulum

Collaborative faculty project sees over twenty years of success

Current and former faculty members of the Walla Walla University School of Engineering and the Southern Adventist University Department of Physics and Engineering collaborated to construct a Foucault pendulum that has been “working” since 1999. In 1851, French physicist Jean Bernard Leon Foucault discovered that a pendulum’s swing plane changes its orientation as a result of the Earth’s rotation, providing scientific proof for the earth’s daily rotation. 

Located in the lobby of Southern’s science center, the pendulum has been able to swing continuously for over 8,500 days thanks to perfectly timed pulses of energy from an electromagnet that was designed by Carlton Cross, WWU professor emeritus of engineering. A switching circuit to switch the magnet off and on was built by Ralph Stirling, WWU professor of engineering and instrument engineer. 

Cross explained that the challenge of the project centered on estimating how much energy would be needed for each swing of the pendulum. To understand this, Cross suggested imagining a person sitting on a swing being pulled back by a friend. When the swing becomes higher, the person in the swing has more potential energy, but has only kinetic energy at the bottom of the swing. When the person rises up again, potential energy increases again, though not quite to the degree of the first swing due to friction and wind resistance. Cross’s electromagnet was designed to pull on the sphere during each swing to counteract the impact of friction.  

According to Cross, this project was an illustration of how science and art can come together to produce something unique that neither could have accomplished alone, providing a great example for students of the benefits of collaboration between disciplines. “In simplified terms, physics is the science of how things work and engineering is the art of making things work the way we wish,” Cross said. The reward of this inter-institutional faculty collaboration is evident in the remarkable 200 pound ball suspended by a 38 foot multi-strand aircraft cable that serves as an educational and entertaining focal piece. 

Learn more about the Edward F. Cross School of Engineering at WWU by visiting

Posted July 26, 2023

Pendulum swinging
The pendulum is the product several WWU faculty members' work and resides at Southern Adventist University.