Information about the Hadley Pendulum

The Hadley Pendulum is a Foucault Pendulum named in honor of Professor Emeritus Lawrence Hadley, who originally joined the CSU (then Colorado Agricultural and Mechanical College) Physics faculty in 1947, departed for a few years, and then returned in 1955 and has remained a CSU faculty member ever since. He served as Chairman of the department from 1965 to 1968.

What is a Foucault Pendulum? It is really just a pendulum, that is to say, a heavy "bob" swinging on a cable suspended from a fixed point above, but which swings for a sufficiently long time that one can observe the effects of the Earth's rotation on the motion of the bob. If the Earth did not rotate, then the motion of the bob should lie in a fixed (vertical) plane; but since the Earth does rotate, anywhere on the surface of the Earth (except along the equator) the plane of motion also rotates. A fairly detailed "cartoon physics" discussion of the Foucault Pendulum is presented by the California Academy of Sciences.

This particular pendulum has a period of about 5 seconds. The mass of the polished steel bob is about 270 pounds. In order to keep the pendulum swinging, there is an actively controlled electromagnetic drive located near the top of the cable. The observed precession rate of the pendulum is very close to the theoretically expected value of 9.76 degrees/hour.

Credits for design, construction, and installation of the Hadley Pendulum go to Dave Warner, Jay Jablonski, and Bob Adame.

Live "Video" from the Pendulum Cameras Now Available!

We are pleased to offer "video" (not really streaming video, but a sequence of images as fast as your computer can receive them, up to a rate of four per second) from the three cameras monitoring the Hadley Pendulum. The video feed will stop after a few minutes; the reload button on your browser will start it up again.

Note that your browser must have Javascript enabled in order to view these image streams. Users of Internet Explorer under Windows will be prompted for permission to download a signed ActiveX control.

Views of the Hadley Pendulum from....

• the first floor
• above
• the second floor (look for the moving cable)