Photo credit: California Academy of Sciences LibraryThere has been a lot of buzz about the innovation of the California Academy of Sciences building as of late. Yet as the opening date draws near it is the nostalgic and historical aspects of the Academy that hold my attention. There are three iconic exhibits of the Academy that have been revived - the Alligator Swamp Tank, African Hall and the Foucault Pendulum. Each exhibit has its own special history and anecdotes but I quite like the science and Academy history of the Foucault Pendulum.

The Foucault Pendulum first demonstrated in February 1851 that the Earth rotates by turning on its axis when French Philosopher Leon Foucault unveiled it in the Meridian Room of the Paris Observatory. His most famous pendulum was exhibited beneath the 279-foot dome of the Pantheon in Paris, hanging from a 219-foot wire. A replica of this famous pendulum swings in the East Pavilion of the Academy, though from only a 30 foot cable. A weight known as a “bob” on the end of a wire swings in a straight arc in relation to the laws of inertia and gravity. Below the constant back and forth arc of the bob a circle of pins set 6 degrees apart rotates. As the Earth rotates the pins come into contact with the constant arc of the bob and are knocked over.

At the Academy located in San Francisco (latitude 37.7°N), the pins will be knocked down every 39 to 40 minutes over a 24 hour period. In twenty-four hours, the pendulum will only knock over 220 degrees worth of pins. Knocking over 360 degrees worth of pins in San Francisco would take 39 hours, where at the North Pole (90° N) it would only take 24 hours.

Why is there a difference? This is because at the North & South Poles, Earth’s rotation is enough to explain the change in the pendulum’s apparent direction of swing. But as soon as you leave the poles and change latitude, something called the Coriolis Effect comes into play. The Coriolis Effect is an apparent deflection of moving objects when they are viewed from a rotating frame of reference, and its strength varies with latitude. Freely moving objects on the surface of the Earth experience a Coriolis force, and appear to veer to the right in the northern hemisphere, and to the left in the southern. Over time, this continual veering-off-course causes the swing of the pendulum bob to gradually precess, or rotate. This precessing is tracked as the pendulum knocks down pegs set up in a circle beneath it. The farther a pendulum is located from the pole, it will take gradually longer and longer for the pendulum’s swing to precess a complete 360°. At the equator, the Coriolis effect is so weak that the pendulum is unaffected - the swing would never precess and therefore the pendulum would never knock over any pegs.

Intestingly, the Coriolis Effect also explains the spiral shapes of hurricanes, cyclonic weather systems, and oceanic gyres and which way they spiral in the northern or southern hemispheres, so the physics works for various natural phenomena, not just for pendulums.

Over two hundred Foucault Pendulums around the world were made in-house at the California Academy of Sciences. In 1958, Academy staff built a Foucault Pendulum for the Smithsonian. In 1960, Foucault Pendulums began to be produced en masses for clients around the globe. Four to five a year were produced in the instrument shop and are still being created today by a retired staff member - Cary Ponchione under “Academy Pendulum Sales”. So the Foucault Pendulum on display at the Academy today is just one of many that demonstrate the axis rotation of the Earth and the specific laws of physics that affects arc, tilt and rotation.

Penguin-cams are now at
the California Academy of Sciences.

Upon writing this blog, the California Academy of Sciences is scheduled to open in 94 days. After years of planning, staff is contemplating two digits - literally three months until opening. It seems surreal. But progress at the park is moving along at a steady clip. African Hall is nearly done, with the backdrops painted and the specimens perfectly placed.

Select staff took a tour the other day across the western expanse of the public floor to see the new changes. The Foucault pendulum is placed in its new home with only a few touches needed before opening. Speculation was given over who will have the job of placing the pegs on a regular basis. The floor exhibits are being placed and labels are being printed. The tanks on the floor are being outfitted and water is being tested before fish are added. The opening is starting to feel palpable.

Yet so much is still to be done and a great deal of the building is off limits for staff because construction is on-going. Yet, so many still just want a little sneak peak. For this, there is one area with constant access albeit through technology. Three webcams have been placed in the new African penguin enclosure that now streams real time video footage. The enclosure sports a more natural rocky look and is twice the size of the penguin enclosure on Howard Street. The new residents at the end of African Hall are acclimating quite well to their new abode. The enclosure holds the 20 African penguins and they are now Academy ambassadors through our website. Views give a wide view of the enclosure, an underwater view and a handheld view from Pam Schaller, senior Aquatic Biologist and Penguin handler.

Along with streaming video, the Academy penguin-cam page features a blog updated by Pam about penguin behavior and research. Amongst the blog tidbits include observations of penguin courting and unusual markings on Ocio, one of the penguins. But you don’t have to take my word for it - you can visit yourself and spend some time with the Academy African penguins by visiting here.