No one knows for sure how the megaliths of Stonehenge were erected 5,000 years ago. With each stone weighing between two and 50 tons, how were these massive weights transported from quarries as much as 200 miles away by neolithic builders—who hadn't even invented wheels or pulleys yet?
This is the kind of question that fascinates Brandon Clifford of Matter Design. Last year, he and a team of MIT students created a 2,000-pound sculpture that replicated the physics with which people of Easter Island moved massive stones across land, centuries ago, to create the legendary Moai of Easter Island. Clifford and his students recreated the effect with a monumental sculpture that could be moved with a fingertip—thanks to engineering ideas from 1100 AD.
This year, Clifford created a new kind of megalith, based on equally ancient construction techniques. Called the Buoy Stone, the 1,850-pound sculpture was inspired by theories that the megaliths of Stonehenge were transported from their quarries down England's River Avon. Designed to mark the centennial of what MIT calls the "crossing of the Charles," when the school moved from Boston's Back Bay to its current Cambridge Campus, the Buoy Stone floats.
The megaliths at Stonehenge are believed to have been floated down River Avon with inflated animal bladders, so the Buoy Stone uses a similar technique to keep its mass bobbing in the Charles River. Although it appears to be solid concrete from the outside, the Buoy Stone contains a foam core, surrounding a carefully calibrated internal bladder which can accommodate up to 6,000 pounds of river water. That's enough to float the stone's nearly 2,000-pound weight indefinitely.
What makes the Buoy Stone such a striking sight isn't just the fact that it floats, but how it floats. Although the whole stone is eight feet wide and 20 feet long, it doesn't rest in the water along its longest axis, as you might expect. Instead, it bobs upright in the Charles, standing over 16 feet tall from the water line to the top of the stone. To accomplish this effect, Matter Design needed to employ some precise computational simulations of the finished megalith's buoyancy, along with some of the same techniques that shipmakers use to float tall-masted sailboats in the water upright.
Although it doesn't use the exact same techniques that some archeologists believe were used at Stonehenge, Clifford says that the Buoy Stone is meant to make people think of the performative, almost theatrical aspects of making enormous objects move. In part, the Buoy Stone recreates the bizarre spectacle of what it must have been like to see 50-ton stones floating down a prehistoric English river. "It's all about the mystique," Clifford says. "The reason we know this is a success is because as we were floating the Buoy Stone, so many joggers and cyclists kept on stopping to gawk at it, and ask how it was possible for a stone to float that way."
Right now, the Buoy Stone is bobbing placidly near the Massachusetts Avenue bridge in Cambridge, right across from MIT's famous Killian Court. And unlike the McKnelly Megalith, Clifford tells me there's no intention on taking it down. "It's possible some authority will come along and tell us to remove it," he says, "but I'd love to see what it looks like out there in winter, when the river's been frozen over."
More than just being a spectacle, though—and like the megalith that preceded it—the Buoy Stone is an attempt to examine how knowledge from the past can influence design today. "If there's anything that megalithic builders were knowledgeable about, it's how to work with massive, heavy stones in practical ways," says Clifford.
Thanks to the ever shrinking gap between what we can simulate and what we can build in the real world, Clifford thinks the time of the megalith may be coming again.