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Besides cutting clean surfaces on their granite, the Egyptians also drilled cylindrical holes into their stones. A hole eight inches in diameter was found drilled in a granite block at the Temple of Karnak. "Even with modern tools—stone chisels and diamond wheels—we would have a tough time doing such fine work in granite," says Hopkins. Stocks was brought along to test his theories about how the cores were drilled. Inspired by a bow drill seen in an ancient Egyptian wall painting, Stocks designs a home-made bow drill. He wraps rope around a copper pipe that the Egyptians could have forged. Hopkins and Lehner then pull back and forth on the bow, which is weighted from above. The pipe spins in place, rubbing the sand, which etches a circle into the stone. With the assistance of the sand, the turning copper pipe succeeds in cutting a hole into the granite slab. Previous Next How Big Were They? | Cutting Granite with Sand | NOVA Raises an Obelisk Lever an Obelisk | Explore Ancient Egypt | Mysteries of the Nile | Resources | Transcript Medieval Siege | Pharaoh's Obelisk | Easter Island | Roman Bath | China Bridge | Site Map Editor's Picks | Previous Sites | Join Us/E-mail | TV/Web Schedule About NOVA | Teachers | Site Map | Shop | Jobs | Search | To print PBS Online | NOVA Online | WGBH © | Updated November 2000 |