Science: How Old Is Stonehenge?

In a laboratory at the University of Chicago, a pinch of powdered carbon was placed in a radiation counter. Chemistry Professor Willard F. Libby carefully measured its faint radioactivity,* made his calculation and gave his verdict: the charred oak from which the carbon came was 3,800 years old—give or take about 275 years.

The charcoal sample that was thus dated came from an excavated pit at Stonehenge, the great "megalithic cromlech" on

England's Salisbury Plain that has mystified scientists since Roman times. Antiquarians, archeologists and astronomers have speculated for years about Stonehenge's double circle...