From Archaeologia Cambrensis, October 1846.
“The size of the Buckstone is about twenty-two feet extreme length, as seen in the sketch; on the top it is nineteen feet long by thirteen feet wide, and about fifty-three feet in circumference. Its height is thirteen feet, and in figure is somewhat of an inverted pyramid poised on its apex, which is about three feet in diameter, where it touches the pedestal.”
Image credit: HJL
It's a wonder it ever rocked, surely that must defy physics?
It's certainly no wonder that those "actors and an innkeeper" (disreputable career choices if ever there were some) toppled the thing.