Note 6 — Chapter II · The Bones.
Reading edition
The mechanism of this remarkable effect is clearly shown by an experiment which the late Dr. Oliver Wendell Holmes used to take delight in performing in his anatomical lectures at the Harvard Medical College. He had a strong iron bar made into a ring of some eight inches in diameter, with a space left between the ends just large enough to be filled by an English walnut. The ring was then dropped to the floor so as to strike on the convexity just opposite to the walnut, which invariably was broken to pieces.