From the December 5, 1936, issue

OLD GLASS IN NEW FORMS

Several centuries ago, the philosophers were mystified by the remarkable properties of a peculiar, pear-shaped bit of glass having an elongated tail. “Prince Rupert Drops” withstand hammer blows on the bulbous section but fly into bits as the tail is broken off. Such drops are highly strained—a heavy compressional layer surrounding a zone of terrific tension.