Note 52 — A CHAPTER ON English Engraving. By WILLIAM WALKER.
Robert Alan Mowbray Stevenson translation
The tear-shaped pieces of glass (Lachrimæ Vitreæ), which resist hard blows applied at the thick end, yet fly to pieces the moment a fragment is broken off the fine end, were first brought to England by Prince Rupert, and are called popularly "Prince Rupert's drops."