Illustration depicting the Aytoun Patent Safety Cage, a mining elevator with safety catches to ensure passenger safety in the event of a chain break. The illustration depicts two scenarios: the shaft elevator descending into the mine without a broken chain, and the shaft elevator with a broken chain and catch disengaged, using "shoes" or "slides" to halt the cage from freefalling.

This figure is from The Playbook of Metals, an informative and entertaining volume on all aspects of the history, mining, smelting, and metallurgy of the metals then known. The author, John Henry Pepper (1821-1900), was an analytical chemist and professor of chemistry at the Royal Polytechnic, London. Nearly 300 engravings illustrate the text, which includes chapters on coal, coal mines, and the art of alchemy, as well as individual metals and their combinations.