Scientific American Supplement No. 822, October 3, 1891

This issue offers a vivid cross‑section of the scientific world as it stood in the early 1890s. Readers can wander from a British anthropologist’s reflections on humanity to a meticulous look at how sugars are measured by polarimetry, and from a fresh illustration of the water molecule’s structure to a reporter’s account of rock demolition techniques being trialled on the Suez Canal.

The supplement also follows the rapid expansion of electrical engineering, describing the English Board of Trade’s measurement standards, the groundbreaking London‑Paris telephone link, and emerging three‑phase alternating‑current systems complete with detailed diagrams. Articles on geography recount an adventurous Labrador expedition, while practical pieces explain variable‑speed gearing, eye‑care for young people, and a new bleaching apparatus for pulp.

A standout feature is the technical portrait of the French central‑battery ironclad Redoutable, outlining its iron‑and‑steel construction, armor thickness, engine power, and formidable array of guns and torpedo tubes. The piece places this warship amid broader discussions of naval armor, mineral discoveries, ant societies, and other contemporary curiosities.