FACT OF THE DAY

The Alloy That Tamed Temperature’s Grip on Time

The Swiss physicist Charles Edouard Guillaume gave watchmaking two of its most quietly important materials: Invar in 1896 and Elinvar in 1913, alloys that barely change shape when the temperature does. A hairspring is the tiny coiled spring that governs a watch’s rate, and ordinary metals expand in heat and contract in cold, throwing a watch off noticeably. Guillaume’s alloys, engineered for near-zero thermal expansion, kept the hairspring steady across warm afternoons and cold nights, sharpening the accuracy of both wristwatches and marine chronometers, as Quill & Pad notes in its history of watchmaking.

Guillaume’s contribution was recognized with a Nobel Prize in Physics in 1920, rare company for a man solving a watchmaker’s problem. Next time your watch keeps its cool, you know who to thank.

Steady hands, steady springs.