National Geographic : 1947 Apr
The National Geographic Magazine National (eographie Soiety Koduahrome Iy \Willard It. ('uler Her Handful of Cobweb Steel Will Make Hairsprings for 4,800 Watches At left is an ingot of elinvar, a nickel-steel alloy which resists magnetization, temperature changes, and rust. Scoops hold materials used to produce elinvar. Forging transforms the ingot into a bar (foreground), from which spring wire is drawn. Hairspring wire for small watches is one-fifth the thickness of a human hair (Plate VIII).