Ewing Named Hysteresis for a Wire Four Years Before His Magnet Paper

The Paper That Named the Lag

James Alfred Ewing named hysteresis on page 22 of a paper the Royal Society received on September 7, 1881, and the apparatus on that page is not a magnet.² It is a length of iron or steel wire, magnetized and then twisted, and Ewing had noticed a quantity he called “polarisation” lagging behind the twist, tracing curves that never coincided.² He was reusing a name. The lag, he wrote, was “like that formerly described by the author as a characteristic of the curves connecting thermoelectric quality with longitudinal pull,” from an earlier paper on stressed metal. For it, “the author now gives the name Hysterésis (ὑστέρησις, from ὑστερέω, to be behind).”²

Four Years to the Magnet

The date itself splits the record. Ewing's own paper carries 1881.² Merriam-Webster's dictionary lists 1882 as hysteresis's first known use, a year the dictionary does not explain.¹

Discovering the phenomenon in magnets is a separate question from naming it, and it has its own contested date. The physicist Emil Warburg linked a magnetic lag to iron around 1879, two years before Ewing's paper, working independently.³ Ewing later credited Warburg with the discovery. He kept the name.³

The magnet came later still. Ewing's best-known result, the closed loop traced by magnetizing and then demagnetizing iron, a curve that does not retrace itself, is the subject of a second paper, in Philosophical Transactions in 1885, four years after the one that coined the word.⁴ His own 1893 textbook draws that line in a single footnote, citing page 22 of the 1881 paper and page 524 of the 1885 one as two separate events.⁴

The Greek word itself was not new. It already had a use in rhetoric before its 1881 debut in science.⁵

What survived from 1881 was not the delay. It was the shape: a system that, once pushed and pulled, does not return by the way it came.

What Economists Kept

Economics borrowed the shape and left the wire behind. Olivier Blanchard and Lawrence Summers used hysteresis in 1986 to describe European unemployment, fifteen years into a rise that showed no sign of reversing while standard theory kept predicting a return to normal.⁶ Blanchard and Summers argued that each shock moves the target instead of fading. Workers who stay unemployed longest lose bargaining power to the insiders who kept their jobs, so wages never fall enough to draw them back in.⁶ The normal unemployment rate settles wherever the shock left it, and stays there until another shock moves it again.⁶

European unemployment never retraced its own curve after the 1970s shocks, the same shape Ewing first drew in a twisted wire.