The ridges on the edge of a coin were invented to stop people stealing the coin a sliver at a time. When coins were made of gold and silver, their value was the metal in them, and a criminal could trim a thin crescent off the rim of every coin that passed through his hands, keep the shavings and spend the coins at full value. The ridges, called reeding or milling, made that impossible to hide.
The crime of clipping
In England the practice was called clipping, and it was taken very seriously. The Royal Mint’s own teaching notes on the subject explain that in the 17th and 18th centuries a coin’s weight was what mattered, because the coin was made of precious metal. Clipping and counterfeiting were both capital offences. A man convicted of coin crime could be hanged, and a woman burned at the stake. In London the cases went to the Old Bailey and the executions took place at Tyburn, near today’s Marble Arch.
The problem was partly the way coins were made. Hammered coins were cut from silver with shears and struck by hand, so they were rarely perfectly round and the design often did not reach the edge. A little missing metal was hard to notice. People stopped trusting the coins in their pockets.
The ridged edge
The answer came from machinery. In the middle of the 17th century, according to the Royal Mint, machines were brought into the Mint that could make thicker coins and put milling around the edge, the same vertical lines still seen on British 5p and 10p pieces. Some coins also carried a Latin inscription around the edge, DECUS ET TUTAMEN, “an ornament and a safeguard”, which later appeared on the round pound coin. With a ridged or lettered rim, any trimming showed at a glance.
There was a catch. The government did not recall all the old hand-made coins at once, so clipped and clippable money stayed in circulation for decades alongside the new machine-made coins.
Isaac Newton, coin detective
The man who took on what was left of the problem was Isaac Newton. In 1696 he became Warden of the Mint, which was then housed in the Tower of London, and he was Master of the Mint from 1699 to 1727. The Royal Mint describes how he set out to interview criminals and informers involved in clipping and counterfeiting, to learn how the trade worked and how to stop it. The physicist who had worked out the laws of gravity spent part of his later career as an investigator of coin crime.
Why coins still have ridges
Modern coins are not worth their metal, so no one clips them. In the United States, the Coinage Act signed by Lyndon Johnson on 23 July 1965 took silver out of the dime and the quarter and replaced it with a copper-nickel sandwich around a copper core. Yet both coins still have reeded edges, as CoinWeek’s specifications for them note.
We found no official statement of why the reeding stayed. Our guess is habit and touch: people are used to ridged dimes and quarters, and the edge helps tell a dime from a penny without looking. That is a guess, not a documented policy. Whatever the reason, the ridges you feel on a quarter today are a memory of a time when a coin’s edge was worth guarding with the gallows.
