Mechanical clocks existed by the 1200s, and the first portable watches showed up in the early 1500s, and for the next two and a half centuries every one of them ran on escapements that were, by modern standards, terrible. The verge wobbled. The cylinder dragged. Then around 1755 an English watchmaker named Thomas Mudge invented the lever escapement, and the long era of workarounds was over. Nearly every mechanical watch made since about 1900 uses it. Everything in this article is what came before.
The verge: the first and the worst
The verge is the earliest known escapement, used in tower clocks from the 13th and 14th centuries and carried into the first watches, the little drum-shaped Nuremberg pieces Peter Henlein was making in the early 1500s. It is brutally simple: a vertical shaft with two pallets sticking out of it engages the teeth of a crown-shaped wheel, rocking back and forth as the wheel pushes past. It works. It also wastes enormous energy, needs a wide swing to function at all, and was never accurate by any standard you would recognize. Verge watches stayed in production into the 1800s anyway, mostly at the cheap end, because simple is its own virtue. Four hundred years of service from the worst escapement ever made is worth some respect.
A labelled verge escapement, the design that ran clocks and watches for four centuries. Photo: Wikimedia Commons, public domain.
The cylinder and the duplex: incremental fixes
George Graham, the great English clockmaker, invented the cylinder escapement around 1726. The balance staff carried a small hollow cylinder, and the escape wheel teeth entered and exited it with each swing. It was thinner than the verge, which meant slimmer watches, and the French industry adopted it enthusiastically for the next century. It was still frictional and fussy, and it never fully displaced the verge in England. Then Pierre Le Roy came along in 1748 with the duplex, which used two sets of teeth to give the balance a direct impulse in one direction. The duplex went into quality English watches and was genuinely accurate for its day, but it was delicate and demanding to manufacture. Each of these was a little better than the last. None of them was the answer.
The fusee: taming the mainspring
The escapements were only half the problem. A mainspring pushes hardest when fully wound and weakest when nearly spent, so a watch runs fast in the morning and slow at night. The fusee fixed that with a cone-shaped pulley and a tiny chain: when the spring was at full strength, the chain pulled on the narrow end of the cone, and as the spring weakened, the chain climbed toward the wide end, evening out the torque delivered to the movement. The idea goes back to the 1400s, and the fusee was standard equipment in good watches for centuries. It finally retired in the 1800s, when the going barrel, a better way of housing the mainspring, made the whole elaborate chain-and-cone arrangement unnecessary.
A fusee cone, which evened out mainspring torque for centuries before the going barrel replaced it. Photo: Wikimedia Commons, public domain.
The lever: Mudge’s answer, 1755
Thomas Mudge had been apprenticed to George Graham, so he knew exactly what was wrong with everything above. Around 1755 he invented the detached lever escapement: the balance swings free almost the entire time, touching the mechanism only to receive its push and unlock the escape wheel. Less contact means less friction, less wasted energy, and far better accuracy. He put it in a clock first, then in a watch made for George III in 1769, which still sits in the Royal Collection at Windsor Castle. The design was refined over the next fifty years by Breguet, Litherland, and Massey, and George Savage’s table roller in the early 1800s gave it its modern form. By about 1900 it had won completely. Virtually every mechanical watch, alarm clock, and kitchen timer since has run on some version of Mudge’s lever.
The cheap one: pin-pallet and Roskopf
There is one more historical type worth knowing, and it is the humblest of the lot. In the 1860s, Georges-Frederic Roskopf set out to build a decent watch a working man could afford, and his answer was the pin-pallet escapement, a simplified lever that used plain metal pins instead of expensive jewels. The Roskopf “proletarian watch” was crude next to a jeweled lever movement, but it was honest engineering: good enough, cheap enough, and producible by the million. It put timekeeping on wrists that could never have afforded a fine watch, and it is the direct ancestor of every inexpensive mechanical movement made since.
Why it matters
The history of the escapement is four hundred years of a problem being solved by inches, and then solved all at once. It is also a reminder sitting inside every mechanical watch you will ever handle: the most important horological invention of the last three centuries happened around 1755, before the United States existed. When you hear a mechanical watch tick, you are hearing Mudge.
Thanks for reading this.
