350 years ago, Christiaan Huygens invented the balance spring, dramatically improving the accuracy of mechanical clocks. This invention supported the development of astronomy, navigation, and science as a whole, and it still beats at the heart of modern mechanical clocks. In 2025, the International Museum of Watchmaking (MIH) in La Chaux-de-Fonds, Switzerland, will hold a special exhibition commemorating the 350th anniversary of the invention of the balance spring. Following this, the Mitsukoshi Main Store in Nihonbashi, Tokyo, is currently holding a special exhibition titled "The Stars Tell the Time: Huygens, the Origin of Clocks, and the Future," with the cooperation of MIH materials. Now is the time to look back at the origins of time measurement.
Photographs & Text by Tomoyo Takai
[Article published on January 29, 2025]
Commemorating the 350th anniversary of the creation of Christiaan Huygens' balance spring
The year 2025 marks 350 years since Christiaan Huygens invented the balance spring. This invention revolutionized the regulating mechanism, often called the heart of a watch, dramatically improving the accuracy of mechanical watches and ushering in an era in which humanity could accurately measure time. To commemorate this achievement, the Musée International des Horlogers (MIH) in La Chaux-de-Fonds, Switzerland, will host a special exhibition from spring to fall 2025 on the technical history and evolution of the balance spring. The exhibits, rich in academic merit, include Huygens's 1675 manuscript and early 17th-century balance spring clocks, as well as research into materials evolution, temperature compensation, and anti-magnetism.
Why did Huygens try to make a clock?
Let's take this opportunity to revisit the role of the balance spring and the background to its creation. A balance spring is a thin spiral spring that maintains a constant oscillation in a mechanical watch. It is placed at the center of the balance wheel, which moves back and forth inside the watch, and its restoring force stabilizes the oscillation period. Before this mechanism was in place, portable watches had large inaccuracies, with daily deviations ranging from tens of minutes to several hours not uncommon. In contrast, the invention of the balance spring made it possible to achieve accuracy within a few minutes per day, bringing portable watches into practical use for the first time. While the materials used in modern mechanical watches have changed, replacing steel and gold with alloys like Nivarox and new materials such as silicon and carbon, the basic principle remains the same as that demonstrated by Huygens, and mankind has continued to use this mechanism for three and a half centuries.
To understand the background to Huygens' invention, we need to imagine the world 350 years ago. In the late 17th century, Europe, and the Netherlands in particular, was in the midst of a period of prosperity known as the "Dutch Golden Age," with shipping and commerce being the source of national power. During the latter stages of the Age of Discovery, ships ventured on long-distance voyages, connecting trade with the rest of the world and accumulating wealth. However, at the same time, a fundamental challenge in navigation technology lay in the "problem of measuring longitude." Because there are no landmarks at sea like on land, one cannot accurately determine one's current position without knowing the precise time. Great powers poured their efforts into developing clocks that could accurately measure longitude, and engineers were even promised huge rewards.
It was against this social backdrop that Huygens was born in 1629 into a family that formed a salon of Dutch intellectuals. His father, Constantijn Huygens, was a diplomat, poet, and scholar, so many intellectuals visited his home during Huygens's youth, naturally providing him with a wealth of intellectual stimulation. With the rise of intellectual freedom after the Protestant Reformation, talented people from Europe flocked to the Netherlands, and Dutch society at the time provided an ideal environment for advancing academic learning.
Huygens grew up in this environment, studying a wide range of subjects, including astronomy, mathematics, and physics, all of which he mastered to a high level. He left behind enduring achievements in the fields of astronomy, optics, and physics, including the discovery of Saturn's moon Titan, elucidating Saturn's rings, and proposing the wave theory of light. So why did he focus on clocks? Perhaps it was his desire to understand nature in a unified way. In an era when natural philosophy was not yet differentiated, Huygens believed it was necessary to conduct cross-disciplinary research into time, light, motion, and the laws of celestial bodies. Furthermore, precise time measurement was essential.
Applying Galileo's suggestion of the isochronism of the pendulum, Huygens completed the world's first practical pendulum clock in 1656. However, because the pendulum relies on the direction of gravity, it could not be used portable or on board a ship, necessitating the development of an alternative regulating mechanism. Huygens then turned his attention to the reciprocating motion of the balance wheel and conceived the idea of a balance spring as a spring that would provide a constant restoring force. He completed his theory in 1674, obtained a patent in Paris in 1675, and watchmaker Isaac Thuret built a prototype (though there was a battle for priority with Robert Hooke). This invention dramatically improved the accuracy of timepieces, revolutionizing maritime navigation and scientific observation, and is remembered as one of the greatest turning points in the history of timekeeping.
Huygens's ideas continue to live on today
Today, 350 years later, the basic structure of the balance spring remains at the heart of mechanical watches. Although materials and processing techniques have evolved, the idea of a spiral spring that generates regular vibrations remains unchanged. In the history of science, it is extremely rare for something to remain true to its origins for such a long period of time.
The special exhibition "The Stars Tell Time - Huygens, the Origin of Clocks, and the Future" being held at the Watch Gallery of Nihonbashi Mitsukoshi Main Store is not just a display of clocks, but is structured to allow visitors to experience the history of time measurement. Another unique feature worth noting is that the participating watchmakers have contributed handwritten letters specifically for the exhibition. The individuality and warmth conveyed through the handwritten letters add a new story to the works.
If you visit this exhibition with an understanding of the accumulation of history, the stories behind the clocks on display will emerge more vividly. You will be able to view clocks not simply as beautiful works of art, but as the crystallization of the accumulated wisdom of humanity. Huygens' spirit lives on today in the heartbeat of mechanical clocks.
"The Origin of Time = Astronomy" Special Exhibition, "The Stars Tell Time - Huygens, the Origin of Clocks, and the Future"
■ Outline
Event period: Until Tuesday, December 2, 2025
Venue: Nihonbashi Mitsukoshi Main Store, 6th floor, Watch Gallery/cal.BAR/Promotion Space
Cooperating organizations:
- La Chaux-de-Fonds International Museum of Watchmaking (MIH)
- The Hague Watch Foundation (Stichting Haegsche Tijd)
- Akashi City Astronomical Science Museum
- Nagoya City Science Museum
- Japan Watch Importers Association
