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The Insider - defying physics



A Clock Powered by Air?

written by A.Morgan - 27th Apr 2011

Cornelius Drebbel may sound like a fictional character from a story about wizards, but he was in fact a Dutchman who had a penchant for inventing things, and was the father of the Atmos. Born in Alkamaar in 1572, he initially apprenticed Hendrick Goltzius, a painter and engraver, but kept himself busy developing a series of weird and wonderful devices in his spare time. These inventions included scarlet dye, a thermostat for a self-regulating oven and the first microscope with two sets of lenses. His somewhat random portfolio gave him a reputation as a sorcerer, which, in 1604, attracted the interest of King James I of England, who was gathering together a collection of the greatest thinkers of the world in his court to entertain him. The first version of the Discovery Channel, perhaps.

Drebbel impressed the King with his inventions, and continued to do so when he built a basic submarine that could stay submerged at fifteen feet for up to three hours. It was built from wood, and sealed with greased leather; the crew (either mad or chosen at pain of death) would dive and surface using bladders with externally connected pipes that could be filled with water and be squashed empty again.

In the early 17th Century, in the irregular nature for which he had become famous, he developed a clock that ran on seemingly nothing. Dubbed the ‘Perpetual Motion Machine,’ it told the time, date and season, and had no obvious power source. What he had created was a movement that used the expansion and contraction of liquid at different air pressures to power it, working on the same principle as a thermometer – another invention of Drebbel’s. The most famous clock of his creation was the Eltham Perpetuum, given to King James himself.

During the Age of Enlightenment, a period in the 18th Century that exhibited an abundance of intellectual, scientific and cultural progression, a collaboration between James Cox and John Joseph Merlin gave birth to Cox’s timepiece, another apparently perpetual clock. It was much the same as Drebbel’s clock, winding the mainspring via movement of the liquid in a mercury barometer during atmospheric pressure changes. In order to provide the required amount of energy, 68 kilograms, the weight of a person, of mercury was used.

After almost a century since the Atmos 0 was created, the legacy still continues

Several hundred years later in 1928, the unofficially titled Atmos 0 was designed by Jean-Léon Reutter, a Swiss engineer who adapted the mercury barometer design to run on temperature change rather than pressure change. This significantly reduced the size of the clocks, and the prototype began production under the official name of Atmos in 1929, built by the Compagnie Générale de Radio in France. After a chance meeting between Reutter and LeCoultre, Jaeger-LeCoultre bought the patent and took over production in 1935. Four years later, they released the Atmos 2, updated with a safer ethyl chloride power source – the same chemical used in the Atmos today.

The secret behind the ability to use such minute temperature changes to power a clock without it being the size of a small car is twofold. Firstly, the engineering has to be incredibly efficient; any friction between components needs to be reduced, if not eradicated altogether. This is done by minimising the number of components used in the movement and the work required to overcome their inertia, as well as using a torsion pendulum rather than a swinging pendulum as it carries more momentum, and also by reducing the rate at which the friction occurs. The Atmos has a pulse of two beats per minute – compared to the four hundred plus bpm of a standard wristwatch movement, it’s practically dead.

The second aspect behind keeping the size down is the generation of power. The power source needs to make the most of the little amount of energy it receives, and it does this by way of the chemicals used. A sealed chamber is divided into two sections by a flexible bellows, filled with a mix of ethyl chloride gas and liquid. When the temperature increases the ethyl chloride expands, inflating the bellows and winding the movement by pulling a chain – the opposite occurs when the temperature drops.

The overall mechanism is so efficient that a temperature change of just a single degree can power the clock for two days. It requires such a small amount of energy to function that 240 million Atmos clocks would be needed to light a single 60 watt bulb. The hands are so finely balanced and require such little power to move that it would only take a fly to land on one to stop it. It is an engineering masterpiece.

As well as perfecting the movement for this unusual and virtually perpetual machine, Jaeger-LeCoultre have also manufactured the clock’s aesthetics to the same exceptionally high standards that they build their wristwatches to. From the gold-plated Classique to the bubble-like, Marc Newson designed 566, the Atmos is a very well built and beautifully finished clock, engineered to the finest detail. It is easy to see why over half a million of these fine clocks were sold in the first fifty years of production, and why Jaeger-LeCoultre have had no need to alter the movement in any way.

A must-have for any mechanical watch aficionado, the Atmos represents mankind’s quest to invent perpetual motion. From as far back as the early 15th century, when Leonardo da Vinci investigated the possibilities of its existence, perpetual motion has only ever been theoretically possible – yet Jaeger-LeCoultre produce a clock that will continue to work forever, as long as the temperature continues to change by a degree every two days. As much as the Atmos is a practical tool for tracking time, it is so much more than that – it is a museum piece to be stared at and pondered over by adults and children alike.

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