4.02 – Propulsion Modes

Last Update: 07-25-2022 @ 02:53

4.02 – Propulsion Modes

Today most clocks run on battery. This is a recent phenomenon in clockmaking history (c. 1970). Indeed, in the beginning, natural elements powered the sources of time. Then followed the use of mechanical elements like weights and springs. With the discovery of electricity, AC/DC and batteries became the main power sources of clocks. Finally, thermopneumatic and atome served as time devices. Therefore, in this second point of view, we classify clocks into 5 categories of propulsion modes: Ancients, Mechanicals, Electrics, Thermopneumatic, and Atomic.

4.02.1 – Ancient Modes

The elements of nature provided the ancients with the necessary propulsion modes to give the time. They used the sun, water, fire, etc. In the following popups, we will describe nine old modes of propulsion:

4.02.2 – Mechanical

There are two general categories of mechanical clocks:

4.02.3 – Electrical

The two main types of electrical clocks are the AC/DC plugged and the battery clock.

4.02.4 – Thermopneumatic

4.02.5 – Atomic (Caesium)

Next: 4.03 – Running Time

Home » 4.00 – Taxonomy of Clocks » 4.02 – Propulsion Modes

The sundial uses sunlight to give an idea of the time of day and, in some cases, the date. It consists of a dial with landmarks of the hour, and a high indicator, called “gnomon” that casts its shadow on the dial. The solar clock is usually an outdoor clock, public or private, depending on its size and location: Illustrated, a flat sundial photographed at the San Diego Sea World.  For more details on sundials, click on Wikipedia. 

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The Clepsydra, named after a water-spring in Messène, Greece, is not strictly speaking a clock but rather a chronograph. A vase filled with water indicates the time it would take for an event, such as a speech by a public speaker in Athens. The vase emptied itself by a small hole at the bottom of it. When it was empty, the speaking time was over—the oldest clepsydra dates from 1400 BC in Egypt. For more details, click Wikipedia. Illustrated, a 5th c. BC clepsydra from the Antique Agora Museum of Athens. The Upper Clepsydra is original, and the bottom one is a reproduction in clay.

There is also a water clock, fashionable in France in the 17th and 18th centuries called the Clepsydre à tambour (Drum), a hydraulic clock that could serve as an alarm clock. Wikipedia (in French only) has a very developed article on this particular Clepsydra.

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HourglassThe hourglass principle is the same as the clepsydra, but this time it is sand that flows into two superimposed vases with a very narrow opening at one end. It is more a tool to measure the time elapsed than a clock. For more details, click Wikipedia.

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The sun used to give the time of day. It was a clock in the strict sense of the word. The water, the sand did not give the time of day but allowed to measure the time that passes rather like a chronometer than a clock. Fire from different sources acted in the same way. In the Western world, in England in the 9th century, candles were graduated to measure time, then oil lamp. In the East, the Chinese and Japanese used fire devices like incense long before the English to measure an event’s duration.

On the same principle as the oil clock, the candle clock gave an appreciation of time, depending on the length it had left to burn, as indicated by marks inscribed on the candlestick that carried it. For more details, click Wikipedia.

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Again on the same principle as the clepsydra or the hourglass, a lamp oil measures time. The lamp container is filled with oil, usually whale oil. As the lamp burns the oil, it measures the duration of an activity. For more details, click Wikipedia. Illustrated an 18th-century Oil-lamp clock from the collection of the German National Museum of Nuremberg

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Of Chinese origin, Song Dynasty (960-1279), the incense clock used powder or incense sticks (illustrated, a reproduction) specially calibrated to measure time. For more details, click Wikipedia.

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A clock that operates by its own weight is called “Gravity Clock“. This type appeared in the 17th century. Gravity clocks appear to slide on a sloped plane, as the movement is installed in a round cylinder within which a weight tries to keep it level, but it descends on its own. Another type of gravity clock descends on a vertical plane attached to a wall. It is manually placed at the top, and it slides downwards on its own. It is also known as the “Rack Clock“. Illustrated a 19th c. French gravity clock in wood and brass from the Cooper Hewitt Collection of the Smithsonian Design Museum.

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John Inshaw (1807-1893), an Englishman, a mechanic, and inventor in f transport and railways created the steam clock. He owned a tavern in Birmingham, the Steam Clock Tavern, where he demonstrated his inventions. The Canadian Raymond Saunders was the first after Inslaw to create and install a steam clock on a city street. It’s in the district of Gastown in Vancouver (illustrated). Saunders has made more than 150 clocks that serve as tourist attractions around the world. See for more details: Wikipedia.

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The first to have experimented with atmospheric pressure in a clock was Cornelius Drebbel around 1610. He designed the following device: in a sealed tube, the atmospheric pressure causes the volume of the liquid to vary, thus inducing a perpetual motion. Later, in 1760, James Cox, in collaboration with John Joseph Merlin, an automaton specialist, designed a clock powered by atmospheric pressure using a mercury barometer, so the clock didn’t have to be rewind. This clock (illustrated) is part of the collection of the Victoria and Albert Museum in London. In 1864, Arthur Beverly designed a clock driven not only by changes in barometric pressure but also by changes in temperature. This clock is on display in the Department of Physics at the University of Otago, Dunedin, New Zealand. In 1913, J. E. Reutter of Neuchâtel, Switzerland, believed that the expansion of gas and liquids could drive a clock. It gave birth to the first Atmos clock marketed in 1926. We can say that all these clocks are the ancestors of the famous clock Atmos of Jaeger-Le Coultre

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Pasquale Andervalt designed a hydrogen clock in Italy around 1835. A replica is on display at the Clockmaker’s Company Museum in London, England.  It consists of two parts: (1) placed on a round brass base, a red glass cylinder filled with a sulphuric acid solution, on which the movement and its skeleton-type dial are mounted, and (2) a brass coil containing zinc balls. The movement has a pin-pallet escapement and an ornate gold pendulum that beats in front of the cylinder, and two weights, a small and a big one. The big one is used to wind up the clock and the small one to keep the clock moving. When the heavyweight is at its lowest level, it releases the zinc balls that fall into the tank, generating gas whose pressure allows the movement to be rewind. When the process is complete, the pressure is released, and a new winding begins. The whole process is very slow. For more details: click on douglas_self.com, from which the image comes.

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3.01 - PROPULSION MODES - Ancient Mode - Ether

In an article published in the French journal La Nature, on page 80 of the first half 1875 issue, under the title “Un nouveau moteur” (A New Motor),” we learn that an Italian physicist, Henri Bernardi, has operated a clock with an ether-powered motor. The article describes it. For an English translation: click

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A Comtoise Weights and Pendulum

A weight-driven clock derives its power from weights, usually made in cast iron or steel, that can be of different shapes, wrapped or not in brass or metal silos of any kind, suspended by ropes or chains, and slowly descends as time passes. In the illustrated French Comtoise clock, the left raw cast iron weight propels time, and the other propels the ringtone. In Comtoises, a crank allows lifting the weights after a week. Each of the ropes wraps around a hub. 

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According to Wikipedia, the spring clock dates back to the 15th century. Philippe le Bon, Duke of Burgundy (1430), had the oldest known spring clock. The Germanisches National Museum in Nuremberg, Germany, owns it. The spring replaced the weight-string set of the first mechanical clocks. The spring is a strip of metal, usually tempered steel wrapped (coiled) around a hub or arbor, while the springs of watches are in stainless steel or sophisticated non-magnetic alloys that appeared around 1947. The flow of the spring provides power to the clock and acts as an engine. The spring is either open or placed in a barrel. It can also take different forms, such as the spring of a wagon. It can also have a special mechanism designed to ensure the clock’s accuracy, such as the fusee. The invention of the coiled spring made possible the creation of watches and portables clocks.

In the history of clockmaking, the helicoïdal spring, made with tempered steel, emerged very early, probably during the 15th century. The spring made possible the creation of watches and other small portable clocks. Stainless steel or sophisticated non-magnetic alloys that appeared around 1947 were the metal of choice for watch springs. Open mainspring is called “Loop-end” to indicate its attachment mode on the arbor around which it is rolled—illustrated: an Arthur Pequegnat movement with two springs, one used for time, the other for ringing. 

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In this case, the spring is located in a barrel. We call that kind of spring Hole-end because there is a hole at one end to attach it to a small bracket inside the barrel. Illustrated, a very robust 1910s Seth Thomas movement that served mainly for commercial application clocks. The two large barrels contain the springs. The second spring is not used for the ringing train but rather as an emergency spring if the first one runs out or double the functioning time. This movement was installed in a timer used to control the opening of a bank vault.

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Joseph Ives (1782-1862) used the so-called wagon spring. He designed it in the 1820s. It was an arrangement of iron blades attached to the center by a bolt, the flexibility of the ends acting as a spring, as on a wagon pulled by horses. Their use began in 1825, but it didn’t last long with the arrival of the cheaper helical spring easier to manufacture. Ives himself slowed the dissemination of the wagon spring by carefully controlling the quantity to be manufactured by others.

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Fusee movementGenerally, in a weight clock, the diameter of the strings hub is the same on its entire surface. But there is another kind of grooved hub whose diameter varies from the largest to the smallest, and it is called “Fusee.” This system, attributed to Jacob Zech of Prague in 1525, balances the strength of the rope’s unfolding. Leonardo da Vinci had made drawings of it before Zech. The fusee also applies in spring movements such as the one depicted from a Gadsby English clock from London, England. The heavy spring is in a barrel. A steel wire connects the barrel and the fusee. When the clock is winded, the wire wraps around the fusee then switch on. It unfolds from the narrowest part of the fusee and wraps around the barrel until the spring runs out. Watches also make use of fusee spring. A fusee spring clock or watch maintains a more accurate time than the standard mainspring.

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The first experiments with electric clocks took place in the 1840s. Alexander Bain, an English clockmaker from Edinburgh, England, designed the first one named Eureka (patent no. 14614-1908. no. 3653). Eureka Clock Co Ltd, London, England, put it on the market in 1906. Illustrated, a Eureka clock from the Museums Victoria Collection, Melbourne, Australia. In 1918, the American H. C. Warren applied the synchronous alternating current motor to the clock.

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The so-called synchronous clock was developed in the United States by Henry E. Warren, who obtained the patent in 1918. The idea is to synchronize the clock engine with the frequency (50 or 60 Hz) of the alternating current (AC/DC) generated by a power plant, and to operate the hands with a minimum of gears, and maximum accuracy. This type of clock has been produced in large quantities by large manufacturers such as Telechron, General Electric, United, etc. They are easy to find at dealers and shops specializing in vintage, and on the web. Illustrated, the Westclox’s Bachelor, an electric alarm clock of 1936. Note the small red dot under the number 12. It is used to indicate that the clock has run out of power or is disconnected. By reconnecting it or adjusting the time, the dot turns white again. The patent belongs to Telechron, which has sold licenses to General Electric and Westclox, among others.

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The photo-electric-powered clock was invented in the 1950s by the famous Swiss watchmaker Patek Philippe from Geneva. The principle is simple: the clock has a lever escapement powered by a spring connected by different gears to a small motor powered by a photo-electric cell, thus by light. For more details, click on Timezone.

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“A pulsar is an astronomical object that produces a periodic signal ranging from the order of milliseconds to a few tens of seconds. (…) The pulsars were discovered in 1967 by Jocelyn Bell and Anthony Hewish in Cambridge, England”  (Wikipedia). The counting of radio waves emitted by the pulsars picked up by the radio telescope produces time. Electricity powers the Pulsar. The world’s first Pulsar clock was installed in Gdansk, Poland.

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The projection clock contains a device that can project the time on a distant surface, such as the ceiling or wall of a room. It may include an alarm as well. This display can be analog as well as digital, in black and white or in color. It’s also an excellent way to display an ad at the same time as the hour. Here is a contemporary example from the Amazon sale site. This type of clock plugs into the alternating current. Some have a backup battery in the event of a power outage.

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You might think the battery is a modern invention, but it dates back to the late 19th century. The first battery clocks were automatic winding mechanical clocks. Subsequently, as the batteries became smaller, clockmakers inserted them into desk or bedside clock cases. Then, with the invention of quartz in 1927, and its much later commercialization in multiple types of clocks and watches, battery clocks became the norm.

A self-winding clock does not need to be manually rewound. A small electric motor or a battery-powered electromagnet takes care of it, as in this illustrated movement from the Self-winding Clock Co., with its batteries, the two black cylinders at the top right of the movement, and in the middle at the bottom.

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André-Marie Ampère invented the solenoid in the 1820s. Alexander Bain (1810-1877) produced the first electromagnetic clock in 1842. An electromagnet (solenoid) activates the pendulum of the clock, producing a magnetic field. In the mid-20th century, a battery placed under the case generated the electricity: Illustrated, a Kieninger and Obergfell from the 1960s. Beware, many of these have problems. Corrosion affects the AA battery connectors, and the small case containing it must then be replaced by a made in China because there are no more parts for these clocks, except perhaps the spring of the escapement.

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A calibrated pitch counts oscillations at a specific frequency to hold the time. Battery clocks before the arrival of quartz in the 1980s had this type of mechanism. Bulova launched in 1960 such watches and electronic clocks under the name Accutron (illustrated). It was a first!

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Here are two examples of a battery-based movement that does not use quartz. Left photo, the battery movement of the Bracket Clock Seth Thomas Exeter II of 1979. This movement activates a floating pendulum and two small hammers that strike on harmonic copper rods to ring for half hours and hours. In the right photo, a battery-operated mechanism with a loudspeaker from which the notes of the Westminster chime emerge is installed in an unknown-brand wooden case that had a Westminster chime movement. One might think that the original movement was defective. Because of the repair cost, the clockmaker proposed replacing it with a much less expensive battery movement.

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The radio-controlled clock is periodically synchronized with the UTC atomic clock via radio waves produced by stations worldwide. Not to be confused with a radio clock. Here, a radio-controlled thermometer-barometer clock branded La Crosse from the 2010s, which I use every day. Not only the time but also the weather forecast are radio-controlled.

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Warren Morrison, a Canadian, and J. W. Horton, an American, developed in 1927 the first quartz clock at the New Jersey Bell Telephone Laboratories. Quartz oscillates at a specific frequency when stimulated by an electrical current, in this case, obtained from a battery. The advantage of quartz is its precision, a second behind in six years. The first quartz clocks and watches appeared on the market in the early 1970s: Illustrated, a quartz Danbury from Taiwan (1970), powered by a small flat battery. The movement is similar to that found in quartz watches but larger.

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In 1940, the German company Jauch und Smid introduced a clock, the Puja, whose furniture case resembled all the others. Still, inside there was a movement that had a perpetual thermo-pneumatic winding device. A website paragraph explains how it works: On the backside of the movement, “at the lower left, shielded by a translucent housing, is a carbon rod resistance that heats the colored alcohol in the glass vessel just above it. This causes some of the alcohol to vaporize, the pressure pushing the liquid up the connecting pipe to the vessel at the top right. As the latter gets heavier, the wheel bearing the four vessels experiences a torque rewinds a rewinding spring driving a conventional gear train and escapement. This clock has a pendulum-controlled escapement, but models with balance wheel escapements also existed.” (Ref.:  The Watchismo Times for illustrations and details).

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The first experiments with the atom were conducted in 1949 at the U.S. National Institute of Standards and Technology, using an ammonia molecule. Although the accuracy was greater than that of quartz, the arrival of the caesium clock stopped experiments with ammonia. The atomic caesium clock was invented in 1955 by two Englishmen, Dr. L. Essen and J.V.L. Parry of the National Physical Laboratory in Teddington, England. It had an accuracy of 1 second in thirty years, or 1 part out of 1 billion. Subsequent models had an accuracy of 1 in a thousand billion and even more. The atomic clock is used to define the second since 1967. Illustration: the console of an early atomic clock used by the Greenwich Observatory. To get more details, click Wikipedia.

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