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:
- Garden Sundial
- Clepsydra (Water Clock)
- Hourglass
- Fire Clocks
- Gravity
- Steam
- Barometric Pressure
- Hydrogen
- Ether-powered
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
The 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 
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 
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
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.
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:
The first to have experimented with atmospheric pressure in a clock was 
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
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. 
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.
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.
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 
“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” 
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.
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.
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!
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.
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.
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 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 
