HOME

TheInfoList



OR:

A striking clock is a
clock A clock or a timepiece is a device used to measure and indicate time. The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month and ...
that sounds the hours audibly on a bell or gong. In 12-hour striking, used most commonly in striking clocks today, the clock strikes once at 1:00 am, twice at 2:00 am, continuing in this way up to twelve times at 12:00 mid-day, then starts again, striking once at 1:00 pm, twice at 2:00 pm, up to twelve times at 12:00 midnight. The striking feature of clocks was originally more important than their
clock face A clock face is the part of an analog clock (or watch) that displays time through the use of a flat dial with reference marks, and revolving pointers turning on concentric shafts at the center, called hands. In its most basic, globally recogn ...
s; the earliest clocks struck the hours, but had no dials to enable the time to be read. The development of mechanical clocks in 12th century
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
was motivated by the need to ring bells upon the canonical hours to call the community to prayer. The earliest known mechanical clocks were large striking clocks installed in towers in monasteries or public squares, so that their bells could be heard far away. Though an early striking clock in
Syria Syria ( ar, سُورِيَا or سُورِيَة, translit=Sūriyā), officially the Syrian Arab Republic ( ar, الجمهورية العربية السورية, al-Jumhūrīyah al-ʻArabīyah as-Sūrīyah), is a Western Asian country loc ...
was a 12-hour clock, many early clocks struck up to 24 strokes, particularly in
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
, where the 24-hour clock, keeping Italian hours, was widely used in the 14th and 15th centuries. As the modern 12-hour clock became more widespread, particularly in
Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It ...
and Northern Europe, 12-hour striking became more widespread and eventually became the standard. In addition to striking on the hour, many striking clocks play sequences of chimes on the quarter-hours. The most common sequence is Westminster Quarters. Today the time-disseminating function of clock striking is almost no longer needed, and striking clocks are kept for historical, traditional, and aesthetic reasons. Historic clock towers in towns, universities, and religious institutions worldwide still strike the hours, famous examples being Big Ben in
London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...
, the
Peace Tower The Peace Tower (french: link=no, Tour de la Paix) is a focal bell and clock tower sitting on the central axis of the Centre Block of the Canadian parliament buildings in Ottawa, Ontario. The present incarnation replaced the Victoria Tower af ...
in
Ottawa Ottawa (, ; Canadian French: ) is the capital city of Canada. It is located at the confluence of the Ottawa River and the Rideau River in the southern portion of the province of Ontario. Ottawa borders Gatineau, Quebec, and forms the c ...
, and the
Kremlin Clock The Kremlin Clock (russian: Кремлёвские часы; ''Kremlyovskiye chasy'') or Kremlin Chimes (russian: Кремлёвские куранты; ''Kremlyovskiye kuranty''), also known colloquially in the West as Moscow Clock Tower, is a ...
in
Moscow Moscow ( , US chiefly ; rus, links=no, Москва, r=Moskva, p=mɐskˈva, a=Москва.ogg) is the capital and largest city of Russia. The city stands on the Moskva River in Central Russia, with a population estimated at 13.0 million ...
. Home striking clocks, such as mantel clocks, cuckoo clocks, grandfather clocks and bracket clocks are also very common. A typical striking clock will have two gear trains, because a striking clock must add a ''striking train'' that operates the mechanism that rings the bell in addition to the ''timekeeping train'' that measures the passage of
time Time is the continued sequence of existence and event (philosophy), events that occurs in an apparently irreversible process, irreversible succession from the past, through the present, into the future. It is a component quantity of various me ...
.


Passing strike

The most basic sort of striking clock simply sounds a bell once every hour. This sort of striking clock is called a ''passing strike'' clock. It is far simpler to create such a clock; all that must be done is to attach a cam to a shaft that rotates once an hour; the cam raises and then lets a hammer fall that strikes the bell. The first
tower clock Clock towers are a specific type of structure which house a turret clock and have one or more clock faces on the upper exterior walls. Many clock towers are freestanding structures but they can also adjoin or be located on top of another buildi ...
s, mounted in towers in cathedrals, abbeys, and monasteries to call the community to prayer, which originated in
Medieval In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
before the invention of the mechanical clock in the 13th century, were water clocks which used the passing strike mechanism; they rang once for each
canonical hour In the practice of Christianity, canonical hours mark the divisions of the day in terms of fixed times of prayer at regular intervals. A book of hours, chiefly a breviary, normally contains a version of, or selection from, such prayers. In ...
. Before European clocks, China developed a water-driven astronomical clockwork technology, starting with the first century AD scientist Zhang Heng (78–139). The
Tang Dynasty The Tang dynasty (, ; zh, t= ), or Tang Empire, was an Dynasties in Chinese history, imperial dynasty of China that ruled from 618 to 907 AD, with an Zhou dynasty (690–705), interregnum between 690 and 705. It was preceded by the Sui dyn ...
Chinese Buddhist monk and inventor Yi Xing (683–727) created a rotating
celestial globe Celestial globes show the apparent positions of the stars in the sky. They omit the Sun, Moon, and planets because the positions of these bodies vary relative to those of the stars, but the ecliptic, along which the Sun moves, is indicated. ...
that was turned by a water clock mechanism driven by a waterwheel This featured two wooden gear jacks on its horizon surface with a drum and a bell, the bell being struck automatically every hour and the drum being struck automatically every quarter-hour. It is recorded that
Confucian Confucianism, also known as Ruism or Ru classicism, is a system of thought and behavior originating in ancient China. Variously described as tradition, a philosophy, a religion, a humanistic or rationalistic religion, a way of governing, or ...
students in the year 730 were required to write an essay on this device in order to pass the Imperial examinations. The use of clock jacks to sound the hours were used in later clock towers of
Song Dynasty The Song dynasty (; ; 960–1279) was an imperial dynasty of China that began in 960 and lasted until 1279. The dynasty was founded by Emperor Taizu of Song following his usurpation of the throne of the Later Zhou. The Song conquered the res ...
China, such as those designed by Zhang Sixun and Su Song in the 10th and 11th centuries, respectively. A striking clock outside of China was the clock tower near the Umayyad Mosque in Damascus,
Syria Syria ( ar, سُورِيَا or سُورِيَة, translit=Sūriyā), officially the Syrian Arab Republic ( ar, الجمهورية العربية السورية, al-Jumhūrīyah al-ʻArabīyah as-Sūrīyah), is a Western Asian country loc ...
, which struck once every hour. It is the subject of a book, ''On the Construction of Clocks and their Use'' (1203), by
Riḍwān ibn al-Sāʿātī Fakhr al-Dīn Riḍwān ibn Muḥammad ibn ʿAlī ibn Rustam al-Khurāsānī al-Sāʿātī ar, فخر الدين رضوان بن محمد بن علي بن رستم الخرساني الساعاتي (died c. 1230), called Ibn al-Sāʿātī (son of t ...
, the son of clockmaker. The Florentine writer
Dante Alighieri Dante Alighieri (; – 14 September 1321), probably baptized Durante di Alighiero degli Alighieri and often referred to as Dante (, ), was an Italian poet, writer and philosopher. His '' Divine Comedy'', originally called (modern Italian: ...
made a reference to the gear works of striking clocks in 1319. The most famous original striking clock tower still standing is possibly the one in St Mark's Clocktower in St Mark's Square,
Venice Venice ( ; it, Venezia ; vec, Venesia or ) is a city in northeastern Italy and the capital of the Veneto Regions of Italy, region. It is built on a group of 118 small islands that are separated by canals and linked by over 400  ...
. The
St Mark's Clock St Mark's Clock is housed in the Clock Tower on the Piazza San Marco (Saint Mark's Square) in Venice, Italy, adjoining the Procuratie Vecchie. The first clock housed in the tower was built and installed by Gian Paolo and Gian Carlo Rainieri, fa ...
was assembled in 1493, by the famous clockmaker Gian Carlo Rainieri from Reggio Emilia, where his father Gian Paolo Rainieri had already constructed another famous device in 1481. In 1497, Simone Campanato moulded the great bell, which was put on the top of the tower where it is alternately beaten by the ''Due Mori'' (''Two
Moors The term Moor, derived from the ancient Mauri, is an exonym first used by Christian Europeans to designate the Muslim inhabitants of the Maghreb, the Iberian Peninsula, Sicily and Malta during the Middle Ages. Moors are not a distinc ...
''), two bronze statues handling a hammer.


Counting the hours

During the great wave of
tower clock Clock towers are a specific type of structure which house a turret clock and have one or more clock faces on the upper exterior walls. Many clock towers are freestanding structures but they can also adjoin or be located on top of another buildi ...
building in 14th-century
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
, around the time of the invention of the mechanical clock itself, striking clocks were built that struck the bell multiple times, to count out the hours. The clock of the Beata Vergine (later San Gottardo) in
Milan Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city ...
, built around 1330, was one of the earliest recorded that struck the hours. In 1335, Galvano Fiamma wrote: The astronomical clock designed by Richard of Wallingford in 1327 and built around 1354, also struck 24 hours. Some rare clocks use a form of striking known as "Roman Striking" invented by
Joseph Knibb Joseph Knibb (1640–1711) was an English clockmaker of the Restoration era. According to author Herbert Cescinsky, a leading authority on English clocks, Knibb, "next to Tompion, must be regarded as the greatest horologist of his time." Life a ...
, in which a large bell or lower tone is sounded to represent "five", and a small bell or high tone is sounded to represent "one". For example, four o'clock would be sounded as a high tone followed by a low tone, whereas the hour of eleven o'clock would be sounded by two low tones followed by a high tone. The purpose is to conserve the power of the striking train. For example, "VII" would be a total of three strikes instead of seven, and "XII" would be four strikes instead of twelve. Clocks using this type of striking usually represent four o'clock on the dial with an "IV" rather than the more common "IIII", so that the Roman numerals correspond with the sequence of strikes on the high and low bells. One small table clock of this type sold from the George Daniels collection at
Sotheby's Sotheby's () is a British-founded American multinational corporation with headquarters in New York City. It is one of the world's largest brokers of fine and decorative art, jewellery, and collectibles. It has 80 locations in 40 countries, an ...
on 6 November 2012 for £1,273,250.


Countwheel

Two mechanisms have been devised by clockmakers to enable striking clocks to correctly count out the hours. The earlier, which appeared in the first striking clocks in the 14th century, is called "countwheel striking". This uses a wheel that contains notches on its side, spaced by unequal, increasing arc segments. This countwheel governs the rotation of the striking train. When the striking train is released by the timekeeping train, a lever is lifted from a notch on the countwheel; the uneven notches allow the striking train to move only far enough to sound the correct number of times, after which the lever falls back into the next notch and stops the striking train from turning further. The countwheel has the disadvantage of being entirely independent of the timekeeping train; if the striking train winds down, or for some other reason the clock fails to strike, the countwheel will become out of synch with the time shown by the hands, and must be resynchronized by manually releasing the striking train until it moves around to the correct position.


Rack striking

In the late seventeenth century, ''rack striking'' was invented. Rack striking is so called because it is regulated by a ''rack and snail'' mechanism. The distance a
rack Rack or racks may refer to: Storage and installation * Amp rack, short for amplifier rack, a piece of furniture in which amplifiers are mounted * Bicycle rack, a frame for storing bicycles when not in use * Bustle rack, a type of storage bin ...
is allowed to fall is determined by a snail-shaped cam, thereby regulating the number of times the bell is allowed to sound. There was a misconception during the 20th century that the rack and snail mechanism was invented by British clergyman Edward Barlow in 1675-6. In fact, the inventor is unknown. The snail-shaped cam is a part of the timekeeping train that revolves every twelve hours; often the snail is attached to the same pipe on which the hour hand is mounted. The diameter of the cam is largest at the one o'clock position, permitting the rack to move only a short distance, after which the striking train is stopped; it is smallest at the 12 o'clock position, which allows the rack to move the farthest. Striking stops when the last tooth of the rack has been taken up by the gathering pallet. Because the number of strikes on the hour is determined by the position of the snail which rotates in tandem with the hour hand, rack striking seldom becomes desynchronized. Rack striking also made possible the repeating clock, which can be made to repeat the last hour struck by pressing a button. Rack striking became the standard mechanism used in striking clocks down to the present.


Parts of mechanism

All hour striking mechanisms have these parts. The letters below refer to the diagram. *''Power source'' – This is usually identical to the device that powers the clock's timekeeping mechanism: in weight driven clocks it is a second weight on a cord (P), in spring driven clocks it is another mainspring. Although older one-day (30-hour) clocks often used a single weight or mainspring to drive both the timekeeping and striking trains, better clocks used a separate power source, because the striking mechanism consumes a lot of power and often has to be wound more frequently, and also to isolate the delicate timekeeping train from the large movements that occur in the striking train. Winding a striking clock requires winding both the timing and striking parts separately. *''Striking train'' – This is a gear train (G,H) that scales down the force of the power source and transmits it to the hammer mechanism which rings the gong. In antique clocks, to reduce the manufacturing cost, it was often exactly the same as the ''timing train'' that ran the clock's timekeeping part, and installed parallel to it, on the left side as one faces the clock. *''Regulator'' – A device to prevent the striking train from running too fast, and control the speed of striking. If it wasn't present, the striking train when released would run out of control under the force of the spring or weight. In most clocks it is a simple '' fly fan'' (or ''fan fly'') (K), a flat piece of sheet metal mounted on the fastest turning gear shaft. When the striking train turns, this beats the air, and the air friction limits the speed of the train. Striking watches and some modern clocks use a centrifugal governor instead. *''Count mechanism'' – This is the critical part mentioned above, that releases the striking train at the proper time and counts out the proper number of strikes. It is the only part of the striking mechanism that is attached to the clock's timekeeping works. Virtually all modern clocks use the rack and snail. The snail (N) is usually mounted on the clock's center wheel shaft, which turns once every 12 hours. There is also a release lever (L) which on the hour releases the rack and allows the timing train to turn. *''Hammer and gong'' – The hammer lever (F) is actuated by pins or teeth (G) on one of the striking train wheels. As the wheel turns the pin lifts the hammer lever, until the lever slips off the pin, allowing the hammer to drop, hitting the gong (E). Early house clocks used traditional hemispherical shaped bells. Later house clocks used gongs made of long steel tubes or bars, which have a sound more like large church bells. Mantel and other small clocks use thick hardened steel wires, which are coiled into a spiral to save space. Clocks that have more elaborate functions than just striking the hours, such as chiming the quarter hours, or playing tunes, are called "chiming clocks" by clockmakers. The additional functions are usually run by a second complete striking mechanism separate from the (hour) striking train, called the "chiming train". These clocks have three weights or mainsprings, to power the timing train, striking train, and chiming train.


How it works

This describes how the rack and snail striking mechanism works. The labels refer to the drawing above. The release lever ''(L)'' holds the rack ''(M)'' up when the clock is not striking. On the shaft of the minute hand (not shown), which rotates once per hour, there is a projection. As the change of the hour approaches, this projection slowly lifts the release lever, allowing the rack to fall until its point rests on the snail ''(N)''. The amount the rack can fall, and thus the number of strikes, is determined by the position of the snail. Exactly on the hour the striking train ''(G, H, K)'' is released and begins to turn. As it turns, the pins ''(G)'' repeatedly lift the hammer ''(F)'' and allow it to drop, ringing the gong ''(E)''. The gear ratios are arranged so that the gear wheel ''(H)'' makes one revolution each strike. A small pin ''(S)'' on this wheel engages the rack teeth, lifting the rack up by one tooth each turn. When the rack reaches the end of its teeth it stops the striking train from turning (using a mechanism not shown in the diagram, in such a way that gear ''(H)'' is held stationary with the pin ''(S)'' not engaging the rack, so that the rack is able to fall freely again on the next hour). So the number of strikes is equal to the number of teeth of the rack which are used, which depends on the position of the snail.


Types of striking clocks

Specialized types of striking clocks: *Chiming clock – Strikes on the hours and chimes on the quarter hours, often playing fragments of a tune such as Westminster Quarters. * Repeater – a striking clock which can repeat the strikes at the push of a lever, for telling the time in the dark. * Musical clock – plays tunes on a music box in addition to counting the time *
Automaton clock An automaton clock or automata clock is a type of striking clock featuring automatons. Clocks like these were built from the 1st century BC through to Victorian times in Europe. A Cuckoo clock is a simple form of this type of clock. The firs ...
– with mechanically animated figures that periodically perform various displays, usually as a part of the clock striking the hours. ** Cuckoo clock – a specific type of automaton clock which originated in
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...
, which displays an animated bird and plays imitation
birdcall Bird vocalization includes both bird calls and bird songs. In non-technical use, bird songs are the bird sounds that are melodious to the human ear. In ornithology and birding, songs (relatively complex vocalizations) are distinguished by fun ...
s in addition to striking on a bell or gong. * Ship's bell clock – strikes the ship's bells instead of the hours. Some
quartz clock Quartz clocks and quartz watches are timepieces that use an electronic oscillator regulated by a quartz crystal to keep time. This crystal oscillator creates a signal with very precise frequency, so that quartz clocks and watches are at leas ...
s also contain speakers and sound chips that electronically imitate the sounds of a chiming or striking clock. Other quartz striking clocks use electrical power to strike bells or gongs.


See also

* Alarm clock * Repeater watches (horology) * St. Michael's chimes *
Thirteenth stroke of the clock Thirteenth stroke of the clock or "thirteen strikes of the clock" is a phrase, saying, and proverb to indicate that the previous events or "strokes to the clock" must be called into question. This is illustrated in the fictional case of "Rex vs Hadd ...
* Westminster Chimes *
Whittington chimes Whittington chimes, also called ''St. Mary's'', are a family of clock chime melodies associated with St Mary-le-Bow church in London, which is related to the historical figure of Whittington by legend. Whittington is usually the secondary ...
* Water clock


Notes


Sources and further reading

* * * * * {{Authority control Articles containing video clips Campanology Clocks Time signals