Turret clock

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Modern striking turret clock movement mounted in a clock tower. Clock faces on all four sides of the tower are driven by a shaft from the movement below
Probably the most famous turret clock is located in the Elizabeth Tower at the north end of the Palace of Westminster in London and rings the bell "Big Ben"

A turret clock or tower clock is a clock designed to be mounted high in the wall of a building, usually in a clock tower, in public buildings such as churches, university buildings, and town halls. As a public amenity to enable the community to tell the time, it has a large face visible from far away, and often a striking mechanism which rings bells upon the hours.

The turret clock is one of the earliest types of clock. Beginning in 12th century Europe, towns and monasteries built clocks in high towers to strike bells to call the community to prayer. Public clocks played an important timekeeping role in daily life until the 20th century, when accurate watches became cheap enough for ordinary people to afford. Today the time-disseminating functions of turret clocks are not much needed, and they are mainly built and preserved for traditional, decorative, and artistic reasons.

To turn the large hands and run the striking train, the mechanism of turret clocks must be more powerful than that of ordinary clocks. Traditional turret clocks are large pendulum clocks run by hanging weights, but modern ones are often run by electricity.


Verge and foliot tower clock mechanism in the De Wyck (De Vick) clock, built in Paris by Henri de Wyck in 1379.

Water clocks[edit]

Water clocks are reported as early as the 16th century B.C. and were used in the ancient world, but these were domestic clocks. Beginning in the Middle Ages around 1000 A.D. striking water clocks were invented, which rang bells on the canonical hours for the purpose of calling the community to prayer. Installed in clock towers in cathedrals, monasteries and town squares so they could be heard at long distances, these were the first turret clocks. By the 13th century towns in Europe competed with each other to build the most elaborate, beautiful clocks. Water clocks kept time by the rate of water flowing through an orifice. Since the rate of flow varies with pressure which is proportional to the height of water in the source container, and viscosity which varies with temperature during the day, water clocks had limited accuracy. Other disadvantages were that they required water to be manually hauled in a bucket from a well or river to fill the clock reservoir every day, and froze solid in winter.

Verge and foliot clocks[edit]

The first all-mechanical clocks which emerged in Europe in the late 13th century kept time with a verge escapement and foliot (also known as crown and balance wheels). In the second half of the 14th century, over 500 striking turret clocks were installed in public buildings all over Europe. The new mechanical clocks were easier to maintain than water clocks, as the power to run the clock was provided by turning a crank to raise a weight on a cord, and they also did not freeze during winter, so they became the standard mechanism used in the turret clocks being installed in bell towers in churches, cathedrals, monasteries and town halls all over Europe.

The verge and foliot timekeeping mechanism in these early mechanical clocks was very inaccurate, as the primitive foliot balance wheel did not have a balance spring to provide a restoring force, so the balance wheel was not a harmonic oscillator with an inherent resonant frequency or "beat"; its rate varied with variations in the force of the wheel train. The error in the first mechanical clocks may have been several hours per day. Therefore, the clock had to be frequently reset by the passage of the sun or stars overhead.

Pendulum clocks[edit]

The pendulum clock was invented and patented in 1657 by Dutch scientist Christiaan Huygens, inspired by the superior timekeeping properties of the pendulum discovered beginning in 1602 by Italian scientist Galileo Galilei. Pendulum clocks were much more accurate than the previous foliot clocks, improving timekeeping accuracy of the best precision clocks from 15 minutes per day to perhaps 10 seconds a day. Within a few decades most tower clocks throughout Europe were rebuilt to convert the previous verge and foliot escapement to pendulums. Almost no examples of the original verge and foliot mechanisms of these early clocks have survived to the present day.

The accuracy of the pendulum clock was increased by the invention of the anchor escapement in 1657 by Robert Hooke, which quickly replaced the primitive verge escapement in pendulum clocks. The first tower clock with the new escapement was the Wadham College Clock, built at Wadham College, Oxford, UK, in 1670, probably by clockmaker Joseph Knibb. The anchor escapement reduced the pendulum's width of swing from 80 to 100° in the verge clock to 3-6°. This greatly reduced the energy consumed by the pendulum, and allowed longer pendulums to be used. While domestic pendulum clocks usually use a seconds pendulum 1.0 meter (39 in) long, tower clocks often use a 1.5 second pendulum, 2.25 m (7.4 ft) long, or a two-second pendulum, 4 m (13 ft) long.[1][2]

Tower clocks had a source of error not found in other clocks: the varying torque on the wheel train caused by the weight of the huge external clock hands as they turned, which was made worse by seasonal snow, ice and wind loads on the hands.[3] The variations in force, applied to the pendulum by the escape wheel, caused the period of the pendulum to vary. During the 19th century specialized escapements were invented for tower clocks to mitigate this problem. In the most common type, called gravity escapements, instead of applying the force of the gear train to push the pendulum directly, the escape wheel instead lifted a weighted lever, which was then released and its weight gave the pendulum a push during its downward swing. This isolated the pendulum from variations in the drive force. One of the most widely used types was the three-legged gravity escapement invented in 1854 by Edmund Beckett (Lord Grimsthorpe).

Electrical clocks[edit]

Electric turret clocks and hybrid mechanical/electric clocks were introduced in the late 19th century.

Some mechanical turret clocks are wound by electric motor. These still are considered mechanical clocks.

Table of early public turret clocks[edit]

This table shows some of the turret clocks which were installed throughout Europe. It is not complete and mainly serves to illustrate the rate of adoption. There are hardly any surviving turret clock mechanisms that date before 1400, and because of extensive rebuilding of clocks the authenticity of those that do survive is disputed. What little is known of their mechanisms is mostly gleaned from manuscript sources.

The "country" column refers to the present (2012) international boundaries. For example, Colmar was in Germany in 1370, but is now in France.

Thirteenth century[edit]

The verge and foliot escapement is thought to have been introduced sometime at the end of the thirteenth century, so very few if any of these clocks had foliot mechanisms; most were water clocks or in a few cases, possibly mercury.

Year Country Place Location Name Type Mention Comment
1283 England Dunstable Priory horologium not known Annals of the priory 1283 – Eodem anno fecimus horologium quod est supra pulpitum collocatum. Probably a verge and foliot clock because it was mounted over the rood screen, where refilling a water clock would have been difficult, it has been proposed as the earliest known mechanical clock.
1284 England Exeter Cathedral Exeter cathedral clock not known grant made July 1284 to Roger de Ropford, bellfounder, to repair "orologium" It is unlikely that this 1284 clock was a verge and foliot clock. The clock mentioned in the grant was probably a water clock. In 1423, a new clock was installed, which is probably the one from which remnants of the striking train can still be seen.
1286 England London St Paul's Cathedral Bartholomo Orologiario clock not known Compotus Bracini 1286 probably a water clock
1288 (?) England Oxford Merton College not known bursarial accounts "Expense orologii" probably a water clock
1290 England Norwich Norwich Cathedral not known Sacrist's roll 1290 "In emendacione orologio" probably a water clock
1291 England Ely Ely Abbey not known Sacrist's roll 1291 "pro custodia orologii" probably a water clock
1292 England Canterbury Christchurch Cathedral novum orolgium not known list of Prior Henry of Eastry's works "novum orologium mangum in Ecclesia" probably a water clock

Fourteenth century[edit]

During the fourteenth century, the emergence of the foliot replaced the high-maintenance water clocks. It is not known when that happened exactly and which of the early 14th century clocks were water clocks and which ones use a foliot.

The Heinrich von Wieck clock in Paris dating from 1362 is the first clock of which it is known with certainty that it had a foliot and a verge escapement. The fact that there is a sudden increase in the number of recorded turret clock installations points to the fact that these new clocks use verge & foliot. This happens in the years 1350 and onwards.

Year Country Place Location Name Type Mention Comment
1304 Germany Erfurt Benedict abbey St. Peter "Schelle" not known consecration of "Petronella" and "Scolastica" probably a mechanical alarm clock
1305 Germany Augsburg cathedral not known the "Domkustos" E. v. Nidlingen donates to the cathedral a "good and well adjusted clock" probably a mechanical alarm clock
1306 England Salisbury Salisbury Cathedral not known composition concluded 26 August 1306 "Before the clock of the cathedral had struck one no person was to purchase or cause to be purchased .... probably a water clock
1308 France Cambrai Cathedral not known mention of a clock, which was mended and equipped with moving figures in 1348, and fitted with a strike and an angel in 1398
1309 Italy Milan church St. Eustorgio not known mention of a metal clock, which was repaired in 1333 and 1555
1314 France Caen church St. Pierre not known mention of a striking clock
1316 Poland Brzeg town hall not known weights of the clock still present. New bell cast for clock 1370, replaced by new clock 1414
1322 England Norwich Norwich Cathedral priory Norwich Cathedral astronomical clock astronomical clock Sacrist's roll of Norwich cathedral of 1322 to 1325 mentions the construction and installation of a clock which had a large astronomical dial and automata including 59 images and a choir or procession of monks earliest detailed account of the organisation and of the craftsmen and materials involved in such a project
1325–43 France Cluny collegiate church not known Petrus de Chastelux builds a new clock
1327 England St Albans St Albans Cathedral astronomical clock drawings Earliest clock for which there is detailed description of the escapement, this had a 'strob' escapement, a variation of a verge and foliot with two escape wheels.
1336 Italy Milan town public striking clock with 24-hour dial Annales Mediolanenses Anonymi According to Bilfinger, this is the first mechanical striking clock and could have been made by de Dondi. This is the first time a clock is mentioned that strikes consecutive hours, e.g. once at 1, twice at two, etc. and that strikes day and night. As there are detailed descriptions of what the clock does, it was considered a novelty. Another candidate for the first mechanical clock.
1348–64 Italy Padua Castle Tower Astrarium astronomical clock with strike, verge and crown balance wheel Il Tractatus Astarii Giovanni de Dondi
1351 England Windsor Castle Great Tower made in London by three Lombards (from Italy) who arrived 8/4/1352 and left on 24 May 1352
1351 Italy Orvieto clock tower next to the cathedral striking clock with jacquemart
1352–1354 France Strasbourg cathedral astronomical clock. Three dials: bottom year dial with saint days, middle hour dial, top hourly procession of 3 kings before Maria, at the top a crowing rooster. taken out of service in 1547
1353 Italy Genoa striking clock
1354 Italy Florence Palazzo Vecchio
1355–71 Italy Reggio striking clock
1356 Italy Bologna castle tower striking clock
1356–1361 Germany Nuremberg Frauenkirche striking clock with display of the prince-electors around the Kaiser substituted in 1508/09 with the clock on the outside of the Frauenkirche
1359 Germany Frankenberg Pfarrkirche astronomical clock with the three kings around the Virgin Mary
1359 Italy Siena city tower Bartolo Giordi mounts a clock on the city tower
1361 Germany Frankfurt cathedral astronomical clock made by Jacob, improved 1383, taken out of service 1605
1361 Germany Munich city tower mention of existing clock
1362 Belgium Brussels St Nicholas church not known mention of a turret clock
1362 Italy Ferrara castle tower clock mounted on castle tower
1362–1370 France Paris Tour de l'Horloge verge and foliot striking clock Froissart's poem "L'Horloge amoureuse" mentions the clock. Drawing exists. a drawing of the going train shows a door frame construction. Built by the German Heinrich von Wiek.
1364 Germany Augsburg Perlachturm striking clock clock was repaired in 1369 and a quarter strike was added in 1526
1365–1367 England London Westminster Palace not known a clock tower on the north wall at the end of the King's Garden opposite the entrance to the great hall was begun in 1365 and finished in 1367.
1366 Spain Toledo cathedral goldsmith Gonzalo Perez supplies a clock for the tower of the cathedral
1366–1368 Switzerland Zurich Petersturm striking clock Master Chunrad von Cloten builds a striking clock for the Petersturm
1366 England Kent Queenborough Castle striking clock
1367 Poland Wrocław town hall mention of existing town hall clock
1368 England Kings Langley Kings Langley Manor striking clock Edward III provided a patent giving safe conduct to three Flemish clockmakers. These people probably built the clock. after the expiry of the patent in 1369 John Lincoln was appointed as Royal clock keeper.
1368 Czechia Opava Town council signs contract with master Swelbel to furnish a clock
1369 Germany Mainz Pfarrkirche St. Quentin striking clock
1370 France Colmar cathedral tower striking clock
1370 Poland Świdnica the town council engages the services of master Swelbel to furnish a clock, that is as good or better than the clock at Wroclaw.
1371 England York York Minster striking clock Fabric Rolls of York Minster record purchase of a new clock made by John Clareburgh in 1371 or £13 6s. 8d.
1372 Belgium Golzinne castle striking clock Louis Defiens furnishes a striking clock for the castle
1372–1373 France Strasbourg cathedral striking clock Heinrich Halder mounts a striking clock on the cathedral tower
1376 Belgium Ghent Belfried striking clock
1376 France Sens a clock with several bells is manufactured
1376 France Beauté-sur-Marne castle Pierre de S. Béate furnishes a clock for the castle
1377 Belgium Dendermonde belfry Jan van Delft manufactures a clock for the belfry
1377 France Valenciennes town hall the town hall clock is replaced and fitted with 2 striking figures
1377 Italy Vicenza town hall striking clock Master Facius Pisanus manufactures a new striking clock for the town hall
1377 Belgium Ypres belfry striking clock with several bells
1380 Germany Bamberg cathedral clock installed at the cathedral
1380 France Nieppe castle Pierre Daimville engaged to furnish a metal clock weighing 300 pounds for the castle, which already has an existing clock
1382–84 Germany Hamburg Nikolaikirche striking clock Blacksmith Schinkel furnishes a public striking clock for the Nikolaikirche
1383–1384 France Dijon Notre-Dame striking clock the clock taken from Courtrai in Belgium in 1382 is mounted on the tower of Notre-Dame
1383 Germany Fritzlar mention of a turret clock
1383 France Lyon eglise St. Jean striking clock mention of a small striking clock at St. Jean
1384 Germany Friedberg striking clock Wernher von Ilbenstedt manufactures a striking clock
1384 Germany Minden cathedral mention of the cathedral clock being repaired
1385 Switzerland Luzern Graggenturm striking clock Blacksmith H. Halder furnishes a striking clock for the Graggenturm and leaves a manual for the treatment of the clock The operating instructions for this clock were written down, and clearly refer to a verge and foliot clock. the "frowen gemuete [happy/agitated mood]" is the foliot.[4]
1386 Germany Braunschweig Katharinenkirche Marquard furnishes a clock for the Katharinenkirche. The cathedral already had a clock in 1346
1386 England Salisbury Salisbury Cathedral Salisbury Cathedral clock Striking Clock Deed might not be the clock on display at the cathedral
1386 Germany Würzburg cathedral clock at the cathedral mentioned
1388 France Béthune belfry striking clock The citizens of Bethune want to re-construct the existing belfry and put up a clock. "... pour pouvoir reconstruire leur beffroi

qui etait a present moult demolis et venus k ruyne et en peril de keir (tomber) de jour en jour et en obtenir l'autorisation d'y placer une orloge pour memore des heures de jour et de nuit sicomme il est en pluseurs autres lieux et bonnes villes du paus environ".

We have a reference here on how common turret clocks have become – they refer to " a clock to remind of the hours of the day and the night as it is now common in other places and good towns ...". This is also a reference that shows that turret clocks struck the time day and night.
1388 Germany Magdeburg Cathedral striking clock mention of a striking clock at the cathedral
1389 France Rouen belfry striking clock with quarter strike Jehan de Felains paid 70 Livres for a clock with a quarter strike for the belfry
1391 France Metz cathedral striking clock with quarter strike Manufactured by Heinrich von Wieck
1392 France Chartres striking clock clockmaker and blacksmith Philibert Mauvoisin instructed to make a striking clock resembling the one at the Paris castle
1392 Germany Hanover market church blacksmiths Meistorpe and Hans Krieten furnish a clock for the market church
1392–1393 England Wells Wells Cathedral striking clock if this is the clock now shown at the British Museum in London is questionable
1394 Germany Stralsund Nikolaikirche astronomical clock Nikolaus Lilienfeld furnished a clock for the Nikolaikirche
1395 Germany Doberan church astronomical clock an astronomical clock similar to the one in Stralsund is put up at the church
1395 Germany Speyer Altburgtor striking clock a striking clock is reported at the Altburgtor and at the Predigerkirche
1398–1401 Germany Villingen astronomical clock Master Claus Gutsch manufactures an astronomical clock after the Strasbourg clock.

It becomes apparent that even small towns can afford to put up public striking clocks. Turret clocks are now common throughout Europe.

No surviving clock mechanisms (apart from the claims from Salisbury and Wells) is known from this era.

See also[edit]


  1. ^ Milham, Willis I. (1945). Time and Timekeepers. MacMillan., p.188-194
  2. ^ Glasgow 1885, p.282
  3. ^ Glasgow, David (1885). Watch and Clock Making. London: Cassel & Co. p. 308.
  4. ^ Graggenturm of Luzerne, instructions (English translation):If you want to adjust the clock and put it forward or backward, disengage the foliot from the escape wheel and hold the escape wheel safely in your hand, or the weight will lose itself which might damage the clockwork. As you are now holding the escape wheel, use it to either let down the weight if you want to shorten the hour, or, if you want to lengthen the hour, pull it up, all in such a way that you are not doing too much nor too little and that you observe it well on the count wheel. If you also pull down the [lute] wheel, you can set the count wheel to whichever hour you want, be it I, II, III, etc. If you feel that the foliot is going too fast, lift the lead weights away from the wheel, and if it is too fast, move them towards the wheel, therewith you hinder or further it, as you like it. You might want to make it faster during the night, as the clock work goes for most of the night slower than during the day. Keep an eye on both weights, and if it happens that they have hardly any more rope, wind them up again, which you can do whenever you want to.
  • C. F. C. Beeson English Church Clocks London 1971
  • Christopher McKay (Editor) The Great Salisbury Clock Trial, Antiquarian Horological Society Turret Clock Group, 1993
  • Alfred Ungerer Les horloges astronomiques et monumentales les plus remarquables de l'antiquité jusquà nos jours, Strasbourg, 1931
  • Ferdinand Berthoud Histoire de la mesure du temps par les horloges, Imprimerie de la Republique, 1802
  • Gustav Bilfinger Die Mittelalterlichen Horen und die Modernen Stunden, Stuttgart, 1892
  • F.J. Britten Old clocks and their makers:an historical and descriptive account of the different styles of clocks of the past in England and abroad : with a list of over eleven thousand makers, London, 1910
  • Ernst Zinner Aus der Frühzeit der Räderuhr. Von der Gewichtsuhr zur Federzuguhr München, 1954