1. History
    Water clocks  Verge and foliot clocks  Pendulum clocks  Electrical clocks 

2. Table of early public turret clocks
     Thirteenth century  Fourteenth century 

3. See also

4. References

A turret clock or a public clock is a clock that is larger than a domestic clock and has a mechanism designed to drive a visual time indicator such as dials and or bells as a public amenity. Turret clocks specifically had mechanisms mounted high in a building often a purpose built tower such as churches, town halls, and other public buildings. Clocks were not referred to as turret clocks by clockmakers until recent times, often old clocks were recognised as turret clocks by their location.

A true turret clock has mechanical and latterly electrical power and therefore sits late in the history of timekeeping. The following timeline of clocks is not comprehensive but does indicate the placement of turret clocks.

History

Water clocks

Water clocks are reported as early as 4000 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 a continual supply of water to be manually hauled from a well, and froze solid in winter.

Verge and foliot clocks

The first all-mechanical clocks which emerged in the 14th century kept time with a verge escapement and foliot. In the second half of the 14th century, over 500 striking turret clocks were installed in public buildings all over Europe. This was the first time public clocks became easy to maintain, as water clocks needed more or less constant attention, so only wealthy institutions with enough manpower could maintain them.{{fact|date=November 2016}} The verge and foliot mechanical clocks were relatively easy to maintain and so found their way into many churches, bell towers and town halls. This new technology spread quite fast (within a decade all over Europe).

Pendulum clocks

The fourth generation of clocks were mechanical clocks with a pendulum, which was invented in 1657 by Christiaan Huygens. As the pendulum was more exact than the foliot, some foliot clocks were converted to pendulum. Again, this new technology was adopted quickly throughout Europe, with many clocks being converted (e.g. Castle Combe Clock, Salisbury cathedral clock, ...).

Electrical clocks

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

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

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.

Fourteenth century

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.

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

• History of timekeeping devices
• List of clocks

References

• 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

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