Turret clocks

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.

Water clocks are reported as early as 4000 B.C. In Europe, water clocks were used from around 1000 A.D. to around 1350 A.D.

Mercury clocks used a drum with several chambers that were connected through calibrated holes. A rope was wound around the drum with a weight connected to one end. The weight pulling down turned the drum, and the mercury in the drum chambers resisted the turning motion by slowly flowing from one segment of the drum to the next, thus inhibiting the movement of the drum and making it turn at a more or less constant speed. The movement of the drum could be used to measure time.

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. 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).

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, ...).

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