From Wikipedia, the free encyclopedia

The Salisbury Cathedral clock, a large iron-framed clock without a dial located in the aisle of Salisbury Cathedral, is almost certainly the oldest surviving mechanical clock in the world. It can be dated to around 1386, and most of the parts are original. Other clocks from the 14th century (the first century in which the mechanical clock flourished throughout Europe) that survive, such as those at Rouen or Dijon, have either been lost, destroyed, or substantially modified. The Wells Cathedral clock might have been made by the same craftsmen as the Salisbury clock, but is usually dated to around 1392, and is now relocated in the Science Museum in London, where it continues to operate.

Contents 1 History 2 Revival 3 References 4 External links

A clock in Salisbury Cathedral that struck the hours was mentioned in 1306. This was probably one of the precursors of the 1386 clock, one of the many early examples of mechanical clocks that are mentioned from c. 1280 onwards.

Like many of these more practical devices, its main purpose was to strike a bell at precise times. It did not have a dial. The wheels and gears are mounted in an open box-like iron frame about 1.2m square. The framework was not held together with nuts and bolts (which had not been invented), but rather with metal dowels and pegs.

The escapement was the verge and foliot type, standard for clocks of this age. The power was supplied by two large stones hanging from pulleys. As the weights fall, ropes unwind from the wooden barrels. One barrel drives the main wheel which is regulated by the escapement, the other drives the striking mechanism and the air brake.

When the weights reach the floor, they have to be lifted back up again, a task that explains the presence of two large wheels shaped like steering wheels at either end of the clock.

The clock was a 'single strike' clock that struck only on the hour. The left half of the clock (as in the photograph above), is the striking part; the right half is the going part.

At the end of the 17th century, the Salisbury clock, like many others, was modified from verge and foliot to pendulum and anchor operation. This usually made clocks much more accurate.

In the 18th century, the bell tower which had housed the clock was demolished, so the clock was moved to the Cathedral's central tower. In 1884, a new clock was installed and the old one was forgotten.

The clock was re-discovered in the tower in 1929 by a maintenance crew in one of the cathedral attics, and was described at that time as 'an unkempt pile of junk'. Eventually its historic importance was realised. It was first put on display in the Cathedral's North transept. Then, in 1956, the clock was restored to its original condition and started working again. The pendulum and recoil escapement were replaced by a new verge and foliot escapement, thus restoring the clock to something like its original design.

Today, the escapement operates, but the striking mechanism has been silenced.

• C F C. Beeson English Church Clocks London 1971
• R P Howgrave-Graham New Light on Ancient Turret Clocks, Antiquarian Horology, 1954

• Richard of Wallingford