Detail of mechanism. This turret clock is the third oldest surviving clock in the world (the oldest in Salisbury Cathedral, was made in 1386). It was in use at Wells Cathedral in Somerset from 1392 until 1835, when its movement was replaced and the old clock movement rehoused in the crypt of the cathedral. In 1871 it was lent to the Patent Office Museum, where a few new bras wheels were made to take the place of the original iron ones which had been lost. In 1884 the collections of the Patent Office Museum were tranferred to the newly created Science Museum in South Kensington, London, and the restored clock is now on display in the Museum's Time Measurement Gallery.
© Science Museum / Science & Society Picture Library