Astrolabe 2

In 1283 a large clock was installed at Dunstable Priory; its location above the rood screen suggests that it was not a water clock.

In 1292, Canterbury Cathedral installed a 'great horloge'. Over the next 30 years there are brief mentions of clocks at a number of ecclesiastical institutions in England, Italy, and France.

In 1322 a new clock was installed in Norwich, an expensive replacement for an earlier clock installed in 1273. This had a large (2 metre) astronomical dial with automata and bells. The costs of the installation included the full-time employment of two technicians for two years.

The first major advance in clock construction occurred in Europe during the 14th century. It was found that the speed of a falling weight could be controlled by using a oscillating horizontal bar attached to a vertical spindle with two protrusions on it which acted like escapements, (cliff like ridges). When the protrusions meshed with a tooth of a gear driven by the weight, it momentarily stopped the revolving wheel and weight. These oldest type of mechanical clocks can still be seen in France and England.