How to change one of the world's oldest clocks
The Science Museum in London has over 500 timepieces in its Measuring Time gallery. The end of British Summer Time means that those clocks still in working order will be changed this weekend.
But while adjusting many of the timepieces by an hour is a relatively straightforward job, the Wells Cathedral Clock - the second oldest surviving clock in England and the third oldest in the world, dating from 1392 - brings its own challenges.
BBC News went along to the Science Museum to find out more.
Video journalist: Dan Curtis