For this creation, Edmund Beckett Denison (one of the designers, along with George Airy) invented the double three-legged gravity escapement, which ensured the best separation between the pendulum and the clock mechanism. The pendulum is just under 4 metres long and weighs 300 kilograms! It has a 2-second beat rhythm. A pile of old pennies on its top keeps the pendulum exactly on time. In fact, as small as it is, the presence of one penny can change the speed of the clock by 0.4 seconds per day. The clock mechanism is situated below the pendulum and weighs 5 tons.
The original Big Ben bell weighed 16 tons. However, when they were trying to install it, it fell and broke. The new bell was made 3 tons lighter. This bell also has a large crack in it. However, it was simply turned and continues to work, crack and all, to this day.
Today, Big Ben is an iconic symbol of London, England and the United Kingdom. It appears in films and on postcards. The clock is also used during New Year Eve broadcasts to indicate the ringing in of the New Year. Its film appearances include:
.National Lampoon's European Vacation
.The Thirty-Nine Steps
For more information, please view: http://en.wikipedia.org