Er.. to be struck on the hour to tell the time ! THE STORY OF BIG BEN (from http://www.whitechapelbellfoundry.co.uk/bigben.htm) At 9'-0" diameter, 7'-6" high, and weighing in at 13 tons 10 cwts 3 qtrs 15lbs (13,760 Kg), the hour bell of the Great Clock of Westminster - known worldwide as 'Big Ben' - is the most famous bell ever cast at Whitechapel. Big Ben was cast on Saturday 10th April 1858, but its story begins more than two decades earlier.... On 16th October 1834, fire succeeded where Guy Fawkes and his fellow plotters had failed on 5th November 1605, and destroyed the Palace of Westminster, long the seat of the British government. Those few bits of the Old Palace that survived the fire - most notably Westminster Hall, which was built between 1097 and 1099 by William Rufus - were incorporated into the new buildings we know today, along with many new features. In 1844, Parliament decided that the new buildings for the Houses of Parliament, by then under construction, should incorporate a tower and clock. The commission for this work was awarded to the architect Charles Barry, who initially invited just one clockmaker to produce a design and quotation. The rest of the trade objected to this, demanding the job be put out to competitive tender. The Astronomer Royal, George Airy was appointed to draft a specification for the clock. One of his requirements was that: "the first stroke of the hour bell should register the time, correct to within one second per day, and furthermore that it should telegraph its performance twice a day to Greenwich Observatory, where a record would be kept." read more at http://www.whitechapelbellfoundry.co.uk/bigben.htm