This giant clock is one of London 's best-known landmarks and looks most spectacular at night when the clock faces are illuminated. You even know when parliament is in session, because a light shines above the clock face.
The four dials of the clock are 23 feet square, the minute hand is 14 feet long, and the figures are 2 feet high. Its name is Big Ben, right? Close but no cigar - as Groucho Marx would have said. The name Big Ben actually refers, not to the clock-tower itself, but to the thirteen ton bell hung within. The correct title is "The Great Clock of the Palace of Westminster". No wonder everyone calls it "Big Ben".
The old Palace of Westminster was destroyed by fire on the night of the 16th of October, 1834. The new design incorporated a clock tower. The dials were to be thirty feet in diameter, the quarter chimes were to be struck on eight bells, and the hours were to be struck on a 14 ton bell. A key requirement of the specification was that the clock was to strike the first blow of each hour correct to one second in time. The Astronomer Royal, Sir George Airy, was appointed as referee for the new clock and produced a specification in 1846. In 1849 the famous horologist, Edmund Beckett Denison (later Lord Grimthorpe), pictured here, was appointed co-referee with Airy. Tenders were invited and were received from three makers, Dent, Vulliamy and Whitehurst. In 1852, Dent was awarded the contract.
Edward John Dent died in 1853 and the clock mechanism was completed by his stepson Frederick Rippon (who changed his name to Frederick Dent). In 1854 the mechanism was ready to be installed in the tower but this was not possible as the tower was incomplete. Denison was therefore able to spend a number of years testing out different types of escapement on the mechanism as it operated in Dent's workshop. It was during this period that he invented the double three-legged gravity escapement which enables the clock to keep such accurate time.
Denison was also invited to produce a specification for, and referee, the casting of the bells. The contract was let to John Warner and Sons who cast the hour bell in 1856. The tower was not yet ready to receive the bell so upon delivery it was mounted in the New Palace Yard where it was struck regularly for the benefit of the public. This bell weighed about 16 tons, which was two tons heavier than intended. To compensate for this, Denison increased the weight of the ball hammer from 4 to 6 cwt, nearly 700 LBS. This was not a wise move, and one year later in 1857, the great bell cracked irreparably while being struck by this hammer.
Denison proclaimed the casting as faulty, but the manufacturers denied this and claimed it was his fault for using too heavy a hammer. George Mears of the Whitechapel Bell Foundry was given the contract to recast the bell from the metal of the old in 1858 which he did successfully, producing a bell weighing 13.5 tons which is the one in use today. The four quarter bells were cast by Warner and Son.
The name 'Big Ben' was first applied to the original hour bell cast by Warner and Sons. There is no firm evidence of the origin of this name, but it may have derived from Sir Benjamin Hall, Commissioner of Works, who was involved with the project and who was a man of considerable size. The name was also applied to the recast hour bell and has since come to indicate not just the bell, but also the clock and the clock tower.
The first radio broadcast of Big Ben's chimes was made by the BBC at midnight on the 31 st of December, 1923 to welcome in the New Year. Shortly afterwards, a permanent microphone installation enabled regular broadcasts of the chimes and the bell to function effectively as a time signal. The broadcasting of the bells on the BBC World Service assumed particular importance during the Second World War, when the sounds were a source of comfort and hope to those praying that Britain would not be overcome. Big Ben is still broadcast today on BBC Radio 4 at certain times.
In 1976 a completely unanticipated event occurred which almost caused the complete destruction of the clock. At 3:45am on the 5th of August, 1976 as the clock started to chime, metal fatigue in the shaft connecting the chiming train to its fly fan caused the shaft to break. Without the retarding and braking effect of the fly, the chiming mechanism, propelled by the 1.25 ton weight in the shaft, increased its speed of rotation dramatically.
This led to the total destruction of the chiming mechanism, with various components and fragments of others being scattered about the clock room. Some pieces of machinery were flung at the ceiling with sufficient force to penetrate to the room above. The cast iron frame was fractured and collapsed onto the winding motor below. The flying debris also caused damage to the going and striking trains.
The sounds of Big Ben have traditionally been the focus of the entry of the New Year. In December, 1999 they were of particular significance, marking the beginning of the new Millennium. The sounds of the chimes were relayed on television and radio broadcasts and to the crowd assembled in the Millennium Dome. For the first time also, cameras were located in the belfry so that viewers could see as well as hear the chimes and twelve o'clock being struck on the bells.