• Big Ben is the bell, not the clock (which is the Great Clock) nor the tower (which is the Clock Tower) (not St Stephen's Tower). • Officially Big Ben is called the Great Bell. • Big Ben first tolled the time on Monday 11th July 1859, which makes today its sesquicentenary.
• Big Ben is thought to be named after Sir Benjamin Hall, First Commissioner for Works 1855-1858, whose name is inscribed on the bell (or maybe after Benjamin Caunt the 17 stone Victorian boxer, nobody's quite sure). • The first Great Bell, cast near Stockton-on-Tees, cracked during testing at Westminster and had to be melted down. • It was recast at the Whitechapel Bell Foundry(yes, I've been) (yes, I've seen the mould they cast Big Ben from, that's it on the wall, top left, in this photo). Casting took place on Saturday 10th April 1858, and the molten metal took 20 days to cool down. • Big Ben weighs 13 tons 10 cwts 3 qtrs 15 lbs. It's 7½ feet high and is 9 feet in diameter. • Big Ben strikes an E (a note-able pub quiz fact, that) • Big Ben was so big that it had to be winched up the clock tower sideways, taking 30 hours to reach the top. • Big Ben cracked after two months use because its hammer was too heavy, and remained silent for four years. Rather than lug the cracked bell back down the tower and recast it again, the Astronomer Royal eventually came up with a better (cheaper) plan. The bell was rotated (through a quarter turn), a small square was cut out of the soundbow (to prevent the crack from spreading further) and a smaller hammer was installed (weighing 'only' 200kg). The crack gives Big Ben its distinctive (but less-than-perfect) tone.
• The clock's central mechanism is the world's first Double Three-Legged Gravity Escapement, invented especially for the Great Clock by Edmund Beckett Denison QC MP. It's still dead accurate. • Approximately two seconds before each hour a one ton strike weight is released, pulling a wire which rotates a barrel which operates a lever which pulls a second wire which causes the bell hammer to fall. • If you'd like to see how the Great Clock's mechanism works, there's a particularly fine animation here. • The clock's pendulum is 14 feet long and weighs 321kg. Adding or removing a penny to the top of the pendulum changes the clock's speed by 2/5 of a second per day.
• The clock's only serious breakdown was on 5th August 1976 when a speed regulator broke causing serious damage to the chiming mechanism. • The tune of the Westminster Chimes originated at the church of St Mary the Great in Cambridge. The chimes were composed in 1793 and are said to be based on the fifth bar of the aria "I know that my Redeemer liveth" from Handel's Messiah. • A verse inscribed on the wall of the clock room provides words for each quarter chime - "All through this hour, Lord be my guide, And by Thy power, No foot shall slide". • At 12 o'clock, the time from the first chime to the last is approximately 45 seconds. (You can watch Big Ben chiming twelve here)
• The Clock Tower is 11 storeys high. There are 334 steps up to the belfry. There is no lift. • Each clock face is made up of 312 pieces of opal glass. • Each dial is just over 7m in diameter, and is cleaned once every five years by abseilingtechnicians. • The tip of the minute hand travels approximately 190km each year. • Above the belfry, at the top of the tower, is the Ayrton light. This shines at night when either House is sitting, and is extinguished upon the House rising.
• There are tours of the clock tower on weekdays at 9.30am, 10.30am, 11.30am and 2.30pm. Only UK residents may visit, and you have to be aged over 10, and you must be fit enough to climb stairs, and the ascent's not recommended for those with vertigo, and you have to apply through your MP, and it's currently fully booked until October. • If you're 10, or unfit, or foreign, or just never likely to visit for yourself, there's a fantastic flash video tour here. (no, really, it's very good indeed)
For even more facts (and some of the same ones), you can celebrate Big Ben's 150th year on its official website here (or unofficial website here).
• Big Ben is thought to be named after Sir Benjamin Hall, First Commissioner for Works 1855-1858, whose name is inscribed on the bell (or maybe after Benjamin Caunt the 17 stone Victorian boxer, nobody's quite sure).
• The clock's central mechanism is the world's first Double Three-Legged Gravity Escapement, invented especially for the Great Clock by Edmund Beckett Denison QC MP. It's still dead accurate.
• The Clock Tower is 11 storeys high. There are 334 steps up to the belfry. There is no lift.
