Big Ben – All you need to know

Big Ben Facts: Everything you need to know about Big Ben
2009 marks the 150th anniversary of Big Ben. Here are some facts and figures about the one of the UK’s landmark images.

Clock started : 31 May 1859

Big Ben Clock Tower
Dimensions: over 96 metres and 12 metres square
Steps to belfry: 334
Steps to lantern (the Ayrton Light): 393
Amount of stone used: 850 cubic metres
Amount of bricks used: 2600 cubic metres
Number of floors: 11

Clock
Number of clock dials: 4
Clock dials diameter: 7m
Length of hour figures: 60cm
Clock dial frames: cast iron
Glass in each clock dial: 312 pieces of pot opal glass
Illumination of each dial: 28 energy efficient bulbs at 85 watt each
Lifetime of each energy efficient bulb: 60,000 hours

Minute Hand
Material: copper sheet
Weight: 100kg, including counterweights
Length: 4.2m
Distance traveled by minute hands per year: equivalent of 190km

Hour Hand
Material: gun metal
Weight: 300kg including counterweights
Length: 2.7m

The mechanism
Clock mechanism frame material: cast iron girder frame
Clock mechanism dimensions: 4.7m long and 1.4m wide
Clock mechanism weight: 5 tonnes
Pendulum length: 4.4m
Pendulum weight: 310kg
Duration of pendulum beat: 2 seconds
Pendulum adjustment: pre-decimal pennies are used to regulate the clock mechanism. Adding one penny causes the clock to gain two-fifths of a second in 24 hours.
‘The Double Three-legged Gravity Escapement’, designed by Edmund Beckett Denison MP, compensates for outside pressure (like the wind) on the clock hands and is crucial for accuracy.

The pendulum bob
Pendulum bob weight: 203kg
Material: concentric tubes of steel and zinc

The clock weights
Number of clock weights: 3
Combined weight: nearly 2.5 tonnes

The Great Bell
Weight: 13.7 tonnes
Height: 2.2m
Diameter: 2.7m
Musical note when struck: E
Hammer weight: 200kg

The Quarter Bells
First quarter bell weight: 1.1 tonnes
First quarter bell diameter: 1.1m
Musical note when struck: G sharp

Second quarter bell weight: 1.3 tonnes
Second quarter bell diameter: 1.2m
Musical note when struck: F sharp

Third quarter bell weight: 1.7 tonnes
Third quarter bell diameter: 1.4m
Musical note when struck: E

Fourth quarter bell weight: 4 tonnes
Fourth quarter bell diameter: 1.8m
Musical note when struck: B

The bells are fixed and struck by hammers from outside rather than swinging and being struck from inside by clappers.

Ringtones:

Big Ben hourly chimes (mp3, 342KB)
Big Ben hourly chimes (m4a, 172KB)
Big Ben strikes (mp3, 918KB)
Big Ben strikes (m4a, 449KB)

More links for Big Ben:

Big Ben on wikipedia
The ‘official’ Big Ben site
Thwaites and Reed
Whitchapel Bell Foundry