Last edited 17 Jan 2020

Main author

Jake Bagby Website

The Restoration of Big Ben

Big ben.jpg

Contents

[edit] Introduction

In October 2019, visitors to London were at last able to take in the view of the top of Big Ben without scaffolding. Conservation work on the clock and the Elizabeth Tower began in 2017 and is expected to continue until 2021.

[edit] The work

Work includes the restoration of the roof, repairs to bell frame and fixing leaks in the clock room. The Elizabeth Tower will be redecorated inside and the clock itself will be dismantled for cleaning and repairs.

The Ayrton light also needs repairs. This is the light that sits on top of the Elizabeth Tower. It is thought that Queen Victoria asked for its inclusion so she would know when either of the houses was sitting after dark.

Most of the work on the tower is being carried out to comply with fire safety regulations. This also includes the installation of a lift, as the design of the tower makes it very difficult to evacuate an injured person quickly. Some disabled visitors will also be able to use the lift if they are not able to use the stairs. Another new installation will be toilets - an amenity that has not been available before.

[edit] The clock tower

Augustus Pugin designed the clock tower. He was commissioned by Sir Charles Barry. Barry was the chief architect of the re-design of the Palace of Westminster which had previously been destroyed by fire in 1834.

Barry’s design did not include a clock tower and so when he decided to add one, he chose Pugin to design it. Pugin was already well-known for his design of many churches in England and Ireland, and Barry admired his use of the Gothic Revival style.

The clock tower had an exterior made of Cornish granite and Yorkshire Anston stone. Cast iron girders came from London, iron roofing plates came from Birmingham while Caen stone from Normandy was used for the interior.

The tower was completed in 1859. At 96m tall and 12m square, it also features 334 steps leading up to the belfry. It was renamed The Elizabeth Tower in 2012 for the Queen’s diamond jubilee.

[edit] The clock faces

There is a clock face on each side of the four-sided tower. The clock was designed by Edmund Dennison and it was built by Edward John Dent. Dent died before the completion of the clock, but his stepson, Frederick took over in.

The Astronomer Royal, Sir George Airy set out two important standards for the clock. First, that the first stroke of each hour should be accurate to within one second. Second, he wanted the clock’s performance telegraphed to Greenwich Observatory twice a day.

During the work on the clock, Dennison invented the ‘Double Three-legged Gravity Escapement.’ This part of the mechanism contributed to the clock’s accuracy. It made sure it was not affected by things like wind pressure on the clock’s hands. This mechanism is still used in clocks all over the world.

The clock’s minute hands were originally made from cast-iron, but this made them too heavy and they would not move so they were replaced with hollow copper hands which worked perfectly.

Each cast-iron clock dial has a 7m diameter and an opaque appearance which comes from the 324 individual pieces of pot opal glass. The hour figures are 60cm long.

The copper-sheet minute hands are 4.2m long and the gunmetal hour hands are 2.7m long. The clock mechanism is cast iron and the pendulum bob is made from tubes of steel and zinc.

The original clock face was blue. But, over the years, air pollution caused it to turn black. Sometime after the 1930s, the metalwork of the clock face was re-painted in black. As part of the renovations, the clock faces will be restored to their original colour of Prussian Blue.

[edit] Big Ben

The famous chimes come from 22 bells, the largest of which is Big Ben. The original bell was made in Stockton-on Tees and it was transferred to London by rail and then by sea. It was taken from the Port of London and placed on a carriage pulled by 16 white horses across Westminster Bridge.

Luckily, it was not immediately placed in the tower. It stayed in New Palace Yard for testing. After almost three weeks of testing the bell cracked. Nobody was sure of the reason. But it was dismantled, and a new bell was created by George Mears in his Whitechapel Foundry (which stayed in business until 2017). This second bell also cracked. It took four years to solve the problem, but eventually Sir George Airy came up with a solution.

First, a small square was cut out of the bell which stopped the crack from spreading. The hammer which struck the bell was replaced with a lighter one and finally, the bell was turned by a quarter. This meant the hammer struck in a different place. The bell was then placed in the Tower in 1863. Weighing 13.7 tonnes, it is slightly heavier than a London double-decker bus.

Due to health and safety, the famous chimes cannot ring during the conservation works as the striking hammer is locked and the bells disconnected. The noise could easily damage the hearing of people working on the tower and the clock.

[edit] Visitors

All visitors to London can visit the Houses of Parliament but only UK citizens can visit Big Ben when the work is completed. Readers who want to visit when it reopens must write to their local MP well in advance as the tours are very popular.

[edit] Related articles on Designing Buildings Wiki

--Jake Bagby 10:24, 14 Jan 2020 (BST)