Learning the History of Big Ben
The construction of Big
Ben was commissioned during the
rebuilding of the Palace of Westminster in the wake of an 1834 fire.
Parliament determined that the new
buildings should incorporate an impressive clock tower and passed a bill to
that end in 1844.
tower was constructed on the northern extremity of the new Houses
of Parliament that were built next to Westminster Hall.
The commission for the clock itself demanded a high level of accuracy; the
specifications drafted by Astronomer Royal George Airy required 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."
Many clock makers were skeptical that such accuracy could be achieved in a mechanical
clock, but Edmund Beckett Denison, a lawyer and amateur horologist, rose to the challenge.
He completed a pendulum clock design in 1851, and its assembly was begun
by Edward John Dent, the owner of a prominent clock making company, and finished by his son Frederick
Dent. It was completed in 1854, but construction on the tower lasted until
1859, providing Frederick Dent five years to test and perfect the clock.
Denison also designed the hour bell. The prototype, cast in August 1856 by John Warner and Sons,
cracked beyond repair during testing. Under owner George Mears, the Whitechapel Bell Foundry (the oldest
foundry in Britain, which coincidentally had cast the original Liberty Bell that cracked and had to be recast
upon its arrival in the American colonies), met with more success when it melted down and recast the hour
Completed in April 1858, the second and final version of the hour bell was
the largest ever cast in the United Kingdom.
In fact, it was so colossal—over seven feet high and weighing more than 13
tons—that a team of 16 horses was needed to pull the wagon upon which it rested from the foundry to the Palace of
The transportation took on the character of a parade, with enthusiastic
crowds lining the streets as the caravan made its way through London.
It took several days in October 1858 to hoist the bell to the top of the
Following the installation of the hour bell and four smaller quarter chime bells, Big Ben rang
out for the first time on May 31, 1859.
Due to the fitting of an oversized hammer stipulated by Denison, the hour
bell cracked the following September and did not come into regular service until its repair in
1862. The distinctive imperfect tone of the bell is the result of the crack,
which was merely patched by a square piece of metal to bolster the bell's strength.
A lighter hammer was also installed to prevent further damage.
Setting of the clock was initially coordinated with the Greenwich
Observatory via telegraph, and throughout its existence, Big Ben has garnered a reputation for remaining extremely
accurate—as a result, it was not deemed necessary to replace the telegraph line after it was destroyed by German
bombs during World War II.
Living up to Airy's specifications, there have been very few instances of the clock's accuracy
straying more than one second. The most notable example was in 1962, when a buildup of snow on the clock arms
caused Big Ben to ring in the new year 10 minutes past midnight.
Surprisingly, the accuracy of the clock has been maintained by a
relatively primitive method; pennies are used to adjust and balance the swing of the clock's pendulum.