Broom Bridge, also known as Brougham Bridge, is a bridge

Bridge

A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...

 along Broombridge Road which crosses the Royal Canal in Cabra, Dublin

Cabra, Dublin

Cabra is a suburb on the northside of Dublin city in Ireland. It is approximately northwest of the city centre, in the administrative area of Dublin City Council. It was commonly known as Cabragh until the early 20th century.- Transport and access:...

, Ireland

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

. Broom Bridge is named after William Brougham, one of the directors of the Royal Canal company. It is somewhat famous for being the location where Sir William Rowan Hamilton

William Rowan Hamilton

Sir William Rowan Hamilton was an Irish physicist, astronomer, and mathematician, who made important contributions to classical mechanics, optics, and algebra. His studies of mechanical and optical systems led him to discover new mathematical concepts and techniques...

 first wrote down the fundamental formula for quaternions on October 16, 1843, which is to this day commemorated by a stone plaque on the northwest corner of the underside of the bridge.

The text on the plaque reads:

Here as he walked by

on the 16th of October 1843

Sir William Rowan Hamilton

in a flash of genius discovered

the fundamental formula for

quaternion multiplication

i² = j² = k² = ijk = −1

& cut it on a stone of this bridge.

Given the historical importance of the bridge with respect to mathematics, mathematicians from all over the world have been known to take part in the annual commemorative walk from Dunsink Observatory

Dunsink Observatory

The Dunsink Observatory is an astronomical observatory established in 1785 in the townland of Dunsink near the city of Dublin, Ireland.Its most famous director was William Rowan Hamilton, who, amongst other things, discovered quaternions, the first non-commutative algebra, while strolling from the...

 to the site. Attendees have included Nobel Prize

Nobel Prize

The Nobel Prizes are annual international awards bestowed by Scandinavian committees in recognition of cultural and scientific advances. The will of the Swedish chemist Alfred Nobel, the inventor of dynamite, established the prizes in 1895...

 winners Murray Gell-Mann

Murray Gell-Mann

Murray Gell-Mann is an American physicist and linguist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles...

, Steven Weinberg

Steven Weinberg

Steven Weinberg is an American theoretical physicist and Nobel laureate in Physics for his contributions with Abdus Salam and Sheldon Glashow to the unification of the weak force and electromagnetic interaction between elementary particles....

 and Frank Wilczek

Frank Wilczek

Frank Anthony Wilczek is a theoretical physicist from the United States and a Nobel laureate. He is currently the Herman Feshbach Professor of Physics at the Massachusetts Institute of Technology ....

, and mathematicians Sir Andrew Wiles

Andrew Wiles

Sir Andrew John Wiles KBE FRS is a British mathematician and a Royal Society Research Professor at Oxford University, specializing in number theory...

 and Ingrid Daubechies

Ingrid Daubechies

Ingrid Daubechies is a Belgian physicist and mathematician. She was between 2004 and 2011 the William R. Kenan Jr. Professor in the mathematics and applied mathematics departments at Princeton University. In January 2011 she moved to Duke University as a Professor in mathematics. She is the first...

.

External links

• John C. Baez
  John C. Baez
  John Carlos Baez is an American mathematical physicist and a professor of mathematics at the University of California, Riverside in Riverside, California. He is known for his work on spin foams in loop quantum gravity. More recently, his research has focused on applications of higher categories...
  
  , Directions, photos and discussion, at University of California at Riverside