Sir William Rowan Hamilton
1 Who was W.R. Hamilton? 
An Irish mathematician.
2 When and where did he live? 
He was born at 29 Dominick St., Dublin at midnight, 3rd August, 1805.  
He was sent to live with his uncle in Trim, Co. Meath at age 3.  
He got a job as an Astronomer and lived at Dunsink Observatory, Co. Dublin from 1827 
until his death on 2nd  Septemberin 1865.
3 Why is this year so special?  
It is the bi-centenary celebration of his birth.
4 Why is 16 October so special? 
 It is the anniversary of his mathematical discovery at Broombridge, Cabra on 16 October 
5 Why is Hamilton considered to be a genius?  
At age 5 he was fluent in Latin, Greek and Hebrew.  
At age 12 he was fluent also in French, Italian, Arabic, Syriac, Persian and Sanskrit.  
At age 13 he was a superb mathematical calculator although he lost in competition to an 
American prodigy.  
At age 14 he invented a semaphore system of communication.  
At age 17 he entered Trinity College, Dublin obtaining 1st place in all examinations, 
while some of his results (in both Science and Classics) were beyond classification in the 
examination system (termed 'optime').  
At age 22 he was appointed as a Professor of Astronomy – some time before he actually 
graduated from the College. 
At age 27 he used mathematics to predict the different paths taken by light as it passes 
through certain objects. (Conical refraction in biaxial crystals). He also developed mathematics which allowed light to be treated as either a wave or a particle.
He was knighted three years later for his discoveries and received 
a pension.
At age 30 he rewrote Newton's Laws of Motion. 
At age 38 he discovered the Quaternions – a new mathematical system of numbers.
He is famous for formulating the laws of Physics in a special way and for developing 
Hamiltonian circuits which are used in Graph Theory as well as his discovery of 
6 What was he like?  
He was a passionate romantic.  He wrote volumes of poetry especially from the age of 14 
after his father and mother had died.  
He felt responsible for his four sisters from that time. Later he provided a home for them 
at Dunsink Observatory.
At age 19 he fell in love with a girl his own age, Catherine Disney.  Unfortunately, she 
was matched with an older man of wealth and although she also loved him, she married 
the older man.   
William fell into despair and felt his life was over.  However, he threw himself into his 
studies and later, at age 27, married Helen Bayly from Nenagh, Co. Tipperary and they 
had two sons and a daughter.  His daughters' descendants (O'Regans) continue to live in 
England to this day.  
He was a religious man and became Churchwarden in the parish of Castleknock, Dublin 
(Church of Ireland).
He was also passionate about mathematics and science.  
At age 22 he discussed the idea of beauty and aesthetics in mathematics with the poet 
William Wordsworth who was aged 57 and led to Wordsworth changing his appreciation 
of this subject.  William Hamilton became a godfather to William Wordsworth's son, 
William, although later, he refused to become godfather to Oscar Wilde who by 
coincidence, was born on the anniversary of Hamilton's quaternion discovery  exactly 11 
years previously.  
Sadly, throughout his life he was troubled by depression and excessive drinking of 
alcohol.  He died from complications of gout and bronchitis at age 60.  He is buried in 
Mount Jerome Cemetery in Dublin. 
 For his epitaph he wished to be remembered as a labour-loving and truth-loving man – 
the same epitaph which the ancient Ptolemy of Geeece gave to the astronomer 
7 How is William Hamilton remembered? 
In 1958 a commeration plaque was erected on Broombridge, Cabra by Taoiseach Eamon 
The Hamilton building in Trinity College is named after him.  
A crater on the moon is named after him.  
The year 2005 is designated as Hamilton Year 2005 to celebrate the bi-centerary of his 
His ideas were developed in the theory of electromagnetism by Maxwell in 1873.  
His ideas also influenced the development of quantum mechanics and the design of 
optical instruments.  This work continues in the search for a Unified Field Theory which 
attempts to link the four principal forces which form the universe.  
Hamilton's mathematical ideas are finding practical application in the realm of computer 
graphics for the manipulation of 3-dimensional shapes. 
He invented the Icosian Game
Here is a link to a diagram of the Semaphore System
The annual Hamilton Walk from Dunsink Observatory to Broombridge, Dublin, on 16th 
October, organised by The Mathematics Department of NUI, Maynooth. Here are some pictures from the 2005 Walk.
Sources: Riocht na Midhe, Records of Meath Archaeological and Historical Society, Vol. 
XI, 2000  ; ; ; ; ; ; 
This portrait of William Rowan Hamilton hangs in the Royal Irish Academy. Image: Royal Irish Academy.
This is a picture of the Hamilton Crater on the Moon
Sir William Rowan Hamilton and one of his sons (circa 1845) 
(Portrait of Hamilton from Enterprise Ireland Portrait Gallery, courtesy of Enterprise Ireland) 
An engraving (Picture from the St. Andrew’s, Scotland, web-site).

William Rowan Hamilton

lived from 1805 to 1865 (Picture from the St. Andrew’s, Scotland, web-site)


(Picture from the St. Andrew’s, Scotland, web-site)
A page from Hamilton's notebook(Picture from the St. Andrew’s, Scotland, web-site)

Broombridge, Dublin



Page created by Neil Hallinan 2005