Brouncker was born in
Castlelyons,
County Cork, the elder son of
William Brouncker (1585–1649), 1st
Viscount Brouncker and Winifred, daughter of Sir William Leigh of Newnham. His family came originally from
Melksham in
Wiltshire. His grandfather Sir
Henry Brouncker (died 1607) had been
Lord President of Munster 1603–1607, and settled his family in Ireland. His father was created a
viscount in the
Peerage of Ireland in 1645 for his services to the Crown. Although the first viscount had fought for the Crown in the Anglo-Scots war of 1639, malicious gossip said that he paid the then enormous sum of £1200 for the title and was almost ruined as a result. He died only a few months afterwards. William obtained a
DM at the
University of Oxford in 1647. Until 1660 he played no part in public life: being a staunch Royalist, he felt it best to live quietly and devote himself to his mathematical studies. He was one of the founders and the first
president of the Royal Society. In 1662, he became
chancellor to
Queen Catherine, then head of the
Saint Catherine's Hospital. He was appointed one of the commissioners of the
Royal Navy in 1664, and his career thereafter can be traced in the
Diary of Samuel Pepys; despite their frequent disagreements,
Samuel Pepys on the whole respected Brouncker more than most of his other colleagues, writing on 25 August 1668 that "the truth is, he is the best man of them all". Although his attendance at the Royal Society had become infrequent, and he had quarrelled with some of his fellow members, he was nonetheless greatly displeased to be deprived of the presidency in 1677. He was commissioner for executing the office of
Lord High Admiral of England from 1679.
Abigail Williams Brouncker never married, but lived for many years with the
actress Abigail Williams (much to Samuel Pepys' disgust) and left most of his property to her. She was the daughter of Sir Henry Clere (died 1622), first and last of the
Clere Baronets, and the estranged wife of John Williams, otherwise Cromwell, second son of
Sir Oliver Cromwell, and first cousin to the renowned
Oliver Cromwell. She and John had a son and a daughter. The fire of 1673 which destroyed the Royal Navy Office started in her private closet: this is unlikely to have improved her relations with Pepys, whose private apartments were also destroyed in the blaze. On Brouncker's death in 1684, his title passed to his brother
Henry, one of the most detested men of the era. William left him almost nothing in his will "for reasons I think not fit to mention". == Mathematical works ==