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 Samuel 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 His mathematical work concerned in particular the calculations of the lengths of the parabola and cycloid, and the quadrature of the hyperbola, which requires approximation of the natural logarithm function by infinite series. He was the first European to solve what is now known as Pell's equation. He was the first in England to take interest in generalized continued fractions and, following the work of John Wallis, he provided development in the generalized continued fraction of pi. Brouncker's formula This formula provides a development of π/4 in a generalized continued fraction: The convergents are related to the Leibniz formula for pi: for instance and Because of its slow convergence, Brouncker's formula is not useful for practical computations of π. Brouncker's formula can also be expressed as References External links 1620 births 1684 deaths 17th-century English mathematicians Founder Fellows of the Royal Society Lords of the Admiralty Presidents of the Royal Society Viscounts in the Peerage of Ireland 17th-century English medical doctors