Mathematician from Anglsey
His father John George Jones relied on a charity school at Llanfechell for William's education. His mathematical talent gained the attention of the Bulkeley family (local landowners) who found him employment in London working at a merchant's counting-house (where goods were inspected and money exchanged).
Jones also worked for the Royal Navy, teaching mathematics on board Navy ships for seven years from 1695. Here his attention focused on navigation. He wrote 'A New Compendium of the Whole Art of Navigation' published in 1702. In this work he applied mathematics to navigation and methods of calculating locations at sea. Later he became a mathematics teacher in London, both in coffee houses and as a private tutor to the gentry. William also held a number of posts in government offices.
He published Synopsis 'Palmariorum Matheseos' in 1706, a work intended for beginners including theorems on various calculus and infinite series. This used π for the ratio of circumference to diameter, following earlier abbreviations for the Greek word periphery (περιφέρεια) by William Oughtred and others. His 1711 work 'Analysis per quantitatum' series, fluxiones ac differentias introduced the dot notation for differentiation in calculus. Then in 1731 he published Discourses of the Natural Philosophy of the Elements.
A noted mathematician, published author and early naval navigator. First to use 'Pi' (1706) as a mathematical symbol. He was a friend of Isaac Newton and Edmund Halley
William was noticed and befriended by two of Britain's foremost mathematicians – Edmund Halley and Sir Isaac Newton. He was elected a fellow of the Royal Society in 1711. Later he became the editor and publisher of many of Newton's manuscripts and built up an extraordinary library that was one of the greatest collections of books on science and mathematics ever known.
After the death of his first wife, widow of his counting-house employer (whose property he eventually inherited), William married the young Mary (daughter of cabinet-maker George Nix). She was just twenty-two at the time and went on to deliver two healthy children. One, their son William (born in 1746) became a renowned philologist going into the history books by establishing links between Latin, Greek and Sanskrit, leading to the concept of the Indo-European language group.