**William Jones (1675 – 1749)**

##### » First mathematician to use the Greek letter π to represent the important ratio

While talk of the ratio has been around for about 4,000 years, and the number itself probably a bit longer, the symbol π is just reaching the big 3-0-0. A fellow from the Welsh island of Anglesey, who grew up to be a rather well-connected but unmemorable mathematician, decided to use the Greek symbol for “p” in a math-for-beginners guide he published in 1706. He figured it would look nicer than the “p” used in prior years, which stood for “periphery.”

It probably wouldn’t have sunken in to the math community, had it only been used by a guy who spent most of his mathematical prime (young adulthood) teaching math onboard naval battleships and in London coffeehouses. But when a much bigger fish named Leonhard Euler used Jones’ new notation in his works about 30 years later, the symbol was here to stay.

Jones attempted to secure a teaching job at an actual math school, but even with references written by his friends, Sirs Isaac Newton and Edmund Halley, he was rejected and stuck to his coffeehouse crowd. He spent his later adult life serving in a variety of cushy political jobs, which he got through some key connections after losing all his money in a bank collapse. It’s always nice to have friends in high places.

We should be glad William Jones didn’t come up with γ (or gamma, the alphabet’s third letter, like “c”) to stand for “circumference” or “circle” in his 1706 writings. Gamma Day sounds a bit less tasty and somewhat more radioactive.