Blaise Pascal, French mathematician, physicist and philosopher, c 1650.
© Science Museum / Science & Society Picture Library
Blaise Pascal (1623-1662) is credited with founding the modern theory of probability. He also discovered the properties of the cycloid (or roulette), contributed to the advance of differential calculus and in 1647 invented the first calculating machine. As a physicist, his attempts to discredit the notion that 'nature abhors a vacuum' led to the invention of the barometer, hydraulic pres and syringe. The SI unit (International System of units) of presure, the Pascal, and a computer programming language are named after him.