Nicole d' Oresme
Nicole d' Oresme

1323-1382

After studying theology in Paris, Nicole Oresme was bursar in the University of Paris, then canon and later dean of Rouen. In 1370 he was appointed chaplain to King Charles V and advised him on financial matters.

Oresme invented coordinate geometry before Descartes, finding the logical equivalence between tabulating values and graphing them. He proposed the use of a graph for plotting a variable magnitude whose value depends on another. It is possible that Descartes was influenced by Oresme's work since it was reprinted several times over the 100 years following its first publication.

Another work by Oresme contains the first use of a fractional exponent, although, of course, not in modern notation. He is also credited with the rules of exponents: xm xn = xm+n (xm)n = xmn. For each rule, specific examples and applications were given. Even more imaginative was his suggestion that irrational powers are possible. Oresme also worked on infinite series. He was the first to prove that the harmonic series diverges.

Oresme also opposed the theory of a stationary Earth as proposed by Aristotle and taught motion of the Earth, 200 years before Copernicus. However he spoiled this fine piece of thinking by rejecting his own ideas in the end. He also wrote a work dealing with the nature of light, reflection of light, and the speed of light.