Henri Lebesgue
lived from 1875 to 1941

**Lebesgue** formulated the theory of measure in 1901 and the following year he gave the definition of the Lebesgue integral that generalises the notion of the Riemann integral.

*Find out more at*:

http://mathshistory.st-andrews.ac.uk/Biographies/Lebesgue.html