-Huygens' Mortality Chart

Building on the “political arithmetic” of John Graunt, whose work is also on display in the exhibit, Christiaan Huygens (1629-1695) created the first graph of a continuous distribution function. In a correspondence with his brother Lodewijk in 1669, Huygens visually graphed the statistical life expectancy table first published by Graunt. Huygens’ graph puts age on the x-axis and the proportion of a population likely to survive to that age on the y-axis. While Graunt’s chart gives fixed numbers for life expectancy, Huygens calculates the median additional years of life and differentiates this calculation from life expectancy. This probabilistic charting of life expectancy is still common in the fields of insurance and actuarial science. Huygens is most well known for observing the rings of Saturn, and discovering its first moon, Titan.

Lehigh University Catalog Record: https://asa.lib.lehigh.edu/Record/112558

A version of this text has been digitized and is available through the Internet Archive.

Christiaan Huygens (1629-1695).
Oeuvres complètes. Volume 6.
La Haye: M. Nijhoff, 1888-1950.