Quetelet (1796-1874) was a Belgian astronomer, mathematician, statistician and sociologist. He founded and directed the Brussels Observatory. He became interested in the young science of probability and statistics as an astronomer to explain measurement errors, but became one of the first to see its applications to the social sciences. He understood the complexities of social phenomena and became interested in using what he called "social physics" as a tool to explain crime rates, marital rates, suicide rates, etc. In 1835, he published Sur l'homme et le dveloppement des ses faculties, essai d'une physique sociale, which made him famous throughout Europe. These letters to the Grand Duke of Saxe Coburg and Gotha are an important sequel to that work. Cajori calls them "Quetelet's best researches on the application of probability to the physical and social sciences" and notes: "He laid emphasis on the 'law of large numbers,' which was advanced also by the Frenchman S.D. Poisson and discussed by the German W. Lexis (1877), the Scandinavians H. Westergaard and Carl Charlier, and the Russian Pafnuti Liwowich Chebichev (1821-1894) of the University of Petrograd." Quetelet's work was enormously influential to Francis Galton, who expanded upon it in Hereditary Genius. Cajori, History of Mathematics, p. 380. Stigler, History of Statistics, p. 392. Goldsmiths' 36193.