Carl Gottlieb Ehler

Carl Gottlieb Ehler (1685 to 1753) is regarded as a mathematician chiefly because of his post as an astronomer in Berlin; he later served as mayor of Danzig from March 1741 until his death. In Berlin he met Gottfried Wilhelm Leibniz and sent him astronomical observations together with a book by Isaac Papin. With his friend, the Prussian mathematician Heinrich Kühn, he corresponded with Leonhard Euler from 1735, and in March 1736 he asked Euler for the solution and a proof of the problem of the seven bridges of Königsberg, an exchange that forms part of the early history of graph theory. He also corresponded with other mathematical figures whose work advanced graph theory and number theory. Much of his early life remains a mystery, though his later posts imply the education of a privileged child.