Johann Helfrich von Müller (January 16, 1746 in Kleve – 1830) was an engineer in the Hessian army who conceived the difference engine in 1786 (first written reference to the basic principles of a difference machine is dated to 1784), an idea that later evolved into modern computers. In 1784, he was responsible for an improved adding machine based on principles of Leibniz's stepped reckoner.