In 1853, Gintl developed an early form of duplex electrical telegraph, which allowed two messages to be transmitted on a single wire in opposite directions. This duplex communication was an early specific case of the general practice of multiplexing. While Gintl's technology was not commercial successful, his method was improved upon by German engineer Carl Frischen and later by J. B. Stearns, who would patent a version in 1872. Edison, who was also working on the design, would further refine his method in his implementation of a quadruplex telegraph.