In 1871, Belgian engineer Zénobe Gramme presented to the Académie des Sciences in Paris the first practical dynamo capable of generating stable direct current at industrial scale. Unlike earlier generators, the Gramme ring produced current smooth and powerful enough to power motors and industrial applications. At the 1873 Vienna Exposition it was accidentally demonstrated that the machine was reversible: connected to another identical one, it functioned as an electric motor. This discovery opened the path to electric transport. The Gramme dynamo is the direct technical link between Faraday's induction principle (1831) and the first practical large-scale applications of electricity, including Pirotski's electric tram (1880) and Edison's networks (1882).