Gramme dynamo

The Gramme dynamo was an electrical generator patented in 1870 by Belgian engineer Zénobe Gramme (April 4, 1826 - January 20, 1901). The design, using a ring armature, was an improvement on earlier dynamos and helped usher in development of large-scale electrical devices. In 1873 it was discovered that the device could be reversed to serve as a motor.