A Gramme machine, or Gramme dynamo, is a continuous current generator invented by Belgian electrical engineer Zénobe Gramme. The first Gramme machine, which purpose was to convert mechanical energy into electricity, was shown to the Academy of Sciences in Paris in 1871.
In 1873, Gramme and his partner, Hippolyte Fontaine, accidentally discovered that the machine was reversible and could convert electricity into mechanical power. It was the first efficient electric motor, which opened the way to the expansion of the electrical industry. The machine shown in this picture was probably built sometime around 1880.
The caption reads in the original French: