Two examples of Gramme's machines for electro-metallurgy.
"This machine differs from all other magneto-electric machines at present known, inasmuch as it is the only one that gives a continuous current in one direction. The current from this machine depends upon the uninterrupted travelling of the magnetic poles of the core in a circle, that is, upon continuous magnetization."
“Plate I: Electro Metallurgy.” In Encyclopædia of Chemistry, Theoretical, Practical, and Analytical, as Applied to the Arts and Manufacturers, Vol. I. Philadelphia, Pennsylvania: J.B. Lippincott & Co., 1877. https://digital.sciencehistory.org/works/6h440s484.