Complex sentence: The electric pen proved ultimately unsuccessful, other simpler methods (and eventually the typewriter) succeeding it for cutting stencils, but Edison licensed his duplicating technology to A.B. Dick, who sold it as "Edison's Mimeograph" with considerable success.
Split into simpler sentences: The electric pen proved ultimately unsuccessful, other simpler methods (and eventually the typewriter) succeeding it for cutting stencils. But Edison licensed his duplicating technology to A.B. Dick, who sold it as "Edison's Mimeograph" with considerable success.