Source : Webster's Revised Unabridged Dictionary (1913)

Siderography \Sid`er*og"ra*phy\, n. [Gr. ??? iron + -graphy.]
   The art or practice of steel engraving; especially, the
   process, invented by Perkins, of multiplying facsimiles of an
   engraved steel plate by first rolling over it, when hardened,
   a soft steel cylinder, and then rolling the cylinder, when
   hardened, over a soft steel plate, which thus becomes a
   facsimile of the original. The process has been superseded by
   electrotypy.