Diagram of electrotype apparatus as devised by George Mathiot of the CoastSurvey. This apparatus allowed the reproduction of copper-plate engravingseach of which could only survive 500 to a 1000 or so press impressions beforewearing away sufficientl
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Date: 1851
Credit: NARA C&GS; Colllection
Subject: Coast and Geodetic Survey
Subject: Archive Sketch