 Bi-metallic coins have been issued for a long time, with known examples dating from the 17th century, while the Roman Empire issued special-occasion, large medallions with a center of bronze or copper and an outer ring of orichalcum, starting with the reign of Hadrian.The silver-center cent pattern produced by the United States in 1792 is another example.In the 1830s and 1840s, British medalist Joseph Moore produced large numbers of bi-metallic "penny model" and less common "halfpenny model" tokens, as a proposal to replace the relatively large penny and halfpenny coins.