The "grievous coppers" mentioned in Aristophanes have consistently been interpreted as "official" fourrees, struck when the supply of gold was exhausted by 406/5 BC. Numismatists have subsequently attempted to distinguish this official issue from fourrees that were fabricated privately, which are voluminous for the issues of the fifth century. The 1902 discovery of a sizable hoard of plated tetradrachms and drachms at the Athenian port city of Piraeus provided the largest single piece of evidence in support of the theory that the fourrees Aristophanes mentioned were "official" issues, and not private fabrications. Re-examining the issue in 1996, John H. Kroll (Essays Oeconomides, pp. 139-142) argued that while the direct evidence was not conclusive that the "grievous coppers" of Aristophanes were "official" fourrees, no plausible alternative hypothesis existed, and that the identification of the 1902 Piraeus Hoard with the emergency coinage struck in 406/5 BC was very persuasive.