In regards to Niall Ferguson's New Book The Ascent of Money: Alan Davisson mentions both Niall Ferguson and Bernard Cornwell as authors who have made misstatements regarding ancient coins. I have recently read Colleen McCullough's book The First Man in Rome. In the glossary (which is generally quite helpful) she describes the Sestertius as a "small silver coin". As any numismatist with even a passing interest in Roman coins will attest, the Sestertius is most certainly not small or silver. I do not think this is being picky at all. One would hope that authors specializing in historical fiction would strive to get such easy-to-verify facts straight.