 The book has been translated in Portuguese.By "heroic age" the author means the era of American history in which individual initiative and enterprise constituted the primary thread in technical innovation, roughly from the early 19th century until mass production and corporate enterprise outpaced that of the individual around the time of World War I.The story of innovation is told through the biographies and inventions of thirty-two key inventors of the United States' industrial revolution, whom de Camp feels were pivotal in converting the country from an agrarian nation to an industrial one.