The Mississippi was discovered by Marquette in 1673 and spanned by James B. Eads in 1874. In his prolific career as an inventor intimately linked to the Mississippi, Eads founded diving salvage companies, designed turrets for Civil War ironclad ships, and-perhaps most spectacularly-built the first bridge that connected the eastern and western halves of the country, previously divided by the Great River. Compiled from the voluminous writings and utterances of James B. Eads, from government...