The real inventor of the locomotive never realized a cent from his invention, says the St. Louis Globe-Democrat. His name was Oliver Evans. He was born in Delaware in 1756 and spent all his life perfecting inventions which were destined to bring him nothing but more poverty. He was the original inventor of the high-pressure engine used in locomotives, the only kind that could be employed to advantage in this form of transportation, but realized nothing for his idea. His application of the notion to both land and water power was somewhat novel. In 1804 the municipality of Philadelphia called for bids for the dredging of the river and the cleaning of the docks. Evans put in a bid lower than any of his competitors, and, when it was accepted, determined to build a steamboat to do the work. He fitted out a scow with a steam engine, building both the engine and the scow in his own workshop. When the boat was ready to be launched Evans determined to give the people of Philadelphia an object lesson in mechanics, so he put the boat on wheels, fitted up a push wheel behind, set his engine to work, and propelled the boat through the streets to the river in the midst of an open-mouthed throng, not a few of whom had a dim idea that he ought to be arrested for witchcraft. When the boat reached the bank of the river the wheels and axles were taken off, the craft was launched, fitted out with other wheels, and made to do the work of dredging the harbor. So far as the invention of mechanical devices went Evans had a splendid genius, but when dollars and cents came up for consideration he was a mere child and even allowed himself to be cheated out of the money that was due him for cleaning the Philadelphia harbor with his newfangled steamboat.
The device was called the “Oruktor Amphibolos” (Amphibious Digger).
Between this article, the wikipedia one, the PBS one, and the one from the University of Houston, I get the distinct impression that Mr Evans was the stereotypical inventor — he made very useful objects, but was a naïve businessman who could not profit from them while others did.