By the 1870s, propellers dominated the propulsion of ocean vessels, and paddle wheels predominated aboard craft working shoal river and coastal waters. Neither type was perfect: propellers often broke blades, and paddle-wheel floats frequently snagged river debris. Jacob Eckhardt of St. Louis, Missouri, proposed as an alternative that steamships could be propelled by the action of oscillating plungers. Pairs of plungers were to be placed in recesses built into a ships hull. By positioning two plunger boxes at each end of the vessel, and by making the vessel pointed at both ends, Eckhardt claimed that the ship would be able to run in either direction without turning around. To protect the plungers when not in operation, Eckhardt designed sliding doors to cover the hull recesses. The corresponding doors on each side of the ship could be opened and closed together through connecting shafts and gearing provided for the purpose. The inventor specified that the entire system be powered by a central steam engine.
Many other nineteenth-century patents proposed boxed propellers, enclosed paddles, water jets, and similar compartmentalized propulsion systems. What set Eckhardts design apart, he argued, was the combination of double-ended hull, plungers, plunger boxes, and sliding doors, all working together as a system. Although he claimed that his system took up comparatively little space aboard shipwhich is a great desideratum in vessels of flat floors and light draftin his model the engine plant, when taken together with the space that would be required for boilers and steam engine, leaves precious little room for cargo or passengers. Eckhardts design also makes no provision for steering. Although theoretically the plungers on either side of the ship could be operated independently to turn the vessel, his model and specification call for linking them together, limiting the ship to forward and reverse only.
Inventor Jacob Eckhardt of St. Louis was a 57-year-old molder or joiner who worked as a foreman at the foundry and machine-works operator Smith, Beggs, and Co. Born in Hessen (now a part of Germany) he immigrated to the United States. In 1868, he married the widow Louise Graff, also a German immigrant. They raised two daughters together, as well as at least one son from her previous marriage.
Jacob Eckhardt, Propulsion of Vessels, U.S. patent no. 179,407, July 4, 1876.
1880 United States Census, NARA film no. T9-0727, 424D.
Goulds St. Louis Directory for 1876
Mrs. Louise Graf, FamilySearch International Genealogical Index (www.familysearch.org)