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Eckhardt's vessel propulsion system

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Eckhardt's vessel propulsion system
Smithsonian Institution, Photo by Richard Strauss, Negative #: 2006-9746


This object appears in the following sections:

Marine Patent Models — Complete Catalog: 1876-1880

Marine Patent Models — Moving Forward

Vessel propulsion patent model
Catalog #: 1990.0114.01, Accession #: 1990.0114
In collection
From the Smithsonian Collection

Jacob Eckhardt submitted this model as part of his application for a patent, June 20, 1876. Fourteen days later the patent was issued, on the very day of the nation's centennial, July 4, 1876. The model represents a system for propelling vessels though water using oscillating plungers.

Physical Description

Eckhardt's model comprises a black-painted hull enclosing an internal mechanism of rods and gears. The bottom of the hull is wood; the sides are metal. Four sliding doors, two on either side of the hull, open to show how water might be admitted into the enclosed chambers of the propelling apparatus. Oscillating plungers in each chamber push against the water. The piston chambers are mechanically linked into pairs, demonstrating how Eckhardt's system permitted a vessel to reverse direction without turning around. The model also has forward and aft connecting rods to operate the hull doors. The model is 12 1/8" L x 5 1/8" W x 4 1/2" H.

Date Made:
St. Louis
Gift of Arthur E. Denu

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 ship’s 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 Eckhardt’s 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 ship—“which is a great desideratum in vessels of flat floors and light draft”—in 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. Eckhardt’s 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.

Gould’s St. Louis Directory for 1876

“Mrs. Louise Graf,” FamilySearch International Genealogical Index (

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