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Isaac Dripps's screw propeller model, 1840

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Isaac Dripps's screw propeller model, 1840
Smithsonian Institution, Photo by Richard Strauss, Negative #: 2006-9721


This object appears in the following sections:

Marine Patent Models — Complete Catalog: before 1850

Marine Patent Models — Who's Inventing?

Marine Patent Models — Moving Forward

Stern of the steam tug New Jersey with John Ericsson's propeller installed
Stern of the steam tug New Jersey with John Ericsson's propeller installed

Stern of the steam tug New Jersey with Isaac Dripps's propeller installed
Stern of the steam tug New Jersey with Isaac Dripps's propeller installed

Screw propeller

Screw propeller model
Catalog #: 180,007, Accession #: 17,193
In collection
From the Smithsonian Collection

Mechanical engineer Isaac Dripps donated this propeller model to the U.S. National Museum in February 1886. Etched on one of the blades is the declaration, "This Screw Propeller was designed by and made under the directions of Isaac Dripps at Bordentown New Jersey in the Year 1840." He did not patent this propeller.

Physical Description

This model shows Dripps's six-bladed propeller design, where each blade has a turned flange at its tip to help grip the water. The blades are separate castings bolted to the central hub. Such construction was the most common way to make large propellers in the nineteenth century, as it allowed ready replacement of the easily damaged blades. The model measures 9 1/2" diameter by 4" deep.

Date Made:
New Jersey, Pennsylvania
Gift of Isaac Dripps

In 1838, U.S. Navy Captain Robert F. Stockton saw a screw-propelled boat designed by the Swedish engineer John Ericsson demonstrated in England. Believing that such a boat would be practical on American canals, he commissioned one, and it was delivered across the Atlantic the next year, the first iron-hulled vessel to cross the Atlantic. Originally named Robert F. Stockton but quickly changed to New Jersey, the boat proved too deep for canal use, and it became a tug boat on the Delaware River. As designed by Ericsson, the boat employed two screws—mounted in line but turning in opposing directions—and a rudder installed forward of the screws, an arrangement that made the boat difficult to control and maintain. In 1840, the boat was turned over to engineers at the Camden & Amboy Railroad for improvement. Under the direction of Isaac Dripps, the mechanics installed a new single propeller and repositioned the rudder aft of the screw. In this configuration, the New Jersey remained in service until 1871, the first commercially successful propeller steamer.

Isaac Dripps (1810-92) was a prominent railroad engineer. Born in Ireland, he arrived in the U.S. with his parents in infancy. He apprenticed to Philadelphia steamboat-engine builder Thomas Holloway in 1826 and in 1831 was hired by Robert L. Stevens to assemble the John Bull locomotive, newly delivered from England for the Camden & Amboy Railroad, although he had never seen such a machine before. He also acted as engineer for the John Bull’s first trip. Dripps continued as an engineer for the Camden & Amboy until 1854, during which time he and Stevens developed the cowcatcher and the bonnet spark arrester, among other early locomotive improvements. After a short time as partner in a locomotive works, he returned to superintending motive power for railroads, ending his career with the Pennsylvania Railroad. One biography says, “In the course of his career he devised innumerable mechanisms, tools, and the like for use in the construction of locomotives, freight and passenger cars, and steamboat machinery, but never patented any of them.”


“Isaac L. Dripps,” Dictionary of American Biography (New York, 1930), vol. V, 458.

“The First Successful Screw Propeller,” The Locomotive Engineer, Jan. 1891, 6.

John White, American Locomotives: an Engineering History, 1830-1880 (Baltimore, 1968), 451.

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