Beginning as an artist, Robert Fulton's interest had shifted to science and engineering by the early 1790's. In 1794 he received a British patent for a double inclined plane, which was used to raise and lower canal boats from one level to another. Fulton moved to France in 1797, and in the same year submitted proposals to the French government for a submarine. His submarine, the Nautilus, was launched in 1800. Although it proved workable, neither the French, British, nor U.S. governments would provide support for the project. Fulton agreed to build for Robert R. Livingston a steamboat that would operate on the Hudson River. His first steamboat was tested successfully on the Seine River in 1803. Fulton returned to the United States in 1806 and the following year his steamboat was launched in New York harbor. Eventually called the Clermont, the boat proved the commercial feasibility of steamboats.