In early 1786, Fulton developed symptoms of tuberculosis and was advised by an eminent doctor to take an ocean voyage for the benefit of his health. Fulton traveled to Europe, where he would live for the next twenty years. He left for England in the autumn of 1786, carrying several letters of introduction to Americans abroad from prominent individuals he had met in Philadelphia. He already corresponded with artist Benjamin West; their fathers had been close friends. West took Fulton into his home, where Fulton lived for several years and studied painting. Fulton gained many commissions painting portraits and landscapes, which allowed him to support himself. He continued to experiment with mechanical inventions.

Fulton became caught up in the enthusiasm of the "Canal Mania". In 1793, he began developing his ideas for canals with inclined planes instead of locks. He obtained a patent for this idea in 1794, and also began working on ideas for the steam power of boats. He published a pamphlet about canals and patented a dredging machine and several other inventions. In 1794, he moved to Manchester to gain practical knowledge of English canal engineering. While there he became friendly with Robert Owen, a cotton manufacturer and early socialist. Owen agreed to finance the development and promotion of Fulton's designs for inclined planes and earth-digging machines; he was instrumental in introducing the American to a canal company, which awarded him a sub-contract. But Fulton was not successful at this practical effort and he gave up the contract after a short time.

As early as 1793, Fulton proposed plans for steam-powered vessels to both the United States and British governments. The first steamships had appeared considerably earlier. The earliest steam-powered ship, in which the engine moved oars, was built by Claude de Jouffroy in France. Called Palmipède, it was tested on the Doubs in 1776. In 1783, de Jouffroy built Pyroscaphe, the first paddle steamer, which sailed successfully on the Saône. The first successful trial run of a steamboat in America had been made by inventor John Fitch, on the Delaware River on August 22, 1787. William Symington had successfully tried steamboats in 1788, and it seems probable that Fulton was aware of these developments.

In Britain, Fulton met the Duke of Bridgewater, Francis Egerton, whose canal, the first to be constructed in the country, was being used for trials of a steam tug. Fulton became very enthusiastic about the canals, and wrote a 1796 treatise on canal construction, suggesting improvements to locks and other features. Working for the Duke of Bridgewater between 1796 and 1799, Fulton had a boat constructed in the Duke's timber yard, under the supervision of Benjamin Powell. After installat…

Read more on Wikipedia

Prior to his marriage in 1808, Robert Fulton had a variety of homosexual and polyamorous relationships. Famous among them was a ménage à trois with noted philanthropist couple Ruth and Joel Barlow while living in Paris with them for six years. Letters between them reveal a sexual relationship among all three, including notes from American Revolutionary and patriot Joel Barlow requesting in baby-talk language for him "to have a wonderful summer of sexual pleasure with his wife" while he was away, and, importantly, that "he must not let...his beautiful body be deranged, and if he does anything wrong, he'll come and cut off his penis." After he left Paris, he lived for two years at the castle of William Courtenay, 9th Earl of Devon, a known homosexual, although there is no confirmed epistolary evidence of an explicit sexual relationship between them

On January 8, 1808, Fulton married Harriet Livingston (1783–1826), the daughter of Walter Livingston and niece of Robert R. Livingston, prominent men in the Hudson River area, whose family dated to the colonial era. During his marriage, he proposed a foursome with himself, his wife, and Ruth and Joel Barlow in Washington, DC, but Harriet rejected the offer. Harriet, who was nineteen years his junior, was well educated and was an accomplished amateur painter and musician. Together, they had four children:
• Robert Barlow Fulton (1808–1841), who died unmarried.
• Julia Fulton (1810–1848), who married lawyer Charles Blight of Philadelphia.
• Cornelia Livingston Fulton (1812–1893), who married lawyer Edward Charles Crary (1806–1848) in 1831.
• Mary Livingston Fulton (1813–1861), who married Robert Morris Ludlow (1812–1894), parents of Robert Fulton Ludlow.
Fulton died in 1815 in New York City from tuberculosis (then known as "consumption"). He had been walking home on the frozen Hudson River when one of his friends, Thomas Addis Emmet, fell through the ice. In rescuing his friend, Fulton got soaked with icy water. He is believed to have contracted pneumonia. When he got home, his sickness worsened. He was diagnosed with consumption and died at 49 years old. After his death, his widow remarried to Charles Augustus Dale on November 26, 1816.

He is buried in the Trinity Church Cemetery for Trinity Church (Episcopal) at Wall Street in New York City, near other notable Americans such as former U.S. Secretaries of the Treasury, Alexander Hamilton and Albert Gallatin. His descendants include Cory Lidle, a former Major League Baseball pitcher.

The Commonwealth of Pennsylvania donated a marble statue of Fulton to the National Statuary Hall Collection in the United States Capitol. Fulton was also honored for his development of steamship technology in New York City's Hudson-Fulton Celebration of the Centennial in 1909. A replica of his first steam-powered steam vessel, Clermont, was built for the occasion.

Five ships of the United States Navy have borne the name USS Fulton in honor of Robert Fulton.

Fulton Hall at the United States Merchant Marine Academy houses the Department of Marine Engineering and included laboratories for diesel and steam engineering, refrigeration, marine engineering, thermodynamics, materials testing, machine shop, mechanical engineering, welding, electrical machinery, control systems, electric circuits, engine room simulators and graphics.

Bronze statues of Fulton and Christopher Columbus represent commerce on the balustrade of the galleries of the Main Reading Room in the Thomas Jefferson Building of the Library of Congress on Capitol Hill in Washington, D.C. They are two of 16 historical figures, each pair representing one of the 8 pillars of civilization.

The Guatemalan government in 1910 erected a bust of Fulton in one of the parks of Guatemala City.

In 2006, Fulton was inducted into the "National Inventors Hall of Fame" in Alexandria, Virginia.
Many places in the U.S. are named for Robert Fulton, including:
• Fulton County, Georgia
• Fulton County, Illinois
• Fulton County, Indiana
• Fulton County, Kentucky
• Fulton County, New York
• Fulton County, Ohio
• Fulton County, Pennsylvania
• Fulton, New York (disambiguation)
• Fulton, Arkansas
• Fulton, Mississippi
• Fulton, Illinois
• Fulton, Missouri
• Fulton, Oswego County, New York
• Fulton, Obion County, Kentucky

Read more on Wikipedia