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Joseph Henry (December 17, 1797According Keith Laidler there is some doubt about the year of his birth, with strong evidence from a member of his family that he was born in 1799. – May 13, 1878) was an American physicist and inventor who served as the first secretary of the Smithsonian Institution. He was the secretary for the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution. He also served as president of the National Academy of Sciences from 1868 to 1878.
While building electromagnets, Henry discovered the electromagnetism phenomenon of self-inductance. He also discovered mutual inductance independently of Michael Faraday, though Faraday was the first to make the discovery and publish his results. Henry developed the electromagnet into a practical device. He invented a precursor to the electric doorbell (specifically a bell that could be rung at a distance via an electric wire, 1831) and electric relay (1835). His work on the electromagnetic relay was the basis of the practical electrical telegraph, invented separately by Samuel Morse and Sir Charles Wheatstone. In his honor, the SI unit of inductance is named the henry (plural: henries; symbol: H ).
In 1819, he entered The Albany Academy, where he was given free tuition. Even with free tuition, he was so poor that he had to support himself with teaching and private tutoring positions. He intended to go into medicine, but in 1824 he was appointed an assistant engineer for the Surveying of the State road being constructed between the Hudson River and Lake Erie. From then on, he was inspired to a career in either civil or mechanical engineering. Henry excelled academically, even often helping his teachers teach science.
Using his newly developed electromagnetic principle, in 1831, Henry created one of the first machines to use electromagnetism for motion. This was the earliest ancestor of modern Electric motor. It did not make use of rotating motion, but was merely an electromagnet perched on a pole, rocking back and forth. The rocking motion was caused by one of the two leads on both ends of the magnet rocker touching one of the two battery cells, causing a polarity change, and rocking the opposite direction until the other two leads hit the other battery.
This apparatus allowed Henry to recognize the property of Inductance. British scientist Michael Faraday also recognized this property around the same time. Since Faraday published his results first, he became the officially recognized discoverer of the phenomenon.
The Trustees have however furnished me with an article which I now find indispensable namely with a coloured servant whom I have taught to manage my batteries and who now relieves me from all the dirty work of the laboratory.
In his letters, Henry described Parker providing materials for experiments, fixing technical issues with Henry's equipment, and at times being used as a test subject in electrical experiments in which Henry and his students would shock Parker in classroom demonstrations. In 1842, when Parker fell ill, Henry's experiments stopped completely until he recovered.
In late 1861 and early 1862, during the American Civil War, Henry oversaw a series of lectures by prominent Abolitionism at the Smithsonian Institution. Speakers included white clergymen, politicians, and activists such as Wendell Phillips, Horace Greeley, Henry Ward Beecher, and Ralph Waldo Emerson. Orator and former fugitive slave Frederick Douglass was scheduled as the final speaker; Henry, however, refused to allow him to attend, stating: "I would not let the lecture of the coloured man be given in the rooms of the Smithsonian."
In the fall of 2014, history author Jeremy T.K. Farley released The Civil War Out My Window: Diary of Mary Henry. The 262-page book featured the detailed diary of Henry's daughter Mary Anna Henry, kept from the years of 1855 to 1878 while living in the Smithsonian Castle. Throughout the diary, Henry is repeatedly mentioned by his daughter, who showed a keen affection to her father.
In June 1860, Lowe had made a successful test flight with his gigantic balloon, first named the City of New York and later renamed The Great Western, flying from Philadelphia to Medford, New York. Lowe would not be able to attempt a transatlantic flight until late Spring of the 1861, so Henry convinced him to take his balloon to a point more West and fly the balloon back to the eastern seaboard, an exercise that would keep his investors interested.
Lowe took several smaller balloons to Cincinnati, Ohio in March 1861. On 19 April, he launched on a fateful flight that landed him in Confederate South Carolina. With the Southern States seceding from the Union, during that winter and spring of 1861, and the onset of Civil War, Lowe abandoned further attempts at a trans-Atlantic crossing and, with Henry's endorsement, went to Washington, D.C. to offer his services as an aeronaut to the Federal government. Henry submitted a letter to U.S. Secretary of War at the time Simon Cameron of Pennsylvania which carried Henry's endorsement:
On Henry's recommendation Lowe went on to form the United States Army/"Union Army" Balloon Corps and served two years with the Army of the Potomac as a Civil War "Aeronaut".
On June 25, 1876, Bell's experimental telephone, using a different design, was demonstrated at the Centennial Exhibition in Philadelphia, where Henry was one of the judges for electrical exhibits. On 13 January 1877, Bell demonstrated his instruments to Henry at the Smithsonian Institution and Henry invited Bell to demonstrate them again that night at the Washington Philosophical Society. Henry praised "the value and astonishing character of Mr. Bell's discovery and invention." Alexander Graham Bell and the Conquest of Solitude, Robert V. Bruce, p. 214
Henry died on May 13, 1878, and was buried in Oak Hill Cemetery in the Georgetown section of northwest Washington, D.C. John Philip Sousa wrote the Transit of Venus March for the unveiling of the Joseph Henry statue in front of the Smithsonian Castle.
In 1915, Henry was inducted into the Hall of Fame for Great Americans in the Bronx, New York.
Bronze statues of Henry and Isaac Newton represent science 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 the 16 historical figures depicted in the reading room, each pair representing one of the 8 pillars of civilization.
In 1872, Almon Thompson named a mountain range in southeastern Utah after Henry. The Henry Mountains were the last mountain range to be added to the map of the 48 contiguous U.S. states.
At Princeton University, the Joseph Henry Laboratories and the Joseph Henry House are named for him.
After the Albany Academy moved out of its downtown building in the early 1930s, its old building in Academy Park was renamed Joseph Henry Memorial with a statue of him in front. It is now the main offices of the Albany City School District. In 1971, it was listed on the National Register of Historic Places; later it was included as a contributing property when the Lafayette Park Historic District was listed on the Register.
The school he attended in Galway, New York was renamed Joseph Henry Elementary School in his honor.
Washington, D.C. named a school, built in 1878–80, on P Street between 6th and 7th the Joseph Henry School; it was demolished at some point after 1932.
The Henry Mountains (Utah) had been so named by geologist Almon Thompson in his honor.
Mount Henry in California is named in his honor.
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