Joseph Henry was an American physicist and inventor who lived from December 17, 1797, to May 13, 1878. He worked as the first secretary of the Smithsonian Institution. Before that, he was the secretary of the National Institute for the Promotion of Science, which was an earlier version of the Smithsonian Institution. He also led the National Academy of Sciences from 1868 to 1878.

While making electromagnets, Henry discovered a scientific effect called self-inductance. He also found mutual inductance on his own, but Michael Faraday discovered and shared his findings first. Henry improved electromagnets so they could be used in real-world applications. He created a device that worked like an early electric doorbell, which could ring a bell from a distance using a wire (invented in 1831). He also made an electric relay in 1835. His work with the relay helped lead to the invention of the practical electrical telegraph, which was created separately by Samuel F. B. Morse and Sir Charles Wheatstone. In his honor, the standard unit of inductance is called the henry (symbol: H; plural: henries).

Early life and education

Henry was born in Albany, New York, to Ann Alexander Henry and William Henry, who were from Scotland. His parents were poor, and his father died when Henry was very young. For the rest of his childhood, Henry lived with his grandmother in Galway, New York. After school, he worked at a general store, and at thirteen, he became a helper in making watches and silver items. Joseph's first love was theater, and he almost became a professional actor. He became interested in science at sixteen after reading a book about science experiments titled Popular Lectures on Experimental Philosophy.

In 1819, he entered The Albany Academy, where he received free education. Even with free education, he was so poor that he worked as a teacher and tutor to earn money. He planned to become a doctor, but in 1824, he was chosen to help as an engineer on a project to build a road between the Hudson River and Lake Erie. From then on, he became interested in becoming a civil or mechanical engineer. Henry did well in school and often helped his teachers with science lessons.

Career

In 1826, he became a professor of Mathematics and Natural Philosophy at The Albany Academy, appointed by Principal T. Romeyn Beck. In this role, he conducted important research. His interest in Earth's magnetism led him to study magnetism more broadly. He was the first to tightly coil insulated wire around an iron core to create a stronger electromagnet. This improved upon William Sturgeon’s electromagnet, which used loosely coiled uninsulated wire. Using this method, he built the strongest electromagnet of his time for Yale. He also discovered that when making an electromagnet with two electrodes connected to a battery, winding several coils of wire in parallel was best. However, when using multiple batteries, a single long coil worked better. This discovery made the telegraph possible. Although some historians believe Henry made discoveries before Faraday and Hertz, he is not credited because he did not publish his work.

In 1831, Henry created one of the first machines that used electromagnetism to produce motion. This was an early version of a modern DC motor. It did not rotate but rocked back and forth. The motion happened when the magnet’s leads touched battery cells, causing a change in polarity and rocking the magnet in the opposite direction until the other leads touched the other battery. This experiment helped Henry discover self inductance, a property also found by Michael Faraday around the same time. Faraday received credit for this discovery because he published his findings first.

From 1832 to 1846, Henry was the first Chair of Natural History at the College of New Jersey, now Princeton University. At Princeton, he taught natural history, chemistry, and architecture, and ran a laboratory. He later wrote that he conducted thousands of experiments on electricity, magnetism, and electromagnetism while teaching there. He relied on an African American research assistant named Sam Parker, who was hired by Princeton trustees. Parker helped with experiments, fixed equipment, and sometimes participated in classroom demonstrations. When Parker fell ill in 1842, Henry stopped all experiments until Parker recovered.

In 1846, Henry became the first Secretary of the Smithsonian Institution, a role he held until 1878. In 1848, he worked with Professor Stephen Alexander to study the temperature of different parts of the sun using a thermopile. They found that sunspots are cooler than the surrounding areas. This work was shared with astronomer Angelo Secchi, who expanded on it, though some questioned whether Henry received proper credit.

During the American Civil War, Henry organized lectures by prominent abolitionists at the Smithsonian. Speakers included Wendell Phillips, Horace Greeley, Henry Ward Beecher, and Ralph Waldo Emerson. Frederick Douglass was scheduled to speak but Henry refused to let him attend, saying, "I would not let the lecture of the coloured man be given in the rooms of the Smithsonian."

In 2014, a book titled The Civil War Out My Window: Diary of Mary Henry was published. It included the diary of Henry’s daughter, Mary Anna Henry, who wrote about her father from 1855 to 1878. She often mentioned her father with affection.

Henry met Thaddeus Lowe, a balloonist interested in lighter-than-air gases and weather patterns, including the Jet stream. Lowe planned a transatlantic flight using a large balloon. Henry supported Lowe’s efforts and introduced him to scientists and institutions. In 1860, Lowe successfully tested his balloon, named The Great Western, flying from Philadelphia to New York. Henry encouraged Lowe to move west to keep investors interested before attempting a transatlantic flight.

In 1861, Lowe launched a flight that landed in Confederate territory. With the start of the Civil War, Lowe abandoned his plans and, with Henry’s support, offered his services to the U.S. government. Henry wrote a letter to the U.S. Secretary of War recommending Lowe. Lowe later formed the Union Army Balloon Corps and served with the Army of the Potomac.

In 1866, Henry was elected vice president of the National Academy of Sciences and became president in 1868. He intended to resign in 1873 but was prevented by a letter from academy members. He remained president until his death in 1878. After his death, the academy created the Joseph Henry Fund in his honor.

As a respected scientist and director of the Smithsonian, Henry advised many visitors, including Alexander Graham Bell. In 1875, Bell brought a letter of introduction to Henry and demonstrated his experimental equipment. Bell shared an idea for transmitting speech using a "harp apparatus" with tuned steel reeds. Henry called it "the germ of a great invention" and advised Bell not to publish until he perfected it. Bell later demonstrated his telephone at the Centennial Exhibition in 1876, where Henry judged electrical exhibits. In 1877, Bell showed his invention to Henry at the Smithsonian, and Henry praised its value and importance.

Legacy

Henry was a member of the United States Lighthouse Board from 1852 until his death. In 1871, he was appointed chairman and served in that role for the rest of his life. He was the only civilian to hold the position of chairman. The United States Coast Guard honored Henry for his work on lighthouses and fog signal acoustics by naming a cutter after him. The Joseph Henry, often called the Joe Henry, was launched in 1880 and remained in service until 1904.

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 are displayed on the balustrade of the Main Reading Room in the Thomas Jefferson Building of the Library of Congress in Washington, D.C. These statues represent science and are part of a group of 16 historical figures depicted in the reading room. Each pair of statues symbolizes one of the eight pillars of civilization.

In 1872, Almon Thompson named a mountain range in southeastern Utah after Henry. The Henry Mountains were the last mountain range 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 in his honor.

After the Albany Academy moved from its downtown building in the early 1930s, its old building in Academy Park was renamed Joseph Henry Memorial. A statue of Henry was placed in front of the building. It is now the main offices of the Albany City School District. In 1971, the building was listed on the National Register of Historic Places. Later, it was included as a contributing property when the Lafayette Park Historic District was added to the Register.

Curriculum vitae

• 1826 – Taught math and science at The Albany Academy in New York.
• 1832 – Led the Natural History department at Princeton University (then called the College of New Jersey) until 1846.
• 1835 – Created the electromechanical relay.
• 1846 – Became the first secretary of the Smithsonian Institution and held the role until 1878.
• 1848 – Helped edit Ancient Monuments of the Mississippi Valley, the Smithsonian Institution’s first published work.
• 1852 – Was appointed to the Lighthouse Board.
• 1871 – Was chosen as chairman of the Lighthouse Board.

Other honors

Joseph Henry was elected as a member of the American Philosophical Society in 1835 and the American Antiquarian Society in 1851. The school he attended in Galway, New York, was later renamed Joseph Henry Elementary School in his honor. In Washington, D.C., a school built between 1878 and 1880 on P Street between 6th and 7th Streets was named Joseph Henry School. This school was demolished sometime after 1932. The Henry Mountains in Utah were named by geologist Almon Thompson in Joseph Henry’s honor. Additionally, Mount Henry in California is named in his honor.

Taxon named in his honor

Isichthys henryi is a freshwater ray-finned fish that is part of the Mormyridae family, which is known as the elephantfishes.