Joseph Henry
Born Albany, NY Dec. 17, 1797
Died in Washington, DC May 14, 1878

Joseph Henry, the leading American scientist after Benjamin Franklin until Willard Gibbs, was a professor at Princeton from 1832 to 1846. His chief scientific contributions were in the field of electromagnetism, where he discovered the phenomenon of self-inductance. The unit of inductance, called "the henry", immortalizes his name. Henry is also remembered as the first Secretary of the Smithsonian Institution, where he made extraordinary contributions to the organization and development of American science.

Joseph Henry Chronology
December 17. Born in Albany, New York to Ann Alexander Henry and William Henry
Moved to Galway, NY, and attended the school later named the Joseph Henry Elementary School in Galway
Elected President of the Rostrum (theatrical society) 
Attends the Albany Academy
Professor of Mathematics and Natural Philosophy at the Albany Academy
Begins research in electromagnetism
Became Librarian of the Albany Institute
Awarded an Honorary A.M. from Union College
May 3. Marries Harriet Alexander (1808-1882)
Publishes seminal paper on electromagnetism in January issue of Silliman's Journal; publishes paper on electric motor in July issue of Silliman's Journal; demonstrates prototype telegraph
Professor of Natural Philosophy at the College of New Jersey (later Princeton University)
First Secretary of the Smithsonian Institution
Establishes Smithsonian meteorological observer network
President of the American Association for the Advancement of Science
Awarded an Honorary LL.D. from Harvard
Member of the United States Light-House Board
President of the National Academy of Sciences
Chairman of the United States Light-House Board
Elected President of the Philosophical Society of Washington, DC
May 13. Dies in Washington, DC

Joseph Henry was born to Scottish immigrants in Albany, New York in the 1799. Henry’s father,William Henry (1764-1811), a day-labore, died when Joseph was eight and financial circumstances forced his mother, Ann Alexander Henry (1760-1835), to send Henry to live with his grandmother in Galway, New York, a village about 40 miles from Albany. There he worked in a general store after school hours and at the age of thirteen was apprenticed to a watchmaker. As a young man he became interested in the theater and was offered employment as a professional actor, but in 1819 several well-positioned Albany friends persuaded him instead to attend the Albany Academy, where free tuition was provided.

At fourteen he moved back to Albany to work a day job and attend night school at the Albany Academy, a boys' school. His friends there considered him an actor, playwright, showman and orator. Slowly, however, his interests shifted and he began reading textbooks on mathematics, philosophy, astronomy and chemistry, most of which were authored by English scientists and philosophers. He read novels after gaining access to the church library through a hole in the floor. The book that most impressed him in life, however, was not fiction but George Gregory's Popular Lectures on Experimental Philosophy, Astronomy, and Chemistry. Years later, giving a copy of the book to his only son, Henry wrote on the fly-leaf, "This... opened to me a new world of thought and enjoyment; fixed my attention upon the study of nature, and caused me to resolve at the time of reading it that I would immediately devote myself to the acquisition of knowledge." Henry found himself in the awkward position of having access to the understandings developed by the world’s top researchers, but lacking the materials to recreate or further their experiments. However, as Henry’s career progressed, these limitations would spur him to make new discoveries.

He supported himself for a time as a kind of circuit-riding grammarian and schoolteacher, earning $8 a week by tutoring the children of well-to-do families. He taught the elder Henry James, religious writer and the father of William James, the philosopher, and Henry James, the novelist. Henry's early career also included surveying. One summer, he headed a party assigned to establish the route of the proposed Great Road in New York State. Ironically, he was denied an appointment with the Corps of Topographical Engineers of the United States Army, a unit that would someday well serve the purposes of his Smithsonian.

Stained glass window in Albany's First Presbyterian Church memoralizing site of Joseph Henry's baptism. The window's ennobling iconography - a beatific Henry instructing twelve disciples at the Albany Academy - is reinforced by captions at bottom of left and right panels: Master Scientist and Devout Christian. First Presbyterian Church.

After graduating from Albany Academy, Henry spent several years working as a district schoolteacher and as a private tutor, then a canal surveyor, and eventually as an engineer for canal construction. In 1826, when Albany Academy offered him the chair of Mathematics and Natural Philosophy, he accepted without question. Here, in spite of a teaching schedule that occupied him seven hours a day, he did his most important scientific experiments. Henry had become interested in terrestrial magnetism, which was then, as today, an important scientific topic. This led him to experiment with electromagnetism. His apprenticeship as a watchmaker stood him in good stead in the construction of batteries and other apparatus.

Henry as a young man, ca. 1829.
From miniature attributed to Julius
Rubens (Smithsonian Institute)

Shortly before he began his new position at the academy Henry went to New York, where he first saw an electromagnet made by William Sturgeon. Back at Albany Academy, Henry wanted to build his own magnet but his lecture schedule and a lack of laboratory equipment made it impossible. Experimental work had to wait until summer vacations, and then could be performed only on a very limited budget. In this regard, the single greatest limitation for Henry was the large, expensive galvanic batteries needed for the electrical experiments. The batteries required large zinc and copper plates, which were rare and very costly, especially in a city as remote as Albany. Working with a much smaller battery than his European counterparts, Henry insulated the copper wire with silk ribbon and wound 540 feet in nine coils of 60 feet each. He then let the current run through the various lengths of wire and recorded the amount of weight the battery could hold.


Sketch of "telegraph" Henry showed
his classes at the Albany Academy in 1831

Oersted and others had observed magnetic effects from electric currents, but Henry was the first to wind insulated wires around an iron core to obtain powerful electromagnets. Henry used his powerful new electro-magnetic devices as pedagogical tools in the classroom. Larger, more powerful magnets, meant larger, more visible demonstrations for his ever-growing classrooms. One fall, when the students returned from the summer break, they found that Henry had strung a mile of wire around and around the inside of the Albany lecture hall. At one of the wire he attached a small electro-magnet with an armature that sat poised and inch or so from a small bell. At the other he stood ready to attach the wire to his battery. Giving the signal for silence, he connected the end of the wire to the battery and the little bell rang. Connecting and disconnecting the wire led to a series of ringing signals from the bell.


Prof. Henry's "Big Magnet"

Before he left Albany, he built one for Yale that would lift 2,300 pounds, the largest in the world at that time. In experimenting with such magnets, Henry observed the large spark that was generated when the circuit was broken, and he deduced the property known as self-inductance, the inertial characteristic of an electric circuit. The self-inductance of a circuit tends to prevent the current from changing; if a current is flowing, self-inductance tends to keep it flowing, or if an electromotive force is applied self-inductance tends to keep it from building up. Henry found that the self-inductance is greatly affected by the configuration of the circuit, especially the coiling of the wire. He also discovered how to make non-inductive windings by folding the wire back on itself. While Henry was doing these experiments, Michael Faraday did similar work in England. Henry was always slow in publishing his results, and he was unaware of Faraday's work. Today Faraday is recognized as the discoverer of mutual inductance (the basis of transformers), while Henry is credited with the discovery of self-inductance.

This picture shows some of Henry's experimental apparatus, including magnets, a battery, relay switches, and insulated coils.


Henry's Yale magnet

Sketch of One of Henry's Magnets from Smithsonian Annual Report, 1857


Henry's oscillating electromagnet motor

In the summer of 1831 Henry described the first of these applications in a short paper, "On a Reciprocating Motion Produced by Magnetic Attraction and Repulsion." It was a simple device whose moving part was a straight electromagnet rocking on a horizontal axis. Its polarity was reversed automatically by its motion as two pairs of wires projecting from its ends made connections alternately with two electrochemical cells. Two vertical permanent magnets alternately attracted and repelled the ends of the electromagnet, making it rock back and forth at 75 vibrations per minute.

Henry at this time considered his little machine merely a "philosophical toy," but nevertheless believed it was important as the first demonstration of continuous motion produced by magnetic attraction and repulsion. Furthermore, "in the progress of discovery and invention, it is not impossible that the same principle, or some modification of it on a more extended scale, may hereafter be applied to some useful purpose." Indeed, one authority has stated, "Henry's apparatus was the first clear-cut instance of a motor capable of further mechanical development. It had the essentials of a modern DC motor: a magnet to provide the field, an electromagnet as armature, and a commutator to apply the mechanical forces at the right time." Other inventors did later develop motors of various designs based on similar reciprocating actions, but it is not clear whether these inventors knew of Henry's device, or created theirs independently. In any case, reciprocating motors never became commercially successful; continuous rotary motion proved to be a more efficient and useful principle.

Today, the commercial applications for Henry’s electromagnetic experiments seem obvious. Eventually, inventors would use the electro-magnet as the basis for the telegraph, the electric motor, and the dynamo. Henry claimed that he did not pursue practical applications for the electro-magnet because:

"I freely renounced all right to the invention as I consider the machine in the present state of the science a philosophical toy."

Later in his life, when asked why he didn’t patent the electromagnet, Henry replied:

"I did not then consider it compatible with the dignity of science to confine the benefits which might be derived from it to the exclusive use of any individual."

These claims have long been heralded by biographers as the mantra of a "pure scientist." However, more recent biographies have pointed out that Henry had actively pursued a relationship with entrepreneurs regarding a way to use the electro-magnet to extract iron from crushed ore. As Albert Moyer pointed out, "To be sure, [Henry] did not share the common belief that natural philosophy was above payment and patents."


In 1832, when Henry was 35, Yale's distinguished geologist Benjamin Silliman was consulted regarding the possible appointment of Henry to Princeton. Silliman replied, "As a physical philosopher he has no superior in our country; certainly not among the young men.'' Henry, always modest, had responded to tentative inquiries, "Are you aware of the fact that I am not a graduate of any college and that I am principally self-educated?''

Princeton University

In the early 1830s Princeton University offered Henry the chair of natural philosophy, which Henry accepted. The Princeton professorship offered a much lighter teaching assignment and a slightly better financial arrangement than he had in Albany, plus the prestige of one of America’s premier universities. For over 15 years, Henry continued to pursue research in natural philosophy at Princeton. Henry was both a leading researcher and an experienced teacher, having taught at the Albany Academy in New York for six years and at the College of New Jersey (now Princeton University) for almost 14 years. About half of the 1,000 or so students taught by Henry became doctors, lawyers, ministers, college professors, or senior government officials. Among the rest were businessmen, teachers, and mid-level government workers.

Henry's initial salary at Princeton was $1,000 per annum plus a house. The Trustees also provided $100 for the purchase of a new electrical machine. At that point the College was near bankruptcy and Maclean was trying to institute reforms and build up the faculty. Henry was a notable acquisition, and he found the lighter teaching schedule and the intellectual companionship at Princeton congenial, especially when his brother-in-law Stephen Alexander joined the faculty to teach astronomy. Henry worked with Alexander in the observation of sunspots and continued his own work on magnets, building for Princeton an even larger magnet than he had built for Yale, one that would lift 3,500 pounds. He also rigged two long wires, one in front of Nassau Hall and one behind, so that he was able to send a signal by induction through the building. Another wire from his laboratory in Philosophical Hall to his home on the campus was used to send signals to his wife; this signal system used a remote electromagnet to close a switch for a stronger local circuit, and constituted in effect the invention of the magnetic relay. A similar arrangement was used by S.F.B. Morse in the invention of the telegraph; Morse had consulted Henry and had used one of his scientific papers. Later, Henry was called to testify in a patent suit involving the telegraph, Morse vs. O'Reilly. Although Henry had encouraged and helped Morse in his project, his testimony that the principle of the telegraph had been known to himself and to Professor Wheatstone in England undermined Morse's claim to originality. This led to much unpleasantness and controversy, but Henry's reputation emerged unscathed.
Henry's house at the Princeton University:

Bedroom in the Henry apartments
by Thomas W. Smillie, ca. 1878

Interior of Joseph Henry's living room,
east wing of the original Castle

In addition to natural philosophy (physics), Henry taught chemistry, geology, mineralogy, astronomy, and architecture -- in the words of Frederick Seitz, Ph.D. '34, former president of the National Academy of Sciences, he was "a very large economy package.'' A rather reserved and quiet man, he was nevertheless a popular teacher. The College gave Henry an opportunity, then unusual, to travel abroad on leave at full salary. In 1837 he met Faraday, Wheatstone, and other British scientists, to whom he explained his idea of "quantity" and "intensity" circuits (low and high impedance, in modern terms). He returned to Princeton with a variety of scientific equipment purchased abroad.

Nassau Hall, at the College of New Jersey,
where Henry taught physics from 1832 to 1846

By all accounts, whether in contemporary letters and diaries or in later reminiscences, Henry was an outstanding teacher, beloved and respected by his students for his knowledge, sense of humor, and willingness to discuss issues outside the curriculum. A former student wrote to Henry: "Until I came under your direction I cannot recollect of ever having possessed an idea-- This is no exaggeration, but my serious opinion - I mean that I had never once thought for myself on any one subject." Henry had, in the words of Asa Gray, a botanist at Harvard and Henry's contemporary, "a genius for education." Henry often said he did not want to teach his students "the mere facts of natural philosophy." What he wanted his students to take away with them when they graduated was a way of thinking and learning that would be applicable in the wider world. They had to be able to distinguish between mere knowledge - "the acquiantance [sic] with facts" - and wisdom, which was "the application of principles."

"A knowledge of general principles gives a man an immense advantage over his less perfectly educated neighbour or competitor," Henry asserted. He reminded his students this was true in "Theology Law or Medicine or in any subject to which you may turn your attention."

Reflecting on his own experience in integrating research and teaching, Henry insisted that the best college professors were researchers. He argued that when selecting professors, a college should give "the preference to a person who has made some advance in the way of original research." Henry was well aware of the shortage of researchers in the United States around 1846. By supporting research, the Smithsonian was also upgrading the quality of college science teaching.

Henry supported educational reform in other ways. He served as first president of the Columbian Association of Teachers, which was organized at the Smithsonian in December 1849 at his suggestion. This local society aimed "to elevate the character of [the teaching] profession, and secure...that rank in society to which...[teachers] were entitled."

Henry was elected first vice president of the Friends of Public Education in 1850. Two years later, he was elected president of the American Association for the Advancement of Education, which was a successor to the Friends of Public Education. The association mainly appealed to public school administrators, who were interested in such questions as school districting, school architecture, teacher qualifications, grade levels, methods of instruction, and taxation policies. The overt purpose of the association, a precursor of the National Education Association, was to formulate national standards for public education.

Henry took advantage of the forums provided by this national education reform movement to argue for the importance of using researchers as educators. In 1854, in addressing the annual meeting of the American Association for the Advancement of Education, he argued that researchers made the best textbook writers, whatever the level of instruction:

But few persons can devote themselves so exclusively to abstract science as fully to master its higher generalizations, and it is only such persons who are properly qualified to prepare the necessary books for the instruction of the many. I cannot for a moment subscribe to the opinion which is sometimes advanced that superficial men are best calculated to prepare popular works on any branch of knowledge. It is true that some persons have apparently the art of simplifying scientific principles; but in the great majority of cases this simplification consists in omitting all that is difficult of comprehension. There is no task more responsible than that of the preparation of an elementary book for the instruction of the community. Henry went on to assert that "it should be our object to bring more into repute profound learning and to counteract the tendency to the exclusive diffusion of popular and mere superficial knowledge."

In Henry's world view, support of basic research resulted in superior teaching, superior textbooks, and superior popular expositions of science. In turn, this served to better equip young men and women to pursue their life's work, whether in law, medicine, the ministry, or any other field of endeavor. Henry believed that by serving the research community, the Smithsonian served a larger public.

The scene at left is from a mural painted by Gifford Beal (Princeton class of 1900) in 1946, for the bicentennial of Princeton's founding. The mural, located in the lobby of the John C. Green School of Engineering, depicts Henry demonstrating electrical phenomena. The backdrop is Princeton's Philosophical Hall, where Henry taught and performed many electrical experiments, including telegraphic ones.


During his remaining years in Princeton Henry continued his electrical investigations, but also branched out into the study of phosphorescence, sound, capillary action, and ballistics. In 1844 he was a member of a committee to investigate the explosion of a gun during a demonstration on the new U.S.S. Princeton; the Secretaries of State and Navy and several congressmen were among the spectators killed. His experiments on gun castings on this committee led him into the subject of the molecular cohesion of matter.

Joseph Henry was important to the history of the telegraph in two ways. First, he was responsible for major discoveries in electromagnetism, most significantly the means of constructing electromagnets that were powerful enough to transform electrical energy into useful mechanical work at a distance. Much of Morse's telegraph did indeed rest upon Henry's discovery of the principles underlying the operation of such electromagnets. Secondly, Henry became an unwilling participant in the protracted litigation over the scope and validity of Morse's patents. Between 1849 and 1852 the defendants in three infringement suits subpoenaed Henry in the hopes that his statements would weaken or invalidate Morse's claims, and his testimony proved crucial to the Supreme Court's 1854 split decision that struck down Morse's broadest claim.4 Because of Henry's involvement in these suits, the two men engaged in a bitter dispute over issues of scientific and technological priority, a conflict that continued until their deaths in the 1870s. As petty and mean-spirited as this conflict was, it nevertheless revealed much about their differing attitudes concerning the relative importance of the work of scientists and inventors in the middle third of the nineteenth century.

Daguerreotype of Henry, probably early 1840s
National Museum of American History

Daguerreotype of Henry, late 1840s
National Museum of American History

The first Smithsonian Secretary

In 1846, having received from an Englishman, James Smithson, a large bequest for the founding of an institution "for the increase and diffusion of knowledge among men," the U.S. Congress established the Smithsonian Institution. A distinguished board was appointed, with instructions to find the best possible man to head the new Institution as secretary, and the invitation was soon extended to Henry. He was reluctant to leave Princeton and the opportunity to do his own scientific investigations. "If I go," he said to a friend, "I shall probably exchange permanent fame for transient reputation." But he finally accepted and threw his enormous energy and knowledge and experience into the development of the Smithsonian, which became the first great driving force in the organization and direction of American science.

When Joseph Henry accepted the position as Secretary of the Smithsonian on December 7, 1846, he was the foremost experimental physicist in the United States. The responsibilities of his new post, however, would require a great personal sacrifice. Never again would Henry have enough time to pursue his own research agenda.

Although Henry never ceased thinking of himself as a research scientist and educator, after becoming Secretary his chief roles were those of science administrator and adviser to presidents, vice presidents, cabinet secretaries, and members of Congress on all aspects of science and technology. When Henry entered the laboratory, he no longer pursued basic research or followed up a random observation that struck his curiosity. As a member of various government boards and commissions, Henry now devoted himself to applied research.

As an adviser, Henry had tremendous influence. His correspondence demonstrates that the careers of individual scientists, the livelihoods of inventors, and the future of certain government scientific activities came to depend in part upon his support and his ability to sway members of Congress or cabinet members. Such was his reputation that, according to Henry, one secretary of the interior assured him that "if the request was . . . backed by myself that would be sufficient!"

The nation came to depend on his expertise in a number of areas. For the United States Capitol Building, for example, he was called upon by the vice-president and various cabinet secretaries to provide advice on the vulnerability of the Capitol dome to lightning; to evaluate the plans of Montgomery C. Meigs for the acoustics, heating, and ventilation of the new chamber of the House of Representatives; and to test samples of marble for the Capitol extension.

Henry devoted even more time to the country's system of lighthouses. In 1852, he was appointed by President Millard Fillmore as one of the six members of the United States Light-House Board. Henry remained on the board for the next twenty-five years, serving as chairman for the last six years of his life. Thus, he had a role in the oversight of a government science-technology activity with an annual budget of more than $500,000 in 1852, or sixteen times the Smithsonian annual budget at the time.

The United States Light-House Board was responsible for the construction and repair of lighthouses; the establishment of procedures; and the procurement of personnel, supplies, and equipment. Henry took charge of its experimental and testing activities. After his death it was estimated that, in addition to attending board meetings, he generally spent from six to eight weeks each year working full-time for the board during his vacations from the Smithsonian. He helped make the board into a center for applied research in optics, thermodynamics, and acoustics.

Henry served the nation in another capacity during the Civil War. Inventors overwhelmed the government with suggestions for various kinds of military technology at a time when there was no mechanism for screening and evaluating the proposals. Henry, to whom the military referred many of these, suggested the establishment of what became known as the Permanent Commission of the Navy Department.

Henry served on the three-member commission from its inception in early 1863, and the group met as often as three times a week, often in the Castle, to evaluate a steady stream of proposals for warship designs, underwater guns, torpedoes, and the like. Henry wrote former President Fillmore after the war that the commission saved the government "from rushing into many schemes which, under the guise of patriotism, were intended to advance individual interest."
Painting by Albert Herter in 1924, depicting President Abraham
Lincoln signing the Charter of the Academy of Sciences in 1863.
Henry is third from left, with Bache to his left.

The National Academy of Sciences was also established in the spring of 1863 to offer scientific advice to the government. Henry was one of its fifty incorporators. When his dear friend and first president of the academy, Alexander Dallas Bache, died in 1867, Henry, who had been acting president of the academy during Bache's illness, agreed to serve as president. Until his death in 1878, he was concurrently Secretary of the Smithsonian Institution and president of the National Academy of Sciences, as was Charles Doolittle Walcott, the Smithsonian's fourth Secretary, some fifty years later.

Father of Weather Service

Joseph Henry helped shape the world we know when he laid the foundation of a national weather service shortly after becoming the Smithsonian's first Secretary.

Henry's interest in meteorology dated to his days as a professor at the Albany Academy in Albany, New York, where he compiled reports of statewide meteorological observations for the University of the State of New York. As a professor of natural philosophy (physics) at the College of New Jersey (Princeton), he conducted research on lightning and engaged in discussions with pioneer meteorologists both in the United States and Britain about storm patterns and atmospheric physics.

When Henry came to the Smithsonian, one of his first priorities was to set up a meteorological program. In 1847, while outlining his plan for the new institution, Henry called for "a system of extended meteorological observations for solving the problem of American storms." By 1849, he had budgeted $1,000 for the Smithsonian meteorological project and established a network of some 150 volunteer weather observers. A decade later, the project had more than 600 volunteer observers, including people in Canada, Mexico, Latin America, and the Caribbean. Its cost in 1860 was $4,400, or thirty percent of the Smithsonian's research and publication budget.

The Smithsonian supplied volunteers with instructions, standardized forms, and, in some cases, with instruments. They submitted monthly reports that included several observations per day of temperature, barometric pressure, humidity, wind and cloud conditions, and precipitation amounts. They also were asked to comment on "casual phenomena," such as thunderstorms, hurricanes, tornadoes, earthquakes, meteors, and auroras.

Enlisting enthusiastic volunteers proved less of a problem than interpreting their observations. In 1856, Henry contracted with James H. Coffin, a professor of mathematics and natural philosophy at Lafayette College in Easton, Pennsylvania, to carry out this task. Coffin, who received as many as half-a-million separate observations in a year, complained that some contained "new-coined characters & hieroglyphics" that made them unintelligible. He also had to employ up to fifteen human "computers" to help make the necessary arithmetical calculations. In 1861, he finally published the first of a two- volume compilation of climatic data and storm observations based on the volunteers' reports for the years 1854 through 1859.

A second aspect of Henry's meteorological project was weather telegraphy. Early on, Henry foresaw the storm-warning potential of the telegraph, an invention he had pioneered himself in the 1830s and that Samuel Morse had made commercially feasible by 1845. Realizing that storms in the United States generally moved from west to east, he wrote in the Smithsonian's 1847 annual report that "the extended lines of telegraph will furnish a ready means of warning the more northern and eastern observers to be on the watch for the first appearance of an advancing storm."

By 1849, Henry worked out an arrangement with a number of telegraph companies to allow free transmission of local weather data to the Smithsonian. He also proposed to supply "the most important stations" with barometers and thermometers. By 1857, telegraph stations from New Orleans to New York were cooperating.

These dispatches enabled Henry to devise a large daily weather map. Its purpose, Henry wrote, was "to show at one view the meteorological condition of the atmosphere over the whole country."
Louise Rochon Hoover's painting, "Secretary
Henry Posts Daily Weather Map in Smithsonian
Building, 1858." Commissioned for the
Smithsonian exhibition at the Chicago Century of
Progress Exhibition in 1933.

The map, which Henry mounted in 1856 for public display in the Castle, was dotted with colored discs. As telegraph reports came in each morning, an assistant placed white discs in locations with fair weather, blue ones where snow fell, black where there was rain, and brown where conditions were cloudy. Arrows on the discs showed the direction of prevailing winds. The map became a popular attraction. Henry noted that tourists who viewed it "all appear to be specially interested in knowing the condition of weather to which their friends at home are subjected at the time." He shared the telegraph dispatches with the Washington Evening Star, which, in May 1857, began publishing daily weather conditions at nearly twenty different cities. Henry thus helped give rise to the popular newspaper weather page. Henry's map also made some forecasting possible. "If a black card is seen in the morning on the station at Cincinnati, indicating rain at that city," he noted, "a rain storm may confidently be expected at Washington at about seven o'clock in the evening." This rule-of-thumb proved reliable enough for Henry to postpone evening lectures at the Smithsonian on days Cincinnati had morning rain.

Henry apparently envisioned a system of storm warnings, announcing in his annual report for 1857 that he hoped the following year to arrange with telegraph lines "to give warning on the eastern coast of the approach of storms." But he was not able to implement the plan before the Civil War engulfed the nation.

The war dealt a major blow to the meteorological project. Henry wrote in 1861 that the project "suffered more from the disturbed condition of the country than any other part of the operations of the Smithsonian establishment." Urgent public business forced weather information off the telegraph lines, and secession cut Henry off from his southern observers. Although he was able to revive the project after the war, Henry began taking steps to transfer its operations to the federal government.

Joseph Henry, by Matthew Brady, ca. 1862

Joseph Henry, by Matthew Brady, ca. 1862

In his annual report for 1865, Henry called for the federal government to establish a national weather service capable of issuing storm warnings and other weather predictions. Others urged similar proposals, and in 1870 Congress passed a bill that put storm and weather predictions in the hands of the U.S. Army's Signal Service. By 1874, Henry convinced the Signal Service to take over the volunteer observer system as well.

Henry, ca. 1875. From engraving by G. R. Hall,
possibly after a photograph by T. W. Smilie

Painting by Henry Ulke, 1875,
National Portrait Gallery.

The weather functions of the Signal Service were transferred in 1891 to the newly established U.S. Weather Bureau, which later became the National Weather Service. That service today, as David Laskin puts it in his 1996 book Braving the Elements: The Stormy History of American Weather, "still adheres to the same fundamental structure and principles that Joseph Henry devised and set in motion."

Smithsonian Secretary Joseph Henry enjoys a relaxed moment on the Mall around 1865
with his wife, Harriet, and their three daughters, Mary, Helen Louisa, and Caroline

Mary Henry, oldest daughter

Henry's motivations and morality

In his research on electricity and magnetism, Henry achieved and sustained the high respect of especially those American and foreign colleagues with whom he had close personal relationships. He never, however, progressed to the point of winning top recognition among more impersonal, elite segments of the broader, international scientific community. Indeed, Henry's published research record, although notable, was patchy. He often failed to report his findings promptly and in widely accessible outlets. Moreover, he often failed to grasp--or, at least, to report--the fuller import of his laboratory gleanings; his pattern was to focus undividedly on a line of investigation only after another researcher announced results involving a similar or identical line.

Unquestionably, in personal temperament Henry displayed a fervent commitment to duty, service, and self-sacrifice. In accepting the secretaryship of the Smithsonian in late 1846, for example, he downplayed the prestige of his new station and repudiated any implication of personal or even professional fulfillment. Instead, insisting that he had made no effort to obtain the post, he voiced an altruistic rationale for conceding to others' calls to serve as Secretary. He had accepted, he maintained, out of duty to the nation and to science.

This high-minded rationale, with its connotation of self-sacrifice and moral obligation, contrasts sharply, however, with a set of baser issues that Henry repeatedly raised in his more intimate correspondence with friends and relatives--issues of salary and recognition. He told his brother that he would not entertain the suggestion of moving from Princeton to Washington unless the salary were generous; he also said that, if award of the secretaryship were dependent on scientific reputation, then he was undoubtedly entitled to the situation. The rationale of dutifully acquiescing to the secretaryship also contrasted with Henry's earlier hints to colleagues about his discontent with existing levels of reward and recognition as a Princeton professor. Nevertheless, he consistently cited duty, rather than self-fulfillment, as his motive for accepting the post.

As his letters and other writings clearly show, Henry believed the rationale--believed that he was selflessly fulfilling a moral obligation. For decades, he had been placing duty and altruism at the core of his personal value system. This stance was an expression of, however, not merely his innate temperament or American culture's prevailing republican and Protestant values. The stance also had psychological shadings traceable to childhood traumas.

The traumas, which Henry kept hushed most of his adult life, arose from a tragedy in his working-class family: his father's alcoholism and death due to delirium tremens. Henry emerged from a troubled youth with a deep need for approval and affirmation. But he masked public expressions of this egocentric side of his personality. Instead, he imposed on himself a regimen of service to others. Cloaking his personal desires, he consistently invoked what he perceived to be his moral duty as his motive for following a particular course of action--whether in professional or personal endeavors.

Joseph Henry
by Walter Ingalls, oil on canvas, ca. 1872
Smithsonian Museum

Henry's years of service as science adviser, as much as his own pioneering research, make fitting the headline in the New York Times upon his death, "A Loss to All the Nation." At Henry's memorial service, held in the Capitol on January 16, 1879, congressional Regent (and later President of the United States) James A. Garfield acknowledged that Henry's move to Washington, D.C., was a loss to research. But he reminded his audience that "the Republic has the right to call on all her children for service. It was needful that the Government should have, here at its capital, a great, luminous-minded, pure-hearted man, to serve as its counselor and friend in matters of science."

Things named after Henry to honor and to remember him

Over the years, people have honored Joseph Henry by naming a variety of things after him, including a laboratory, a professorial chair, ships, and even a mountain range. Note that the naming began during Henry's own lifetime.

Henry medal

After hearing of Henry's death in May 1878, William Barber, engraver of the U.S. mint, offered to design this medal in honor of Henry. He and his son Charles completed the design the following year and donated the medal to the Smithsonian Institution for "any application that afterwards suggested." Henry's birth date is mistakenly given as 1799, rather than 1797, due to confusion over Henry's age. On the back of the medal is a Latin inscription taken from the Odes of Horace, Book 1, Ode 24: "Incorrupta Fides Nudaque Veritas Quando Ullum Inveniet Parem." The lines from which this inscription is excerpted read, according to one modern translation, "Where then will Justice, and Faith, the sister of Justice, and Decency, and Truth that needs no ornament, find his equal?" In January 1967, the Smithsonian's Board of Regents proposed to use the Henry medal to recognize distinguished service to the institution. Since that time, recipients of the medal have included a Smithsonian secretary, Charles Abbot, an astrophysicist, Fred Whipple, an anthropologist, T. Dale Stewart, and a U.S. vice-president and Smithsonian regent, Hubert H. Humphrey. In 1997, on the occasion of the bicentennial of Henry's birth, the medal was awarded to physicist Frederick Seitz, a long-time supporter of the Henry Papers Project and chair of its advisory committee.

Delegates to the congress; Mascart, at center in
light colors, proposed the "henry."

In August 1893, an International Congress of Electricians met in Chicago during the World's Columbian Exposition. Scientists and engineers at the congress adopted names and agreed on definitions for eight units of electrical measure: the ohm, the ampere, the volt, the coulomb, the farad, the joule, the watt, and the henry. The motion to adopt the henry, the only unit named after an American, came from the leader of the French delegation, physicist Éleuthère Élie Nicolas Mascart. The henry was defined as "the induction in a circuit when the electro-motive force induced in this circuit is one international volt, while the inducing current varies at the rate of one ampère per second."

In 1872, John C. Green, founder of the School of Science at Princeton, endowed a chair of physics in Henry's honor (held since then by C. F. Brackett, W. F. Magie, E. P. Adams, H. D. Smyth, and J. A. Wheeler). Almost a century later, when the main physics building, Jadwin Hall, was dedicated in 1970, the Physics Department manifested its continuing esteem for Henry by declaring that all of the laboratory facilities housed in Jadwin and Palmer Halls and the Elementary Particles Laboratory should be collectively known as the Joseph Henry Laboratories. Some of Henry's laboratory equipment is on display in the lobby of Jadwin Hall. His campus home, built to his design, is called the Joseph Henry House.

The statue of Joseph Henry in front of the Smithsonian Castle, Washington, D.C., was unveiled late on the sunny afternoon of April 19, 1883, five years after Henry's death.

You can read some original Henry's papers available in the Internet: