Joseph Henry: Wikis


Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.


From Wikipedia, the free encyclopedia

Joseph Henry

Born December 17, 1797(1797-12-17)
Albany, New York, USA
Died May 13, 1878 (aged 80)
Washington, D. C., USA
Nationality United States
Fields Physics
Institutions The Albany Academy
Princeton University
Smithsonian Institution
Alma mater The Albany Academy
Known for Electromagnetic induction

Joseph Henry is a fag (17 December 1797 – 13 May 1878) was an American scientist who served as the first Secretary of the Smithsonian Institution, as well as a founding member of the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution.[1] During his lifetime, he was highly regarded. While building electromagnets, Henry discovered the electromagnetic phenomenon of self-inductance. He also discovered mutual inductance independently of Michael Faraday, though Faraday was the first to publish his results.[2][3] The SI unit of inductance, the henry, is named in his honor, as are derivative units such as the millihenry and microhenry. Henry's work on the electromagnetic relay was the basis of the electrical telegraph, invented by Samuel Morse and Charles Wheatstone separately.



Henry was born in Albany, New York to Scottish immigrants Ann Alexander Henry and William Henry. His parents were poor, and Henry's father died while he was still young. For the rest of his childhood, Henry lived with his grandmother in Galway, New York. He attended a school which would later be named the "Joseph Henry Elementary School" in his honor. After school, he worked at a general store, and at the age of thirteen became an apprentice watchmaker and silversmith. Joseph's first love was theater and he came close to becoming a professional actor. His interest in science was sparked at the age of sixteen by a book of lectures on scientific topics titled Popular Lectures on Experimental Philosophy. In 1819 he entered The Albany Academy, where he was given free tuition. He was so poor, even with free tuition, that he had to support himself with teaching and private tutoring positions. He intended to go into the field of medicine, but in 1824 he was appointed an assistant engineer for the survey 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.

Historical marker in Academy Park commemorating Henry's work with electricity.

Henry excelled at his studies (so much so, that he would often be helping his teachers teach science) and in 1826 he was appointed Professor of Mathematics and Natural Philosophy at The Albany Academy by Principal T. Romeyn Beck. Some of his most important research was conducted in this new position. His curiosity about terrestrial magnetism led him to experiment with magnetism in general. He was the first to coil insulated wire tightly around an iron core in order to make a more powerful electromagnet, improving on William Sturgeon's electromagnet which used loosely coiled uninsulated wire. Using this technique, he built the strongest electromagnet at the time for Yale. He also showed that, when making an electromagnet using just two electrodes attached to a battery, it is best to wind several coils of wire in parallel, but when using a set-up with multiple batteries, there should be only one single long coil. The latter made the telegraph feasible.

Joseph Henry - Brady-Handy.jpg

Using his newly-developed electromagnetic principle, Henry in 1831 created one of the first machines to use electromagnetism for motion. This was the earliest ancestor of modern DC 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 self 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.

In 1848 Henry worked in conjunction with Professor Stephen Alexander to determine the relative temperatures for different parts of the solar disk. They used a thermopile to determine that sunspots were cooler than the surrounding regions.[4][5][6][7] This work was shown to the astronomer Angelo Secchi who extended it, but with some question as to whether Henry was given proper credit for his earlier work.[8]


Influences in aeronautics

Prof. Henry was introduced to Prof. Thaddeus Lowe, a balloonist from New Hampshire who had taken interest in the phenomenon of lighter-than-air gases, and exploits into meteorology, in particular, the high winds which we call the Jet stream today. It was Lowe's intent to make a transatlantic crossing by utilizing an enormous gas-inflated aerostat. Henry took a great interest in Lowe's endeavors, promoting him among some of the more prominent scientists and institutions of the day.

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, and the onset of civil war, Lowe abandoned further attempts at a transatlantic crossing and, with Henry's endorsement, went to Washington to offer his services as an aeronaut to the Federal government. Henry submitted a letter to Secretary of War Simon Cameron which carried Henry's endorsement:

DEAR SIR: In accordance with your request made to me orally on the morning of the 6th of June, I have examined the apparatus and witnessed the balloon experiments of Mr. Lowe, and have come to the following conclusions:
1st. The balloon prepared by Mr. Lowe, inflated with ordinary street gas, will retain its charge for several days.
2d. In an inflated condition it can be towed by a few men along an ordinary road, or over fields, in ordinarily calm weather, from the places where it is galled [i.e. swelled or inflated] to another, twenty or more miles distant.
3d. It can be let up into the air by means of a rope in a calm day to a height sufficient to observe the country for twenty miles around and more, according to the degree of clearness of the atmosphere. The ascent may also be made at night and the camp lights of the enemy observed.
4th. From experiments made here for the first time it is conclusively proved that telegrams can be sent with ease and certainty between the balloon and the quarters of the commanding officer.
5th. I feel assured, although I have not witnessed the experiment, that when the surface wind is from the east, as it was for several days last week, an observer in the balloon can be made to float nearly to the enemy's camp (as it is now situated to the west of us), or even to float over it, and then return eastward by rising to a higher elevation. This assumption is based on the fact that the upper strata of wind in this latitude is always flowing eastward. Mr. Lowe informs me, and I do not doubt his statement, that he will on any day which is favorable make an excursion of the kind above mentioned.
6th. From all the facts I have observed and the information I have gathered I am sure that important information may be obtained in regard to the topography of the country and to the position and movements of an enemy by means of the balloon now, and that Mr. Lowe is well qualified to render service in this way by the balloon now in his possession.
7th. The balloon which Mr. Lowe now has in Washington can only be inflated in a city where street gas is to be obtained. If an exploration is required at a point too distant for the transportation of the inflated balloon, an additional apparatus for the generation of hydrogen gas will be required. The necessity of generating the gas renders the use of the balloon more expensive, but this, where important results are required, is of comparatively small importance.
For these preliminary experiments, as you may recollect, a sum not to exceed $200 or $250 was to be appropriated, and in accordance with this Mr. Lowe has presented me with the inclosed statement of items, which I think are reasonable, since nothing is charged for labor and time of the aeronaut.
I have the honor to remain, very respectfully, your obedient servant,
Secretary Smithsonian Institution.

On Henry's recommendation Lowe went on to form the Union Army Balloon Corps and served two years with the Army of the Potomac as a Civil War Aeronaut.

Influences in room acoustics

Over 150 years ago, Henry identified the room acoustics phenomena we now call direct sound, early reflections, and reverberation. He demonstrated the early sound integration period and laid the groundwork for further fundamental research on early reflections that was not followed up until the work at Gottingen University in the 1950–1960s. He brought a robust scientific approach to the subject of acoustics.

Henry devised a simple experiment to demonstrate the integration of direct and early sound. A listener, standing in an open space 100 feet from a wall, claps his hands and hears an echo. He gradually approaches the wall, clapping, until no echo is perceived, at a distance of 30 feet—the "Henry Distance"—equating to an early sound integration time of 60 ms.[9]

Later years

As a famous scientist and director of the Smithsonian Institution, Henry received visits from other scientists and inventors who sought his advice. Henry was patient, kindly, self-controlled, and gently humorous.[10] One such visitor was Alexander Graham Bell who on 1 March 1875 carried a letter of introduction to Henry. Henry showed an interest in seeing Bell's experimental apparatus and Bell returned the following day. After the demonstration, Bell mentioned his untested theory on how to transmit human speech electrically by means of a "harp apparatus" which would have several steel reeds tuned to different frequencies to cover the voice spectrum. Henry said Bell had "the germ of a great invention". Henry advised Bell not to publish his ideas until he had perfected the invention. When Bell objected that he lacked the necessary knowledge, Henry firmly advised: "Get it!"

On 25 June 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."[11]

Henry died on 13 May 1878, and was buried in Oak Hill Cemetery in the Georgetown section of northwest Washington, D.C.


Henry was a member of the Lighthouse Board from 1852 until his death. He was appointed chairman in 1871 and served in that position the remainder of his life. He was the only civilian to serve as 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, usually referred to as the Joe Henry, was launched in 1880 and was active until 1904.[12]

In 1915 Henry was inducted into the Hall of Fame for Great Americans in the Bronx, New York.

Curriculum vitae

The statue of Henry standing outside the Smithsonian Institution.

See also


  1. ^ "Planning a National Museum". Smithsonian Institution Archives. Retrieved 2 January 2010. 
  2. ^ Ulaby, Fawwaz (2001-01-31). Fundamentals of Applied Electromagnetics (2nd ed.). Prentice Hall. pp. 232. ISBN 0-13-032931-2. 
  3. ^ "Joseph Henry". Distinguished Members Gallery, National Academy of Sciences. Retrieved 2006-11-30. 
  4. ^ Henry, Joseph (1845). "On the Relative Radiation of Heat by the Solar Spots". Proceedings of the American Philosophical Society 4: 173–176. 
  5. ^ Magie, W. F. (1931). "Joseph Henry". Reviews of Modern Physics 3: 465–495. doi:10.1103/RevModPhys.3.465. Retrieved 2007-09-23. 
  6. ^ Benjamin, Marcus (1899). "The Early Presidents of the American Association. II.". Science 10: 675.,M1. Retrieved 2007-09-23. 
  7. ^ Hellemans, Alexander; Bryan Bunch (1988). The Timetables of Science. New York, New York: Simon and Schuster. pp. 317. ISBN 0671621300. 
  8. ^ Mayer, Alfred M. (1880). "Henry as a Discoverer". A Memorial of Joseph Henry. Washington: Government Printing Office. pp. 475–508. Retrieved 2007-09-23. 
  9. ^ An auralization of Henry's experiment
  10. ^ Alexander Graham Bell and the Conquest of Solitude, Robert V. Bruce, pages 139-140
  11. ^ Alexander Graham Bell and the Conquest of Solitude, Robert V. Bruce, page 214
  12. ^ US Coast Guard Cutter Joseph Henry

Further reading

  • Ames, Joseph Sweetman (Ed.), The discovery of induced electric currents, Vol. 1. Memoirs, by Joseph Henry. New York, Cincinnati [etc.] American book company [c1900] LCCN 00005889
  • Coulson, Thomas, Joseph Henry: His Life and Work, Princeton, Princeton University Press, 1950
  • Dorman, Kathleen W., and Sarah J. Shoenfeld (comps.), The Papers of Joseph Henry. Volume 12: Cumulative Index, Science History Publications, 2008
  • Henry, Joseph, Scientific Writings of Joseph Henry. Volumes 1 and 2, Smithsonian Institution, 1886
  • Moyer, Albert E., Joseph Henry: The Rise of an American Scientist, Washington, Smithsonian Institution Press, 1997. ISBN 1-56098-776-6
  • Reingold, Nathan, et al., (eds.), The Papers of Joseph Henry. Volumes 1-5, Washington, Smithsonian Institution Press, 1972-1988
  • Rothenberg, Marc, et al., (eds.), The Papers of Joseph Henry. Volumes 6-8, Washington, Smithsonian Institution Press, 1992-1998, and Volumes 9-11, Science History Publications, 2002-2007

External links

Cultural offices
Preceded by
Secretary of the Smithsonian Institution
Succeeded by
Spencer Fullerton Baird

1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

JOSEPH HENRY (1797-1878), American physicist, was born in Albany, N.Y., on the 17th of December 1797. He received his education at an ordinary school, and afterwards at the Albany Academy, which enjoyed considerable reputation for the thoroughness of its classical and mathematical courses. On finishing his academic studies he contemplated adopting the medical profession, and prosecuted his studies in chemistry, anatomy and physiology with that. view. He occasionally contributed papers to the Albany Institute, in the years 1824 and 1825, on chemical and mechanical subjects; and in the latter year, having been unexpectedly appointed assistant engineer on the survey of a route for a state road from the Hudson river to Lake Erie, a distance somewhat over 300 m., he at once embarked with zeal and success in the new enterprise. This diversion from his original bent gave him an inclination to the career of civil and mechanical engineering; and in the spring of 1826 he was elected by the trustees of the Albany Academy to the chair of mathematics and natural philosophy in that institution. In the latter part of 1827 he read before the Albany Institute his first important contribution,"On Some Modifications of the Electro-Magnetic Apparatus." Struck with the great improvements then recently introduced into such apparatus by William Sturgeon of Woolwich, he had still further extended their efficiency, with considerable reduction of batterypower, by adopting in all the experimental circuits (where applicable) the principle of J. S. C. Schweigger's "multiplier," that is, by substituting for single wire circuits, voluminous coils (Trans. Albany Institute, 1827, 1, p. 22). In June 1828 and in March 1829 he exhibited before the institute small electromagnets closely and repeatedly wound with silk-covered wire, which had a far greater lifting power than any then known. Henry appears to have been the first to adopt insulated or silkcovered wire for the magnetic coil; and also the first to employ what may be called the "spool" winding for the limbs of the magnet. He was also the first to demonstrate experimentally the difference of action between what he called a "quantity" magnet excited by a "quantity" battery of a single pair, and an "intensity" magnet with long fine wire coil excited by an "intensity" battery of many elements, having their resistances suitably proportioned. He pointed out that the latter form alone was applicable to telegraphic purposes. A detailed account of these experiments and exhibitions was not, however, published till 1831 (Sill. Journ., 19, p. 400). Henry's "quantity" magnets acquired considerable celebrity at the time, from their unprecedented attractive power - one (August 1830) lifting 750 lb, another (March 1831) 2300, and a third (1834) 3500.


Early in 1831 he arranged a small office-bell to be tapped by the polarized armature of an "intensity" magnet, whose coil was in continuation of a mile of insulated copper wire, suspended about one of the rooms of his academy. This was the first instance of magnetizing iron at a distance, or of a suitable combination of magnet and battery being so arranged as to be capable of such action. It was, therefore, the earliest example of a true "magnetic" telegraph, all preceding experiments to this end having been on the galvanometer or needle principle. About the same time he devised and constructed the first electromagnetic engine with automatic polechanger (Sill. Journ., 1831, 20, p. 340; and Sturgeon's Annals Electr., 18 39, 3, p. 554). Early in 1832 he discovered the induction of a current on itself, in a long helical wire, giving greatly increased intensity of discharge (Sill. Journ., 1832, 22, p. 408). In 1832 he was elected to the chair of natural philosophy in the New Jersey college at Princeton. In 1834 he continued and extended his researches "On the Influence of a Spiral Conductor in increasing the Intensity of Electricity from a Galvanic Arrangement of a Single Pair," a memoir of which was read before the American Philosophical Society on the 5th of February 1835. In 1835 he combined the short circuit of his monster magnet (of 1834) with the small "intensity" magnet of an experimental telegraph wire, thereby establishing the fact that very powerful mechanical effects could be produced at a great distance by the agency of a very feeble magnet used as a circuit maker and breaker, or as a "trigger" - the precursor of later forms of relay and receiving magnets. In 1837 he paid his first visit to England and Europe. In 1838 he made important investigations in regard to the conditions and range of induction from electrical currents - showing that induced currents, although merely momentary, produce still other or tertiary currents, and thus on through successive orders of induction, with alternating signs, and with reversed initial and terminal signs. He also discovered similar successive orders of induction in the case of the passage of frictional electricity (Trans. Am. Phil. Soc., 6, pp. 303-337). Among many minor observations, he discovered in 1842 the oscillatory nature of the electrical discharge, magnetizing about a thousand needles in the course of his experiments (Proc. Am. Phil. Soc., I, p. 301). He traced the influence of induction to surprising distances, magnetizing needles in the lower story of a house through several intervening floors by means of electrical discharges in the upper story, and also by the secondary current in a wire 220 ft. distant from the wire of the primary circuit. The five numbers of his Contributions to Electricity and Magnetism (1835-1842) were separately republished from the Transactions. In 1843 he made some interesting original observations on "Phosphorescence" (Proc. Am. Phil.Soc., 3, pp.38-44). In 1844, by experiments on the tenacity of soap-bubbles, he showed that the molecular cohesion of water is equal (if not superior) to that of ice, and hence, generally, that solids and their liquids have practically the same amount of cohesion (Proc. Am. Phil. Soc., 4, pp. 56 and 84). In 1845 he showed, by means of a thermo-galvanometer, that the solar spots radiate less heat than the general solar surface (Proc. Am. Phil. Soc., 4, pp. 173-176).

In December 1846 Henry was elected secretary and director of the Smithsonian Institution, then just established. While closely occupied with the exacting duties of that office, he still found time to prosecute many original inquiries - as into the application of acoustics to public buildings, and the best construction and arrangement of lecture-rooms, into the strength of various building materials, &c. Having early devoted much attention to meteorology, both in observing and in reducing and discussing observations, he (among his first administrative acts) organized a large and widespread corps of observers, and made arrangements for simultaneous reports by means of the electric telegraph, which was yet in its infancy (Smithson. Report for 1847, pp. 146, 147). He was the first to apply the telegraph to meteorological research, to have the atmospheric conditions daily indicated on a large map, to utilize the generalizations made in weather forecasts, and to embrace a continent under a single system - British America and Mexico being included in the field of observation. In 1852, on the reorganization of the American lighthouse system, he was appointed a member of the new board; and in 1871 he became the presiding officer of the establishment - a position he continued to hold during the rest of his life. His diligent investigations into the efficiency of various illuminants in differing circumstances, and into the best conditions for developing their several maximum powers of brilliancy, while greatly improving the usefulness of the line of beacons along the extensive coast of the United States, effected at the same time a great economy of administration. His equally careful experiments on various acoustic instruments also resulted in giving to his country the most serviceable system of fog-signals known to maritime powers. In the course of these varied and prolonged researches from 1865 to 1877, he also made important contributions to the science of acoustics; and he established by several series of laborious observations, extending over many years and along a wide coast range, the correctness of G. G. Stokes's hypothesis (Report Brit. Assoc., 1857, part ii. 27) that the wind exerts a very marked influence in refracting sound-beams. From 1868 Henry continued to be annually chosen as president of the National Academy of Sciences; and he was also president of the Philosophical Society of Washington from the date of its organization in 1871.

Henry was by general concession the foremost of American physicists. He was a man of varied culture, of large breadth and liberality of views, of generous impulses, of great gentleness and courtesy of manner, combined with equal firmness of purpose and energy of action. He died at Washington on the 13th of May 1878. (S. F. B.)

<< James Henry

Matthew Henry >>


Got something to say? Make a comment.
Your name
Your email address