Joseph Henry

Princeton

From 1832 to 1846, Henry served as the first Chair of Natural History at the College of New Jersey, which is now Princeton University.^[13] While in Princeton, he taught a wide range of courses including natural history, chemistry, and architecture, and ran a laboratory on campus. Decades later, Henry wrote that he made "several thousand original investigations on electricity, magnetism, and electro-magnetism" while on the Princeton faculty.^[14] Henry relied heavily on an African American research assistant, Sam Parker, in his laboratory and experiments. Parker was a free black man hired by the Princeton trustees to assist Henry. In an 1841 letter to mathematician Elias Loomis, Henry wrote:

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.^[15]

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.^[13] In 1842, when Parker fell ill, Henry's experiments stopped completely until he recovered.^[13]

Smithsonian

Henry was appointed the first Secretary of the Smithsonian Institution in 1846, and served in this capacity until 1878. In 1848, while Secretary, 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.^{[16][17][18][19]} 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.^[20]

In late 1861 and early 1862, during the American Civil War, Henry oversaw a series of lectures by prominent abolitionists at the Smithsonian Institution.^[21] 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."^[13][21]

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.^[22]

Influences in aeronautics

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, 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:

Hon. SIMON CAMERON

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 in closed statement of items, which I think are reasonable, since nothing is charged for labor and time of the aeronautic.

I have the honor to remain, very respectfully, your obedient servant,

JOSEPH HENRY,

Secretary Smithsonian Institution.^{[citation needed]}

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".

National Academy of Sciences

On January 25, 1866, Henry was elected as vice president of the National Academy of Sciences. He was elected as president in January 1868. In 1873, he stated his intention of resigning from the role, but a letter signed by members of the academy prevented his resignation. In April 1878, he again stated his interest in resigning if his health did not improve in the next six months. He remained in the role until his death the following month. Upon his death, the academy dedicated a trust named the Joseph Henry Fund.^[23]

Later years

As a public 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.^[24] 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 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."^[25]

Henry died on May 13, 1878, and was buried in Oak Hill Cemetery in the Georgetown section of northwest Washington, D.C.^[26] John Philip Sousa wrote the Transit of Venus March for the unveiling of the Joseph Henry statue in front of the Smithsonian Castle.