Reports of Explorations and Surveys, to Ascertain the Most Practicable and Economical Route for a Railroad from the Mississippi River to the Pacific Ocean; V.10
Reports of Explorations and Surveys, to Ascertain the Most Practicable and Economical Route for a Railroad from the Mississippi River to the Pacific Ocean; V.9
Reports of Explorations and Surveys, to Ascertain the Most Practicable and Economical Route for a Railroad from the Mississippi River to the Pacific Ocean; V.7
Reports of Explorations and Surveys, to Ascertain the Most Practicable and Economical Route for a Railroad from the Mississippi River to the Pacific Ocean; V.6
Joseph Henry was an American scientist, who served as the first Secretary of the Smithsonian Institution.
Background
Henry was born on December 17, 1797 in Albany, New York, United States, 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.
Education
Joseph Henry received his education at an ordinary school. In 1819 he entered The Albany Academy, where he was given free tuition.
Joseph Henry intended to go into 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.
Joseph Henry excelled at his studies 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 battery- power, 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.
In June 1828 and in March 1829 Joseph Henry 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 silk- covered 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. 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.
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. 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.
As a famous scientist and director of the Smithsonian Institution, Henry received visits from other scientists and inventors who sought his advice. He was appointed the first Secretary of the Smithsonian Institution in 1846. One his visitor was Alexander Graham Bell, who 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. 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."
Henry died on 13 May 1878, and was buried in Oak Hill Cemetery in the Georgetown section of northwest Washington, United States.
Joseph Henry was elected a member of the American Antiquarian Society in 1851.
Personality
Henry was patient, kindly, self-controlled, and gently humorous.
Connections
Joseph Henry was married to Hariet Henry (née Alexander). He had 4 children, William Alexander (1832–1862), Mary Anna (1834–1903), Helen Louisa (1836–1912), and Caroline (1839–1920).