Joseph Henry.

Joseph Henry was born on December 17, 1797 in Albany, New York, to two immigrants from Scotland, Ann Alexander Henry and William Henry.
His parents were poor, and Joseph’s father died while he was still a young boy. For the rest of his childhood, Joseph lived with his grandmother in Galway, New York. He attended a school which would later be named Joseph Henry Elementary School in his honour.

Joseph's interest in science was sparked at the age of sixteen, by a book of lectures on scientific topics entitled 'Popular Lectures on Experimental Philosophy'. In 1819, he entered The Albany Academy, where he was given free tuition. He was so poor that even with free tuition 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 civil or mechanical engineering.

Joseph excelled at his studies and he would often be helping his teachers teach science to the other students! By 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 an extremely powerful electromagnet, improving on William Sturgeon’s electromagnet, which used loosely coiled uninsulated wire. Using this technique, he built the most powerful electromagnet at the time for Yale University. 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. This latter observation made the telegraph feasible.

In 1831 he created one of the first machines to use electromagnetism for motion. This was the earliest ancestor of the modern DC motor. It did not make use of rotating motion, but was merely an electromagnet perched on a pole, rocking back and forth. Here, he also discovered the property of self inductance. Around the same time, the British scientist Michael Faraday discovered it as well, however, being quicker to publish his results, Faraday became the officially recognised discoverer of the phenomenon.

He discovered the laws upon which the transformer is based. He also found that currents could be induced at a distance and in one case magnetised a needle by utilising a lightning flash eight miles away. This experiment was apparently the first use of radio waves across a distance.

Joseph Henry also identified the room acoustics phenomena we now call direct sound, early reflections, and reverberation. He demonstrated the early sound integration period and laid the ground work for further fundamental research on early reflections that was not followed up until the work at Gottingen University in the 1950-1960’s. He brought a robust scientific approach to the subject of acoustics, a subject which is plagued by misunderstanding and misinformation to this day.

He devised a beautifully 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.

Some of his many achievements in date order:

1826 - Professor of Mathematics and Natural Philosophy at The Albany Academy, New York.
1831 - Designed, built and successfully operated a telegraph over a distance of 1 mile (1.6 km).
1832 - Professor at Princeton.
1835 - Invented the electromechanical relay.
1846 - First secretary of the Smithsonian Institution (continued until 1878).
1848 - Edited Ephraim G. Squier and Edwin H. Davis' 'Ancient Monuments of the Mississippi Valley', the Institution's first publication.
As the Smithsonian's director, Henry acted as one of the major co-ordinators of government science. Among the projects he originated was the system of receiving simultaneous weather reports by telegraph and basing weather predictions on them. From these beginnings came the U.S. Weather Bureau.
1863 - Cofounder and second president of National Academy of Sciences. The Joseph Henry Press, a publication arm of the NAS, is named for him.
1866 - Became vice president of the National Academy.
1868 - Became president of the National Academy and held this post until his death 10 years later.

He died in Washington, D.C. on May 13, 1878 aged 80.

On January 16 1879 a memorial service was held in his honour in the hall of the House of Representatives.

In 1872, John C. Green, founder of the School of Science at Princeton, endowed a chair of physics in Henry's honour.

In 1893 Joseph Henrys' name was given to the standard electrical unit of inductive resistance, the 'Henry'.

By act of Congress a bronze statue was erected outside the Smithsonian Institution Building, Washington, in his memory.