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Thursday, 28 April 2016

Michael Faraday, 19th century scientist



Michael Faraday holds a very important place in the history of science, notably for his discoveries in the fields of electricity and magnetism and for his work in science education.

Early life

He was born on 22nd September 1791 at Newington Butts, Surrey, the son of a blacksmith and his wife. Newington Butts is now part of the London Borough of Southwark.

His education was only rudimentary and his first job was as an errand boy who delivered newspapers.

At the age of 14 he entered a 7-year apprenticeship to a bookbinder, and it was while perusing the pages of books that he became interested in chemistry. He followed up this interest by attending lectures, and during his final year as an apprentice he was given tickets for lectures at the Royal Institution given by Humphrey Davy, the Institution’s Professor of Chemistry.

Faraday wanted to leave bookbinding for a career in science, although the people he approached advised him to stick with what he knew. However, while still a bookbinder he was able to help Humphrey Davy on a casual basis when the latter was temporarily blinded after a laboratory accident, and Davy remembered the young man when a permanent position became available in February 1813.

From October 1813 to April 1815 Faraday accompanied Davy and his wife and maid on a tour of continental Europe, visiting chemical laboratories in France, Italy, Germany and Switzerland. Faraday was thus able to meet many leading European scientists including André-Marie Ampère and Alessandro Volta.

Back in London, Faraday resumed his job as an assistant at the Royal Institution, helping to set up demonstrations and helping Humphrey Davy with the latter’s development of the miners’ safety lamp.

Faraday began giving his own lectures, at both the City Philosophical Society and the Society of Arts, where he became joint chairman of its chemistry committee.
Work at the Royal Institution

At the Royal Institution Faraday worked on chemical analyses – often to provide expert testimony for legal and insurance purposes. It was while working on an analysis in 1825 that he discovered a new compound of hydrogen and carbon that was later given the name benzene.

In 1821 Michael Faraday married Sarah Barnard, the daughter of a silversmith, and the couple set up home in the Institution building, where Faraday had just been appointed as acting superintendent.

1821 was also the year in which he made his first major scientific discovery, namely that of electromagnetic rotation. This was the realisation that a vertically mounted wire carrying an electric current would rotate continuously round a magnet protruding from a bowl of mercury. This was the principle of the electric motor. The discovery also showed the value of experimentation as opposed to relying on mathematics to produce a complete account of electromagnetism.

Relations between Michael Faraday and Humphrey Davy began to become strained from 1823, when Faraday published a paper without Davy’s permission. Davy then opposed Faraday’s election to a fellowship of the Royal Society but Faraday obtained this anyway.

Faraday was appointed to the position of Director of the Royal Institution Laboratory in 1825, and was keen on furthering the educational work of the Institution. One of his initiatives, in 1826, was to begin an annual series of lectures aimed at children, held at around Christmas time. The tradition of the Christmas Lectures has continued right down to the present day.

Faraday found the late 1820s to be a frustrating time in that he was required to perform duties that took up time that he would have preferred to devote to research. In particular, he had to work on methods to improve optical glass, which was a task that had more to do with furthering Humphrey Davy’s career than his own.

In 1829 he was appointed to a professorship at the Royal Military Academy. This was a part-time post, but it paid well enough to give some financial independence from the Royal Institution. This appointment, together with the death of Humphrey Davy, meant that Faraday could at last abandon the glass work and devote himself more fully to research in his chosen field.

Major discoveries

In August 1831 Michael Faraday discovered the principle of electromagnetic induction based on wire coils and magnets. He thereby invented the first transformer and dynamo and made possible the practical use of electricity.

He then spent a number of years investigating the nature of electricity, particularly in its relation to chemistry. This led to discoveries in electrolysis, namely the deposition of substances in a solution on to a substrate when an electrical current is passed through the solution. He devised the “Faraday cage” – a 12 foot cube covered in wire – to investigate electric charge.

In the 1840s he became particularly interested in trying to discover the nature of magnetism, beginning with the question of why it appeared that only iron and nickel possessed this property. He sought to prove that it was a property of all matter (diamagnetism) and that it was non-atomic in that it operated across space. He was also interested in the magneto-optical effect.

As a result of his experiments, Faraday laid the foundations for the field theory of electromagnetism, in that he described the concept of lines of magnetic force.

Other investigations were into the magnetic properties of gases and the way magnetism worked within crystals. Faraday believed that compass needles reacted as they did because of the magnetic properties of oxygen, although this theory would prove to be incorrect.

His last major investigation was into fluorescence, although he was not able to explain why the wavelengths of light changed when they passed through certain substances.

His later life

During the 1850 and 1860s Faraday spent a lot of time working on behalf of Trinity House to improve the efficiency of lighthouses by electrifying them. The work consisted of evaluating and improving the designs of others, but the practical applications, particularly at the South Foreland lighthouse in Kent, proved not to be sustainable.

Michael Faraday’s health declined during the 1860s and he was forced to abandon his various activities, for example giving his last series of Christmas lectures in 1861/2. He turned down an opportunity to become President of the Royal Institution in 1864. He died on 25th August 1867 at his home near Hampton Court, at the age of 75.

Michael Faraday’s work on electromagnetic induction has ensured his permanent place on the scientific and engineering roll of honour.
He is the only person to have had two SI units named after him (the farad for capacitance and the faraday for electric charge). His name has been used for awards, lectures and university buildings, and he is one of only handful of people to have been featured on a Bank of England banknote.

© John Welford