John Ambrose Fleming

- biography of the life of Professor Sir John Ambrose Fleming, inventor of the oscillation diode valve or vacuum tube who some say is the founder of electronics

Professor Sir John Ambrose Fleming is one of the great men of radio and electronics.

Fleming's invention of the thermionic valve or vacuum tube could be said to be the beginning of modern electronics. It enabled wireless and later electronics technology to move forward, enabling the first wireless sets with a reasonable performance to be manufactured. As a result of this contribution, some refer to Ambrose Fleming as the Father of Electronics.

Although the invention of the thermionic valve or vacuum tube is Fleming's major claim to fame, he also made many other important contributions to the field of electrical machinery, measurements during his working life. During Fleming's retirement he took a keen interest in a vast number of other topics associated with electronics which included the new area of television.


Fleming's early years and education

John Ambrose Fleming was born on 29th November 1849. He was the eldest of seven children born to a Congregational minister. Although born in Lancaster his family moved to North London where he spent most of his early life. He was educated mainly at University College School on Gower Street in the West End of London.

On leaving school Ambrose Fleming entered University College London where he studied for his bachelor's degree under two famous names: de Morgan the mathematician; and Carey Foster the physicist.

Unfortunately Fleming had to leave after the end of his second year. His studies stretched the family's limited resources and he had to earn some money to continue. This he did by taking a job with a ship builder in Dublin. He soon tired of this job and took employment at a stock jobbing firm in the London Stock Exchange where he spent two years.

The job at the stock exchange was very convenient. Work finished at 4 pm and this enabled Fleming to study in the evening and as a result, he graduated in 1870 with a first class degree, one of only two that year. Not content with this he determined to further his studies, but before he could achieve this he needed to replenish his funds. With this aim he took up a post at Rossall School for 18 months before entering the Royal College of Science to study Chemistry in Kensington in 1872.

While Ambrose Fleming was here he first studied the electric battery and this resulted in the first paper he presented. It was actually the first one read at the newly formed Physical Society of London which later became the Institute of Physics. As such it appears on the first page of their proceedings.


Fleming at Cambridge

The lack of funds again forced Fleming to seek employment, and he became a science master at Cheltenham College. When he was here he was able to continue his research even corresponding with James Clerk Maxwell at Cambridge University. It was as a result of this that Fleming decided to study at Cambridge under Maxwell.

Whilst at Cheltenham, Fleming managed to accrue sufficient funds to return to University so that in September of 1877 at the age of 28 Fleming entered Cambridge. Here he studied under Maxwell for part of the time, commenting that he found his lectures difficult to follow. He graduated from Cambridge with a first class degree in Physics and Chemistry. A year later he gained his D.Sc. from London University and then spent a year as a demonstrator at Cambridge, although by this time Maxwell had died.

 John Ambrose Fleming the inventor of the diode valve
John Ambrose Fleming the inventor of the diode valve

Fleming enjoyed the academic life and he managed to secure the post of Professor of Physics and Mathematics at University College Nottingham, but despite this job he still wanted to return to London.

His time at Nottingham was relatively short, as he took up a position as a consultant to the Edison Telephone Company. This enabled him to see many of Edison's inventions, and he even travelled to the Edison's laboratories in the USA. This was to be a crucial event although Fleming did not know it at the time because it was to shape his future. The invention he saw was known as the Edison effect. It was found that an evacuated light bulb with a second electrode would allow current to flow from one electrode to the other, but only in one direction. While Fleming did not use the idea immediately, he took a keen note of it.


Fleming becomes professor at UCL

Fleming's long term aim was to be able to return to London. At the time there were no positions in the new and developing science of electrical engineering. Instead the nearest subject was physics. However Fleming was invited to give a series of lectures on electrical engineering at University College London, UCL, the premier college of London University. Then in 1885 he was asked to set up a new department for electrical engineering for which he would be professor. This was the beginning of a long association as he held the chair at UCL for 41 years. It was also a notable first because it was the first department of its sort in the country.

Professor Fleming enjoyed both research and lecturing. As a lecturer, his students said that his lectures were well thought out and clearly presented. He even devised methods to remember things - examples are the left and right hand rules for the relationship between magnetic field, current and force in electrical machines. Even today, these are called Fleming's left hand motor rule.

Fleming spent many hours ensuring that the demonstrations were clear and that they worked well. He would arrive very punctually to present the lecture and he would expect everything to be in place with "lantern slides" set out ready for projection and nothing was allowed to go wrong.

He spoke with great enthusiasm but so fast the undergraduates were unable to take notes easily. It is said that after a lecture, many students would come out exhausted only to have to spend many hours writing up and decoding their notes that were taken in great haste.

Whilst he was an excellent lecturer he also undertook a significant amount of research. During his first ten years at University College London, UCL, most of his researches were focused towards refining the theory behind transformers. The low voltage testing was undertaken at UCL, whilst the majority of the testing was carried out at a sub-station owned and operated by the London Electric Supply Corporation. The results were presented to the Institution of Electrical Engineers in London in November 1892 and represented a major landmark in the understanding of transformer theory. Accordingly Fleming became a leading authority on transformers as well as performing much valuable work on improving the accuracy of AC measurements.

By Ian Poole


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