Michael Pupin developed the technique of 'loading' telephone cables, which made long-distance telephone calls possible.
He was born in Serbia, which at the time was a turbulent nation sandwiched between the Austro-Hungarian and Ottoman empires. He decided to find a new life in the USA, where he arrived aged 16 as a penniless immigrant. Despite this he managed to graduate from New York's Columbia University 9 years later.
He developed a keen interest in science, which led him to study further in Cambridge and Berlin. He returned to the USA in 1901 and was made Professor of Electro-Mechanics at Columbia, where he stayed until 1931.
Pupin's introduction of 'loading' allowed the phone network to expand across far greater distances before amplifiers were invented.
His work also included developing electrical resonators, designing early radio transmitters and expanding theories to make electrical networks perform better. As a sideline, he developed the fluoroscope - a screen that allows x-rays to be looked at directly.
