Henri Abraham

He performed some of the first measurements of the propagation velocity of radio waves, helped develop France's first triode vacuum tube, and with Eugene Bloch invented the astable multivibrator.

He was also president of the Society of clotting France in 1932, and in 1934 Secretary General of the International Union of Pure and Applied Physics (IUPAP).

[2][3] Arrested by the militia on the night of 23 June 1943 in Aix-en-Provence, he was delivered to the Gestapo and taken to Marseille on 7 December at Drancy before being deported from the Bobigny station on "Convoy No.

[5] As a student at the ENS, Henri Abraham was fascinated by the pioneering experiments of Heinrich Hertz in 1888 on radio waves which confirmed the predictions of Maxwell's equations, established in 1864.

Mobilized in 1914 in the Department of Military Telegraphy, under the direction of Commander Ferrie, in collaboration with Eugene Bloch he developed the first French triode amplifying vacuum tube for radio reception.

After the war, Abraham helped his former pupil Alexandre Dufour achieve the first devices foreshadowing our modern CRT oscilloscopes, and to record the oscillations of high frequency radio waves.

The same measurement method, applied with modern techniques after the Second World War in 1973, achieved a precision of nine significant digits, leading to a change in the definition of the meter.