William Sansome Tucker

William Sansome Tucker was born in Kidderminster, Worcestershire, in 1877, the son of William Tucker, an artist painter, and Anna his wife. William married in Chorlton,dn Lancashire, in 1906. He lectured on physics in London, and joined the British Army.

In 1916, Corporal W. S. Tucker, of the Royal Engineers, joined Lawrence Bragg to undertake research into 'sound ranging': the process of using microphones and mathematics to determine the position of enemy artillery. Bragg had been wracked by doubts and problems with the military command structure. Promoted to lieutenant by June 1916, Tucker formed an experimental sound ranging section, which spearheaded the development of an effective system of 'sound ranging' enemy guns. vital to the success was Tucker's invention of a 'hot wire' microphone, capable of identifying the shell wave and the following report of the gun that fired it. The break-through had come from Bragg, who found that the wc at the farmhouse where he was billeted, allowed him, once seated inside, to detect sound and pressure differences of shell waves and gun waves as they passed overhead.

Tucker researched how to cool platinum wire with the air currents caused by the sound-waves they were detecting. Mouse-holes and rum jars provided a clue here, as there were two mouse-holes by Tucker's bed and he noticed a draught of cool air whenever the gun-wave arrived. Tucker devised a microphone consisting of a thin, electrically heated wire, stretched over a small hole in a container (he used rum jars). The decrease in the electrical resistance of the wire as the gun-wave struck was recorded by a galvanometer.

Tucker had to send for platinum wire to be delivered to him at Kemmel Hill, before he could run trials. The rapid oscillations of the shell waves had almost no effect on the wire, whilst the gun-reports resulted in well-defined 'breaks' on the cine film used as a detector, due to the deflection of the wire by the pressure of the gun wave. By September 1916, Tucker's new microphones had been supplied to all sound-ranging sections.

In 1917, sound-ranging was further developed, so that allowances could be made for poor weather conditions. Tucker developed a system of moveable microphones to improve detection techniques, allowing for a high degree of accuracy in determining the position of the enemy guns. By the end of the war it was possible to determine where the gun was pointing, and how large it was.

The technique could also be extended to listen out for enemy aircraft; as a result, Tucker became Director of Acoustical Research, Air Defense Experimental Establishment, Biggin Hill. His work eventually led to vast parabolic 'sound mirrors' being constructed from concrete. Some of these sound mirrors still survive along England's south coast, such as those to be found at Denge, near Dungeness, to the west side of a lake slightly north of Lydd-on-Sea.

Tucker's work led into the development of RADAR, which made sound-ranging using the great concrete mirrors obsolete.