Zahlen, bitte! Start of mine clearance thanks to invention of the metal detector
Minefields can make a war zone uninhabitable for decades after the conflict. The fight against this began with the invention of the metal detector.
Ukraine is now the most heavily mined country in the world since the Second World War. But what lies in the soil in the fields of the breadbasket of the world is affected by the legacy that Egypt suffers from. In its desert regions lie 20 million mines from the Second World War, most of them in the "Devil's Gardens", which the German General Erwin Rommel had laid.
Only the invention of the metal detector created an effective tool for clearing minefields after the war. Despite great advances in technology, progress was slow.
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The First World War had not even completed its first year when the mine problem was discussed in France. In the spring of 1915, the prefecture of the Meurthe-et-Moselle district commissioned physicist Camille Gutton to design a device that could detect explosive mines. The aim was to enable farmers to plow up their fields safely.
First mine detector presented in 1915
Gutton, who later became known as a pioneer of radar technology and radio communication with airplanes, was able to present a prototype as early as July 1915. His invention was described on pages 425 and 434 of the scientific magazine "Scientific American" under the title "Detecting Buried Shells with Induction Balance".
Gutton used what physicist David Edward Hughes called the "electromagnetic balance" effect in 1879 to present a mine detector that already bore a certain resemblance to today's metal detectors.
(Image:Â gemeinfrei)
What Gutton did not know at the time was that his system had already been used once before, but in a slightly different context. On July 2, 1881, US President James A. Garfield was injured by an assassin. His personal physician Willard Bliss tried in vain to remove the lead bullet – he simply could not find it. The inventor Alexander Graham Bell, who was in Washington at the time, constructed a "bullet detector" with colleagues, which was supposed to provide acoustic interference like a metal detector.
Unsuccessful detection of the metal ball
The device worked in tests with animals and Civil War veterans, but it failed with the president. Garfield died on September 19, 1881, and Bell, who examined the US president with several improved instruments, blamed the metal bedsprings for not receiving a clear signal.
However, the doctor prevented him from examining the President's entire upper body. The autopsy revealed that the bullet was lodged in a completely different place.
A simple detector consists of a battery system, a transmitter coil and a receiver coil connected to a small loudspeaker.
1. when the detector is switched on, current flows from the battery into the lower, round area of the transmitter coil. This is usually located in the plate-shaped detector area.
2. as soon as current is applied to the transmitter coil, it generates a magnetic field around itself. This happens periodically and therefore in pulses.
3. when the detector moves over a piece of metal lying close to the floor, the magnetic field generates an eddy current in the piece of metal.
4) This current flow in the metal in turn generates a magnetic field, which causes a signal change in the receiver area.
5. the signal, emitted by the loudspeaker and previously only influenced by the emitted magnetic beams, changes due to the magnetic field of the metal object – The sound emitted by the loudspeaker changes pitch and varies depending on the position.
The next step in improving the technique was taken by physicist Gerhard R. Fischer. Born in Landeshut (now Kamienna GĂłra) in Lower Silesia, Fischer had studied electrical engineering in Dresden and emigrated to the USA in 1925. There he worked with ace pilot Harold B. Miller from the US Navy on the technology of radio direction finding, which was intended to help pilots with navigation. Both received a patent for their invention in February 1937, which Fischer handed over to the Navy and then the Air Force.
From patent to detector company
While working with the direction finders, pilots repeatedly told him about mysterious distortions that Fischer attributed to metals. Based on these reports, he developed a metal detector, which was patented in January 1937 under patent US2207750A as the Metalloscope. With this patent, he founded the company Fisher Research Labs, which to this day not only manufactures detectors for mobile searches and for checking people at airports.
The development from metal detector to specialized mine detector took place in Great Britain. It was here that JĂłzef Kosacki researched the development of mine detectors after escaping from a German internment camp as a member of the 1st Polish Corps. Kosacki had studied electrical engineering in Warsaw and in 1937 worked at the Polish Ministry of Defense on a method for detecting unexploded shells.
He resumed this work after a tragic incident in 1941: British troops had installed mines on the beaches in anticipation of a German invasion, but had not informed their allies of this. A Polish patrol was killed.
Competition for an effective mine detection system
The British army announced a competition, which Kosacki won with his assistant. He decided not to patent his detector and left the production of the minesweepers to the army. Thousands of them were used in the Second Battle of El Alamein, when the Allies succeeded in cutting a swathe through the Devil's Garden at a rate of 100 to 200 m² per hour with the help of the detectors and tanks. The basic technique of this combined mine search was retained until 1991 during the first Iraq war.
Egypt is still suffering from the consequences of the war today, partly because the mines are still buried deep in the sand after all these years, while at the same time the populated land continues to advance. Around 20 million mines are said to still lie in the ground today.
(Image:Â Gemeinfrei, Cpl. Alejandro Pena)
It was only in the 1980s that the number of victims began to be recorded. By 2015, 3300 people had been killed and 7500 maimed. According to an unconfirmed report by Al Jazeera, Egypt has stopped clearing explosive ordnance, although around 60 percent of the minefields still need to be cleared.
Metal detectors also play a role in the search for ancient finds. In Saxony-Anhalt, for example, one of the most important finds, the Nebra Sky Disk, was discovered using a metal detector. However, it was the work of robber diggers who damaged the disk through improper recovery and ruined further archaeological research into the site. Considering this, such detections by private individuals without permission are usually illegal.
(olb)
