Geologist’s Tool Fights German U Boats In WW 2
Mining history by Harold Hough

            It was early 1943 and the Battle of the Atlantic was going badly for the Allies.  By the spring of 1943, there were so many U-boats on patrol in the North Atlantic that it was difficult for the convoys to evade detection - resulting in a succession of vicious convoy battles. In March 1943, five convoys were hit by German wolfpacks and merchant ships were being lost faster then they could be replaced. One hundred twenty ships were sunk worldwide and 82 ships in the Atlantic.  The situation was so critical that British leaders were worried that Britain couldn’t continue the war.
            Although many technologies were responsible for turning the tide against the German submarines, including radar, breaking the German Enigma code, and long range maritime patrol aircraft, one of the most important tools was a device originally designed to find mineral deposits – the Magnetic Anomaly Detector.
            A magnetic anomaly detector (MAD) is an instrument used to detect minute variations in the Earth's magnetic field.  These small variations in the magnetic field can be used to find ore bodies.  In fact, geoexploration by measuring and studying variations in the Earth's magnetic field has been conducted by scientists since 1843. The first uses of magnetometers were for the location of ore deposits. Thalen's 'The Examination of Iron Ore Deposits by Magnetic Measurements', published in 1879, was the first scientific treatise describing this practical use.  However, in order to make MAD more economical for geological exploration, a smaller, more powerful device was necessary.
            Fortunately, a new MAD device had just been invented a few years before WW II.  The inventor was Victor Vacquier, a Russian émigré who had escaped with his family from the Communists when 13.  In the 1930s he was an electrical engineer working for Gulf Research Laboratories in Pittsburgh, PA.  He was tasked with developing a better MAD device for Gulf Minerals.
            The result of his work was the Fluxgate Magnetometer.  A fluxgate magnetometer consists of a small, magnetically susceptible, core wrapped by two coils of wire. An alternating electrical current is alternately passed through one of the coils. This constantly changing field induces an electrical current in the second coil, and this output current is measured by a detector.  But, what was important was that fluxgates were for the first time affordable, rugged, and compact. They also used less power than other MAD devices.
            In addition to being an ideal device for detecting mineral deposits, it also proved to be perfect for the raging battle in the Atlantic.  As large, steel objects, submarines deflected the earth’s magnetic field more than a mineral deposit.  Knowing that, the British had developed a crude MAD device that was so bulky that it could only be used in ports.  However, Vacquier’s fluxgate was small and cheap enough that it could be easily installed on aircraft and blimps.
            When America entered World War II, Vacquier went to work for the Airborne Instruments Laboratory (AIL) at Columbia University, which was responsible for developing new anti-submarine warfare technology.  Preliminary experiments at AIL showed that Vacquier’s MAD device could successfully identify a submerged submarine. 
After that demonstration, he went to the Lighter-Than-Air Naval Headquarters in New Jersey, where the magnetometer was installed in an R3 blimp. The magnetometer worked, but the blimp didn't -- often failing to make headway or even moving backward relative to the ground because of winds. After 200 hours of airborne testing, Vacquier convinced the Navy that the device would work much better in a PBY Catalina flying boat.  It was also installed on the famous B-17 bomber, which was the other American aircraft with long range capability.
The fluxgate wasn’t only used against submarines.  Several squadrons of PBYs in the Pacific theater were specially modified to operate as night convoy raiders. Outfitted with fluxgates and painted flat black, these "Black Cats" attacked Japanese supply convoys at night.  Catalinas were surprisingly successful in this highly unorthodox role. Between August 1943 and January 1944, Black Cat squadrons had sunk 112,700 tons of merchant shipping, damaged 47,000 tons, and damaged 10 Japanese warships.
Although the invention of the fluxgate would have been enough for most scientists, Vacquier continued to break ground in mining and geology.  In 1953 he moved to the New Mexico Institute of Mining and Technology.  There he used the same method to search for ground water in the Southwest.  He joined Scripps Institution of Oceanography in 1957 to direct its geomagnetics program, in which war surplus magnetometers were towed behind ships to measure the magnetic fields imprinted on the sea floor.  His work at Scripps was a major factor in the theory of plate tectonics, which says that major plates of the Earth's surface are moving with respect to each other.
When Vacquier died on January 11, 2009 at the ripe age of 101, he had compiled a remarkable history.  His life work included more than 50 publications and 18 patents.  But for the sailors and members of the merchant marine who served in the Atlantic in World War Two, none will ever be as important as his fluxgate magnetometer.