According to [Joanna Goodrich]  in IEEE Spectrum, prior to World War II, soldiers who wanted to find land mines, simply poked at the ground with pointed sticks or bayonets. As you might expect, this wasn’t very safe or reliable. In 1941, a Polish signals officer, [Józef Stanislaw Kosacki], escaped to Britain and created an effective portable mine detector.

[Kosaci] was an electrical engineer trained at the Warsaw University of Technology. He had worked as a manager for the Polish National Telecommunication Institute. In 1937, the government tasked him with developing a machine that could detect unexploded grenades and shells. The machine was never deployed.

When Germany invaded Poland in 1939, [Kosacki] returned to military service (he had done a year of compulsory service earlier). He was captured and kept in a prison camp in Hungary. But he managed to escape in late 1939 and joined the Polish Army Corps in Britain, teaching Morse code to soldiers.

Britain buried landmines along their coastline to thwart any invasion. Unfortunately, they failed to notify allied forces about it and several Polish soldiers were killed. In response, the British Army set a challenge to develop a mine detector and, as a test, the device had to locate some coins on a beach.

There were seven devices entered, and [Kosacki’s] won. As a military secret, there isn’t much detail, but it sounds like it was the (now) usual BFO metal detector affair with two coils at the end of a bamboo pool. With the tech of the day, the whole affair came in at around 30 pounds. We’d bet a lot of that was in batteries.

By 1942 during the second battle of El Alamein, the new detectors allowed mine clearing operations to happen twice as fast as before. Our engineer didn’t get much recognition. Just a letter from King George. Part of that was due to fear that his family in Poland would suffer.

While land mines aren’t as common for most people as FM radios, we love to meet inventors. Even when it isn’t a very happy story.