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Shirl Herr’s “hidden-metal detector” paved the way for the development of mine detectors used by the world’s militaries.

It was late August 1929 when the black limousine pulled to the front of an Italian hotel to retrieve Shirl Herr. An American businessman, inventor, and self-educated historian, Herr had offered his assistance to the Italian government in uncovering centuries-old relics of Caligula, the third Roman emperor. While the emperor’s barges—once luxurious floating pleasure palaces—had recently poked through the surface of Lake Nemi, just south of Rome, during a four-year project to lower its water level, many priceless artifacts were still buried deep within the volcanic lake’s mucky floor. Herr was confident that the hidden-­metal detector he had invented would serve the Italians well, helping them to locate and recover the artifacts efficiently. Without hesitation, the elder Herr and his son entered the limo bound for the excavation site. Waiting for them inside was the Italian dictator, Benito Mussolini.

That the fascist authority should accompany the visiting Americans may seem unlikely. It wasn’t for Shirl Herr. For him, life was about finding possibilities in improbable situations. The Indiana native was a problem solver, whether in spite of—or thanks to—little more than an eighth-grade education, most of which had taken place in a one-room Hoosier schoolhouse.

“Higher learning would not have been good for me,” Herr once said. “I’ve been told, too often, by physicists and engineers that certain things couldn’t be done and could be proved impossible by the books. Only I found that those things sometimes could be done.”

Always undeterred by naysayers, Herr was a man of ideas. For some of those ideas—like the “color-changing screen” for theater lights, railway signals, and the like, for which he received his first patent, and his theory of fluorescent light technology (“cold light,” he called it)—the time had come. Other ideas, such as his invention of air soles for athletic shoes, were perhaps ahead of their time. The air sole design, which incorporated pneumatic tubes, was heartily supported by the athletes who had tried his prototypes. But without money to underwrite his efforts, Herr was unable to pursue the project.

Among his subjects of experimentation, Herr was particularly drawn to the science of agriculture, and he developed a process to remove weed seeds from clover seeds. Shortly after he received the patent for his color-changing device, he received another patent for his seed-cleaning machine. The idea was well received in Indiana, where manufacturing and industry were developing rapidly in the early 20th century. After seeing the machine in action, a seed company in Crawfordsville, Indiana, hired him as its foreman. He also replicated the machine for companies in Chicago, New York, and Toronto.

In 1910 Herr married Sallie Remley, the daughter of Ambrose Remley, a well-to-do Civil War veteran. At least one Crawfordsville store summarily canceled her credit account on hearing the news, fearing that Sallie’s marriage to an inventor who had no affluent family members or apparent fortune would mean certain financial failure. Whether or not his bride had taken issue with the store’s decision, Herr readily dismissed the judgment. He was fixated far more on solving problems than on dollar signs.

Herr’s seed-separating machine and patented improvements continued to earn him professional accolades and financial gains, perhaps to the surprise of at least one local business. By 1914 he had founded his own seed company with a partner and was well on his way to financial security. His successes in the agricultural world had given him the freedom to invent and the luxury of remaining unattached to the financial outcomes of those inventions. This independence allowed him to move from project to project as he wished, investigating theories for no other reason than to appease his own curiosity. One of those projects was his work on magnetic balance and the hidden-metal detector.

The idea of detecting metal wasn’t a new one. In fact, Alexander Graham Bell had developed and used a similar device after the attempted assassination of President James Garfield in 1881. Bell hoped to locate the bullet that remained lodged in Garfield’s body weeks after Charles J. Guiteau had shot him. Unfortunately, the magnetic balance was thrown off by the metal coils in Garfield’s mattress.

Herr set out to improve and simplify the older, often unreliable invention by having it use radio frequencies to locate the metal. Describing his intentions in his patent application, dated February 4, 1924, Herr said his primary objective was to “provide portable means of locating submerged, buried, or hidden metallic objects by the production of sound waves effected through distortion of a magnetic field.”

Although Herr was first to apply for a patent on the device, his request wasn’t granted until 1928, three years after another man, Gerhard Fischer, applied for—and received—a patent for a metal detector. The reasons for the four-year delay remain unknown. Nevertheless, Herr was credited with numerous underground discoveries during this period, including the exact site near West Lafayette, Indiana, of Fort Ouiatenon, a French trading post built in 1717. Sometimes partnering with others, he retrieved battleground artifacts from Yorktown and Jamestown, Virginia, and from a camp used by Major General Edward Braddock during his 1755 retreat from Fort Duquesne in western Pennsylvania. During this time, his seed-separating machines provided increasing financial security while Herr pursued his love of perpetual discovery, regardless of where it took him. And that is how he found himself in the boot of Europe, more specifically in the back of a limo with a dictator.

Under Mussolini’s orders, the Italian government was two years into a project to recover Caligula’s barges. Adorned with gold and silver, alabaster and bronze, marble and mosaic, the floating palaces are thought to have served the emperor in all his excess. Mussolini’s English was broken at best, but his outward excitement evidenced his thirst for unearthing ancient treasures, effectively bridging any language barrier as he interacted with his American guests.

While the ride gave the men time to conjure visions of a utopian site, all notions of glamour were dashed when the Herrs arrived. Herr’s son, Remley, recalled the scene to be “no more romantic than a pig pile of heavily-creosoted railroad ties dumped like jackstraw on the mud floor of an out-sized gravel pit.” Unappealing aesthetics aside, their work was rewarded, as the men helped retrieve a number of artifacts, including iron and lead fountain pieces and a solid gold figurehead.

“Over here!” Herr would periodically yell as he walked on the planking. A particularly strong buzz pulled Herr to the edge of the planking, where he lost his balance, fell into the mud, and emerged covered in large black leeches.

The incident rendered the magnetic balance temporarily useless and ended the Americans’ field study in Italy. But Herr continued to influence world exploration, ultimately sending his metal detector to the southernmost reaches of the globe.

Herr met physics professor Thomas Poulter in 1932 when both men were in Arizona. A year later Admiral Richard E. Byrd named Poulter his second in command for his second Antarctic expedition. Remembering the magnetic balance, Poulter approached Herr about taking the device on the journey—brutally cold temperatures would provide a rare test of durability. Herr readily agreed.

Poulter’s letters to Herr during the expedition confirmed that the balance, altered to be both water- and snowproof even in extreme weather conditions, was performing as expected. With the help of the detector, the men had been able to locate Byrd’s original base camp, Little America, and its still usable provisions left behind after the first expedition ended in 1930. The device proved effective to a depth of eight feet. In 1935 Byrd sent a personal letter of thanks to Herr, attaching a piece of insulation from the base.

In 1936, a year after the second expedition had ended, Shirl Herr died of heart disease. Still, the refined applications of his magnetic balance continued to shape the world and its militaries. In the early years of World War II, Józef Kosacki, a Polish soldier, advanced the design. Used as a mine detector and produced by the hundreds, the device allowed Allied forces to pass through German minefields. It was used in several Allied invasions and was still operational through the 1991 Gulf War.

Modern metal detectors have both military and commercial applications. They continue to play a significant role in battlefield archaeology and have been used successfully at both Revolutionary and Civil War era battlegrounds, including Little Bighorn (Montana); Wilson’s Creek (Missouri); Pea Ridge (Arkansas); Monmouth (New Jersey), and Kings Mountain (South Carolina). While the artifacts they unearth can help to recreate past events, their application in active theaters of war can mean the difference between life and death.

As metal detectors and their applications continue to evolve, they will serve as a reminder that Shirl Herr’s advances in the field of magnetic detection were as significant as the history he worked so hard to unearth. MHQ

Beth Underwood, a journalist whose work has appeared in many newspapers, magazines, and anthologies, is the author of Gravity (Red Engine Press, 2015).

Featured in MHQ magazine’s Summer 2017 issue.


Boone County (Ind.) Historical Society