When was the metal detector invented?

The metal detector was invented in 1874 by French Gustave Trouve. He created the prototype for medical purposes. Americans first implemented it in 1881 when Graham Bell tried to find bullet slugs within the bullet wounds of President James Garfield.

In 1881, two things of significance happened. Assassins shot and killed President James Garfield around the same time when the treasure hunting industry was about to revolutionize. The president never got to enjoy Graham Bell’s treasure-hunting invention: the metal detector.

The attempts failed because of interferences from the bed metal springs. The president’s assassination necessitated the invention of a technology that would change the world after his passing. However, the failure of Bell’s Bullet Detector made Americans disregard the technology for 40 years when a German immigrant built the first effective metal detecting device.

If you’re wondering, a metal detector is an electronic device that people use to detect nearby metals. Distance and proximity are essential variables that determine the effectiveness of a metal detector because they rely on decaying electromagnetic fields to transmit signals.

Today, you can use metal detectors for various medical and industrial applications that continue to support life as we know it.


Who invented the metal detector?

Gustave Pierre Trouve invented the metal detector in 1874 for medical and mining applications. However, Graham Bell widely received praise for building and improving on Gustave’s prototype in 1881. He was trying to locate the bullets lodged into the back of President James Garfield.

Gustave’s prototype was multi-purpose. He used it to treat patients and to find suitable grounds for miners to extract ore pockets. However, Graham focused solely on saving the president when he was building the first crude metal detector .

Gustave also sought medical application for the metal detector, aiming to locate metal fragments in wounded patients. Thus, Graham Bell didn’t conceive the working mechanism of metal detectors.

However, Gerhard Fischer made away with the first-ever metal detector patent in 1925. The German immigrant to the United States invented and built the first portable metal detector, expanding the industrial uses of this technology.

  • Gustave Pierre Trouve invented metal detectors (1874)
  • Alexander Graham Bell built first crude metal detector (1881)
  • Gerhard Fischer got patent for first portable metal detector (1925)
  • Gerhard Fischer developed metal discrimination in metal detectors (1930)
  • VLF metal detectors popularized the use of metal detectors in the 1970s and 1980s


Where was the first metal detector invented?

The first metal detector was invented by Gustave Pierre Trouve, in Paris, in 1879. He built it to detect gold in streams, but Pierre Trouve soon realized that it could also locate other metals and minerals on land.

Pierre Trouve learned about electromagnetic fields from his brother-in-law, Dr. Lucien Gaudin. He was working with him at the Paris Observatory in the early 1870s. The research, led by Gustave Pierre Trouve, could be the most important discovery about electromagnetism since Nikola Tesla.

Tesla experimented on electricity generation and transmission through coils, and Heinrich Hertz’ discovered wireless communication in 1893. But Gustave’s 1874 invention was equally life-changing.

Trouve went bust shortly after inventing his metal detector prototype because he could not find a way to manufacture it.

However, British inventor James Beaumont bought the patent for ‘Trouve’s detector’ in the late 19th century. He then used his money to mass-produce metal detectors, making them commercially available.


What did the first metal detector look like?

The first metal detector looked a lot different than modern models. It was a large metal box that was open at the top. A person would walk inside, careful not to touch any of the wirings. Touching the wires could cause interferences to the readings.

The detector consisted of an electromagnet built into its base. The scientists run wire coils around iron cores to generate a magnetic field when current passes through them.

If there were no metals near the magnet, then nothing happened. The metal detector would attract ferromagnetic materials if any pieces of metal were nearby, hidden within your clothing or luggage.

After all, like charges repel one another, while the unlike ones stick together.

If someone walked up beside you with a metal object, they would affect the magnetic field, and the detector would go off. Nowadays, they consist of non-ferromagnetic materials like plastic. Thus, they can’t react to your body.

Moreover, these devices were much bigger and bulkier than they are today. Nowadays, detectors are also much more sensitive and can detect even the smallest piece of metal.

They are also more portable, and you can carry one around on your belt or hold it in one hand.


Why did Alexander Graham Bell invent the metal detector?

Alexander Graham Bell made exceptional contributions to humanity through his various innovations, like sound recording or telephone communication systems, among others.

Alexander Graham did not invent the metal detector, but he built his version when they didn’t exist in any production line. He did it as a matter of life and death, relying on information from Gustave Pierre’s design to detect bullet slugs in the dying President.

He’s credited with the invention for improving it and making it available to law enforcement. He also invented the photophone, which enabled live video transmissions over a distance of about 250 yards (230 m.) It’s just an example of Alexander Graham Bell’s many patents and inventions.

He earned the trust and call to save the president’s life because of his unique abilities. Some of his previous scientific achievements before the 1881 metal detector were admirable. He had an exceptional contribution to humanity through his various innovations like sound recording or telephone communication systems, among others.

What else did Alexander Graham Bell invent, and what were his achievements?

Well, it’s not easy for the American Federal government to trust anyone to test some new, unsed technology on the President of the United States. Graham Bell was a reputable brain and professional academic.

His works in related scientific fields earned him the confidence and government approval to build the crude metal detector. He was one of the world’s most famous scientists at the turn of the 20th century.

Some of his notable inventions include:


1. The telephone (1876)

It enabled sound to be transmitted over lines without using any form of electricity. The ‘harmonic telegraph’ first appeared in 1875 before being patented as ‘the harmonic telephone’ two years later.


2. Dictaphone or stereophone devices

In 1886, he also invented devices that used wax cylinders instead of flat recording surfaces, which were previously available.


3. Graphical sounds

  • These sounds had recorded music, and human speech played from tinfoil sheets via an Edison The cylinder phonograph.
  • The photophone (1880)


This technology could transmit sound across a distance of about two miles.


When was the metal detector first used?

People widely believe that the first metal detector came into use in 1925, and it was called Metalloscope. Gerhard Fischer didn’t intend to invent portable metal detectors, and he was initially working on an airborne direction-finding technology (radar.)

He built his airborne direction-finding equipment, which detected ore pockets on expansive locations from above ground. Though unintentional, the equipment became the first metal detector to suit mining applications, leading to the metal differentiation and device portability features we enjoy in modern metal detectors.

Fischer found that the radio beams he was using for his navigational systems got distorted by ores and rocks. He discussed the anomalies with the legendary Albert Einstein, and they both agreed the discovery could create portable metal detectors.

However, Shirl Herr, originally from Indiana, was the first to apply for a metal detector patent. He applied to have a patent for a hand-held metal detector.

Shirl worked for Italian dictator Benito Mussolini. In 1929, he used a metal detector to recover the treasures of Emperor Caligula lost under Lake Nemi. His invention later picked up military use to find sunken naval ships by 1933.

Later, the technology became valuable in clearing World War II mine bombs.


When was the portable metal detector invented?

Gerhard Fischer made away with credits and the patent for inventing the first hand-held metal detector. The patent dates back to 1925. So officially, the portable metal detector was invented in 1925.

However, Shirl Herr was first to file in 1924, and he deserves his due credits because the application got patented in 1929.


When was the crude metal detector invented?

The crude metal detector was manufactured in 1888 by Graham Bell to detect the two bullets lodged inside the spine of dying President James Garfield. Graham improved the design and prototype of French Gustave Trouve, who invented the initial working mechanism (1874) but could not reliably manufacture it.

The crude metal detector failed its purpose, but it laid a foundation for further improvements on the tech. It couldn’t provide a lifeline for the late President James Garfield, but it changed the world significantly.


When Was the Gold Detector Invented?

There are distinct differences between gold detectors from regular metal detectors. Ideally, gold detectors are metal detectors that discriminate gold signals from the frequencies of other metals.

I find no fault in attributing the science behind gold detectors to Gerhard Fischer, though no accurate records officially recognize the minds behind this invention. He once consulted Albert Einstein over the anomalies he detected every time different metals went through his detecting equipment.

They discussed the possibility of metals producing distinct and varying eddy current frequencies when hit with electromagnetic pulses. Eventually, Gerhard Fischer invented and patented the first metal detector.

Thus, gold metal detectors detect the low eddy currents of gold via high-frequency pulse inductions because gold features low conductivity. Over time, the metal detecting industry could customize metal detectors for finding only gold and silver.

Typically the devices apply electromagnetic induction to detect metals at low concentrations in alluvial deposits. They discriminate between metal types and also filter out unwanted signals like rock disturbances, etc.

In general, they have two coils:

  • One concentric
  • One with a larger diameter (paddle coil)


You can wind these coils differently or use different core materials such as ferrite to eliminate mineralization effects. The use of superconductor technology offers better performance for high conductivity ores and detection depth. However, it’s hindered by sensitivity to temperature variations.

Although there are several designs available on the market, each design has its own merits and demerits. It depends on the specific task at hand.

However, all of them indicate metallic mineralization. Signal strength increases with sweep motion due to increased conductivity or decreased resistivity relative to the surrounding rock matrix.

There are four types of gold detectors, namely:


1. Induction Type

It works with the induction principle. When the gold gets close to the coil, it changes the surrounding magnetic field, producing an amplified signal. This type of gold detector mostly suits shallow-ore detection i.e, up to three feet depth or more, depending on mineralization.

This design comes in both salt and freshwater versions.


2. VLF Type

These gold detectors work on the principle of low-frequency signals, i.e. less than 100 kHz.They function at lower frequencies because the metal (gold) doesn’t cause much interference. So, an induction coil can be used as a detector coil.

This design also comes in both salt and freshwater versions.


3. Pulse Induction Type

These gold detectors also work on the principle of induction, but they have additional features, including:

  • Automatic tuning control
  • Noise reduction capacity


Thus, they are extra effective for mineral prospecting using metal detectors where ground mineralization interference is high. High mineralization is common in areas where you’re likely to discover gold.


4. Superconducting Quantum Interference Device (SQUID) Type

These gold detectors work on the principle of superconductor technology for high conductivity ores. This design comes in both salt and freshwater versions.


When were metal detectors first used in airports and law courts?

Law courts and airports first used metal detectors for security checks in the 1920s and 1930s. At that time, they were very crude devices compared to today’s machines. A simple detector was created by placing an unbalanced steel weight on a spring with one end attached to a copper plate that rested on the ground.

When people walked across its top, it would swing toward them due to their body resistance. The device was called a ‘wig warm’ because of its shape and size; it looked like two semicircles lying on their sides facing each other.

These ancient metal detectors still apply at low-security facilities. For example, they are common at parking lots, elevators, and museum exhibits, where visitors shouldn’t carry weapons.

The ‘gridiron’ was also popular around that time. It consisted of two strips of thin mica carrying electrical current from a battery and spaced about six inches apart. A person walking across the grid would cause the area between the two strips to become more conductive, completing an electrical circuit that could be heard over a loudspeaker or recorded on graph paper.

It was popular for many years until electronic amplification made it obsolete.

Today’s metal detectors use powerful electromagnets with different frequencies, wave shapes, and pulse rates, allowing them to distinguish between unwanted objects such as weapons, brass knuckles, keys, etc.

Metal detectors can also identify specific metals, depending on their resonant frequency. They hit the metals with a sensor tuned to the resonant frequency.

Another type of metal detector uses radiofrequency waves and pulses, transmitting them through a subject or an area. Receivers electronically pick and analyze the reflected energy from the source.


Final Thoughts

In conclusion, metal detecting is a hobby that allows people to pursue their interests. It can be anything from treasure hunting, artifact collecting, relic hunting, pulling nails out of old buildings, to farming for hidden underground water pipes and cables.

Metal detectors are diverse, but they all have one thing in common: they rely on detecting electromagnetic fields created by materials with higher conductivity than their surroundings. They’re normally used to find various lost metals such as gold nuggets, coins, jewelry pieces, and artifacts.

They’re also essential for law enforcement officers at airports or courts during security checks. The help to catch criminals carrying weapons or other dangerous objects.

In the end, metal detecting is a great hobby, and I recommend trying it out. As you’ve learned in this post, metal detectors have a rich history, and having wireless Bluetooth commands for your metal detector is a deal. You probably won’t appreciate the power of these historical devices if you don’t know how far the technology has come.

When was the metal detector invented
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Shimon Leizerovich
Shimon Leizerovich
I like to Find Gems and Treasures Around My Area, So Enjoy From My Biggest passion, Metal Detecting. I fall in love with the Metal Detecting area, and it connected with me to another hobby I had as a child, that to find gems and "treasures" around me and my area.