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silver treasure. The French law on metal detecting is ambiguous because it refers only to the objective pursued by the user of a metal detector. The first law to regulate the use of metal detectors was Law No. 89–900 of 18 December 1989. This last is resumed without any change in
Article L. 542–1 of the code of the heritage, which states that "no person may use the equipment for the detection of metal objects, for the purpose of research monuments and items of interest prehistory, history, art and archeology without having previously obtained an administrative authorization issued based on the applicant's qualification and the nature and method of research."
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magnetized the ground with a relatively powerful, momentary current through a search coil. In the absence of metal, the field decayed at a uniform rate, and the time it took to fall to zero volts could be accurately measured. However, if metal was present when the machine fired, a small eddy current would be induced in the metal, and the time for sensed current decay would be increased. These time differences were minute, but the improvement in electronics made it possible to measure them accurately and identify the presence of metal at a reasonable distance. These new machines had one major advantage: they were mostly impervious to the effects of
472:"The new law does not prohibit the use of metal detectors but only regulates the use. If the purpose of such use is the search for archaeological remains, prior authorization is required from my services. Apart from this case, the law ask to be reported to the appropriate authorities an accidental discovery of archaeological remains." The entire letter of Jack Lang was published in 1990 in a French metal detection magazine, and then, to be visible on the internet, scanned with permission of the author of the magazine on a French metal detection website.
518:, the Crown has claim over any object of any material value where the original owner cannot be traced. There is also no 300 year limit to Scottish finds. Any artifact found, whether by metal detector survey or from an archaeological excavation, must be reported to the Crown through the Treasure Trove Advisory Panel at the National Museums of Scotland. The panel then determines what will happen to the artifacts. Reporting is not voluntary, and failure to report the discovery of historic artifacts is a criminal offence in Scotland.
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should be possible to design a machine which would detect metal using a search coil resonating at a radio frequency. In 1925 he applied for, and was granted, the first patent for an electronic metal detector. Although
Gerhard Fischer was the first person granted a patent for an electronic metal detector, the first to apply was Shirl Herr, a businessman from Crawfordsville, Indiana. His application for a hand-held Hidden-Metal Detector was filed in February 1924, but not patented until July 1928. Herr assisted Italian leader
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423:. However archaeologists oppose the use of metal detectors by "artifact seekers" or "site looters" whose activities disrupt archaeological sites. The problem with use of metal detectors in archaeological sites or hobbyist who find objects of archeological interest is that the context that the object was found in is lost and no detailed survey of its surroundings is made. Outside of known sites the significance of objects may not be apparent to a metal detector hobbyist.
174:. After much experimenting the best bullet detection range he achieved was only 2 inches (5 centimeters). He then used his own earlier discovery, the partially overlapping 2-coil induction balance, and the detection range increased to 5 inches (12 centimeters). But the attempt was still unsuccessful because the metal coil spring bed Garfield was lying on confused the detector. Bell's 2-coil induction balance would go on to evolve into the popular double D coil.
276:) machine. With the invention and development of the transistor in the 1950s and 1960s, metal detector manufacturers and designers made smaller, lighter machines with improved circuitry, running on small battery packs. Companies sprang up all over the United States and Britain to supply the growing demand. Beat Frequency Induction requires movement of the detector coil; akin to how swinging a conductor near a magnet induces an electric current.
53:. Metal detectors are useful for finding metal objects on the surface, underground, and under water. A metal detector consists of a control box, an adjustable shaft, and a variable-shaped pickup coil. When the coil nears metal, the control box signals its presence with a tone, light, or needle movement. Signal intensity typically increases with proximity. A common type are stationary "walk through" metal detectors used at access points in
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induced a voltage in the secondary coils. When the secondary coils were wired in opposition, the induced voltages cancelled as confirmed by the
Professor holding the ends of the secondary coils. When a piece of metal was placed inside one glass tube the Professor received a shock. This then was the first magnetic induction metal detector, and the first pulse induction metal detector.
163:"electric sonometer". Hughes did much to popularize the induction balance, quickly leading to practical devices that could identify counterfeit coins. In 1880 Mr. J. Munro, C.E. suggested the use of the 4-coil induction balance for metal prospecting. Hughes's coaxial 3-coil induction balance would also see use in metal detecting.
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systems. In 1995 systems such as the Metor 200 appeared with the ability to indicate the approximate height of the metal object above the ground, enabling security personnel to more rapidly locate the source of the signal. Smaller hand held metal detectors are also used to locate a metal object on a person more precisely.
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was wounded in the foot. It was difficult to distinguish between bullet, bone, and cartilage. So
Professor Favre of Marseilles quickly built a simple probe that was inserted into the track of the bullet. It had 2 sharp points connected to a battery and a bell. Contact with metal completed the circuit
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Even with discriminators, it was still a challenge to avoid undesirable metals, because some of them have similar phase responses (e.g. tinfoil and gold), particularly in alloy form. Thus, improperly tuning out certain metals increased the risk of passing over a valuable find. Another disadvantage of
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transmitter, the other as a receiver; in some cases these can be tuned to between 3 and 100 kHz. When metal is in their vicinity, a signal is detected owing to eddy currents induced in the metal. What allowed detectors to discriminate between metals was the fact that every metal has a different
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The metal detecting community and professional archaeologists have different ideas related to the recovery and preservation of historic finds and locations. Archaeologists claim that detector hobbyists take an artifact-centric approach, removing these from their context resulting in a permanent loss
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General metal detecting is very similar to coin shooting except the user is after any type of historical artifact. Detectorists may be dedicated to preserving historical artifacts, and often have considerable expertise. Coins, bullets, buttons, axe heads, and buckles are just a few of the items that
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Outside the research of archaeological objects, using a metal detector does not require specific authorization, except that of the owner of the land. Asked about Law No. 89–900 of 18 December 1989 by a member of parliament, Jack Lang, Minister of
Culture at the time, replied by letter the following:
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published his experiments with the 4-coil induction balance. He used his own recent invention the microphone and a ticking clock to generate regular pulses and a telephone receiver as detector. To measure the strength of the signals he invented a coaxial 3-coil induction balance which he called the
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The sale of metal detectors is allowed in France. The first use of metal detectors in France which led to archaeological discoveries occurred in 1958: people living in the city of
Graincourt-lès-Havrincourt who were seeking copper from World War I bombshell with military mine detector found a Roman
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when exposed to alternating current; longer waves (low frequency) penetrate ground deeper, and select for high-conductivity targets like silver, and copper; than shorter waves (higher frequency) which, while less ground penetrating, select for low-conductivity targets like iron. Unfortunately, high
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On
December 16, 1881, Captain Charles Ambrose McEvoy applied for British Patent No. 5518, Apparatus for Searching for Submerged Torpedoes, &c., which was granted Jun 16 1882. His US269439 patent application of Jul 12 1882 was granted Dec 19 1882. It was a 4-coil induction balance for detecting
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Due to eddy currents induced in the metal, a signal is detected when metal is present. The fact that every metal has a different phase response when exposed to alternating current allowed detectors to differentiate between metals. Longer waves (low frequency) penetrate the ground deeper and select
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by profession, began metal detecting as a pastime in the early 1960s. He tried a number of machines on the market but couldn't find one that could do what he needed. As a result, he started developing his own metal detector. He was able to develop a system that removed oscillator drift, as well as
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Company and
Western Air Express to establish airborne direction finding equipment in the late 1920s. He received some of the first patents in the area of radio-based airborne direction finding. He came across some unusual errors in the course of his work; once he figured out what was wrong, he had
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The sale of metal detectors is allowed in the United States. People can use metal detectors in public places (parks, beaches, etc.) and on private property with the permission of the owner of the site. In the United States, cooperation between archeologists hunting for the location of colonial-era
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had developed a system of radio direction-finding, which was to be used for accurate navigation. The system worked extremely well, but
Fischer noticed there were anomalies in areas where the terrain contained ore-bearing rocks. He reasoned that if a radio beam could be distorted by metal, then it
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The coil configuration is such that it creates an opening whereby the product (food, plastics, pharmaceuticals, etc.) passes through the coils. This opening or aperture allows the product to enter and exit through the three-coil system, producing an equal but mirrored signal on the two receiving
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published an invention he called the "differential inductor". It was a 4-coil induction balance, with 2 glass tubes each having 2 well-insulated copper wire solenoids wound around them. Charged Leyden jars (high-voltage capacitors) were discharged through the 2 primary coils; this current surge
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Coil designers also tried out innovative designs. The original induction balance coil system consisted of two identical coils placed on top of one another. Compass
Electronics produced a new design: two coils in a D shape, mounted back-to-back to form a circle. The system was widely used in the
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evolved in the form of the rectangular gantry now standard in airports. In common with the developments in other uses of metal detectors both alternating current and pulse systems are used, and the design of the coils and the electronics has moved forward to improve the discrimination of these
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governs whether or not items that have been discovered are defined as treasure. Finders of items that the Act defines as treasure must report their finds to the local coroner. If they discover items which are not defined as treasure but that are of cultural or historical interest, finders can
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in the ground. This gave greater depth, but was a non-discriminate mode. It worked best at lower frequencies than those used before, and frequencies of 3 to 20 kHz were found to produce the best results. Many detectors in the 1970s had a switch which enabled the user to switch between the
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At the same time, developers were looking at using a different technique in metal detection called pulse induction. Unlike the beat frequency oscillator or the induction balance machines, which both used a uniform alternating current at a low frequency, the pulse induction (PI) machine simply
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Fisher received the patent for the first portable electronic metal detector in 1925. In 1931, he marketed his first Fisher device to the general public, and he established a famous Fisher Labs company that started to manufacture and develop hand-held metal detectors and sell it commercially.
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Current practice at garment or apparel industry plants is to apply metal detecting after the garments are completely sewn and before garments are packed to check whether there is any metal contamination (needle, broken needle, etc.) in the garments. This needs to be done for safety reasons.
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Modern top models are fully computerized, using integrated circuit technology to allow the user to set sensitivity, discrimination, track speed, threshold volume, notch filters, etc., and hold these parameters in memory for future use. Compared to just a decade ago, detectors are lighter,
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Despite the fact that Fisher was the first to receive a patent for an electronic metal detector, he was only one of many who improved and mastered the device. Charles Garrett, the founder of Garrett Metal Detectors, was another key figure in the creation of today's metal detectors.
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discriminate mode and the non-discriminate mode. Later developments switched electronically between both modes. The development of the induction balance detector would ultimately result in the motion detector, which constantly checked and balanced the background mineralization.
1195:. Electromagnetic technologies have been used in conjunction with ground-penetrating radar. Specially trained dogs are often used to focus the search and confirm that an area has been cleared, mines are often cleared using mechanical equipment such as flails and excavators.
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coils. The search coil works as sensing probe and must be moved over the ground to detect potential metal targets buried underground. When the search coil detects metal objects, the device gives an audible signal via speaker or earphone. In most units, the feedback is an
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Humanitarian demining aims to clear all landmines to a certain depth and make the land secure for human use. Landmine detection techniques have been studied in various forms. Detection of mines can be done by a specially designed metal detector tuned to detect mines and
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Many manufacturers of these new devices brought their own ideas to the market. White's Electronics of Oregon began in the 1950s by building a machine called the Oremaster Geiger Counter. Another leader in detector technology was Charles Garrett, who pioneered the BFO
926:. The design and physical configuration of the receiving coils are instrumental in the ability to detect very small metal contaminates of 1 mm or smaller. Today modern metal detectors continue to utilize this configuration for the detection of tramp metal.
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coils. The resulting signals are summed together effectively nullifying each other. Fortress Technology innovated a new feature, that allows the coil structure of their BSH Model to ignore the effects of vibration, even when inspecting conductive products.
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Metal detectors are also used to search for discarded or lost, valuable man-made objects such as jewelry, mobile phones, cameras and other devices. Some metal detectors are waterproof, to allow the user to search for submerged objects in areas of shallow
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significantly impacted the design of metal detectors as we know them today: lightweight, compact, easy-to-use, and deep-seeking systems. The invention of a tunable induction device was the most significant technological advancement in detectors. Two
214:, Italy, in August 1929. Herr's invention was used by Admiral Richard Byrd's Second Antarctic Expedition in 1933, when it was used to locate objects left behind by earlier explorers. It was effective up to a depth of eight feet. However, it was one
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Jarvi, A, Leinonen, E, Thompson, M, and Valkonen K, Designing Modern Walk-through Metal Detectors, Access Security Screening: Challenges and Solutions, ASTM STP 1127 TP Tsacoumis Ed, American Society for Testing of Materials, Philadelphia 1992,
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900:, and other components made of plastic or elastomers can be manufactured with embedded metallic particles, allowing them to be detected as well. Metal detectors for this purpose are widely used and integrated into the production line.
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developed a 4-coil induction balance to detect unexploded shells in farmland of former battlefields in France. Unusually both coil pairs were used for detection. The 1919 photo at the right is a later version of Gutton's detector.
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adapted mining metal detectors in the 1970s, still housed in a large cylindrical pipe, to make a commercial walk-through security detector. The development of these systems continued in a spin-off company and systems branded as
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The first metal detector was likely the simple electric conduction metal detector ca. 1830. Electric conduction was also used to locate metal ore bodies by measuring the conductivity between metal rods driven into the ground.
1179:, also known as mine removal, is the method of clearing a field of landmines. The aim of military operations is to clear a path through a minefield as quickly as possible, which is mostly accomplished using equipment like
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500:, laws against metal detecting are very strict: it is illegal to use a detection device to search for archaeological objects anywhere within the State or its territorial seas without the prior written consent of the
1391:), particularly in alloy form. As a result, tuning out those metals incorrectly increased the chance of missing a valuable discovery. Discriminators also had the downside of lowering the sensitivity of the devices.
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submerged metallic torpedoes and iron ships and the like. Given the development time involved this may have been the earliest known device specifically constructed as a metal detector using magnetic induction.
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is hunting for lost coins or jewelry on a beach. Beach hunting can be as simple or as complicated as one wishes to make it. Many dedicated beach hunters also familiarize themselves with tide movements and
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When a metal contaminant is introduced into the product an unequal disturbance is created. That creates a very small electronic signal. After suitable amplification a mechanical device mounted to the
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Metal detectors are also used to detect foreign bodies in food, as well as steel reinforcement bars in concrete and pipes. The building industry uses them to find wires buried in walls or floors.
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As the creation and refinement of the device was a wartime military research operation, the knowledge that Kosacki created the first practical metal detector was kept secret for over 50 years.
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The industrial metal detector was developed by Bruce Kerr and David Hiscock in 1947. The founding company Goring Kerr pioneered the use and development of the first industrial metal detector.
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Contamination of food by metal shards from broken processing machinery during the manufacturing process is a major safety issue in the food industry. Most food processing equipment is made of
1216:, a French electrical engineer also had a similar device however his buzzer made a different sound for lead and iron. The electric bullet locators were in use until the advent of X-rays.
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are commonly found by relic hunters; in general the potential is far greater in Europe and Asia than in many other parts of the world. More valuable finds in Britain alone include the
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1970s, and both concentric and double D type (or widescan as they became known) had their fans. Another development was the invention of detectors which could cancel out the effect of
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The biggest technical change in detectors was the development of a tunable induction system. This system involved two coils that are electro-magnetically tuned. One coil acts as an
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developed a portable metal detector in 1925. His model was first marketed commercially in 1931; he was responsible for the first large-scale hand-held metal detector development.
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to operate and became more sensitive but still quite cumbersome. One of the early common uses of the first metal detectors, for example, was the detection of landmines and
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Coin shooting is specifically targeting coins. Some coin shooters conduct historical research to locate sites with potential to give up historical and collectible coins.
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system is signaled to remove the contaminated product from the production line. This process is completely automated and allows manufacturing to operate uninterrupted.
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by Fisher Labs in the 1930s; other companies like Garrett established and developed the metal detectors in terms of technology and features in the following decades.
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interference. This selectivity or discrimination allowed detectors to be developed that could selectively detect desirable metals, while ignoring undesirable ones.
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interference affects high frequency as well. This selectivity or discrimination allowed the development of detectors that can selectively detect desirable metals.
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The first metal detector proved inductance changes to be a practical metal detection technique, and it served as the prototype for all subsequent metal detectors.
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In 1926, two Leipzig, Germany scientists installed a walk-though enclosure at a factory, to ensure that employees were not exiting with prohibited metallic items.
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Metal detectors are widely used in archaeology with the first recorded use by military historian Don Rickey in 1958 who used one to detect the firing lines at
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soil; in some cases the heavy mineral content may even help the PI detector function better. Where a VLF detector is affected negatively by soil
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The first industrial metal detectors came out in the 1960s. They were used for finding minerals among other things. Metal detectors help find
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Graves M, Smith A, and Batchelor B 1998: Approaches to foreign body detection in foods, Trends in Food Science & Technology 9 21-27
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The difference between archaeology and looting, explained Brian Jones, Connecticut's state archaeologist, is the recording of context.
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Even with discriminators, avoiding undesirable metals was difficult because some of them have similar phase responses (for example,
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The basic principle of operation for the common industrial metal detector is based on a 3-coil design. This design utilizes an AM (
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Metal detecting clubs exist for hobbyists to learn from others, show off finds from their hunts and to learn more about the hobby.
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One particular advantage of using a pulse induction detector includes the ability to ignore the minerals contained within heavily
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In the 1960s, the first industrial metal detectors were produced, and they were widely used for mineral prospecting and other
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State-of-the-art metal detectors have further incorporated extensive wireless technologies for the earphones, connect to
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many special search coils that he patented, both of which effectively revolutionized metal detector design at the time.
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488:. It is also illegal to remove an archaeological object found with a detector from such a site without written consent.
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and rang the bell. In 1867 Mr. Sylvan de Wilde had a similar detector and an extractor also wired to a bell. In 1870
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initially used a 4-coil induction balance to attempt to locate a bullet lodged in the chest of American President
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led the United States in 1972 to adopt metal detector technology to screen airline passengers, initially using
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1590:"Sur une balance d'induction destinée à la recherche des obus enterrés dans les terrains à mettre en culture"
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Connor, Melissa; Scott, Douglas D. (1 January 1998). "Metal Detector Use in Archaeology: An Introduction".
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locator technology to keep track of searching location and the location of items found. Some connect to
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metal detecting is legal provided that the landowner has granted permission and that the area is not a
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In 1892 George M. Hopkins described an orthogonal 2-coil induction balance for metal detecting.
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the foresight to apply the solution to a totally unrelated area, metal and mineral detection."
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was one of the first customers of Goring Kerr using their Metlokate metal detector to inspect
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2231:"A chronological account of the development of treasure and gold locators from 1830 to 1930"
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1457:"Ueber die durch Magnetisiren des Eisens vermittelst Reibungselektricität inducirten Ströme"
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Hobbyists often use their own metal detecting lingo when discussing the hobby with others.
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Outline of the Scientific Accomplishments of the Byrd Antarctic Expedition II, 1933-1935
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1937:"A Guide to Metal Detecting, Archaeology and the Law | Department for Communities"
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serve as evidence against allowing unsupervised metal detecting in historic locations.
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1955:"Advice for finders of treasure in Northern Ireland | Department for Communities"
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An early metal detector, in 1919, used to find un-exploded bombs in France after
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Alexander Graham Bell: The Life and Times of the Man Who Invented the Telephone
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before emigrating to the United States. When working as a research engineer in
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The Polish Contribution to The Ultimate Allied Victory in The Second World War
1489:"On an Induction-Currents Balance, and Experimental Researches made therewith"
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1536:"Alexander Graham Bell's 1881 efforts to help save President Garfield's Life"
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The metal detectors were first invented and manufactured commercially in the
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to clear the minefields of the retreating Germans, and later used during the
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1923:"Detecteur-de-metaux.com - Or natif et trésor - Conseils et guide d'achat"
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Fisher, the founder of Fisher Research Laboratory, was contracted by the
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The most common type of metal detector is a hand-held metal detector or
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Politics and conflicts in the metal detecting hobby in the United States
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There are various types of hobby activities involving metal detectors:
594: in this section. Unsourced material may be challenged and removed.
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discriminators was that they reduced the sensitivity of the machines.
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2042:"The Fundamentals of Electronic Prospecting :: goldgold.com"
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Exposing mines planted during the war or after the end of the war
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of historical information. Archaeological looting of places like
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deeper-seeking, use less battery power, and discriminate better.
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The modern development of the metal detector began in the 1920s.
1576:"Unscientific and Scientific Divining Rods", George M. Hopkins,
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Electronic instrument which detects the presence of metal nearby
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that were originally designed for logging operations to detect
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The design invented by Kosacki was used extensively during the
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deal primarily with the United States and do not represent a
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tuned coils were used in this method. One coil serves as an
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Native American villages and hobbyists has been productive.
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in concrete and pipes and wires buried in walls and floors.
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Hand-held metal detectors can be used to search people for
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1753:"Archaeologists and Metal Detectorists Find Common Ground"
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in a number of European countries following the First and
555:"Detectorist" redirects here. For the comedy series, see
2289:"The History of the Metal Detector | MetalDetector.com"
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Colin King (Editor), Jane's Mines and Mine Clearance,
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Initially these machines were huge and complex. After
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The simplest form of a metal detector consists of an
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that passes through a coil producing an alternating
221:, a Polish officer attached to a unit stationed in
1519:"Prospecting metal veins by the Induction Balance"
1506:"Professor Hughes Induction Balance and Sonometer"
1343:, discriminators, modern search coil designs, and
1251:detection finders. Fisher shared the concept with
704:in their natural forms, such as nuggets or flakes.
1123:invented the triode in 1907 metal detectors used
158:In late 1878 and early 1879 Professor (of music)
1606:"Detecting Buried Shells with Induction Balance"
1477:A Treatise on Electricity in Theory and Practice
502:Minister for Culture, Heritage and the Gaeltacht
1011:In civil engineering, special metal detectors (
37:soldiers use a military standard metal detector
304:applications to further extend functionality.
787:The examples and perspective in this section
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1804:"Treasure Act 1996 – Coroners jurisdiction"
1782:"Treasure Act 1996 – Meaning of "treasure""
1084:. Unsourced material may be challenged and
979:. Unsourced material may be challenged and
720:gold, sold for ÂŁ3,285,000, the gold Celtic
383:Large portable metal detectors are used by
2321:. New York: Harry N. Abrahms, Inc., 1997.
1973:"Archaeology and treasure | nidirect"
1651:: CS1 maint: location missing publisher (
1612:, 1915 Nov 13, front cover & page 425.
1549:"APPARATUS FOR FINDING TORPEDOES, &c."
1493:Proceedings of the Royal Society of London
805:, or create a new section, as appropriate.
233:, who refined the design into a practical
1104:Learn how and when to remove this message
999:Learn how and when to remove this message
821:Learn how and when to remove this message
654:Learn how and when to remove this message
2317:Grosvenor, Edwin S. and Wesson, Morgan.
1142:Metal detectors can be used for several
1991:"The Law on Metal Detecting in Ireland"
1449:
206:in recovering items remaining from the
1904:
1893:
1857:
1644:
1561:"McEvoy's Electric Submarine Detector"
1296:purposes. De-mining (the detection of
443:(SSSI), or covered by elements of the
322:frequency is also sensitive to ground
229:, Scotland, during the early years of
2057:"Finding Jewelry with Metal Detector"
296:devices. Some also utilize built in
7:
2217:"Company | Fortress Technology"
2178:from the original on 23 October 2016
1082:adding citations to reliable sources
977:adding citations to reliable sources
692:is looking for valuable metals like
592:adding citations to reliable sources
547:A man metal detecting on a beach in
459:and the UK Detector Finds Database.
49:that detects the nearby presence of
2040:Dave McCracken (23 November 2011).
1751:Tyler J. Kelley (16 January 2017).
1364:for high conductivity targets like
1328:are just some of the applications.
1153:Detecting dangerous explosives and
441:site of special scientific interest
670:This 156-troy-ounce (4.9 kg)
391:to locate metallic items, such as
25:
2119:"The History of Airport Security"
2071:"Metal Detecting Jargon Glossary"
2055:Scott Clark (30 September 2012).
1666:Croll, Mike; Cooper, Leo (1998).
1641:. Worthing, England. p. 221.
1463:, 1841 series 2 vol 54, page 305.
512:Under the Scots law principle of
2272:"A new method of probing wounds"
2102:"The Radio Watchman at the Gate"
1360:ranging from 3 to 100 kHz.
1054:
949:
778:
568:
107:. They also detect weapons like
2256:"An ingenious bullet detector "
2197:Pehanich, Mike (16 July 2007).
2108:, April 1926, pages 1408, 1493.
840:Petersburg National Battlefield
748:and thousands of smaller finds.
579:needs additional citations for
455:voluntarily report them to the
244:when 500 units were shipped to
2104:, April 1926, Dr. K. Schuett,
1495:, 1879 May 15 vol 29, page 56.
445:Countryside Stewardship Scheme
1:
2123:savvytraveler.publicradio.org
1759:. No. The New York Times
1461:Annalen der Physik und Chemie
1401:List of metal detecting finds
2147:"Industrial metal detectors"
1596:, 1915 July 26, pages 71-73.
411:buried beneath the surface.
2027:www.metaldetectingworld.com
1551:, C. A. McEvoy, 1882 Dec 19
1438:Portable Antiquities Scheme
1335:Discriminators and circuits
1157:dangerous to people's lives
801:, discuss the issue on the
457:Portable Antiquities Scheme
242:Second Battle of El Alamein
2388:
2199:"Detecting Foreign Matter"
1995:National Museum of Ireland
1692:"How Metal Detectors Work"
1637:Modelski, Tadeusz (1986).
1491:, Professor D. E. Hughes,
890:Industrial metal detectors
554:
486:Department for Communities
437:Scheduled Ancient Monument
2009:"Treasure Trove Scotland"
1867:Cite uses generic title (
1670:. Pen & Sword Books.
856:Berlin Schönefeld Airport
274:beat frequency oscillator
250:Allied invasion of Sicily
210:galleys at the bottom of
115:, which is important for
2168:"History of Goring Kerr"
1668:The History of Landmines
1567:, 1882 Aug 18, page 154.
1376:. Unfortunately, ground
1207:In 1862 Italian General
267:Beat frequency induction
254:Allied invasion of Italy
246:Field Marshal Montgomery
2372:19th-century inventions
2244:Morning Herald (London)
1580:, 1892 Aug 20, page 114
1525:, 1880 Jan 17, page 103
1479:, 1853 vol I, page 424.
1235:Gerhard Fisher studied
403:and other accessories,
219:Józef Stanisław Kosacki
135:History and development
2278:, 1870 Jan 19, page 45
1903:Cite journal requires
1882:"Le Prospecteur" (5).
1707:Historical Archaeology
1475:, Auguste de la Rive,
1220:Technology development
1035:or digital indicator.
876:. The Finnish company
858:
679:
552:
147:
129:steel reinforcing bars
38:
2293:www.metaldetector.com
2262:, 1867 July, page 457
2246:, 1862 Nov 13, page 5
1241:University of Dresden
1015:) are used to locate
883:Metor Metal Detectors
853:
738:Crosby Garrett Helmet
730:West Bagborough Hoard
669:
546:
168:Alexander Graham Bell
152:Heinrich Wilhelm Dove
142:
125:construction industry
67:psychiatric hospitals
33:
2023:"Coin Shooting Tips"
1979:. November 12, 2015.
1943:. November 12, 2019.
1350:electro-magnetically
1300:), the detection of
1078:improve this section
973:improve this section
799:improve this section
588:improve this article
407:, and other various
375:, a PI unit is not.
258:Invasion of Normandy
235:Polish mine detector
73:on a person's body.
69:to detect concealed
2233:. 23 November 2011.
2219:. 10 November 2016.
1977:www.nidirect.gov.uk
1961:. November 8, 2019.
1925:. 30 December 2021.
1622:Poulter, Thomas C.
1610:Scientific American
1578:Scientific American
1345:wireless technology
1339:The development of
1281:electrical engineer
920:amplitude modulated
866:aircraft hijackings
854:Metal detectors at
734:Milton Keynes Hoard
714:Staffordshire Hoard
498:Republic of Ireland
492:Republic of Ireland
193:Modern developments
160:David Edward Hughes
82:alternating current
2357:1881 introductions
2203:foodprocessing.com
1757:The New York Times
1719:10.1007/BF03374273
1419:Television series)
1209:Giuseppe Garibaldi
1172:War mine detection
1133:Second World Wars.
1017:reinforcement bars
859:
846:Security screening
680:
553:
208:Emperor Caligula's
184:In 1915 Professor
150:In 1841 Professor
148:
39:
1826:"Report Treasure"
1677:978-0-85052-628-8
1312:(particularly in
1260:Federal Telegraph
1138:Uses and benefits
1114:
1113:
1106:
1009:
1008:
1001:
941:Civil engineering
909:Mars Incorporated
831:
830:
823:
664:
663:
656:
638:
544:
452:Treasure Act 1996
433:England and Wales
427:England and Wales
92:will be induced (
16:(Redirected from
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1521:, Mr. J. Munro,
1516:
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1496:
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1454:
1423:Inductive sensor
1326:treasure hunting
1314:airport security
1129:unexploded bombs
1109:
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603:"Metal detector"
596:
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482:Northern Ireland
476:Northern Ireland
389:treasure hunters
334:New coil designs
204:Benito Mussolini
121:treasure hunting
117:airport security
94:inductive sensor
21:
2387:
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2367:Metal detecting
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2174:. 27 May 2012.
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1471:
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1271:Charles Garrett
1253:Albert Einstein
1230:Gerhard Fischer
1227:
1225:Gerhard Fischer
1222:
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898:stainless steel
892:
874:spikes in trees
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674:, known as the
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421:Little Big Horn
417:
401:clothes buttons
381:
350:
348:Pulse induction
336:
310:
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269:
199:Gerhard Fischer
195:
137:
28:
23:
22:
18:Metal detectors
15:
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1905:|journal=
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1694:. 23 May 2001.
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1594:Comptes Rendus
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1497:
1481:
1465:
1459:, H. W. Dove,
1448:
1447:
1445:
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1441:
1440:
1435:
1433:Magnet fishing
1430:
1428:Induction loop
1425:
1420:
1408:
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1396:
1393:
1378:mineralization
1354:RF transmitter
1336:
1333:
1289:
1288:To present day
1286:
1272:
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1249:aircraft radio
1226:
1223:
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1214:Gustave Trouvé
1200:
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1019:inside walls.
1007:
1006:
957:
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793:of the subject
791:worldwide view
786:
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749:
746:Collette Hoard
742:Stirling Hoard
726:Ringlemere Cup
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385:archaeologists
380:
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373:mineralization
355:mineralization
349:
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341:mineralization
335:
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324:mineralization
319:phase response
309:
308:Discriminators
306:
281:
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268:
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194:
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186:Camille Gutton
172:James Garfield
136:
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86:magnetic field
43:metal detector
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2338:0-7106-2555-3
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1852:www.louvre.fr
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1145:
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1121:Lee de Forest
1117:
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1063:This section
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1040:United States
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958:This section
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644:November 2013
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577:This section
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522:United States
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515:bona vacantia
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19:
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2296:. Retrieved
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2172:Goring Kerr
2091:. NBC News.
1959:Communities
1941:Communities
1832:18 February
1810:18 February
1788:18 February
1565:Engineering
1358:frequencies
1341:transistors
1322:archaeology
1318:geophysical
1245:Los Angeles
1237:electronics
1185:blast waves
1094:August 2023
989:August 2023
924:transmitter
722:Newark Torc
718:Anglo-Saxon
690:Prospecting
672:gold nugget
415:Archaeology
369:mineralized
359:mineralized
280:Refinements
145:World War I
59:courthouses
2351:Categories
2311:References
2260:The Lancet
2152:22 October
2106:Radio News
1763:21 January
1294:industrial
1199:First idea
1181:mine plows
1166:explosives
836:Slack Farm
614:newspapers
531:As a hobby
362:black sand
302:smartphone
223:St Andrews
216:Lieutenant
127:to detect
105:land mines
78:oscillator
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1888:1169-3835
1735:163861923
1647:cite book
1298:landmines
1065:does not
960:does not
913:Mars bars
878:Outokumpu
811:June 2013
803:talk page
409:artifacts
294:Bluetooth
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2176:Archived
1860:cite web
1727:25616646
1395:See also
1304:such as
1177:Demining
1046:Military
935:conveyor
797:You may
736:, Roman
508:Scotland
256:and the
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2362:Hobbies
2136:pp21-25
1385:tinfoil
1302:weapons
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1162:weapons
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1071:sources
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635:JSTOR
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397:coins
290:Wi-Fi
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2323:ISBN
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