Metal Detector First Used By Alexander Graham Bell
Toward the end of the 19th century, many scientists and engineers used their growing knowledge of electrical theory in an attempt to devise a machine which would pinpoint metal.
The use of such a device to find ore-bearing rocks would give a huge advantage to any miner who employed it. The German physicist Heinrich Wilhelm Dove invented the induction balance system, which was incorporated into metal detectors a hundred years later. Early machines were crude, used a lot of battery power, and worked only to a very limited degree. Alexander Graham Bell used such a device to attempt to locate a bullet lodged in the chest of American President James Garfield in 1881; the attempt was unsuccessful because the metal coil spring bed Garfield was lying on confused the detector.
Bell is also credited with the invention of the metal detector in 1881. The device was quickly put together in an attempt to find the bullet in the body of U.S. President James Garfield. The metal detector worked flawlessly in tests but did not find the assassin's bullet partly because the metal bed frame on which the President was lying disturbed the instrument, resulting in static. The president's surgeons, who were skeptical of the device, ignored Bell's requests to move the president to a bed not fitted with metal springs. Alternatively, although Bell had detected a slight sound on his first test, the bullet may have been lodged too deeply to be detected by the crude apparatus. Bell gave a full account of his experiments in a paper read before the American Association for the Advancement of Science (AAAS) in August 1882.