Editing Alexander Graham Bell (section)

===Metal detector===
[[File:Telephone Inventor’s Voice Heard in Restored Recording « Science World.theora.ogv|thumb|Bell's voice, from a Volta Laboratory recording in 1885. Restored by the Smithsonian in 2013.]]

Bell is also credited with developing one of the early versions of a [[metal detector]] through the use of an induction balance, after the [[Assassination of James A. Garfield|shooting]] of [[President of the United States|U.S. President]] [[James A. Garfield]] in 1881. According to some accounts, the metal detector worked flawlessly in tests but did not find [[Charles J. Guiteau|Guiteau]]'s bullet, partly because the metal bed frame on which the President was lying disturbed the instrument, resulting in static.{{sfn|Grosvenor|Wesson|1997|p=107}} Garfield's surgeons, led by self-appointed chief physician [[Doctor Willard Bliss]], were sceptical of the device, and ignored Bell's requests to move the President to a bed not fitted with metal springs.{{sfn|Grosvenor|Wesson|1997|p=107}} 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.{{sfn|Grosvenor|Wesson|1997|p=107}}

Bell's own detailed account, presented to the [[American Association for the Advancement of Science]] in 1882, differs in several particulars from most of the many and varied versions now in circulation, by concluding that extraneous metal was not to blame for failure to locate the bullet. Perplexed by the peculiar results he had obtained during an examination of Garfield, Bell "proceeded to the [[White House|Executive Mansion]] the next morning&nbsp;... to ascertain from the surgeons whether they were perfectly sure that all metal had been removed from the neighborhood of the bed. It was then recollected that underneath the horse-hair mattress on which the President lay was another mattress composed of steel wires. Upon obtaining a duplicate, the mattress was found to consist of a sort of net of woven steel wires, with large meshes. The extent of the [area that produced a response from the detector] having been so small, as compared with the area of the bed, it seemed reasonable to conclude that the steel mattress had produced no detrimental effect." In a footnote, Bell adds, "The death of President Garfield and the subsequent ''post-mortem'' examination, however, proved that the bullet was at too great a distance from the surface to have affected our apparatus."<ref>{{Cite journal |last=Bell |first=Alexander Graham |date=1882 |title=Upon the electrical experiments to determine the location of the bullet in the body of the late President Garfield; and upon a successful form of induction balance for the painless detection of metallic masses in the human body |journal=American Journal of Science |volume=25 |issue=145 |pages=22–61 |url=https://archive.org/details/uponelectricalex00bell |access-date=April 29, 2013 |bibcode=1883AmJS...25...22B |doi=10.2475/ajs.s3-25.145.22 |s2cid=130896535 }}</ref>