The wire recorder was the first practical recording device to use a magnetic medium to store information.
The technology was originated by a Dane, Valdemar Poulsen, in 1898. He called his invention the telegraphone, since it combined some of the electrical and physical traits of the telegraph with the audio recording principle of Edison's phonograph. His first version used a piano wire stretched across his laboratory, and two different trolleys that could be run down its length - one for recording, one for playback. In order to record something, one had to walk alongside the trolley while speaking into the microphone. Not surprisingly, he had a bit of trouble finding venture capital to fund commercial development of that idea.
The next incarnation of the 'telegrafoon', as it was called in Denmark, borrowed a little more from Edison. It used a wire spirally wrapped on a cylinder, so the distance that the recording and playback devices had to travel was much reduced.
Eventually, Poulsen figured out that he could leave the electromagnetic heads stationary and wrap the moving wire on spools, but by the time his invention was becoming commercially viable, he was off to other pursuits in telephony and radio.
The wire recorder had better frequency response and environmental tolerance than the wax cylinders in use in the early 20th century, and soon became the technology of choice for field recording. Many of the century's most important audio recordings are on wire.
Over the decades, many improvements have been made upon Poulsen's idea of recording with ferrous materials and electromagnets. First steel ribbons, then disks. Later, people learned to coat other media, like belts and tapes, with ferrous oxides, and to store other types of information on them.
The wire recorder has been supplanted by superior refinements, but the inspired notion on which it was based is still very much in use today. Thank Valdemar Poulsen for your hard drive, and the cheap, compact information storage that makes such wonders as E2 possible.