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Poulsen Telegraphone, 1898

Valdemar Poulsen, Danish telephone engineer and inventor, patented the Telegraphone in 1898. It was the first practical apparatus for magnetic sound recording and reproduction. It recorded, on a wire, the varying magnetic fields produced by sound. The magnetized wire could then be used to play back the sound.
The Telegraphone received considerable attention when it was exhibited at the Exposition Universelle in Paris in 1900. The few words that the Austrian emperor Franz Joseph spoke into it at that exhibition are believed to be the earliest surviving magnetic recording (sound excerpt).

Valdemar Poulsen (1869 - 1942)

Valdemar Poulsen

Valdemar Poulsen, son of a Danish High Court judge was born 23rd November 1869. At the age of 24, he obtained a position in the technical section of the Copenhagen Telephone Company. There seems to be no record of what gave Poulsen the idea of magnetising steel wire to make sound recordings. Maybe he had read an article written in 1888 by American scientist Oberlin Smith for the magazine Electrical World, where he discussed the possibility of permanent magnetic impressions for recording sound and suggested, as a medium, cotton or silk thread, in which steel dust was suspended. Smith also considered steel wire but didn't think it would be possible to establish a magnetic pattern as a replica of currents produced by a microphone. Smith never built a machine or proved his theory practically.
On 1st December 1898, Poulsen filed a patent in Denmark for the Telegraphone, the first device in history to use magnetic sound recording.
Another of Poulsen's devices may be said to be the original version of the hard disk. It consisted of a 4.5 inch diameter steel disk with a raised spiral on the surface which was traced by the electromagnet as the disk rotated
That the idea of recording sound magnetically was Poulsen's alone is proven by the fact that nobody else has ever claimed credit for the invention. Wire recording, tape recording, hard disk, floppy disk, credit cards and train tickets - Poulsen had them all covered in his UK Patent No 8961, that was published in 1899.

Related topics:
Magnetic tape
Hard disk
Floppy disk