Many different approaches to record sound with magnetic recording for were developed over the years since the first demonstration of magnetic recording on steel wires by Danish inventor, Vladimir Poulsen, sometime between 1893 and 1898.

FORBES: Magnetic Tape Turns 60

Note that an American, Oberlin Smith, described how magnetic recording could be done on magnetic impregnated thread or steel wire in 1888.

FORBES: Magnetic Tape Turns 60

Imagine travelling from Miami, Florida to Chattanooga, Tennessee, and changing in Atlanta from a steel-wheeled fast train to a magnetic levitation one.

BBC: The futurist: Putting the choo-choo back in Chattanooga