It was autumn 1861. Philipp Reis was standing in his living room in the small Hessian town of Friedrichsdorf near Frankfurt am Main. In front of an interested audience, he presented a device with which sounds and the human voice could be transmitted over a distance. Reis had laid a long wire from the living room over the plum tree in the garden to a barn, where his brother-in-law was the assistant operating the device.
The audience in the living room was to immediately witness the first documented telephone conversation in history. A year earlier, the physics teacher Reis (1834–1874), who was passionate about making models for school lessons in his free time, had presented the device to his colleagues – he called the device the “telephone”. At that time, however, it still had one major shortcoming: sounds and melodies could be transmitted, but human language could not be understood.
A physics teacher built the forerunner of the telephone
With his invention, Reis tried to replicate the workings of the human ear. His prototypes consisted of a bell over which he stretched a piece of natural gut. On top of this type of eardrum, Reis had placed a strip of platinum, essentially the auditory ossicles, connected to an electrical circuit. Sound waves caused the membrane to vibrate, which was transmitted through the platinum plate into the circuit.
On the other side, the opposite end, was a coil of copper wire with a knitting needle attached. The changing magnetic field of the coil caused the knitting needle to move, thus transmitting the sound signal. However, the “talking knitting needle,” as Reis called it, was fairly quiet, so the signal had to be amplified. A music teacher friend of mine helped solve this problem. During a visit, the musician had his violin with him. And when the two teachers laid the knitting needle on the instrument, the violin proved to be an excellent resonance body.