Behind the scenes of the Teylers Museum
Guglielmo Marconi made wireless telegraphy possible in 1895, after experimenting for years with transmitting electromagnetic waves over ever greater distances. The curator of the Physics Cabinet, Elisa van der Ven, purchased this demonstration set without a moment's hesitation in 1897, and was soon demonstrating it to an enthralled audience in Teylers' auditorium. An eye witness recalls the secene:
"There was a silence, a collective holding of breath, as we waited to see if the experiment would succeed. Then we heard the tick-tock of one set followed immediately by the tick-tock of the other one, and suddenly the auditorium erupted with loud applause, since now we could believe and understand it, we had seen and heard that what had seemed almost impossible was possible after all."
The transmitter - This is how it works
This so-called ‘Righi-transmitter’ (image above) is part of the equipment that was purchased by Teylers Museum in 1897 to demonstrate the transmission of Morse signs by radio waves. Two years earlier the Italian Guglielmo Marconi (1874-1937) was the first to succeed in the transmission. Two metal spheres are connected to an induction coil, which produces a high alternating voltage with a high frequency. The spheres close off an ebonite cylinder containing vaseline oil. The high-frequency voltage discharges between the spheres, straight through the oil. Because of this the device emits electromagnetic waves. With a Morse key these radio waves can be interrupted and a message in Morse signs can be transmitted. Wireless telegraphy was realized. In 1902 a distance of 50 metre was bridged with this device.
The receiver - This is how it works
This receiver for radio waves, a so-called ‘Marconi-coherer’, is part of the equipment that was purchased by Teylers Museum in 1897 to demonstrate the transmission of Morse signs. Two years earlier the Italian Guglielmo Marconi (1874-1937) was the first to succeed in the transmission. The central part of the ‘coherer’ consists of a glass tube with metal powder that becomes conductive as soon as the electric circuit to which the powder belongs, resonates with the received radio waves. In the thus formed magnetic field, the metal particles will form a string and an electric circuit is closed. An electromagnet, energized by this, pushes a pencil onto a moving paper tape of a telegraph. When the radio signal stops, the electromagnet falls back: the metal powder is tapped and the original, insulating condition restored.
Instruments by R. Erneceke after a design by Guglielmo Marconi (1874-1937). Transmitter & receiver for wireless telegraphy, 1897.