This **cast iron telephone** was used for communication in the mines underground. Its resistant and heavy material make it **explosion-proof** and robust so that it can take the sometimes rough conditions in the underground operation. This is especially important because of the **risk of explosions** due to mine gas.
Location: [Nederlands Mijnmuseum](http://https://www.nederlandsmijnmuseum.nl/) in Heerlen
created by: Theresa, Geulen