Paris pneumatic post

The Paris pneumatic post was a pneumatic tube message-carrying service that operated in the French capital from 1866. It was established because of the popularity of the electric telegraph in the city which had led to the signal cables becoming overloaded and messages being sent by road. The pneumatic system allowed the telegraph companies to send messages underground through sealed lines laid in the Paris sewers, bypassing any traffic on the roads above. The network was taken into public ownership in 1879, under the Ministry of Posts and Telegraphs, and opened to messages sent by the general public. Messages continued to be considered officially as telegrams and for a fixed cost users could write a message on a "petit bleu" form to be sent anywhere in the city. After arriving at the office nearest the recipient it would be taken to their address by a courier.

Originally driven by steam-powered vacuum pumps and compressors the network was modernised to electricity-driven machinery from 1927. The Paris pneumatic post reached its greatest extent in 1934 with 427 kilometres (265 mi) of pneumatic pipes and 130 offices in service. The number of messages sent peaked in 1945 at 30 million. Budget restrictions from 1945 hampered the network as maintenance and upgrades were cut. With declining usage the network was closed in 1984. A parallel system operated for official purposes and connected several government buildings. Part of this network, connecting the senate, national assembly and officers of the Journal Officiel de la République Française, survived in use until 2004.