@ Rolf,

Moin Moin,

vieleicht hilft Dir das weiter:

The practice of loading mail into canisters and shooting them through tubes with compressed air dates back to the nineteenth century. A pneumatic line linked the London Stock Exchange and a telegraph company in 1853, and there was a pneumatic telegraph and mail system in London soon after. By 1909, there were more than 40 miles of pneumatic tubes running under London, and pneumatic mail in Birmingham, Liverpool, Manchester, Newcastle, Glasgow and Dublin.

Gruß Carsten