Pneumatic mail of the 19th century
Since the middle of the 19th century, pneumatic mail has become widespread in many major cities of Europe and America. The post office stations were connected by underground pipes, in which capsules with letters were moved by means of compressed or rarefied air. Gradually, with the development of new technologies, the pneumatic mail systems were closed. The last of them operated in Prague before the flood of 2002, although they are now engaged in its restoration.
