'Pneumatic Tubes, Instrument Gallery', 1874.

Plate taken from the Illustrated London News, showing men at work in the Instrument Gallery at the Central Telegraph Establishment of the General Post Office (GPO), in London. In the 19th century, pneumatic tubes were used to deliver mail within, or in some cases between, buildings by means of compresed air or a partial vacuum. In London, the Post Office set up a pneumatic tube system for telegraph mesages in 1853. In New York City, from the 1890s, pneumatic tubes were used to carry letters between the Brooklyn and New York City post offices, a distance of 1.75 miles.