The pneumatic tube room in the The Central Telegraph Office, St Martinˇs Le Grand, London, England in the late 19th century. The room was linked to almost all of the central London post offices by a pneumatic tube. By placing a telegram awaiting dispatch into a container, that resembled a 25lb shell case covered in felt like material, it was possible to send the telegram via an underground tube direct to the CTO or the smaller tube officer located in the basement of King Edward Building, for dispatch. From Living London, published c.1901