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//Source(s): The Pneumatic Post of Paris by J.D. Hayhurst O.B.E. Edited by C.S. Holder Prepared in digital format by Mark Hayhurst Copyright1974. The France & Colonies Philatelic Society of Great Britain.// "Today, the pneumatic post survives only in Paris and Italy. Pneumatic tubes are still however widely used for the transport inside many cities of the world of small batches of telegrams, express letters and air mail letters. These tubes are generally of a diameter of about 3 inches and the messages are carried in cylinders which are propelled along the tube by an air pressure differential from the back to the front, attaining speeds of around 25 mph. "Letters and cards which have been transported in the tubes are invariably creased where they have been rolled up for insertion in a cylinder. "The Most Famous Pneu in History "For generations the pneumatic letter-card was known affectionately as the petit bleu since, between 1897 and 1902, it was on blue paper and it was under this name that a 'Telegramme' was a vital piece of evidence in the enquiries which led to the eventual acquittal of Dreyfus. At a court-martial in December 1894 he had been found guilty of passing military secrets to the Germans and was transported to Cayenne. In 1896 the contents of a waste paper basket in the office of Schwartzkoppen, the German military attache in Paris, were taken to the French Intelligence Staff and found to include a torn-up pneu which had never been sent. "When pieced together, it was found that the petit bleu contained a message to another French officer, Esterhazy, implicating him in the offences attributed to Dreyfus. Thus started the chain of events which culminated in 1906 with the ceremonial restoration of his commission to Dreyfus in that courtyard of the Ecole Militaire lying just behind the Pavillon de l'Artillerie which had housed the telegraph office Ecole Militaire until its closure in 1891. "The standard work in France on the pneumatic post is 'Cent ans de tubes pneumatiques' J Boblique, Echo de la Timbrologie, 1966. "The engineering aspects of the service are recounted in 'Le rseau pneumatique de Paris' M Gaillard, Revue des PTT de France, 1, 1959." Mark Hayhurst (Mark.Hayhurst@unilever.com)
 * Dead medium: the pneumatic post**
 * From: Mark.Hayhurst@unilever.com (Mark Hayhurst)**