PRAGUE PNEUMATIC TUBE MAIL SYSTEM'S 100th ANNIVERSARY
By Henry Hahn, Fairfax, USA

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On March 4th, the Prague Pneumatic Mail System reached its 100th anniversary of public service. It's not the world's first such system, nor is it the world's largest. You might say „so what?" Here is „WHAT". It is the world's ONLY system still operating without major technical change. Its role has changed - it is no longer available to the general public - but the pipes and equipment installed between 1923 and 1929 serve its subscribers, mainly banks, industry, government offices, hospitals and also the regular post offices. Its 60-kilometer network of pipes carries messages or small items in canisters at a speed of 38 kilometers per hour at a cost of about 10c per dispatch on top of a monthly subscription fee which differs from subscriber to subscriber.
The system has survived the invention of the telephone, FAX and e-mail, none of which can transmit currency, signed documents, laboratory specimens or other items generally delivered by couriers on bicycles.

The network of tubes is configured in the form of a star and all mail passes the same central station in the post office on Jindrisska Street which was also the central station a century ago. Entering the "dispatch room" one feels like stepping back in time. Along one wall of the system's nerve center stands a row of brass and black steel tubes and hatches. Each tube is fitted with a display of lights that blink different colors to indicate the tube's status. A pressure gauge is located on top of the apparatus. Below the receiving tubes sit sturdy dispatch hatches labeled with engraved and painted brass plaques bearing the clients' names. In the system's heyday in the 60's and 70's about one million canisters per year passed through the network. Today the system handles 8,000 to 9,000 canisters per month. 

The system tubes have an inside diameter of 65 mm and a wall thickness of 2.5-3.0 mm. The canisters are made of alloyed aluminum with an outside diameter of 48 mm and a length of 200 mm. The end of each canister is equipped with a soft seal to prevent air escaping between the outside of the canister and the tube wall. Each canister is also equipped with a plastic ring to reduce friction between the alloy aluminum and the tube wall. Hence the over-all diameter of the canister with seal is 57 mm and the total length is 300 mm. The empty canister weighs 0.4 kilograms and can carry weights up to 3 kilograms. The tubes are buried 80 - 120 centimeters below ground and are wound with a 20 cm wide tape for corrosion protection. Each branch of the system leading to the various districts is equipped with a separate air compressor. Each compressor delivers about 5 cubic meters of air per minute. The compressors are reversible and can produce pressure to drive the canister or create a vacuum in front of the canister. Due to the age of the equipment, spare parts are generally not available and must be manufactured, along with canisters, by the system operators.

The system is fast compared to couriers, and perfectly reliable. Unique in Europe, negotiations are currently under way to designate the system as a "National Technical Heritage". 
The pneumatic mail system that opened to the public in 1899 consisted of just three stations, emanating from the main post office on Jindrisska Street. It was modeled after the Vienna system, which opened in 1875.
The philatelic aspects of Vienna and Prague pneumatic mails have been covered and illustrated elsewhere.

The Society for Czechoslovak Philately will commemorate this significant anniversary at its annual convention and show, which will take place at STAMPSHOW in Cleveland, August 26th - 29th. Pneumatic mail exhibits, lectures and a cachet showing a first day of operation postcard will be sold. Orders for blank cachets at $ 1 each or stamped and postmarked cachets at $ 2 may be ordered in advance of STAMPSHOW (August 20th) from Mr. Edwin Lehecka, 217 Hazel Ave., Westfield, NJ 07090. Please include SASE or postage when ordering.

What is the future for pneumatic mail? Not only will it be collected, but it has been reported that the Japanese have recently placed in service a huge pneumatic inter-city system capable of handling three meter long containers.

1. Hahn H., "Pneumatic Tube Mail of Vienna and Prague", The Collectors Club Phil., Parts I andII, v. 77 Number 3, May-June'98 p. 163-177 and Number 4, July-August '98, p. 199-206

2. Hák, J. „O mestské síti potrubní pošty", TELEKOMUNIKACE No. 4/97, p. 20-22.