WASHINGTON, D.C.- In the last decade of the 19th century, one of the world’s most famous travelers was a dog. At a time when mass communication sped at the rate of a train, a mongrel pup gained fame for riding the rails with the mail. The dog, Owney, is the centerpiece of an exhibit renovation at the National Postal Museum. The new exhibit, “Owney: Mascot of the Railway Mail Service,” opens today and features this extraordinary dog and his story. The museum and its visitors will be joined in that celebration by the U.S. Postal Service, which is issuing a commemorative postage stamp in the dog’s honor at an event in the museum’s atrium. When Owney died in 1897, mail clerks raised money to preserve their beloved mascot. Now a taxidermy specimen, Owney was sent to the Post Office Department’s building in Washington, D.C.,and was transferred to the Smithsonian Institution in 1911. Owney has b