Robert St. John, with long white hair, white mustache and the beard of a prophet, has lived long and prospered with pen, pencil, typewriter and microphone, on paper and on the air, writing and lecturing in 49 states. At 97, he is the walking, talking front page of the 20th century, the reality of that legendary movie character the Foreign Correspondent.

For four hours, the Chronicler sat captivated by tales of his reporting on two world wars, five Middle Eastern wars, Al Capone's crimes and punishments, Franklin D. Roosevelt's political campaigns and John F. Kennedy's presidency.

St. John is the author of two novels, two travel books, five biographies, three autobiographies and 12 books of reportage. In a splendid biography of St. John in the George Washington University newspaper By George! recently, Danny Freedman calls him one of a "disappearing breed of journalists." As a young reporter he was "cloaked in a trenchcoat, the pockets of which, at all times, contained a pencil, paper, and a nickel for a phone call.

We sat in the St. Johnses' library of wall-to-wall books, including his own translated into many languages, with St. John and his wife, Ruth, who met him when she asked him twice to speak to her club in Charleston, W. Va. She is appropriately named since she is a "whither thou goest" wife who went with him to 88 countries after they were married 34 years ago.

In the late '30s a writer friend suggested St. John meet him in Paris and that they get jobs covering the coming war. The friend never showed up, so in late 1939, St. John took a train to Bucharest, Romania. On the way the train stopped in Budapest.

He went to the station restaurant but the menu was in German and Hungarian, and he could read neither. Taking a chance, he pointed at an offering on the menu. The waiter returned with two pickles.

Like the best reporters, St. John had "useful-someday" notes tucked away in his memory. The Associated Press bureau was just around the corner. Surely someone there could order something to eat. He charged down the streets, noticing that the people looked cold and frightened.

"When I got to the AP door, I opened it and stood in the open doorway. 'Close the goddamn door,' yelled a man at a typewriter. 'Can you write English?' I said yes. He yelled again, 'Come and get to work. The Luftwaffe is bombing Warsaw.' "

After the fall of Poland, St. John said, the two-man Warsaw bureau was "one of the first casualties. In Budapest, the Associated Press hired a woman who spoke fluent Polish. Our powerful radio set was tuned to Warsaw. Its mayor would come on every hour or two to broadcast where they could find food for sale." St. John and his colleagues would turn the mayor's reports into stories for the Associated Press.

After Warsaw fell, the AP sent St. John to Bucharest to cover, he said, "among everything else, [the Romanian] King Carol and his flight to Bulgaria en route to Spain with his red-haired mistress. A terrible pogrom was engineered by the Romanian Iron Guard during the German occupation in Yugoslavia and Greece."

Then St. John went to Bulgaria to await the German troops. After the German takeover he went to Yugoslavia, where he rented a sardine boat sailing down the Adriatic. St. John was on a Greek troop train when it was strafed by a Nazi plane that left hundreds of Greek soldiers dead in the wreckage and three pieces of shrapnel in St. John's right leg. "I still carry it as a reminder of my World War II."

Eventually, in early 1942, with his typewriter as his only baggage, he took a ship back to New York, limping into the Roosevelt Hotel in New York. "In 28 days, I wrote the story of those 28 days," he said. The 300-page book was published a few months later as "From the Land of the Silent People."

Walter Winchell, St. John said, "put out a piece saying I had a contract with Doubleday for the book. An AP superior quoted its rule that none of its writers could lecture or write books."

St. John could either tear up his book contract or resign from the Associated Press. He resigned and was hired by NBC Radio to head its London bureau. He arrived in the midst of the Blitz, with bombs dropping on London. Two years later, back in New York, he spent 117 hours at the microphone, reporting the Allied invasion on D-Day, June 6, 1944. When the Japanese surrendered in August 1945, he reported the end of the war for 72 hours.

Today, St. John has finished his latest autobiography, using two fingers on a manual typewriter but faster than the typist who quit, saying, "He can write faster than I can on an electric typewriter." St. John shrugged and said, "I can only write as fast as my mind tells me."

St. John also has contributed photographs and a course in how to be a television commentator to the new Radio-Television Museum. The museum, which opens to the public on Saturday, is at 2608 Mitchellville Rd., Bowie. For more information call 301-390-1020.

CAPTION: Now 97, Robert St. John has traveled all over the world as a writer and lecturer, often taking along his wife, Ruth.