Richard E. Byrd, the famed American polar explorer who claimed in 1926 -- 70 years ago today -- to have been the first person to fly over the North Pole, may actually have turned back two hours and 150 miles short of his goal, according to new evidence released by Ohio State University's Byrd Polar Research Institute.

The clues are in Byrd's long lost diary of the expedition, which an archivist at the center recently found in a mislabeled box of Byrd's memorabilia. The diary contains navigational notes that Dennis Rawlins, a Baltimore navigation expert and historian of polar expeditions, has interpreted to mean that Byrd failed in his attempt at the pole even though he claimed to have reached it.

One incriminating finding: The diary contains an erased -- but still readable -- sextant reading that put Byrd about 165 miles south of where he would later claim, in his official report, to have been at that moment toward the end of the flight north.

If confirmed, Byrd's disqualification would hand the title of "first person to reach the North Pole" to Roald Amundsen, the Norwegian explorer who traveled over the pole in a dirigible three days after Byrd's airplane expedition -- arriving there May 12, 1926.

Dismissal of Byrd's claim to have reached the once-fabled spot on the globe -- a goal of explorers for many decades -- would be the second in recent years, at least in the minds of historians of exploration.

The long-controversial claim of Robert E. Peary, who said he reached the North Pole by dog sled in 1909, is now largely discounted by polar experts, partly because of research by Rawlins. Amundsen's claim, by contrast, is documented by detailed navigational records and corroborated by experts who traveled with him. It has never been in doubt. Fifteen years earlier, Amundsen was also first to the South Pole.

Byrd's claim to have flown over the North Pole was controversial in its day, for one reason because he failed to drop the hundreds of American flags he carried to prove his priority to Amundsen, a longtime rival who he knew would be arriving days later.

Critics in Byrd's time alleged that instead of flying toward the pole, the explorer and his pilot, Floyd Bennett, simply flew out of sight of the international press corps that saw him off from the Norwegian island of Spitsbergen, wandered for many hours and returned.

Rawlins said, however, that the diary establishes that Byrd, brother of Virginia's then-Gov. Harry Byrd, did, indeed, attempt the pole, venturing some 600 miles over the ice in a primitive Fokker trimotor. Just a year earlier, Amundsen had made a similar attempt at the pole but suffered engine failure that stranded him and his crew for several weeks on the ice. Moreover, the diary indicates that Byrd's navigation was on target, disputing an old allegation that the explorer lacked the navigational skill to find his way above the trackless ice sheet.

But, Rawlins said, "What we find in his diary is not consistent with Byrd getting all the way to the pole."

Rawlins, a longtime specialist in skeptical analyses of ancient claims involving astronomy or navigation, publishes a journal called DIO that focuses on these subjects and has carried articles critical of Byrd and Peary.

The Byrd Center asked Rawlins to analyze Byrd's diary earlier this year after it was discovered in a mislabeled box among the vast collection of the explorer's papers held at the center. The Byrd Polar Research Center is one of the largest devoted to modern scientific study of polar climates, geology, geography and biology.

Raimund E. Goerler, chief archivist at the center, found the diary while going through contents of a box labeled "artifacts." Not only was it not an artifact, the diary was labeled "1925." Byrd used the first part to make notes during a 1925 expedition to Greenland but used other pages for the 1926 polar venture and a 1927 crossing of the Atlantic 40 days after Charles Lindbergh's.

"When we realized these were notes from 1926, we called in Dennis because of his prominence in this field," Goerler said. "He's very well qualified to make this kind of analysis."

Goerler said neither he nor the Byrd Center endorse Rawlins's interpretation. "Our job simply is to make his findings available," he said. In fact, Goerler said he believes the diary's words make it clear that Byrd believed he had reached the pole at the time of the flight.

Goerler said his conclusion is based on a sentence in the diary in which Byrd wrote, "We should be at the pole." To Rawlins, the "should" implies doubt about an achievement that would, upon return to land, be asserted as a certainty. To Goerler, the wording is entirely consistent with certainty, at least during the flight.

"He may well have realized after the expedition that he was short of the goal," Goerler said.

Rawlins's conclusion is based on diary pages that record navigational calculations and conversations between Byrd and pilot Bennett. Engine noise forced the two to communicate in writing.

"The Stb {starboard} motor has an oil leak," Byrd wrote to Bennett. "Can you get all the way back on two motors?" In those early days of aviation, multiengine planes were not able to fly well without all engines. In his autobiography, Byrd said the oil leak occurred when the plane was just an hour from the pole and that he was "99 percent sure" the engine would stop. Rawlins noted that Byrd did not ask whether the plane could continue toward the pole and still get safely back.

Rawlins found that the diary contains various calculations and notations -- including some that were erased but still discernible. One erased sentence was a query put to Bennett, the pilot: "How long were we gone before we turned around?" He noted that it does not say ". . . before we reached the pole." Bennett's reply: "8 1/2 {hours}."

At the plane's recorded average air speed of 85 mph, that would have put Byrd about 40 miles short of the pole, assuming a straight course and no wind. The diary says there were winds that slowed them, making the ground speed considerably slower.

"You can't accept a claim based on a record like this," Rawlins said, referring to the alteration of data in the diary and the conflict between Byrd's official report and his erased sextant reading. Figuring from details in the diary, Rawlins estimated turnaround was at 87 3/4 degrees north latitude.

Rawlins praised the intellectual honesty demonstrated by the Byrd Center in consulting him. "This may be the first time in history," Rawlins wrote in his 14-page report to the center, "that an institution, devoted to the memory of a great explorer, has immediately and unstintingly invited a skeptical critic to take a prominent part in the technical investigation of records pertaining to a questionable claim by that explorer." CAPTION: The diary of polar explorer Richard E. Byrd, shown in 1926 checking the engine of his airplane, contains an erased -- but still readable -- sextant reading that put Byrd about 165 miles south of where he would later claim, in his official report, to have been at that moment as he neared the end of his flight toward the North Pole 70 years ago today.