Phantom of the Poles
The Phantom of the Poles is a book written by William Reed, and published in 1906. It attempts to explain certain mysterious phenomena reported by polar explorers by postulating that the Earth is in fact hollow, with holes at its poles. Phenomena to be explained by the Hollow Earth theory. In the General Summary chapter of "The Phantom of the Poles", Reed posed several questions that he claimed were explained by the Hollow Earth theory: Failure of Reed's theory. Admiral Peary claimed to have reached the North Pole on April 6, 1909. This would have  invalidated Reed's premise that the poles cannot be reached. Although Peary's claim was, in its day, and continues to be controversial, on December 14, 1911, Roald Amundsen undisputedly reached the South Pole. Subsequent expeditions to and flights over the south pole have conclusively demonstrated that there are no large holes there.