In the 1820s, the Hollow Earth Theory had two powerful advocates. They went to the United States Congress to lobby for a sponsored expedition to the center of the Earth. Congress turned them down, but one president said yes.
John Cleves Symmes was an American army officer, born during the Revolutionary War, who spent his life advancing a few revolutionary ideas, including the notion that the Earth was completely hollow, and built as inhabitable concentric spheres (his ideas were revolutionary, not good.) He lectured on the subject, and some think he wrote a book about a voyage to the North Pole, and then down into the interior of the world. The book, called Symzonia: Voyage of Discovery, was attributed to a Captain Adam Seaborn, but some modern versions list Symmes as the author.
A fictional book about such a journey was as close as Symmes got to making it, despite his best efforts. His best efforts were very good, because he had the support of a rich person. James McBride had made a fortune as a surveyor, and he was ready to spend it on any project he saw fit to endorse. While he did some good work in archaeology, he was also taken by Symmes’ vision of a hollow earth. McBride took Symmes off the lecture circuit and to Washington. The two lobbied Congress for years, trying to get funding for an expedition to the center of the Earth. Congress said no.
John Quincy Adams said yes. Adams was president as the result of a decision of the House of Representatives, after an election in 1824 that gave no single candidate a needed majority. Although Andrew Jackson had more votes, he was too devisive. The House went for Adams, but soon repented of it. The trip to the center of the Earth wasn’t the main factor in that – Adams was a proponent of a more powerful federal government and so clashed with the representatives of the states – but it certainly didn’t help. Even at the time, the theory was considered laughable by most. Adams still backed it, but his unpopularity led to a single term in office, and the conquering Jackson killed any momentum for the idea.
An addendum to the story – John Cleves Symmes’ son, who was also called John Cleves Symmes, became a geography professor at West Point.