“The 18th-century Astronomer Royal Edmond Halley believed that unusual compass readings could be explained by the fact that the planet was composed of a hollow shell, two inner concentric shells and an innermost core about the diameters of the planets Venus, Mars and Mercury respectively.
One of the most famous Hollow Earth theorists, and a true predecessor of Thompson, was a veteran of the 1812 Anglo-American war, John Symmes. In his book Banvard’s Folly, Paul Collins recounts the “theory of concentric spheres and polar voids” that preoccupied the soldier.
Symmes published a pamphlet, in which he wrote, “I declare that the Earth is hollow and habitable within; containing a number of solid concentric spheres, one within the other, and that it is open at the poles 12 or 16 degrees.” He pledged his life to promoting his notion, boldly declaring, “I am ready to explore the hollow.”
He toured the US with a handmade wooden globe that opened out to reveal its secret layers. Converts, in ever increasing numbers, began petitioning the government to finance his adventures. On March 7 1822 Senator Richard Thompson presented a case to Congress that Symmes be supplied with “the equipment of two vessels of 250 to 300 tons for the expedition, and the granting of such other aid as Government may deem requisite”.
During the debate, it was suggested that the Committee for Foreign Relations become involved, as the trip may well bring Symmes and his crew into contact with new races of interior people. But the motion was to fail. Seven further bills were presented to the House. Not one succeeded.
Symmes spent the rest of his life lecturing and lobbying for action. “In May 1829,” writes Collins, “Symmes died, believing right up to the end that the greatest discovery in human history had eluded his grasp.”
(original story here)