Perhaps some of the most bizarre scientific theories ever considered were those concerning the possibility that the Earth was hollow. One of the earliest of these was proposed in 1692 by
Edmund Halley.
Edmund Halley was a brilliant English astronomer whose mathematical calculations pinpointed the return of the comet that bears his name. Halley was fascinated by the earth's magnetic field. He noticed the direction of the field varied slightly over time and the only way he could account for this was there existed not one, but several, magnetic fields. Halley came to believe that the Earth was hollow and within it was a second sphere with another field. In fact, to account for all the variations in the field, Halley finally proposed that the Earth was composed of some four spheres, each nestled inside another.
Halley also suggested that the interior of the Earth was populated with life and lit by a luminous atmosphere. He thought the aurora borealis, or northern lights, was caused by the escape of this gas through a thin crust at the poles.
Others picked up Halley's hollow-earth theory often adding their own twists. In the eighteen century
Leonhard Euler, a Swiss mathematician, replaced the multiple spheres theory with a single hollow sphere which contained a sun 600 miles wide that provided heat and light for an advanced civilization that lived there. Later Scottish mathematician
Sir John Leslie proposed there were two inside suns (which he named Pluto and Proserpine).
One of the most ardent supporters of hollow-earth was the American John Symmes. Symmes was an ex-army officer and a business man. Symmes believed that the Earth was hollow and at the north and south poles there were entrances, 4,000 and 6,000 miles wide, respectively, that led to the interior. Symmes dedicated much of his life to advancing his theory and raising money to support an expedition to the North Pole for the purpose of exploring the inner earth. He was never successful, but after his death one of his followers, a newspaper editor named Jeremiah Reynolds, helped influence the U.S. government to send an expedition to Antarctica in 1838. While the explorers found no hole there, they did bring back convincing evidence that Antarctica was not just a polar ice cap, but the Earth's seventh continent.
