Sir Edmund Halley (1656-1742, Halley’s Comet) – Halley’s most controversial theory originated from his study of magnetism. Halley realized that the magnetic poles were constantly moving. He believed this could be explained by having two fixed magnetic poles (north and south) in the crust of a hollow earth, and two more inside which were moving. He envisaged hollow spheres, one inside the other, rotating at slightly different speeds. One of these inner shells would contain the other set of magnetic poles. If that shell rotated slightly slower than the outermost shell, then that might account for the apparent motion of two of the magnetic poles while the other two stood still.
From Lost Science by Gerry Vassilatos
The drama of Twentieth Century Science and its intriguing relationship with financiers and governments unfold together in the remarkable life of Nikola Tesla. His is a biography replete with all the elements of tragedy. Tesla, a great discoverer of unsurpassed force, became the focal point of old insidious forces intent on destroying the future for the selfish sake of the status quo. Tesla remains a focal point of wonderment, of dream, and of worlds, which yet should be to those who are familiar with his biography. For them, Tesla stands astride the quaint past century and the gleaming future. He is a technological Colossus, pointing the way to a new dawn.