THE WORLD'S WONDERS. 633 



venturers from seeking to penetrate the forbidden iields of nature. 



Of the theories respecting the North Pole the most singularly 

 interesting is that advanced by John Cleves Symmes, an Ameri- 

 can, who, in a wonderfully plausible manner, argued that the 

 earth is hollow, open at the poles, and cq^oleof being inhabited 

 within. He both lectured and wrote extensively on this theorv, 

 but though his arguments were well conceived, and not without 

 a measure of consistency, yet some of his claims appeared so 

 absurd that he made few converts. His theory of concentric 

 spheres, however, was pretty well received by many scientists, 

 which had the effect of preserving his name among the list of 

 noted men. 



It will be remembered by readers of the Greely Expedition, 

 that Lockvvood and Brainerd, upon reaching the greatest altitude 

 ever attained by man, found a current setting in so string to- 

 ward the north that they were compelled to turn back, to avoid 

 being caught in the drift and carried irresistibly away into the 

 unknown, although their nearest approach to the North Pole was 

 four hundred miles. This is an important fact, explainable only 

 upon two hypotheses, viz : that there is a current which sweeps 

 constantly toward and around the pole, where a warmer climate 

 exists ; or that a fissure or verge in the earth attracts the waters to 

 that spot, as Symmes maintained. The former, it must be con- 

 fessed, is altogether the more reasonable, and must, therefore, 

 be popularly accepted. There is another almost equally important 

 fact, however, which tends materially to confuse all theories 

 respecting the North Pole, except that of Symmes, which is, that, 

 after reaching 80 North, there is a gradual increase of tempera- 

 ture and a corresponding increase of animal life. Symmes' theory 

 is that this warmth is the result of the electrical force of the inner 

 earth expending its effect on the atmosphere adjacent to the pole. 

 This theory, though, is combatted by the discovery that the cold 

 toward the North Pole is not nearly so intense as that which sur- 

 rounds the South Pole, and the yet further and still more import- 

 ant fact, that the lowest temperature is not found at either pole, 

 but in the neighborhood of Yakoutsk, Siberia. We are there- 



