Narwhal The tusks were staples of the cabinet of curiosities. European knowledge of the tusk's origin developed gradually during the Age of Exploration, as explorers and naturalists began to visit Arctic regions themselves. The narwhal was one of two possible explanations of the giant sea phenomenon written by Jules Verne in his 1870 novel "Twenty Thousand Leagues Under the Sea". Verne thought that it would be unlikely that there was such a gigantic narwhal in existence. The size of the narwhal, or "unicorn of the sea", as found by Verne, would have been . For the narwhal to have caused the
Twenty Thousand Leagues Under the Sea of underwater breathing apparatus designed by Benoit Rouquayrol and Auguste Denayrouze in 1865. They designed a diving set with a backpack spherical air tank that supplied air through the first known demand regulator. The diver still walked on the seabed and did not swim. This set was called an "aérophore" (Greek for "air-carrier"). Air pressure tanks made with the technology of the time could only hold 30 atmospheres, and the diver had to be surface supplied; the tank was for bailout. The durations of 6 to 8 hours on a tankful without external supply recorded for the Rouquayrol set in