All navigators know the difficulty of attempting to break their way through the ice fields, since it requires a vessel of tremendous power and great weight to break down or through solid ice. A vessel of this type was first proposed by me in 1899 for exploration purposes in ice-covered seas. In 1903 experiments were made with the _Protector_ in order to demonstrate the practicability of navigating in ice-covered waters. [Illustration: UNDER-ICE NAVIGATION Under-ice boat designed by the author for navigating between ice-bound ports. A boat of this character could keep up communication between ports that are now closed by ice for several months of the year. Passengers, mail and freight can readily be transported in this manner with perfect safety. (See text.)] Professor Nansen, in his North Polar explorations, has stated in his book that his average rate of progress during eighteen months, in attempting to reach the North Pole, was only three-quarters of a mile per day, and that the thickest ice he found during these months of endeavor was fourteen feet. His progress was delayed by open waters, slush ice, and in the winter by the intense cold which compelled him to "hibernate" for a considerable period of time. An under-ice submarine as illustrated, with large storage battery capacity, could navigate underneath the ice in perfect comfort and safety. The temperature surrounding the vessel, even in the most severe winter weather, would not exceed the temperature of the water surrounding the vessel. The vessel illustrated is designed to make a continuous submerged voyage of one hundred and fifty miles on one charge of the storage battery. After such a run, it would be necessary to stop and recharge the batteries. If open water should be encountered, this recharging process would be done by bringing the vessel to the surface. If the ice was not too thick, then by blowing out the water ballast the ice would be broken, since it is very much easier to lift the ice and break it than it is to force it apart or downward, as surface vessels are compelled to do. Provision is made for boring a hole up through the ice so as to permit the drawing in of sufficient air to run the engines and to recharge the batteries. Provision has also been made for putting out small mines underneath the ice to blow an opening to permit the submarine to come to the surface. A telescopic conning tower arranged to cut its way up through ice twelve or fourteen feet thick is also provided to enable the boat to remain under the ice and still permit the crew to reach the surface.