Another form, known as the Fleuss dress, makes the diver also independent of exterior aid. The helmet contains a supply of compressed oxygen, and the exhaled breath is passed through a filter in the breast-piece which deprives it of its carbonic acid, while the nitrogen goes back into the helmet to be mixed with the oxygen, the supply of which is under the diver’s own control, and to be successively breathed. A diver has remained an hour and a half under thirty-five feet of water in this suit. A considerable enlargement of the field of deep-sea diving is the result of the invention recently of a form of diving apparatus which is unaffected by the limitations hitherto imposed on work of this kind. A possible depth of 204 feet is recognized by the British Admiralty regulations under the conditions that obtain with the common form of diving suit. Yet this depth has probably never been reached. One hundred feet is the rare descent of the average diver and 150 feet his maximum. With the new apparatus a submergence of 212 feet has been obtained, and this might have been indefinitely extended had there been a greater depth of water at the place where the experiment took place--Long Island Sound during the latter part of 1914. The new diving apparatus is constructed entirely of metal, is rigid and is made of such materials that it is strong enough to resist the great pressures found in the depths to which it can penetrate. The material used is an alloy of aluminum, and the diving case weighs complete about 500 pounds. When in the air, the man inclosed in it is incapable of imparting movement to it, but in the water, which counterbalances the dead weight of the apparatus, he can easily move the articulated sections as well as give himself motion through the water. The articulated portion consists of about fifty turning joints, fitted with leather packing, which swells and has an increased effectiveness under increased water pressure. To prevent the pressure-force of the deep sea from jamming the joints, roller bearings are so arranged about them that freedom of action is constantly maintained. The diving case is not absolutely water-tight, nor is it desired that it should be so, as the slight leakage acts as a lubricant to the joints, and aids in their movements. The danger arising from the intake of water thus into the diving case is averted by the action of an ingenious pump appliance, which serves two purposes: that of pumping the water out and pumping the air in. The diver in this invention carries his pump with him and has air supplied to him at atmospheric pressure.