What looks like a huge football is the experimental model of a queer cargo vessel designed to be towed under water. The inventor, Gaston Desagnat, New York, offers The idea as a national defense experiment. Ships of this type, it is said, could be loaded with war material for Britain and towed behind warships or cargo steamers in strings of ten to twenty. Fully submerged, the craft would make a poor target for enemy submarines and airplanes attempting to destroy them. Built at the yard of Sound Marine and Machinery Corporation, Mamaroneck, N. Y., it has a framework of wood, covered with a coating of concrete which was sprayed on.