In the "Berthon" collapsible boat the stem, the stern-post, and the keel are permanently joined together. The fore and aft stringers are hinged at their ends to the stem and stern-post on each side, those uppermost being blocked out in order to allow the stringers to fold down to the keel. When opened for use, the stringers are kept in position by the thwarts and struts under them resting on the keel. Th<j hinges are about 1 1/2 in. apart up and down the posts, and are covered with leather, which is kept pliable by castor oil, neat'sfoot oil, or both. Shredded soap, dissolved and mixed with the paint, would keep the painted canvas pliable. For one person the size of boat would be: Length, 7 ft.; beam, 3 ft.; depth, less keel, about 20 in.; the width, when closed, about 8in.; approximate weight, 30 lb. The wood used for these boats is Canadian elm; the canvas covering is double, the stringers and air space being between; on opening the boat the air enters this enclosure at the tholes.