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454 THE MARINE REVIEW fairing this portion of the ship, either in the drawing room or on the mold- loft floor, as described in the chapter appearing in the October issue of THE MarInE Review. The _ buttock lines afford a very accurate conception of the nature of the surface, when studied by an experienced man. ; The elliptical stern, when viewed in the sheer plan, rakes aft, the boundary line being straight and making an obtuse angle with the line forming the boundary of the buttock. This angle, which is continued around the stern until the curvature of the but- tock breaks continuously into the in- ward inclination of the ship’s side, is FIG. 1246—ANOTHER VIEW OF THE STERN SHOWN IN FIG. 125. POST TO OTHER STERN ELEMENTS. termed the knuckle. This knuckle is shown clearly in Fig. 129. In the sheer draft, showing the lines of the ship, it is called the knuckle line. Now on account of the inward in- clination or tumble-home. of the ship’s side and the rake of the stern right aft, the surface of the ship’s side be- tween these limits must necessarily be twisted. Now it has been found that if square. openings are cut in such a stern they are very unsightly. Round portholes, therefore, are much to be preferred. In order to give this type of stern a still more pleasing appearance, the following procedure may be adopted. Produce upward indefinitely the line of rake right aft. Now draw a line from the end of the knuckle line in the direction of the tumble-home of the side. The point of intersection of these lines may be chosen as_ the apex of a cone containing the knuckle line and enveloping the stern. The sides of the stern timbers are then inclined so as to be straight lines on this cone. These lines, if produced, will pass through the apex. The character of the cone is gov- erned by the rake of the stern right aft and the tumble-home of the side as well as by the curvature of the knuckle line. The after extremities of the topside or rail form curves approximating those of an_ ellipse. Hence the name elliptical stern is given to this style of construction. The surface of the stern above the knuckle, being approximately an elliptical cone, and the surface of the stern below the knuckle a continua- tion of the contotir of the ship’s bot- tom, it remains: to be decided just what kind of a line the knuckle shall be. It is evident that although the former surface may be invariable, it is possible to modify the surface of the bottom, consistent with fairness, so that the position of the. knuckle may be varied slightly to suit appear- ances. It is customary to place the knuckle line in the surface containing the upper sides of the beams of a deck, both for the sake of beauty and’ to suit the internal arrangements of the ship. Therefore, the knuckle line conforms to the round of the beam and the sheer of the deck. In disposing the fimbers in an elliptical type stern, the quarter tim- bers are so placed that their edges are straight lines on the cone surface just where the latter blends into the surface of the topside. Spaces _ be- tween these and the aftermost fashion timber are filled up by a number of December, 1917 short cants which, like the quarter- timbers, are heeled upon the fashion timber. Quarter-timbers and _ those abaft them are known by the generic name of stern timbers. In disposing these stern timbers it is necessary that they should be canted in such positions as will avoid excessive bevel- ing. At the same time it is necessary for the timbers to heel on the fashion timber or on a short cant which itself heels upon another’ stern timber. Sometimes it is necessary to give the stern timbers a double cant. The chief feature of the parabolic stern is the absence of a _ knuckle. This stern, therefore, becomes a con- FIG. 127—NATURAL KNEE USED TO CONNECT STERN- FIG. 128—SHAFT LOG IN TWIN-SCREW MOTOR SHIP tinuation of the buttock, the post tim- bers forming the backbone, as it were, of the ship abaft the body post. These timbers are close jointed from the gunwale to the body post. Boxen wood is left on the post timbers to house the aftermost ends of the side and bottom planks in this form of construction. Instead of the compli- cated arrangement of timbers required by the systems previously described, the framing of this type of stern con- sists of ordinary cants. Those before the screw aperture heel against the deadwood and those abaft “it heel against the sides of the post timbers. It is not necessary to go into detail regarding methods of laying off these timbers. The post timbers are laid off in the sheer plan on the mold loft and the remaining timbers, as_previ- ously stated, are ordinary cants. In most modern wooden ships the sternpost simply heels square against the keel and after ends of deadwood.