Engineering Wonders of the World
Volume I

76 ENGINEERING WONDERS OF THE WORLD. Fig. 18.—SECTION OF AFTER END OF CRADLE. The upper ends of the cradle timbers rest against an angle plate attached to the ship’s side. under the vessel, being built up from the ground to the required height on heavy timber. These ways, which may be described as huge wooden slides, extend from near the stem cf the vessel right down the full length of the berth, and far enough into the water to en- sure that there shall be sufficient depth to prevent the ship “ tipping ” off the way-ends before she is properly water-borne. The ground-ways are usually laid at a mean decliv- ity of about -j^-inch in the foot towards the water’s edge, and present a perfectly smooth surface at the top. Upon the ground-ways are placed the slid- ing-ways, which move with the vessel. At the ends of the ship, where her sides Sliding-ways and Cradles. are “fine,” and her bottom no longer pre- sents a wide and almost flat surface, the weight is supported by the timbers forming the “ cradles,” built up between the top of the sliding- ways and the outside plating of the ship. A view of the forward cradle prepared for the launch of the White Star liner Adriatic at Belfast is shown in Fig. 1, while a good idea of the arrangement of an after cradle may be gathered from an examination of Fig. 19, which is reproduced from a photo- graph of the after cradle of the Mauretania. In the latter case it will be observed that the cradle was built up under the “ bossing ” of the plating carried round the shafting of one of the inner propellers ; while the outside pro- peller on this side of the vessel is seen further forward, the Mauretania, like the Lusitania, having in all four pro- pellers. The bearing surfaces of the ground and sliding ways are covered with an efficient lubricant, generally tallow and soft soap, to prevent exces- sive friction between them. Upon the morning of the launch wedges are driven in between the sliding- ways and the bottom of the ship, in order to lift most of her weight off the blocks and shores by which, she has been supported during building. At the time fixed for the launch, provided wind and weather are favourable, and there is a sufficient depth of water at the end of the ground-ways, the christening party assembles on th© special platform usually erected near the vessel’s bow; a bottle of wine, gaily decorated with ribbons, is broken over the bow; and at a given signal the keel and bilge blocks still remaining are knocked out from beneath, Fig. 19.—AFTER LAUNCHING-CRADLE OF THE “ MAURETANIA.”