The carrying of petroleum in bulk has spread enormously of late years in both steamers and sailing vessels specially designed for the purpose. In all such vessels the method of the subdivision of the holds into tanks is of the greatest importance, together with that of ventilation, and every builder and owner of such vessels has his own theories as to the best means to be adopted. A later type of tanker has the engines astern. A further innovation in this class of steamer is to fit them for burning oil fuel, the two big tankers _Oberon_ and _Trinculo_ having had the necessary installation placed in them last year at Smith’s Dock, North Shields, sometimes called “the home of tank-steamer repairing work.” An economical method of transporting oil in bulk across the Atlantic is adopted in the case of the steamer _Iroquois_, which herself carries about 10,000 tons of oil in bulk, and also tows with her the sailing barge _Navahoe_, carrying an equal quantity, one set of engines thus doing duty for both cargoes. The _Navahoe_ is the largest sailing ship in the world, is schooner-rigged on all her six masts, and is able to make her way to port in case she becomes separated from her consort. The floating dock is one of the most interesting of the many developments in connection with the naval and mercantile marine of the second half of the nineteenth century. Like all innovations, floating docks were received with derision. Now they have proved their worth, but circumstances are easily conceivable in which all the marvels they have already accomplished will be far eclipsed by what they may be called upon to do. In the case of a naval battle, for instance, it may be a matter of impossibility for a crippled warship to enter a dry dock, or even to get to one; but a floating dock can be sent to meet the injured warrior and possibly save it from going to the bottom altogether. The floating dock is a sort of raft, and the first man who ever hauled a boat from the water upon another boat or raft to repair, it started the idea of the floating dock. The first real floating dock, as the term is now understood, was probably that which was improvised in the Baltic Sea, so tradition says, by the skipper of a vessel which had sustained some damage in those waters. He bought an old hulk, removed the stern, and in its place constructed a flap gate. His vessel was then floated into the hulk, the flap gate was closed and the water pumped out. Floating docks of this type were almost the only kind known up to the beginning of the nineteenth century, and are in use to-day at some ports for small yachts, fishing-boats, and vessels of similar dimensions.