Pontoon bridge using a single 'o'. The U.S. military differentiated between the bridge itself ("ponton") and the floats used to provide buoyancy ("pontoon"). The original word was derived from Old French "ponton", from Latin "ponto" ("ferryboat"), from "pons" ("bridge"). When designing a pontoon bridge, the civil engineer must take into consideration the Archimedes' principle: Each pontoon can support a load equal to the mass of the water that it displaces. This load includes the mass of the bridge and the pontoon itself. If the maximum load of a bridge section is exceeded, one or more pontoons become submerged. Flexible connections have to
Cable layer The first transatlantic telegraph cable was laid by cable layers from 1857–58. It briefly enabled telecommunication between Europe and North America before misuse resulted in failure of the line. In 1866 the successfully laid two transatlantic cables, securing future communication between the continents. Modern cable ships differ greatly from their predecessors. There are two main types of cable ships: cable repair ships and cable-laying ships. Cable repair ships, like the Japanese "Tsugaru Maru", tend to be smaller and more maneuverable; they are capable of laying cable, but their primary job is fixing or repairing broken sections of cable. A cable-laying