Her hull was well on the way to completion when her designer chanced to see the "Archimedes," the first screw steamer built, and straightway changed his plans to admit the use of the new method of propulsion So from 1842 may be dated the use of both screw propellers and iron ships.

We must pass hastily over the other inventions, rapidly following each other, and all designed to make ocean travel more swift, more safe, and more comfortable, and to increase the profit of the shipowner.

The compound engine, which has been so developed that in place of Fulton's seven miles an hour, our ocean steamships are driven now at a speed sometimes closely approaching twenty-five miles an hour, seems already destined to give way to the turbine form of engine which, applied thus far to torpedo-boats only, has made a record of forty-four miles an hour.

Iron, which stood for a revolution in 1842, has itself given way to steel.

And a new force, subtile, swift, and powerful, has found endless application in the body of the great ships, so that from stem to stern-post they are a network of electric wires, bearing messages, controlling the independent engines that swing the rudder, closing water-tight compartments at the first hint of danger, and making the darkest places of the great hulls as light as day at the throwing of a switch.