Page:Popular Science Monthly Volume 24.djvu/552

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Without it the boring of most of our tunnels and the placing of masonry foundations under water could not have been accomplished. In 1832 the turbine wheel had just been invented, but not brought into use; in fact, hydro-mechanics has made as great steps forward in the last fifty years as any of her sister sciences.

A recent invention of Sir W. Armstrong deserves mention. A steam-engine actuating a pump is used to secure an artificial head of water, which water is afterward employed in driving various hydraulic motors operating cranes, lifts, driving riveting machinery, and the artificial head is secured by loading a ram of sufficient size with weight enough to place a pressure of seven or eight hundred pounds to the inch in the cylinder. The pumping-engine pumps against this ram, the chamber of which is connected with each of the machines requiring to be driven; whenever the work done in the various motors is less than the work of the engine, the surplus is expended in raising the ram, and when the ram is fully extended an automatic device stops the pump, which again resumes work on the withdrawal of water from the ram by leakage or use in motors. By the aid of this system of storing power, a small steam-pump attached to an accumulator is capable of furnishing three hundred or more horse-power for a short time. This arrangement is adopted in all docks and ship-yards of any pretensions.

Our modern turreted man-of-war handles its eighty and one hundred ton guns, and all the loading machinery, by the aid of similar hydraulic devices. These accumulators give an efficiency of ninety-eight per cent in practice, which amounts to perfection.

In 1832 rolled plates such as are now rolled were unknown, and the rolling of armor-plates twenty-two inches thick, weighing thirty tons, was not thought of.

The process of making wrought-iron by puddling has not changed much, though larger masses are handled. The manufacture of iron by puddling seems doomed; steel is taking its place rapidly; in 1832 masses of steel of over sixty pounds were not made; steel was dealt in by the pound for cutlery-use. Thanks to Sir Henry Bessemer and Dr. Siemens, steel is made on the Bessemer and open-hearth process, and in masses of many tons' weight. The rapid advancement made in engineering skill is due in a great measure to the cheapening of iron and steel making. Never in the history of the iron industry were there so many partially developed processes, the completion of which will revolutionize the industry, and furnish iron and steel at a cost much below present prices.

The unprecedented expanding of our railway interests since 1865 has had much to do with the development of the iron interests. Inventors of prominence promise us steel at one cent a pound, and in the light of the past it is not safe to assert that it will not be done. Steel rails have been sold within a few years at one hundred dollars a