536 THE POPULAR SCIENCE MONTHLY. 



Without it the boring of most of our tunnels and the placing of ma- 

 sonry 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 requir- 

 ing 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 hun- 

 dred 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 18C5 

 has had much to do with the development of the iron interests. In- 

 ventors 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 



