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The Steam Engine Again Challenges Starboard engine on Pennsylvania Railroad Com- pany’s new S. S. ‘‘Del-Mar-Va’’ Marine Unaflow with oil cooler and tank HE development of the steam engine has proceeded in cycles occasioned by competition and the continuous demand for higher economy. Starting with James Watt, we find a progressive improvement in the successive types with a resulting aban- donment of the older and less economical. Following Watt came the higher speed throttling engine; then the single-valve automatic, allowing full boiler pressure in the cylinder; then the Corliss; and then the compounding of single-valve as well as Corliss engines. At this stage, the gas engine, the Diesel engine, the steam tur- bine and purchased electricity began mak- ing great inroads into the manufacturing of stationary steam engines; and to the rescue came the poppet-valve unaflow engine, which has been developed to such a degree of high economy that this engine, as built by the Skinner Engine Company, is being sold for replacing other types of prime movers, on a self-liquidating basis. This company is the recognized leader in the unaflow engine industry, having built approximately 50% of all stationary unaflow engines and all of the large-capacity ma- rine unaflow engines produced in this country. With the higher steam pressures and temperatures that can now be safely ob- tained, we prophesy that marine unaflow engines will, in the near future, be offered with a steam rate of from 7.5 pounds at slow speed to 8 pounds at full speed per i.hp-hour. The steam engine is a by-word for rugged - ness, durability, dependability and sim- plicity; and if the economies prophesied above can be obtained without the loss of any one of these four qualities—and we are sure they will be retained—it will be the poppet-valve unaflow steam engine that will henceforth set the pace in marine propulsion. (Skinner Unaflow engines are built in the largest shops in this country devoted ex- clusively to the building of steam engines. ) Built only by SKINNER ENGINE CO., ERIE, PA. Branch Offices in All Principal Cities ee ————————————————————— EEE MARINE REevieEw—July, 1934 Cs