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which is further increased by the admission of the secondary air at the center of the burner. Official tests have not been com- pleted with this installation, but the preliminary operating runs which have been made indicate a_ still further advance in the progress of the development of pulverized fuel for marine purposes. In fact, the results obtained show that the original ideal of 80 per cent boiler efficiency in continuous operation when operat- ing boiler at 150 per cent rating is entirely feasible. The reason for setting this over- load clause in the program is based on the fact that the average cargo earrier has three boilers, and it is desired to operate the vessel on two boilers only, thereby permitting the third boiler to be cleaned while ves- sel is at sea, and so maintain at all times clean fire and water sides in all three boilers instead of waiting until vessel arrives in port, and then cleaning the three boilers, which pro- cedure means a vessel may start out on voyage with all three boilers clean, but on the return leg of the voyage, at a time when bottom conditions are apt to be considerably worse than at the start of the voyage, especially on long runs in tropical seas, her boilers will be comparatively dirty. Pulverized fuel for marine purpose has gone through a_ considerable amount of the development work which will make it real sea-going but it is not quite ready to shove off. However, it does give most en- couraging prospects, and it is safe to say that within a comparatively short time the marine engineer, in studying his operating costs, is going to be forced to consider another competitor against the hand fired coal, or the oil burning steam plant—a com- petitor which will also question the superiority of the diesel’s operating costs, and will have the advantage of a reasonable’ initial installation ' charge. New Channel Steel 1 pene CONTRACT has been let by A Merritt, Chapman & _ Scott Corp., to the Newport News Shipbuilding & Dry Dock Co., Newport News, Va., for a 300-ton derrick barge, to be constructed on the Ellis channel system. Edward T. Gillen of Milwaukee has ordered two more 90-foot pile driver barges to be built under the Ellis channel system of steel hull con- struction. These barges are to be duplicates of the Ellis barge built for Mr. Gillen last fall by the Wis- consin Bridge Co. The same com- pany is doing the work on the two new barges which will be ready for launching shortly. The accompanying illustration shows the original chan- nel system pile driver in operation. PILE DRIVER BARGE BUILT ON CHANNEL STEEL SYSTEM 100 MARINE REVIEW—April, 1927 Largest Diesel-Electric Drive for Tanker The contract to supply the electric propulsive and auxiliary equipment for the conversion to diesel-electric drive. of the former United States shipping board tanker, DISTRICT OF COLUMBIA, which will be the largest drive of this type ever installed, has been awarded to the Westing- house Electric & Mfg. Co., East Pittsburgh, Pa. The DISTRICT OF COLUMBIA was built in February, 1921, has a length overall of 450 feet, a beam of 59 feet, and a molded depth of 33 feet, 3 inches. The new propelling equipment com- prises four 8-cylinder, 2-cycle Busch- Sulzer diesel engines of 1000 shaft horsepower each, four 700-kilowatt direct current generators direct con- nected to the engines, and one double armature propelling motor, rated 3200 horsepower at 90-105 revolutions per minute. Excitation for the gen- erators is supplied by two 175 kilo- watt machines direct connected to each of the outboard diesel engines. Among the larger auxiliary mo- tors are two circulating pump mo- tors of 60 horsepower each, two lubri- cating oil pump motors also of 60 horsepower each, and a fire and bilge pump motor of the same rating. There are a ventilating blower motor of 35 horsepower, a fuel oil transfer mo- tor of 20 horsepower, and smaller mo- tors for the sanitary pump, refrigera- tion plant, lighting and other use. To Build New Carferry A new carferry is to be built by the Manitowoc Shipbuilding Corp. for the Pere Marquette railroad at a cost of about $800,000. She will be used to carry cars across the river between Detroit and Windsor, Can., and between Port Huron and Sarnia, Can. The design will be similar to that of PERE MARQUETTE No. 14, now in the Detroit river service. Its con- struction requires 3000 tons of shapes and plates. The vessel will be 400 feet long overall, 53 feet moldel beam and 22 feet molded depth, and will be equipped with four scotch marine boilers and two 38-cylinder compound engines of 1800 indicated horsepower each. Each of the engines will drive a bow and stern propeller, enabling the boat to cross and recross. the river without turning around. The new boat will increase the Pere Mar- quette fleet to ten ferries. Seven are used on Lake Michigan, betwen Mil- wauke and Manitowoc, Wis. and Man- istee and Ludington, Mich. : : :