THEChemin de Fer du Nord has recently introduced into service, huge “Baltic” type, four-cylinder compound superheater locomotives for operating the Nord Express, connecting Paris with Brussels, Berlin, the Baltic seaboard and St. Petersburg. This international express service ranks as the fastest train service in the world, and, with 400 tons coach load, the French engine attains 75 miles per hour, developing in the cylinders about 2,000 horse-power. Two engines of the “Baltic” wheel arrangement have been built by the Chemin de Fer du Nord for comparative working, the only difference being that the first engine, 3.1101, is fitted with ordinary locomotive firebox and boiler, while the later engine, 3.1102, has a marine pattern water-tube firebox. This firebox was designed by the Nord company's engineers, although actually constructed at the Creusot Works of the Schneider Company. Both engines are fitted with apparatus for _ highly-superheated steam, and the cylinders in each engine are identical. Instead of constructing the ordinary type boiler for saturated steam and placing a water-tube boiler for superheated steam over a simple engine, the same system of compounding is here employed in both engines. The previous largest engines in Europe are the “Pacific” type, class 10, of the Belgian State Railways, which have four cylinders, each 500 millimeters by 660 millimeters (19.68 x 25.98 inches). The new Nord engines have, however, two high-pressure cylinders, 440 millimeters (17.32 inches) by 640 millimeters (25.19 inches) and two low-pressure cylinders 620 millimeters (24.41 inches) by 730 millimeters (28.74 inches). Further, while the steam pressure in the Belgian engines is 200 pounds per square inch, the French engines carry a pressure of 227.5 pounds per square inch with direct admission from the boiler to all the cylinders whenever it is found desirable for starting. These French engines, although very much more powerful in starting effort than the Belgian locomotives, are of the same weight, loaded and empty, as the latter, but the boilers of the Nord engines have 23 per cent more heating surface. The chief interest in these new locomotives is the novel solution of the cylinder problem, which has, for years past, been an obstacle in the design of very powerful locomotives, the difficulty occurring when specially large cylinders are necessary, either for low-pressure saturated steam, superheated steam, or extra low pressures in one-half of a compound engine. The high-pressure cylinders are mounted outside the frames and drive on the center pair of the three sets of coupled wheels with cranks set at 90 degrees apart. The low-pressure cylinders are inside the frames and drive on the forward pair of coupled cylinders. The cranks in this case are also set rut right angles to one another and each high-pressure is at 180 degrees from its corresponding low-pressure crank. One of the low-pressure cylinders is set in advance of the other, so as to get the centers of the piston rods close together. Although intended for cylinders working at 80 pounds maximum pressure, this device is applicable to any system of engine with such modification as may be desirable. The driving wheels have a diameter of 6 feet 81;.4 inches and the bogie wheels a diameter of 3 feet 412 inches. The firebox grate is 8.56 feet in length and 5.3 feet in width and the grate area is 46 square feet. The total heating surface amounts to 4,394.93 square feet, to which the water-tubes and firebox contribute 1,097.95 square feet, and the smoke tubes 2,629.6 square feet, while the superheater surface is 667.38 square feet. The boiler barrel has a diameter of 6 feet 2% inches. The water capacity is 1,886 gallons, and the steam capacity 690.8 gallons. The tractive force of these locomotives working compound, is 32,429 pounds, and simple 42,834 pounds. An interesting innovation is the adoption of mechanical stokers. On the Northern Railway the express engines are served with “smalls” and “tout-venant” which, to avoid choking the fire and evolving heavy smoke, must be laid on thinly and with great frequency. Opening the fire-door frequently is injurious to the tube plate and tends to lower the temperature of the steam in the superheating pipes. With mechanical stokers' these and other objections disappear, the fuel in fine powdery form may be blown into the fire-box with suitable tuyeres. In running order, the engine weighs 102 tons, of which 24 tons is on the leading bogie, 5-1 tons on the coupled wheels and 24 tons on the trailing bogie. The tender is of the standard Nord 8-wheels type and weighs 5612 tons, so that in working order these “Baltic” locomotives have a total weight on rails of 15812 tons.