IN France, the United States, Germany, Italy and Great Britain, experiments are being made with train units driven at high speed by internal combustion engines. The carriages are constructed of either stainless steel or aluminium, all weights are reduced to a minimum and the trains are stream-lined to lessen so far as possible the resistance due to the air. Oil or petrol engines are used, generally with electric transmission. Several of these train units have been described in our contemporaries, the Engineer and Engineering, and the Times of October 26 recorded a very fast passage made across the United States by a stream-line train belonging to the Union Pacific Railroad. This train, named M 10001, which it is stated is driven by a 900 h.p. Diesel engine, arrived at the Grand Central Terminal, New York, at 9.55 o'clock on October 25, after crossing from Los Angeles in 56 hours 55 minutes, beating every existing record in America. During the passage of the 508 miles between Cheyenne and Omaha, the train had an average speed of 84 miles an hour, while over short distances it ran at 120 miles an hour. The train with two others, larger and more powerful, which are being built, will be put in regular service between Chicago and California.