The paper describes methods by which the analysis of steam locomotive power can be most advantageously applied to traffic working in the case of railways not having special testing facilities, such as dynamometer cars. The first section describes the method used for the determination of cylinder and boiler output, the treatment of locomotive and train resistances, and the application of these factors to train loading, speed, and running time. The calculation of fuel and water consumptions on a horse-power-hour basis is given, also the method of application to train working. The second section describes the procedure for the practical application of locomotive power to traffic working, and the measurement of train capacity in terms of ton-kilometres per train hour.