Experience proves that a great many young men prepare for the engineering pro fessions who have no engineering ability, and who would do better in some other line. The fact that a boy displays an interest in the working of machinery or in the opera tion of a dynamo does not indicate that he is destined to become an engineer. If the same boy, however, has shown himself apt at mathematics, and is interested in general science, he may safely take up one of the engineering professions, and with hard work will achieve success. The first clew to engineering ability is aptness at mathematics. The foundation of engineering is mathematics, and he who has no ability in this subject will never make a success as an expert engineer.