context: Firemen were in practice often engineers-in-training, learning the skills of train operation and assisting the engineer with the observation of signals and other routine aspects of his job performance, waiting for a job opportunity for promotion.
source: It was the conductor, not the locomotive engineer, who was most comparable to the captain of a ship.
reference_original: Era el conductor, no el ingeniero de locomoción, quien era el más comparable al capitán de un barco.
reference_flipped: Era el conductor, no la ingeniera de locomoción, quien el era más comparable al capitán de un barco.