Symphonic movement by ARTHUR HONEGGER, 1924, first performed in Paris. The designation 231 indicates the number of wheels (2-3-1 ) on this type of American locomotive.

The score is a highly effective if rudimentary representation of accelerated motion, beginning with one note to a bar, and progressing through two, three, four, five, and six, picking up the tempo as a locomotive gains speed. There is a lyric middle section before Pacific 231 slows to a stop.