"humming 'Casey Jones' to himself"

Casey Jones (1863-1900) was an American railroad engineer who dies in a train crash in Mississippi in 1900, but was hailed a hero for his efforts to stop the train.  He was immortalised in a ballad sung by his friend Wallace Saunders, although Sybil's powers must have been hard at work to allow Colonel Kearney to sing the song in 1899 before Jones' death.

The song of Casey Jones remains a popular ballad in America, and versions have been performed by Johnny Cash (below) as well as the Grateful Dead and numerous lesser-known musicians.