Pinkerton helped the newly elected Abraham Lincoln arrive safely into Washington DC. There was a planed attempt on his life in route. They left a dinner early, got on a PRR train to Baltimore, pulled the passenger car through the city of Baltimore with horses (quieter) to a waiting train bound for DC, cut the telegraph wires along the line, and arrived in DC before the plotters knew he had left.
I read it in the compilation book:
A Treasury of Railroad Folklore, editor B.A. Botkin and Alvin F. Harlow; Bonanza Books, New York, 1989.
Their source was The Pennsy, Vol. 2 (February, 1953), No. 2, pp. 6-7. Philadelphia: The Pennsylvania Railroad Company.
Nathan
(the English teachers will be correcting me for my improper citation style...)