#1365 is one of forty S-4 class Vauclain compound Ten Wheeler (4-6-0) type locomotives built for the Northern Pacific in 1902 by Burnham, Williams & Co., an early incarnation of the Baldwin Locomotive Works. As built, it had 15½" x 30" high pressure and 26" x 30" low pressure cylinders (few Vauclains had such a long stroke).
#1365 was first assigned to haul the Northern Pacific's prestige passenger service, the North Coast Limited, between Missoula, MT, and Spokane, WA. The assignment was shortlived, however, as NP’s Q class Pacifics (4-6-2) soon took over. It was then reassigned to branchline freight, mixed and passenger service.
By this time, compounding, other than in Mallets, was falling out of favour amongst US railroads. The main advantage was claimed to be lower fuel and water consumption, but the arrangements were mechanically complex, Vauclains produced uneven forces and excess wear at the crosshead, and increased maintenance costs largely offset any fuel economies. The S-4s were consequently superheated and simpled with 21" x 30" cylinders at NP's South Tacoma Shops in 1917.