Philip is correct that the engine (#1 or 2) is facing north. However, this may only be evidence that the wye shown on the bird's-eye drawing of Monson actually existed during the early years of the railroad. The wye also is shown in a plan of the branches of the Monson Railroad that I have seen at the Maine Archives. The third leg of the wye was to have run from the west side of Chapin Ave. (Hebron Pond Quarry Branch) almost to the eastern boundary of the station grounds (Monson Pond/Kineo Quarry Branch).
This is also the only photo that I have seen that shows lettering on a Monson box car.