It's a very low serial number, so it could be from before the First World War, but it has to be after 1889 when the first anastigmatic lens was produced at Zeiss. Ross are one of the earliest camera lens manufacturers and had very close ties with Zeiss, manufacturing Zeiss lenses under license.
The focal length would indicate it was probably for something like a 10"x8" camera, very few glass plates were enlarged at that time, and the f8 aperture is the same as an early 12"/300mm Ross lens I bought a few years ago, mine's marked as covering 8"x5". It's the Double anastigmatics like Protars and Dagors which have wider fields of coverage.
Ian