By any measure this late 19th Century "watch and clockmaker's" lathe is unusual. With, for its type, an enormous centre height of around 6 inches  - yet admitting only 7 inches between centres, it must have been constructed for either a production machining job - the single-speed drive by a wide flat belt to the headstock spindle* lends support to this argument - or for some very specific and special task. Sitting on a thin, cast-iron base plate, the lathe had its headstock bolted on and the tailstock, sitting on a wide base,  adjustable along a T-slot machined down the centre line of the bed. The carriage ways were strips of steel screwed to the base using countersunk, slot-head screws - the permanently-engaged, hand-operated feed screw passing through the headstock casting to emerge at the left-hand end of the machine where a small "balanced" handle was fitted.
Almost as long as the ways on which it ran, the  cross slide was formed with a full-length T-slot in which sat a very tall, lantern toolpost of the "American" kind.
Although most of the machine appears to be original - even the closed hexagonal spanners to adjust the tailstock and lock the cutting tool in place appearing to have survived - there is evidence that the headstock casting has been cut away beneath she spindle to allow the large, flat-belt pulley to be fitted. *Hence, there is the possibility that the drive might not be that fitted by the maker but a later adaptation by a previous owner who would have removed the original three or four-step pulley.
If you have a Steham, Jenks & Stehman lathe, the writer would be pleased to receive details and pictures.