Superbly-built, high-class, French-made lathes, the late-models from Vuilleumier Freres incorporated a number of advanced features and fine detailing - including, on some versions, a clever metric thread-dial indicator that coped with all pitches without the need to engage alternative gears.  The lathe was also built as an earlier version (shown lower down the page) the VF250, this having more rounded styling and a sloping face to the headstock; its speed range was not as wide as the later 250/35 models and there were also some minor control differences.
If you have a machine tool made by this company, or any sales or technical literature, the writer would be pleased to hear from you.