Surprisingly common - two have just turned up with a month of each other during 2009 - this G.Boley watchmakers' lathe is believed to take 6.5 mm collets. Stamped "Patent G.Leinen", the bed had a semi-circular base but a triangulated "bevelled" top section. Not a design that caught on - it was advertised alongside contemporary WW and "Geneva" designs of watchmakers' lathe - and vanishes completely from later Boley publicity material.
If you also have an example of the lathe below, or as similar type, the writer would be interested to hear from you.