Components of Microscope No. 62: A: Objective with two biconvex lenses; B: Sample holder; C: Brass spring to compress sample; D: Focussing screw barrel; E: Instrument body
Nicholas Hartsoeker described this microscope in 1694 in his book Dioptrique. It is the first documentation of a "Screwbarrel" microscope; predating Wilson's improvements by eight years (Phil. Transactions No. 281, 1702).
The condenser section of this microscope has this curious threaded collar. It is possible that it retained a condenser lens, which is now missing, however there is no obvious lens seat. Another possibility is that this instrument never had a condenser lens and that the collar is simply an eyecup.
All other screwbarrel microscopes had both an objective lens and a condenser lens (e.g., Left: Hartsoeker Fig 102 "N")
Assembled screwbarrel microscope.