No guesses at all on the mystery object. It was an instrument called an algometer, which was supposed to measure pain threshold, though I doubt it gave consistent or useful results. The instrument was applied to the skin and the needle advanced using the sliding knob on the side. When a certain level of pain was reported the position of the knob on a scale gave a reading supposedly indicating pain threshold.
The needle was not removable or disposable and would have been used on multiple patients. The risks to us are obvious. Before we congratulate ourselves on how far we have advanced in the area of sterile disposables, how many can remember the not so distant days when medical students and housemen would carry around a hatpin stuck in their lapel. This was for use in neurological examinations and was as crude and worthless as the algometer. I never saw anyone clean them between patients either.