Lee Davison wrote: mercury barometer comes to mind. I have two that I have filled at various times. I think they take a few pounds to fill, but are quite reliable for weather prediction, much more accurate than horse hair I had to help persuade a friend many years ago to return a cobalt camera to a clinic who had conned him into taking it. He thought he would send a really super gizmo to some third world clinic, and we explained that the paperwork outweighed the camera. We also arranged for the lab director who had given him the camera to be properly briefed in disposal of the unit, which was what he was trying to avoid. It was quite a thrill to see such a thing there, but good sense kept anyone from taking it, and now having it would be a liability of large proportions, with the scare over things high tech these days. Jim