I toured a multi-million-dollar electron microscope at ORNL. They had a piece of tissue paper taped to the side. I asked about it, and they said that it was an

I toured a multi-million-dollar electron microscope at ORNL. They had a piece of tissue paper taped to the side. I asked about it, and they said that it was an airflow monitor. It turned out to be more sensitive than some very expensive sensors, according to the tour guide.