Empress Go-Sakuramachi (後桜町天皇) was the 117th imperial ruler of Japan. She was the last empress out of ten in the history of Japan, ruling from 1762 to 1771 before abdicating in favor of her nephew, Go-Momozono.
... Modern devices come with electronic rev counters and light emitting diodes powered by a little generator embedded in the gyroscope.
The physics of this device look ...