Vintage Stroboscope No. 19
This is a stroboscope mounted on a tuning fork made to resonate at 150 Hz. At the end of the for are tow metal plates with a slit between them that opens and closes when the fork is struck. This will create a stroboscope effect when held against a source of light. The tuning fork is dated with the year 1990 and there is some rust on the fork.