it may be a nervously oscillating (funny?) special, but it just aint't got it for me: white "rim" too wide.
precision useless as it's still man(ual) operated.

I've got some asdic (WWII sonar) timers about as nervous as this, but at least those served a purpose...
"hittin' the hun" ... 6 second (1 turn) ping meant the torpedos s/b set at 5000 yards.
I've got two..regulating them to run in tune is a real challenge.

my "deux centimes"
Jur