Watching a SBS program on the restoration of Big Ben, one of the most photographed buildings in the world.
On the pendulum, to keep it balanced & swinging in perfect timing amongst other weights is a small stack of ten, of the humble British Penny.
Too remove a single penny, will cause the clock to gain two-fifths of a second in 24 hours
Place an extra penny on the stack, will cause the clock to then lose two-fifths of a second in 24 hours
Here is the stack.
(//%5Bimg%5Dhttps://www.australian-coins.net/gallery/albums/userpics/10029/442/20190303_225415_28229.jpg)[/img]
I remember seeing that on a TV program many years ago.
Oh nice - I vaguely remember reading something about this but thought it was just a tall tale.