I’ve built the kit clock a long time ago. I;ve also seen a picture of the bowling ball clock.

Now I can finally get one of my own!

The one they had looked just like this one, made of plastic and utilizing steel balls (ball bearings probably). There was an arm attached to the second-hand wheel with a little scoop on the end. On the 30 second mark, it picks up a ball from the “available ball chute” and at the 0/60 second mark would deposit it on the top track, where it winds its way down the path. When it reaches the minute mark, it stops, and if there are enough balls on the minute chute, the weight causes that chute to rotate, sending the balls onto the next chute, which marks a larger amount of time.

You really have to see this thing in action to appreciate it, although after looking at it for a few minutes it seems quite simple.

Oh, and yes, it does make a little bit of a racket, especially at the noon and midnight mark when all of the balls cascade from the top chute through the lower chutes and all of the balls are returned to the “available” chute, but the one we had actually kept pretty accurate time.