I’ve told many people about this sculpture over the last few years. It’s in the MIT museum in Boston (or at least, it was there six or so years ago!). At the left, a motor turns the first cog fairly quickly, maybe once a second. The next cog is connected to the first as a step-down gear so that it rotates more slowly, maybe once every thirty seconds. This continues on for a few more cogs, gradually getting slower until you reach the punchline: the final cog is embedded in a concrete block attached to the base.
It’s awesome to watch. There’s no tricks at work. There’s no need for slack in the system or anything like that. You can set up the gear ratios such that the final cog moves maybe 0.1mm over the next 100 years. Whilst concrete doesn’t stretch as much as an elastic band does (when a given force is applied), it can certainly still stretch a little bit. The cogs are still all turning, all the way down.
The sculpture is a visual poem about scale, a physics lesson and a funny joke all rolled into one. Genius.