> Maybe that much water in buckets would be too heavy for the water wheel to drag up alongside the hill? One benefit of the spoons is they only lift the total v

> Maybe that much water in buckets would be too heavy for the water wheel to drag up alongside the hill? One benefit of the spoons is they only lift the total volume of one of the spoons at a time, since each tower has a store of water it's holding but not moving yet. I think that is the primary reason. Looking at the animation linked in another comment (https://www.youtube.com/watch?v=MwU6m9tjM2A&t=74s https://www.youtube.com/watch?v=MwU6m9tjM2A&t=74s), it becomes clear just how many of these chains would've been necessary. Not only would a single water wheel have to be able to lift probably thousands of liters of water without any counterweight - you also need some continuous power transmission mechanism which can withstand the enormous forces to achieve that. Also, you would need some kind of safety catch to prevent catastrophic back-flow of all the kinetic energy stored in the system in case the water wheel is suddenly out of the water. On the other hand, the oscillating spoons probably wouldn't work when too many of them are submerged in water, and their delicate wooden mechanism probably also wouldn't survive a flood or driftwood. Which is why they used a simple robust iron chain for getting the water to a flood-safe level. It's really quite ingenious.