Archimedes Screw
One of humanity's oldest machines — a helical surface inside a cylinder that lifts water as it turns. Adjust the pitch, speed, and tilt to see how geometry becomes engineering.
Performance
About this experiment
The Archimedes screw is traditionally attributed to Archimedes of Syracuse (287–212 BC), though historical evidence suggests the device may have originated in Egypt or Assyria centuries earlier. The Greek historian Diodorus Siculus described Egyptians using screw-like devices to irrigate fields along the Nile, and some scholars believe Archimedes encountered the technology during his time in Alexandria and refined the mathematical understanding of why it works. Regardless of its precise origin, the screw stands as one of the earliest examples of applied geometry — a helicoid surface wrapped around a central axis, enclosed in a tight-fitting cylinder, transforming rotational motion into the steady upward transport of water.
The geometry of the screw is everything. The key parameter is the tilt angle: too steep and gravity pulls the water back down between the helical blades faster than the screw can lift it; too shallow and the vertical lift per rotation is trivially small, making the machine inefficient for its footprint. The sweet spot for most practical applications falls between 22 and 38 degrees. The pitch of the helix — the distance between successive turns — determines how many discrete pockets of water the screw holds at any moment. A tighter pitch creates more, smaller pockets with gentler per-pocket lifting, while a looser pitch creates fewer, larger pockets that must each be lifted higher per turn. The optimal number of helical flights (typically two or three interleaved helices) balances volume capacity against structural complexity.
The Archimedes screw has experienced a remarkable modern resurgence. In wastewater treatment plants, screw pumps handle sludge and debris that would clog centrifugal pumps, because the open channel design passes solids gracefully. In hydropower, the screw has been run in reverse — water flowing downhill turns the screw to generate electricity — and these "Archimedes screw turbines" are celebrated as one of the most fish-friendly hydropower technologies, with survival rates above 95% for fish passing through. The screw's gentle, low-speed operation produces none of the pressure differentials or blade strikes that make conventional turbines lethal to aquatic life. From ancient irrigation to modern renewable energy, the same helicoid geometry that Archimedes (or his predecessors) first exploited continues to solve engineering problems at every scale.