Diving machine

Edmund Halley's diving bell of 1691 solved the problem that had limited all earlier designs: air supply. Divers in previous bells could work only until they breathed the enclosed air foul—perhaps fifteen minutes. Halley developed a system of weighted barrels that could lower fresh air to the bell, extending dive times to hours rather than minutes.

The principle of the diving bell was ancient. Aristotle described inverted vessels that carried trapped air underwater. Medieval salvage operations used bells to recover cargo from wrecks. But the air limitation constrained what divers could accomplish before surfacing or suffocating.

Halley, the astronomer who would give his name to the comet, turned his systematic mind to underwater engineering. His air barrels were lowered on ropes, positioned beneath the bell, and then inverted to release their contents upward into the bell. Stale air escaped from a valve at the bell's top. The system worked: Halley reported descending to 60 feet and remaining for over ninety minutes.

Further innovations followed. Halley experimented with leather tubes connecting the bell to smaller helmets, allowing divers to venture short distances from the main bell. John Smeaton added pumped air supply in the 1780s, eliminating the need for barrel systems. The diving suit eventually replaced the diving bell for most underwater work.

Modern saturation diving—where divers live at depth pressure for extended periods—traces back to Halley's fundamental insight that supplied air enables extended underwater work. The diving bell persists in specialized applications: offshore construction, submarine rescue, and archaeological excavation all still use bell systems.

An astronomer's engineering hobby established principles for working underwater that remain relevant three centuries later.