The diving bell

Dr. Edmund Halley (1656-1742), of comet fame, lived in the era of seafaring buccaneers who sometimes sank to a watery grave with their treasure. If this happened near the coast, adventurers might dive for salvage but this was dangerous. Halley’s development in 1691 of a diving bell with an air replenishment system allowed divers to explore for up to 90 minutes at depths of 20-60ft..

The ‘bell’ was a lead-covered wooden cone, open at the bottom, with a bench around the inside. Due to water being held at bay by the trapped¬† air, two men in ordinary clothes could sit inside and operate the weighted barrels of air and leather tubes for a third man, the diver. Along with his diving gear was a helmet, also designed by Halley, which was supplied with air by the tubes. The barrels were relayed up to a boat where they were refilled. Messages could be sent with the barrels on a lead block inscribed with an iron stylus.

In 1788/9, Yorkshireman John Smeaton (1724-92) added a force pump at the top to mechanise the air supply. Smeaton was ‘the father of civil engineering’ and had many bridge-building projects, so the issue cropped up as a matter of efficiency.

(Image: Wikimedia Commons / CC BY 4.0)


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