The history of the world's first closed diving suit

From an unsuccessful businessman, John Lethbridge became a rich man with the invention of a diving suit that helps him dive to a depth of about 20m .

The Cité de la Mer museum in Cherbourg, France, displays a strange device that looks like some kind of medieval torture device, but is actually a replica of the world's first closed diving suit . The inventor of the suit, John Lethbridge (1675 - 1759), was a wool merchant in the town of Newton Abbot, Devon, England. Not much is known about his childhood or what inspired him to create a diving suit. According to BBC , he has 17 children, so he has to work hard to make money.

Replica of John Lethbridge's diving suit in the Cité de la Mer museum, Cherbourg, France. (Photo: Ji-Elle)

Before Lethbridge's invention, diving was done with the help of a "diving bell" - a device resembling an inverted cup or bell without a pendulum, which was lowered into the water to allow the person inside to breathe. air trapped in the bell. Divers can crawl out from the open bottom, do their duty, then crawl back into the bell.

In 1715, John Lethbridge became the first person to design a usable diving suit and called it a "diving machine". The suit looks like a wooden barrel about 1.8 m long, with the diver lying face down inside. The device has a round window for viewing and two holes for sticking the arms out. Two oil-soaked leather tubes wrap around the biceps creating a nearly waterproof seal.

The wetsuit has no air supply other than the air trapped inside before it is sealed. Although it may not sound like much, this amount of air is still enough for Lethbridge to dive underwater for about 30 minutes at a time. The suit has two air valves on the top. Fresh air can be pumped inside by hoses connected to valves when the diver surfaces. The wetsuit is raised and lowered by cables, but Lethbridge also provides weights so divers can dispose of them and float to the surface without assistance.

Lethbridge hopes his device can reach great depths. But when testing, he discovered that water pressure deeper than 15m caused leaks around sleeves, windows and entrances. He found that he could still easily dive down to 18m. The maximum depth is 22m, but diving down will be difficult.

Despite its limitations, the suit was used effectively by Lethbridge in British waters and elsewhere in the Atlantic to salvage valuable cargo from shipwrecks. Many shipping companies in London quickly took notice of Lethbridge and hired him for salvage work.

In 1794, on the way from the Netherlands to Java, the ship Slotter Hooge of the Dutch East India Company, sank due to strong winds near Porto Santo, Madeira island. Of the 254 people on board, only 33 survived. The ship sank at a depth of about 18 m, carrying 3 tons of silver bars and 3 large chests of coins. Lethbridge was hired at a salary of £10 a month, plus expenses and bonuses. In the first attempt, Lethbridge recovered 349 silver bars, more than 9,000 coins, and two guns. During that summer, he made many dives to the wreck and recovered nearly half of the treasure.

For the next 30 years or so, Lethbridge worked on many wrecks and earned large sums of money. From an unsuccessful wool merchant struggling to support his family, Lethbridge became a wealthy man, owning the Odicknoll estate in Kingskerswell.

The original Lethbridge diving suit no longer exists, but the drawings are still preserved . Based on that, experts built a number of replicas and displayed them in many maritime museums around the world, including one in his hometown, Newton Abbot.