South West

On 3 May 1715 John Lethbridge chose the moment of a total eclipse to complete his first experiment with his incredible 'diving machine'.

As a wool merchant in Newton Abbot, he knew little of the sea.

But Lethbridge did know that there was shipwrecked treasure under the waves.

So, he designed a diving machine.

Diving barrel

To a wooden barrel he added a porthole to see out of, and arm holes with leather sleeves through which he could grab the treasure.

This extraordinary contraption was winched down into the sea from a ship.

There are no known pictures of Lethbridge and his story might have been forgotten - were it not for Robert Stenuit, a famous Belgian Marine Archaeologist and world expert on Lethbridge.

Reconstruction of Lethbridge barrel.

He told Inside Out: "He was the first man to invent a diving machine that had no communication with the surface.

"He went down with the barrel filled with air, breathed in the air, then came up and had the air changed, and then dived again!"

Back in the 1970's the BBC made a documentary about Robert as he attempted to dive in a replica of Lethbridge's machine.

"To me he was a remarkable man. All I was trying to do and did with all the ease and convenience of modern equipment, he did with next to nothing," says Robert Stenuit.

"I have great admiration for his courage, of course, and his practical way of solving complicated problems…

"He was like a flyer, flying with self made wings really!"

Recreating Lethbridge's invention

Robert Stenuit made a faithful copy of Lethbridge's diving machine but didn't have the specially treated leather for the sleeves.

So he thought it would be just as good to use neoprene, but at a depth of just 10 feet the pressure squeezed the neoprene in and he ran into problems.

No doubt Lethbridge had similar teething problems as he recounted 'near drowning' at least five times during his dives.

Reconstruction - Lethbridge on trial.

In spite of all probability, Lethbridge's invention took off.

He was snapped up by the mighty Dutch East India Trading Company.

Their ships traversed the globe trading their cargo of silver bars and coins for luxuries like silk and spices.

When these ships ran onto rocks or hit storms - the fortunes that they carried were lost.

As a result there were many men feverishly devising ways of retrieving the treasure.

But Lethbridge's diving engine stood apart

Hidden treasure

Stenuit's fascination with Lethbridge didn't end once he'd tested the engine.

He was convinced that there must be some treasure left under the ocean from the wrecks Lethbridge had dived on.

Treasure trove - silver bars.

Sure enough, he discovered a treasure map made by Lethbridge himself that led him to the wreck of Dutch East India ship - the Slot Der Hooge - off the coast of Porto Santo island in Madeira.

And the hunch paid off when Robert eventually dived the wreck.

"We found one, the only silver bar in the world that anyone had seen in this century. For three hours a day we kept digging, deeper and deeper and there it was! A real chest. A chest of silver bars…"

It took a long time but Robert and his team eventually lifted 144 silver bars.

The missing 10% of the original cargo. Lethbridge had found the rest but this chest was buried under a canon which was then hidden under an overhanging rock.

Famous 'diving machine'

Newton Abbot Museum is holding a special exhibition to mark the 250th anniversary of its famous son from 10 March, 2009.

Robert Stenuit will be opening the exhibition and has loaned some of that treasure to show as part of it.

Mark Horton with Robert Stenuit.

The centrepiece will be a replica of Lethbridge's famous 'diving machine' which has been faithfully reconstructed by local craftsmen, father and son Nick and Adam Hunt

Lethbridge was still diving in his barrel into his 1970's and still applying for contracts at the grand old age of 81.

He was eventually buried at Wolborough Church near Newton Abbot but now everyone will be able to see how he became a 'silver fisher' and made his fortune many times over.