This strange apparatus hanging at the Cité de la Mer museum in Cherbourg, France, looks like some kind of a medieval torture device, but is actually the world’s first diving machine. And a very successful one at that.

Its inventor, John Lethbridge, was a wool merchant of Newton Abbot, a market town of Devon, England. Not much is known of his childhood or what inspired him to create a diving machine. A BBC article simply notes that John Lethbridge had a lot of mouths to feed—he had 17 children—which necessitated him to come up with an ingenious method of making money.