Antiques Roadshow guest's shock as his passion project book's real value is revealed

An Ohio man was stunned to learn that a book about his passion project would go for tens of thousands of dollars at auction during an episode of Antiques Roadshow.

The popular television program has been running since 1997, following auction house specialists around the country as they offer free appraisals of antiques and collectibles.

During a trip to Ohio, the PBS series met up with a man who'd purchased a worn-looking book dating back to 1792 - and was fully aware of its significance.

'I brought a very old book, which is an essay on clockmaking that I found in an antique mall,' the guest said. He shared that his 'main interest' was collecting watches, particularly those pertaining to navigation.

'I saw this book. What caught my eye was "Essai d’Horloge" on the outside cover, which is French for "An Essay on Clockmaking,"' the man explained, sounding like an expert himself.

The man identified the item as a book written by French clockmaker Ferdinand Berthoud

The guest said he'd purchased the book at an antiques mall in Canada, sharing that his 'main interest' was collecting watches, particularly those having to do with navigation

He opened the book and was floored to discover that it was handwritten by Ferdinand Berthoud, a fabled Parisian clockmaker who was involved in the creation of the first marine chronometers, specialized devices used for finding longitude at sea. 

Devon Eastland, the senior specialist of early printed books at Swann Auction Galleries, agreed that the item was 'really important for our entire history of navigation.'

Back then, she explained, 'there wasn't a way to determine longitude on a moving ship in a way that we now take it for granted that we know we’re going through time zones and so on.'

Addressing the guest, she said, 'You know more about the subject matter than I do.'

The man stepped in to explain that King George put a prize following a shipwreck 'to see who could solve the problem of determining longitude at sea so this sort of thing wouldn’t happen.'

Eastland said British watchmaker John Harrison 'figured it out' before turning her attention to the centuries-old book. 

'There is original material like these drawings inside,' she said, reiterating that the item was handwritten rather than printed.

'This is a very unusual occurrence, because we do sometimes find manuscript versions of printed books but, as far as I can tell, I cannot find a printed version of this book.'

An Ohio man was floored to learn how much a book about his passion project would go for at auction during an episode of Antiques Roadshow

Appraiser Devon Eastland agreed that the book was 'really important for our history of navigation'

She was impressed by the book's contents, identifying 'original material' like hand-drawn illustrations

Eastland estimated that the book would go for anywhere between $40,000 and $60,000 at auction

The guest appeared visibly stunned. 'Wow, I had no idea what it’s worth,' he said

She explained that a firm in Switzerland, bearing Berthoud's name, still makes watches by hand.

'They have a bibliography and they do not mention a work of this name at all anywhere that I can find, which is, again, very unusual,' she said.

'I also looked in library catalogues, I can’t find it. It looks to be, for all intents and purposes, something that he is directly working on.'

To make the find even more 'extraordinary,' Eastland said, there were apparent working notes at the end of the book. 

The guest shared that he closed the sale for only $200 Canadian dollars.

'There’s a lot of interest in this collecting area,' Eastland said before estimating an auction price between $40,000 and $60,000.

The guest appeared at a loss for words. 'Wow,' he finally blurted out. 'Wow, I had no idea what it’s worth.'

The show is known for capturing the shocked reactions of guests, for better or for worse. One of the most memorable was during a 2012 episode where a Texas man discovered that an artwork left to collect dust behind a door was the most expensive painting ever appraised on the show.

After receiving a retail estimate between $800,000 and $1 million, the man opted to donate the painting to the San Antonio Museum of Art, saying he was 'really scared to carry it around'.