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F. W. Sinclair: Separating Fact From Fiction

6 min readJun 30, 2026

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One of the only known photographs of Francis Withersby Sinclair (1845–1888)

If you have been online in the past few months, you may have come across dramatic tales about a French author from the 1800’s named F. W. Sinclair. Amateur historians and content creators alike have praised him as ‘the most interesting man you’ve never heard of.’ The stories about this guy make him sound like a combination of Leonardo Da Vinci and Tony Stark. But how much of this is actually real, and how much is 130 years of exaggerated tall tales, botched translations, and good old fashioned misunderstandings? Today, we’re going through some of the most famous Sinclair legends and try to figure out who F. W. Sinclair actually was.

The Facts

Here’s what we know for sure: Francis Withersby Sinclair was a real person. He was born in Versailles, France, in 1845, and graduated from the University of King’s College London in 1867. We know this from schooling and birth records. Because of a marriage certificate dated October 11th, 1868, we also know that he married Molly Elizabeth Cortwright, who he met at university. However, since Sinclair did not come from any particularly important lineage, we don’t know much else about his early years. In those days, unless you were a member of the nobility, records were spotty, and most people did not have the events of their lives written down.

After this, the line between fact and hearsay begins to blur. Sinclair was reported to have written over thirty novels, but scholars have only found seven. He is also said to have created over two hundred inventions, but only a handful of sketches and journals have ever been recovered. We know that Sinclair and Cortwright would end up separating, but the specifics surrounding their divorce are murky at best.

Now that we’ve got the important stuff out of the way, let’s take a look at some of the most incredible claims about F. W. Sinclair.

He Discovered The Planet Pluto

According to Sinclair enthusiasts and fans, F. W. Sinclair theorized the existence of the planet Pluto in the early 1870s. Why is this important? Because Pluto was not officially discovered until 1930, nearly 60 years later, which would make F. W. Sinclair the mind behind one of the most important astronomical discoveries of the last 300 years…if it’s true.

Unfortunately for Sinclair heads, this claim is…shall we say, greatly exaggerated. The claim comes from one of Sinclair’s journals in which he mentioned his belief of the existence of a planet beyond Neptune. Sinclair was a vocal believer in extraterrestrials, and believed that they came from “a land beyond the furthest planet of our understanding.” He did not use mathematics, telescopes, or any scientific instruments to back up his claim. He never referred to the planet by any name other than “Stupid Alien Planet,” making the idea that he was a celestial visionary dubious, to say the least.

Verdict: While Sinclair did theorize the existence of a planet past Neptune, to say that he “discovered” Pluto is a gross overstatement.

He Sunk Jules Verne’s Nautilus Prototype By Adding Airholes

This is probably the wildest F. W. Sinclair story. According to legend, Sinclair helped famed author Jules Verne design his groundbreaking submarine Nautilus in 1868. However, when the two attempted to launch a prototype from the Seine river in France, the vessel sank because Sinclair insisted on adding airholes, which quickly flooded with water, drowning the fourteen men set to embark on the voyage. Sinclair and Verne had a violent falling out over the tragedy, with the latter removing all credit or mention of Sinclair from his classic novel 20,000 Leagues Under The Sea.

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So what do we actually know about this? Well, we know that F. W. Sinclair did have a prior relationship with Jules Verne. Letters between the two paint the picture of a student-teacher relationship, with Verne acting as something of a mentor to the eager Sinclair. We also know that the two did have a falling out sometime around 1868–1870, as that’s when the letters abruptly turn bitter before stopping altogether.

So, what about the sinking? This is where things get tricky. The Le Petit Journal, as well as the Le Figaro newspaper, both published accounts of a mechanical accident in the Seine river on April 1st, 1868. However, the details of the accident vary wildly. Le Petit names the craft as a ‘submarine boat’ designed by Verne and Sinclair, which is likely where the story originated. However, Le Figaro describes it as a standard boat of that time, and neither Verne nor Sinclair are mentioned anywhere in the piece. Both papers say fourteen men died, but no obituaries have ever been found. Since Verne was a close friend of Le Petit’s chief editor at the time, Timothée Trimm, it’s entirely possible that the account was completely fabricated, or at the very least, doctored, as promotion for Verne’s upcoming novel. As for Sinclair’s involvement, he was never confirmed to have anything to do with the accident, or with the Nautilus in general, for that matter.

Verdict: While it’s true that Verne and Sinclair were, at one time, close friends, the idea that they had a falling out because Sinclair sank Verne’s prototype is likely fabricated. The claim about airholes, while humorous, is probably the result of 150 years of word of mouth exaggeration, rather than historical fact.

He Invented Air Travel

This is one of the more bizarre Sinclair claims, and yet, perhaps the most widely circulated in online circles. The story goes that, between 1881 and 1887, F. W. Sinclair spent basically all of his time in his workshop; sketching, designing, and constructing his magnum opus: a flying machine. It was a large, zeppelin-like craft that he referred to as a “clockwork airship.” In 1888, Sinclair departed from Paris to traverse the world in his ship and cement his name in history. This was the last time Francis Withersby Sinclair was ever heard from.

This seems like the easiest claim to disprove, right? After all, everybody knows that the Wright Brothers invented the first sustained flying machine in 1903. If Sinclair had beat them by 15 years, it would be documented in every textbook. Well, oddly enough, the most ridiculous Sinclair story is the one with the most truth to it.

It’s true that the Wright Brothers were the first people to invent a heavier-than-air flying machine. However, they were far from the first people to achieve flight. Hot air balloons and blimps, while not common, did exist by the mid-1800’s. In addition, both types of travel were invented in Sinclair’s home country of France, not far from where the author resided.

Unlike most Sinclairian tall tales, this one actually has some evidence to back it up. Dozens of witnesses reported seeing Sinclair depart from Paris in a large flying craft, and the accounts are remarkably consistent. In addition, sketches and blueprints have been recovered by Sinclair’s estate that seem to show a design for a craft matching the airship’s description. While skeptics have pointed out that no vessel of any sort was ever found, that actually isn’t all that surprising. If Sinclair did crash over the Alps, as reports claim, then there’s no reason a ship, especially one that was mostly air, could not hide under the remote snow and ice without being discovered.

Verdict: While he didn’t ‘invent air travel’, it’s entirely possible that Sinclair developed some sort of a modified hot air balloon. The public departure, coupled with the lack of sightings and reports in the years after, give merrit to the idea that Sinclair did leave Paris in a ship of his own invention, and did crash somewhere over the Alps. Though we can’t go as far as to call this a definitive historical fact, we also can’t rule out that something did happen here.

Conclusion

Now that we’ve separated fact from fiction, where does that leave us? Was F. W. Sinclair a visionary genius unappreciated by the primitive minds of his time? Or was he simply an unremarkable author propped up by postmortem legend and publicity? Like with most things, the answer lies somewhere in the middle. Sinclair was not a larger-than-life tech wizard who could see the future before it happened. But he was a highly creative person with a lot of forward thinking ideas, and, though his exploits may be exaggerated, I’m glad that his name is back in the public consciousness. Embellished or not, men like Francis Withersby Sinclair deserve to be remembered. Thanks to the internet, he finally will be.

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Jonathan Sterling, PhD
Jonathan Sterling, PhD

Written by Jonathan Sterling, PhD

Professor of historical studies at Columbia Commonwealth College. The world's leading scholar on F. W. Sinclair.