When the Inventor of the Diesel Engine Disappeared

Rudolf Diesel’s fate is still intriguing to this day

Rudolf Diesel
Public Domain via Wikimedia Commons

For more than a century, the Diesel engine has been the backbone of heavy industry. The internal combustion engine that ignites fuel by heating it up through compression powers everything from tractors to trucks. But for decades, historians have been puzzled by the mysterious disappearance of its inventor, who vanished 103 years ago today while taking a steamship across the English Channel.

Rudolf Diesel was a talented inventor who designed devices from refrigerators to steam engines, but his eponymous engine is what he is best known for. A trained engineer, Diesel became interested in developing a new kind of internal combustion engine in the late 1880s, as he believed that he could devise one that was more powerful and efficient than the gas engines that were becoming widely used at the time, as the Encyclopedia Britannica notes.

Unlike gas engines, Diesel designed his device so it could run on nearly any type of fuel. At the time, the standard petroleum-powered internal combustion engines were large, expensive and inefficient. The alternatives weren’t much better either: if a factory workshop didn’t use a gas engine, it was probably powered by a steam engine, which were even more wasteful and expensive, Jason Stein wrote for Newsday.

“Diesel saw his engine as a tool that was adaptable in size and cost, but also able to use available fuels,” Stein wrote. “It would allow independent craftsmen to avoid having to use expensive, fuel-wasting steam engines. It would help the small businessman try to beat out the big companies.”

Diesel filed a patent for his engine in 1892 and within just a few years he had developed a series of small, efficient engines that could run on anything from vegetable oil to peanut oil. By the end of the 19th century, everything from power plants to cars were running on Diesel engines. So it came as a shock to many when Diesel mysteriously vanished on September 30, 1913, while crossing the English Channel from Belgium on his way to a business meeting, Jennifer Latson wrote for TIME magazine.

“On the arrival of the vessel at Harwich at 6 o’clock this morning he was missing,” the New York Times reported at the time. “His bed had not been slept in, though his night attire was laid out on it.”

Diesel’s disappearance threw the world for a loop. He appeared extremely well-off thanks to his many patents and was a titan of invention. However, after his disappearance and the ruling of his death, new details revealed that he was actually in serious debt due to bad investments and was stricken by bad health, Latson writes.

While his death was officially ruled a suicide, the mysterious circumstances around it kept Diesel in the news for years. Some conspiracy theorists were convinced that he had been assassinated by German spies because of the Diesel engine’s significance in the early U-boat designs, or that his rivals in the business world wanted him out of the way. Other stories cropped up over the years, with some accounts saying he left his wife with a bag full of money and documents detailing his debt along with instructions not to open it until the week after his disappearance, and that he had drawn a small cross next to the date in his journal. Some people even claimed to have found him alive and well in hiding in Canada.

Diesel’s demise may never be fully explained, but the mark he left on the industrial world remains undeniable.

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