On this day in 1913, Rudolf Diesel, inventor of the engine that bears his name, disappears from the steamship Dresden while traveling from Antwerp, Belgium to Harwick, England. On October 10, a Belgian sailor aboard a North Sea steamer spotted a body floating in the water; upon further investigation, it turned out that the body was Diesel's. There was, and remains, a great deal of mystery surrounding his death: It was officially judged a suicide, but many people believed (and still believe) that Diesel was murdered.
Diesel patented a design for his engine on February 28, 1892,; the following year, he explained his design in a paper called "Theory and Construction of a Rational Heat Engine to Replace the Steam Engine and Contemporary Combustion Engine." He called his invention a "compression ignition engine" that could burn any fuel--later on, the prototypes he built would run on peanut or vegetable oil--and needed no ignition system: It ignited by introducing fuel into a cylinder full of air that had been compressed to an extremely high pressure and was, therefore, extremely hot.
Such an engine would be unprecedentedly efficient, Diesel argued: In contrast to the other steam engines of the era, which wasted more than 90 percent of their fuel energy, Diesel calculated that his could be as much as 75 percent efficient. (That is, just one-quarter of their energy would be wasted.) The most efficient engine that Diesel ever actually built had an efficiency of 26 percent--not quite 75 percent, but still much better than its peers.
By 1912, there were more than 70,000 diesel engines working around the world, mostly in factories and generators. Eventually, Diesel's engine would revolutionize the railroad industry; after World War II, trucks and buses also started using diesel-type engines that enabled them to carry heavy loads much more economically.
At the time of Diesel's death, he was on his way to England to attend the groundbreaking of a new diesel-engine plant--and to meet with the British navy about installing his engine on their submarines. Conspiracy theories began to fly almost immediately: "Inventor Thrown Into the Sea to Stop Sale of Patents to British Government," read one headline; another worried that Diesel was "Murdered by Agents from Big Oil Trusts." It is likely that Diesel did throw himself overboard--as it turns out, he was nearly broke--but the mystery will probably never be solved.