Rudolf Diesel

b 1858, Paris, d 1913 English Channel

After studying the internal combustion engines developed by Nikolaus Otto (who developed the four-stroke engine called the Otto cycle to this day), Diesel conceived of an engine that would approach the thermodynamic limit established by Sadi Carnot in 1824. If the fuel in a cylinder could be expanded at constant pressure, it could get closer to Carnot's limit. He patented the concept in 1892, while working at the firm of the refrigeration engineer Carl von Linde in Berlin.

Unfortunately, expanding at constant pressure meant that the engines had to be run at a low speed, limiting their power. Diesel insisted that they be run this way, which delayed their development.

Bert Hall of the Institute for History and Philosophy of Science and Technology at the University of Toronto writes:

"He threw himself over the rail of an English Channel steamer in 1913 after having lost control over his invention and after receiving a great deal of criticism in the German engineering journals for his theories of how the Diesel cycle supposedly worked.

His family was never willing to accept the idea that it was suicide, but most historians seem to agree that he was despondent and suffering from a form of depression. Most historians agree that it was likely suicide.

Diesel had had some sort of mental breakdown about 12-14 years earlier, when he was working madly to develop his engine. He had to be hospitalized and he never fully regained control over the project even after he came back to the firm. The more the engine was developed, the farther it seemed to drift from his original conception, and there was the question of whether his patents would stand up if the engine didn't work according to the theories he had advanced to justify its being patented. He was also coming in for criticism, as I mentioned, and this seemed to worsen his depression. His death seems likely to have been self-inflicted."