(March 18, 1858 – last seen alive September 29, 1913) was a European inventor and mechanical engineer, famous for the invention of the diesel engine. Diesel was born in Paris, France in 1858 the second of three children to Theodor and Elise Diesel. Diesel's parents were German-born immigrants who lived in France. Theodor Diesel, a bookbinder by trade, had left his home town of Augsburg/ Bavaria, in 1848. He met his wife, Elise Strobel, daughter of a Nuremberg merchant, in Paris in 1855 and became a leather goods manufacturer himself. Diesel was first brought up in France, but with the beginning of the Franco-Russian War in 1870, the family, among other foreigners, was forced to escape the country and therefore emigrated to London. Before the end of the war, Diesel's mother sent 12-year-old Rudolf to Augsburg to live with his aunt and uncle, Barbara and Christoph Barnickel, giving him the chance to learn German and visit the Königliche Kreis-Gewerbsschule [Royal County Trade School], where his uncle worked as a teacher for mathematics. At age 14, Rudolf sent a letter to his parents in which he stated his intention to become an engineer. After he had finished his basic education in 1873, he enrolled at the newly-founded Industrial School of Augsburg. In 1875, he received a merit scholarship from the Royal Bavarian Polytechnic in Munich which he accepted against the will of his parents who would rather have seen him begin earning money instead. In Munich, one of his professors was Carl von Linde. Diesel could not graduate in July 1879 because of a bout of typhoid. While waiting for a new exam date, he engaged in practical engineering at the Gebrüder Sulzer Maschinenfabrik [Sulzer Brothers Machine Works] in Winterthur, Switzerland. He graduated with highest academic honors from his Munich alma mater in January 1880 and went back to Paris, assisting his former professor Carl von Linde with the design and the construction of a refrigeration and ice plant. One year later, Diesel became director of the plant. In 1883, Diesel got married to Martha Flasche, and continued working for Linde, garnering plenty of patents in Germany and France. In 1890, Diesel moved his wife and their three children (Rudolf Jr, Heddy, and Eugen) to Berlin to assume management of Linde's corporate research and development department and to join several other corporate boards there. Not being allowed to use the patents he had developed being an employee of Linde for his own purposes, Diesel decided to expand into an area outside refrigeration. He first toyed with steam, his research into fuel efficiency leading him to build a steam engine using ammonia vapor. During tests, the machine exploded with almost fatal consequences for him. Diesel spent many months in the hospital in consequence, dealing with a great amount of ill health and eyesight problems. He also started designing an engine based on the Carnot cycle, and after Gottlieb Daimler and Karl Benz had invented the automobile in 1887, Diesel published a treatise entitled Theorie und Construktion eines rationellen Wärmemotors zum Ersatz der Dampfmaschine und der heute bekannten Verbrennungsmotoren [Theory and Construction of a Rational Heat-engine to Replace the Steam Engine and Combustion Engines Known Today] in 1883 which formed the basis for his work on and his invention of the diesel engine. Diesel understood thermodynamics and the constraints on fuel efficiency very well. He was aware of the fact that even the most excellent steam engines were only 10-15% thermodynamically efficient, leading to 90% of the energy available in the fuel getting lost. His work in engine design was driven by the goal of much higher efficiency ratios. He tried to design an engine based on the Carnot Cycle. However, he gave up on this trying to develop his own approach instead. Eventually he designed his own engine and obtained a patent for his design. In his engine, fuel was injected at the end of compression and the fuel was ignited by the high temperature resulting from compression. In 1893 he published a German book entitled "Theory and design of a rational thermal engine to replace the steam engine and the combustion engines known today" (English translation of the original title in German) with the support of Springer Verlag, Berlin. He then managed to construct a working engine according to his theory and design. His original engine and its successors are known as diesel engines today. >From 1893 to 1897, Heinrich von Buz, director of MAN AG in Augsburg, made it possible for Diesel to test and develop his ideas. Rudolf Diesel obtained patents for his design in Germany and various other countries, thereunder the USA On September 29, 1913, Diesel boarded the post office steamer Dresden in Antwerp on his way to a meeting of the Consolidated Diesel Manufacturing company in London. He took dinner on board and then retired to his cabin at about 10 p.m., leaving word for him to be called the next morning at 6:15 a.m. He was never seen alive after that. Ten days later, the crew of the Dutch boat "Coertsen" came upon the corpse of a man floating in the sea. The body was in such an advanced state of decomposition that they did not bring it aboard. Instead, the crew retrieved personal items (pill case, wallet, pocket knife, eyeglass case) from the clothing of the dead man, and returned the body to the sea. On the 13th of October these items were identified by Rudolf's son, Eugen Diesel, as his father´s belongings. No one knows for sure how or why Diesel was lost overboard. Grosser presents a credible case for suicide. There are conspiracy theories that suggest that various people's business interests may have provided motives for homicide. Evidence is limited for all explanations. Source: Wikipedia