The Diesel engine is a type of internal combustion engine which runs on Diesel fuel. It is named for its German inventor Rudolf Diesel (1858-1913). Diesel obtained patents for the engine in 1893 and 1898.  Inventors in several countries had obtained patents for oil engines a little earlier but their engines differed from Diesel's in that they were not true compression-ignition engines.
Rudolph Diesel fell from a cross-channel ferry in 1913 and drowned. The circumstances of his death are unknown but theories include suicide and murder.
These engines have some similarities to diesel engines but they are not true compression ignition engines because they have a lower compression ratio and use an auxiliary source of heat to ignite the fuel.
George Brayton, of Boston, Massachusetts was a builder of gas engines. He later built engines capable of running on liquid fuel using a fuel injection system similar to that used in Diesel engines. He obtained patents in 1872, 1874 and 1890.  
Hot bulb engine
British inventors Herbert Akroyd Stuart and Charles Richard Binney obtained two patents for a Hot bulb engine in 1892.   The Hot bulb engine has a lower compression ratio than a Diesel engine and the hot bulb, in which the fuel is vaporized, has to be heated by a blowlamp before the engine can be started.
The diesel engine is a compression-ignition engine. Unlike a gasoline engine, it does not require an electric spark to ignite the fuel. The high temperature needed to ignite the fuel is obtained purely by compression of air in the engine cylinders. Because of its high compression ratio, the diesel engine has a higher thermal efficiency than a gasoline engine.
Diesel engines are widely used throughout the world to power electrical generators, ships, submarines, railroad locomotives, trucks, buses, construction machinery and automobiles. They have been used to power aircraft, notably airships, but for fixed wing aircraft, they have been supplanted by jet engines.
Under load, diesel engines produce black smoke, see Rolling Coal. They also produce larger volumes of Nitrogen Oxides than gasoline engines. Modern diesel engines are tuned to minimize smoke production and they can be fitted with urea injection systems to reduce emission of nitrogen oxides.
In the United Kingdom, Global warming hysteria has led to confused policies on diesel pollution. The UK government initially promoted diesel cars as "environment friendly" because they produce less carbon dioxide than petrol (gasoline) cars. Then they discovered that, because of the growth in diesel car use, air pollution from nitrogen oxides was rising. Diesel cars are now unpopular with the UK government and a scrappage scheme (similar to the Cash for Clunkers scheme in the United States) may be introduced.