the Explosion of Mixtures of Combustible Vapour or Gas and Air, and No. 15994. In the former, the Akroyd engine's operating principle is described as follows: "... at the desired part of this compression stroke, the supply of liquid hydrocarbon is forced, in a spray form, on to the heated vaporiser, which almost instantly changes it into a gas...". Early Akroyd engines indeed operated on this principle. Rudolf Diesel had a patent on the combustion process described in his essay (DRP 67207). The Diesel engine neither operates on the process described in the Akroyd patent, nor on the process described in the DRP 67207 patent. It operates instead on a different operating principle, also invented by Rudolf Diesel (patented in 1893, DRP 82168), which is why Diesel is in fact the Diesel engine's inventor. However, Diesel never admitted that his engine operated on a "secret" operating principle, and claimed that the Diesel engine operates on the (impossible) operating process described in the DRP 67207 patent. The key difference between the Akroyd and Diesel engines is the ignition: In an Akroyd engine, an ignition device – the so-called "hot bulb" or "vaporiser" – ignites the fuel, because the compression is too low for compression ignition (<300 kPa). A Diesel engine on the other hand has no discrete ignition devices. The fuel instead ignites due to high heat caused solely by piston compression inside the cylinder (>3000 kPa). Since higher compression leads to better efficiency, the lower-pressure Akroyd engine consumes ~ 80% more fuel than a Diesel engine doing the same work. Death In 1900, he moved to Australia and set up a company Sanders & Stuart with his brother Charles, late in life moving back to Yorkshire, England. He died on 19 February 1927 in Halifax of throat cancer, and was buried in All Souls church in Boothtown, Halifax. The University of Nottingham has hosted the Akroyd-Stuart Memorial Lecture on occasional years in his memory since 1928. One was presented by Sir Frank Whittle in 1946. Akroyd Stuart had worked with Professor William Robinson in the late 19th century, who was professor of engineering from 1890 to 1924 at University College Nottingham. Akroyd-Stuart also left money to the Institution of Mechanical Engineers, Royal Aeronautical Society and Institute of Marine Engineering, which provided for their respective bi-annual Akroyd-Stuart Prizes. See also History of the internal combustion engine Notes External links Biography Relation