Rudolph Diesel and Herbert Akroyd Stuart

Calling a compression ignition oil engine a diesel is only engineering shorthand. It could just as well have been called a carnot, after the Napoleonic theoretician who drew up its principles in 1824, or an akroyd after the English engineer who went ahead and built one in 1890. Like many nineteenth century inventions, the diesel was the work of several engineers. Nicholas Léonard Sadi Carnot (1796-1832) was the son of Napoleon's chief of staff, the mathematician Lazare Carnot and while he worked out the thermodynamic principles and provided a detailed description, he never actually got round to making one.

Herbert Akroyd Stuart

Herbert Akroyd Stuart (1864-1927) did. His patented oil-fired engine of 1890 was manufactured by Richard Hornsby & Sons of Grantham, Lincolnshire and one was sold to Newport Sanitary Authority as a pumping engine. Alas, its compression was too low and it needed heat applied round its cylinders to start. Once running it worked quite well, and Hornsby developed a high-compression version in 1892 closer to the modern compression ignition engine through having the fuel injected by a plunger pump. Diesel was still blowing it into the cylinders in a blast of air. In any case Diesel’s fuel was not - to begin with at any rate - oil, but a mixture of powdered coal. Working out an effective injection system vexed him for the rest of his life and Akroyd was three years ahead of Dr Diesel's celebrated “Theory and Construction of a Rational Heat Motor” but his lower compressions were about a fifth of what Diesel proposed. 

By the end of the century, small portable gasoline engines with spark ignition were driving cars, motor boats and motorcycles. Compression-ignition engines working on gas or coal-dust were generally large, heavy, stationary power generators or were used for working machinery as an alternative to steam.  

 One Hornsby-Akroyd Patent Safety Oil Traction engine was sold in 1897 to Hugh Fortescue Locke-King, builder of Brooklands, probably as an electric generator. Hornsby advertised four sizes between 16 and 30 horse power and although not many seem to have been sold, they hold the distinction of being the first compression ignition engines to drive motor vehicles. In 1895 four went to Valentine Lynn & Son, the Brooklyn, New York carriage makers, for installation in delivery wagons for the De La Vergne Refrigerating Company. 

Still, it is Dr Rudolph Christian Karl Diesel (1858-1813) whose name stuck and the first truly commercial high-pressure compression ignition engine was patented in Germany. It was 28 February 1892 and he was the Paris-born sales manager of the Linde Ice-Making Machine Company. The Franco-Prussian war had made life in Paris difficult, so at the age of twelve Diesel fled to London before moving to Augsburg Technical High School in 1878. His study of compressing machinery for the Linde company had led to a fresh look at Carnot’s theories on thermodynamics. With help from Krupp and the Maschinenfabrik Augsburg (later MAN the truck manufacturer) he set up a workshop.

 One early engine exploded when he tried to start it, and the air-jet injection system proved troublesome, yet by 1897 Dr Diesel felt confident enough to sell American rights to the German-American brewer Adolphus Busch for a million marks ($250,000). An engine built by the St Louis Iron & Marine Works, installed in the Anheuser Busch Brewery on 2nd Street St Louis, Mo., in September 1898 was the first diesel in commercial operation after Hornsby-Akroyd's municipal power unit of 1890. 

It was 1908, with the work of a British engineer James McKechnie, before Dr Diesel had injection pumps capable of delivering fuel at a pressure of 50 atmospheres. Slow, steady diesel engines found applications at sea, particularly in submarines, which had used petrol engines to generate electricity for their under-water motors. But in 1906 one of the German fleet was destroyed when refuelling and an alternative became imperative.

 Diesel fuel had a lower flash-point and it was more economical, giving submarine longer range. In 1906 the French navy commissioned two diesel-engined submarines and in May 1908 the Royal Navy launched its first diesel submarine the D.1 at Barrow. When Germany laid down the U19 in 1911 it was equipped with two strong diesel engines. 

Jane's Fighting Ships of 1914 carried an advertisement featuring a submarine Krupp built for the Italian navy but by then Dr Diesel was dead. On 29 September 1913 he disappeared off the cross-channel packet SS Dresden between Antwerp and Harwich. His cabin was empty, his belongings, watch and cash were intact, his bed not slept in, and when his body was recovered by the crew of a Dutch trawler in the mouth of the River Scheldt it had a head injury. The only item missing was the briefcase and documents Dr Diesel had brought on board. 

An Antwerp coroner claimed the wound must have occurred before Dr Diesel's death. British police interrogation of the Dresden's crew and Dr Diesel's companions, who had dined with him on board, led nowhere. Could the Kaiser's secret service have been trying to prevent him communicating with the British Admiralty? Admiral Lord Fisher had been in touch with him, but Grand Admiral von Tirpitz may have been determined to keep the secrets to himself.