Herbert Akroyd Stuart

Herbert Akroyd Stuart 1864 - 1927. Inventor of the hot bulb heavy oil engine

Herbert Akroyd-Stuart (January 28 1864, Halifax Yorkshire, England - February 19 1927, Halifax) was an English inventor who is noted for his invention of the hot bulb engine, or heavy oil engine.


Akroyd-Stuart had lived in Australia in his early years. He was educated at Newbury Grammar School and Finsbury Technical College on Cowper Street. He was the son of Charles Stuart, founder of the Bletchley Iron and Tinplate Works, and joined his father in the business in 1887.[1]

In 1885 Akroyd Stuart accidentally spilt paraffin oil (kerosene) into a pot of molten tin. The paraffin oil vaporised and caught fire when in contact with a paraffin lamp. This gave him an idea to pursue the possibility of using paraffin oil (very similar to modern-day diesel) for an engine, which unlike petrol would be difficult to be vaporised in a carburettor as its volatility is not sufficient to allow this.

His first prototype engines were built in 1886. In 1890, in collaboration with Charles Richard Binney, he filed Patent 7146 for Richard Hornsby and Sons of Grantham, Lincolnshire, England. The patent was entitled entitled: "Improvements in Engines Operated by the Explosion of Mixtures of Combustible Vapour or Gas and Air".[2] One such engine was sold to Newport Sanitary Authority, but the compression ratio was too low to get it started from cold, and it needed a heat poultice to get it going.[3]

Akroyd-Stuart's engines were built from June 26th 1891 by Richard Hornsby and Sons as the Hornsby-Akroyd Patent Oil Engine under licence and were first sold commercially on July 8th 1892.

Similar engines were built by Bolinder in Sweden and some of these still survive in canal boats. Hot bulb engines in the USA were made by De La Vergne Company of New York, later the New York Refrigerating Company - inventing the modern refrigerator in 1930, who purchased a licence in 1893.

Richard Hornsby and Sons built the world's first oil-engined railway locomotive LACHESIS for the Royal Arsenal, Woolwich, England, in 1896. They also built the first compression-ignition powered automobile.

Patent dispute with Rudolf DieselEdit

The modern Diesel engine is a hybrid incorporating the features of direct (airless) injection and compression-ignition, both patented (No. 7146) as Improvements in Engines Operated by the Explosion of Mixtures of Combustible Vapour or Gas and Air by Akroyd-Stuart and Charles Richard Binney in May 1890.[2] Another patent (No. 15,994) was taken out on October 8th 1890, which details the working of a complete engine, essentially that of a diesel engine where air and fuel are introduced separately.

Rudolf Diesel patented compression-ignition in 1892; his injection system, where combustion was produced isobarically (the technique having been patented by George Brayton in 1874 for his carburettor), was not subsumed into later engines, Akroyd-Stuart's injection system with isochoric combustion developed at Hornsbys being preferred.

Akroyd-Stuart's compression ignition engine (as opposed to spark-ignition) was patented two years earlier than Diesel's similar engine; Diesel's only patentable idea was to increase the pressure. The hot bulb engine, due to the lower pressures used (around 280 PSI), had only about a 12% thermal efficiency.

In 1892, Akroyd-Stuart patented a water-jacketed vaporiser to allow compression ratios to be increased. In the same year, T.H. Barton at Hornsbys built a working high-compression version for experimental purposes whereby the vaporiser was replaced with a cylinder head therefore not relying on air being preheated, but by combustion through higher compression ratios. It ran for six hours - the first time automatic ignition was produced by compression alone. This was five years before Rudolf Diesel built his well-known high-compression prototype engine in 1897.

Diesel was, however, subsequently credited with the innovation despite the adduced evidence to the contrary.


In 1900, he moved to Australia and set up a company Sanders & Stuart with his brother Charles, latterly moving back to Yorkshire, England. He died 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 1800s, 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 alsoEdit


  1. "Victoria Road". Bletchley Archaeological & Historical Society. Retrieved on 2007-07-29.
  2. 2.0 2.1 "The Akroyd Oil Engine". Ray Hooley's - Ruston-Hornsby - Engine Pages. Retrieved on 2007-07-29.
  3. "Diesel has come a long way but still doesn't get the tax breaks it deserves". The Scotsman, Scotland on Sunday (2003-01-16). Retrieved on 2007-07-29.

External linksEdit


  • US Patent 845140 Combustion Engine, dated February 26th 1907.
  • US Patent 502837 Engine operated by the explosion of mixtures of gas or hydrocarbon vapor and air, dated August 8th 1893.
  • US Patent 439702 Petroleum Engine or Motor, dated November 4th 1890.

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