Robert Stirling

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Robert Stirling
Robert Stirling.jpg
Reverend Dr Robert Stirling
Born (1790-10-25)25 October 1790
Methven, Perthshire
Died 6 June 1878(1878-06-06) (aged 87)
Galston, East Ayrshire
Nationality Scottish
Citizenship United Kingdom
Occupation Engineer
Children Patrick Stirling b.1820
Jane Stirling b.1821
William Stirling b.1822
Robert Stirling b.1824
David Stirling b.1828
James Stirling b.1835
Agnes Stirling b.1838
Parent(s) Patrick Stirling and Agnes Stirling
Engineering career
Institutions University of Edinburgh, University of Glasgow
Projects Stirling engine

The Reverend Dr Robert Stirling (25 October 1790 – 6 June 1878) was a Scottish clergyman, and inventor of the Stirling engine.

Background and Christian ministry[edit]

Robert Stirling was born at Fatal Fields, a location in Scotland near the village of Methven, Perthshire.[1] A member of the Dublane side of the Stirling family, Robert was born to Patrick and Agnes Stirling.[2] He was one of eight children that Patrick and Agnes shared.[2] His grandfather was Michael Stirling, most famously known for his invention of the threshing machine.[1] Robert's father Patrick also spent time experimenting and innovating with industrial agricultural equipment.[1]

Though Robert, like his father and grandfather, had a natural inclination for engineering, he began attending Edinburgh University in 1805 at the age of fifteen to study divinity in hopes of becoming a minister.[1][3] His brother James, who would play a major role in Stirling's future engineering endeavours, also attended Edinburgh at the age of 14.[3] Robert concluded his studies at Edinburgh and continued to study at Glasgow University in November of 1809.[1][3] In 1814, he returned to Edinburgh University studying divinity for a final time.[3]

Robert was licensed to preach in the Church of Scotland in 1816 by the Presbytery of Dumbarton. In September of 1816, the commissioner of the Duke of Portland granted Stirling the title of Minister as the second charge for the Laigh Kirk parish in Kilmarnock.[1][4]. Finally, in February of 1824, Stirling was appointed as the minister of nearby Galston Parish Church where he continued his ministry until 1878.[5]

In July of 1819, Robert Stirling married Jane Rankine.[2] Together, they had seven children, five sons and two daughters.[1]

Engineering and science[edit]

Hot air engine[edit]

Robert Stirling’s best known invention is the heat engine now referred to as the Stirling Engine. In 1816 Robert Stirling and his younger brother, James Stirling, applied for a patent in both Scotland and England for a device they invented, a Heat Economiser. The function of this invention was to store and release heat as air circulated through its mechanisms. This differed from most heat engines which used steam as their method of storing and releasing energy.[6]

While in Kilmarnock, he collaborated with another inventor, Thomas Morton, who provided workshop facilities for Stirling’s research.[7] By 1818 Stirling had incorporated this Heat Economiser into a piston engine that created a closed cycle heat engine, which was powered by air, a contrast to the steam engines that were predominant at the time. This updated version of the heat engine was used to pump water from a quarry.[8] Stirling’s heat engine was able to run well but was limited by the weaker metals available at the time. Due to the flimsiness of the materials used, the air vessels were eventually crushed by the high pressure of the heated air.[9]

In 1824 Stirling sought to improve the efficiency of the heat engine by attempting to separate the air present in the economizer. This was done by making the plungers in the air engine from thin plates of metal. This was to improve airflow and offer better heating and cooling of the engine.[10] Although this idea received a patent, it was ultimately unsuccessful in improving the heat engine’s overall efficiency.[11]

In 1840 Stirling received another patent for the heat engine after altering the design in a new attempt to increase durability. The improvements added by Stirling included the addition of rods or plates in the passage through which hot air travelled to the cold section of the engine. By having these surfaces, the air was able to be cooled to a lower temperature when travelling from the hot section of the engine to the cold section of the engine. Additionally, Stirling added cupped leather collars around the piston rods to seal gaps and minimize the leakage of air from the engine.[12] After developing these improvements, Stirling built two of these heat engines to use at an iron foundry he managed in Dundee.[11] One of these air engines was started in March of 1843 where it ran until December of 1845 when an air vessel failed. The air vessel failure could be attributed to the metals being unable to withstand the high temperatures at which the engine was running. After replacing the air vessel a couple times, the air engine was dismantled in 1847 after Stirling left the Dundee iron foundry.[13]

In 1876 Robert Stirling wrote a letter acknowledging the importance of Henry Bessemer’s new invention, the Bessemer process for the manufacture of steel. Sterling was optimistic that the new steel would improve the performance of the air engines.

Robert Stirling's development of the hot air engine was in part motivated by safety. His engine was designed to fail far less catastrophically than the steam engines of the time while obtaining greater efficiency.[1] Though the Stirling engine is rarely used today, it's seemingly perpetual motion capability continues to draw the interest of research institutions like Los Alamos National Laboratory and NASA.[1]

Rev Stirling's air engine, 1827, Hunterian Museum, Glasgow

Personal life and death[edit]

On 10 July 1819, Stirling married Jean Rankine at Kilmarnock. They had seven children:[14][15]

  • Patrick Stirling, born 29 Jun 1820, became a locomotive engineer
  • Jane Stirling, born 25 Sep 1821, housewife
  • William Stirling born 14 Nov 1822, became a civil engineer and railway engineer in South America
  • Robert Stirling, born 16 Dec 1824, became a railway engineer in Peru.
  • David Stirling, born 12 Oct 1828, became the Minister of Craigie, Ayrshire
  • James Stirling, born 2 Oct 1835, became a locomotive engineer
  • Agnes Stirling, born 22 Jul 1838, became an artist

Rev. Robert Stirling died in Galston, East Ayrshire on 6 June 1878. He is buried in Galston Cemetery where a new gravestone was erected in December 2014 by public subscription replacing the original stone which was in a ruined state. It was rededicated on Sunday 3 May 2015.[15]


On 11 January 1840, Stirling was awarded the title Doctor of Divinity by the University of St. Andrews for his excellence in ministry.[16][15][17]

On 3 October 2014 Stirling was inducted into the Scottish Engineering Hall of Fame.[17][18]


  1. ^ a b c d e f g h i Howard, Bromberg (2010). Great Lives from History: Inventors and Inventions. Salem Press. pp. 1037–1039. ISBN 1-58765-522-5. 
  2. ^ a b c Sier, Robert (1995). Rev Robert Stirling D.D. Essex: L A Mair. p. 2. ISBN 0 9526417 0 4. 
  3. ^ a b c d Sier, Robert (1995). Rev Robert Stirling D.D. Essex: L A Mair. p. 8. ISBN 0 9526417 0 4. 
  4. ^ Sier, Robert (1995). Rev Robert Stirling D.D. Essex: L A Mair. p. 10. ISBN 0 9526417 0 4. 
  5. ^ Sier, Robert (1995). Rev Robert Stirling D.D. Essex: L A Mair. p. 20. ISBN 0 9526417 0 4. 
  6. ^ Sier, Robert (1995). Rev Robert Stirling D.D. Essex: L A Mair. p. 58. ISBN 0 9526417 0 4. 
  7. ^ Sier, Robert (1995). Rev Robert Stirling D.D. Essex: L A Mair. p. 16. ISBN 0 9526417 0 4. 
  8. ^ Sier, Robert (1995). Rev Robert Stirling D.D. Essex: L A Mair. p. 73. ISBN 0 9526417 0 4. 
  9. ^ Trevino, Marcella (2013). Encyclopedia of Energy. Salem Press, Incorporated. pp. 1185–1186. ISBN 0-470-89439-3. 
  10. ^ Sier, Robert (1995). Rev Robert Stirling D.D. Essex: L A Mair. p. 79. ISBN 0 9526417 0 4. 
  11. ^ a b Marsden, Ben (2004). Oxford Dictionary of National Biography. Oxford University Press. 
  12. ^ Sier, Robert (1995). Rev Robert Stirling D.D. Essex: L A Mair. p. 83. ISBN 0 9526417 0 4. 
  13. ^ Sier, Robert (1995). Rev Robert Stirling D.D. Essex: L A Mair. p. 93. ISBN 0 9526417 0 4. 
  14. ^ "Robert Stirling". 2009-05-18. Retrieved 2012-06-18. 
  15. ^ a b c "Robert Stirling". KiRK News. Galston Church of Scotland Parish. 2015. Retrieved 15 August 2015. Stirling Service link 
  16. ^ Sier, Robert (1995). Rev Robert Stirling D.D. Essex: L A Mair. p. 24. ISBN 0 9526417 0 4. 
  17. ^ a b "Reverend Doctor Robert Stirling (1790-1878)". Scottish Engineering Hall of Fame. Retrieved 15 August 2015. 
  18. ^ "Selection of Media Coverage". Scottish Engineering Hall of Fame. 4 October 2014. Retrieved 15 August 2015.