Robert Stirling, inventor of the Stirling engine, was born at Gloag, Methvin, Perthshire on 25 October, 1790 and was the third of a family of eight children. His father was Patrick Stirling, son of Michael Stirling of Threshing Machine fame and his mother was Agnes Stirling, daughter of Robert Stirling, farmer in the Cromlix, Dunblane.

In 1850 the simple and elegant dynamics of the engine were first explained by Professor McQuorne Rankine. Approximately one hundred years later, the term "Stirling engines" was coined by Rolf Meijer in order to describe all types of closed cycle regenerative gas engines. Perhaps his most important invention was the "regenerator" or "economizer" as he called it. This is used today in Stirling engines and many other industrial processes to save heat and make industry more efficient.

Stirling engines are unique heat engines because their theoretical efficiency is nearly equal to their theoretical maximum efficiency, known as the Carnot Cycle efficiency. Stirling engines are powered by the expansion of a gas when heated, followed by the compression of the gas when cooled. The Stirling engine contains a fixed amount of gas which is transferred back and forth between a "cold" end (often room temperature) and a "hot" end (often heated by a kerosene or alcohol burner). The "displacer piston" moves the gas between the two ends and the "power piston" changes the internal volume as the gas expands and contracts.

Stirling engines are being studied at NASA for use in powering space vehicles with solar energy!

Robert was a bright lad and, from 1805 to 1808, attended Edinburgh University, where he studied Latin, Greek, Logic, Mathematics and Law. His younger brother James was later to attend at the age of 14 and became a Civil Engineer of some fame.

Robert enrolled as a student of Divinity at Glasgow University in November 1809 and completed five sessions. He was a model student there. On 15th November 1814, he was enrolled at Edinburgh University as a Student of Divinity, where again his conduct was exemplary. In 1815, Robert Stirling was examined by the Presbytery of Dunbarton and, after the usual tests, found competent to preach the Gospel, a license being issued to this effect on 26th March, 1816. In 1816, he was presented by the Commisioners of the Duke of Portland to the second charge of the Laigh Kirk, Kilmarnock. He appeared before the Presbytery of Irvine, who unanimously agreed on his suitability and, after satisfactory execution of varied trials had him ordained Minister of the Second Charge of Laigh Kirk on 19 September, 1816.

At an early age, Robert had been introduced to engineering by his father, Patrick Stirling, who had assisted his own father, Michael, in the maintenance of his threshing machines, and had always shown a keen interest in anything mechanical, and in particular in sources of power for machinery. On 27th September, 1816, he applied for a patent for his now well famed engine. He had his patent enrolled on 20 Jan 1817. He had been working on this engine for several years before moving to Kilmarnock, and his research continued there.