context: The Scottish Researcher Robert Stirling invented the first practical example of a closed-cycle air engine in 1816, and Fleming Jenkin, in 1884, referred to all such machines as Stirling engines in general. The name proposition became less popular, and the various types of engines available on the market continued to be named after their designers or manufacturers, for example Ryder, Robinson or Henrici's (thermal) air engines. In the 1940s, Phillips began searching for a suitable name for its own "air engine", which at that time tested their engine with other gases, and in April 1945 decided to name it the "Stirling Engine". However, nearly thirty years later, Graham Walker is unhappy with the use of terms such as "thermal gas" as a synonym for "Stirling engine", while the Stirling engine name is widely used. The situation has now improved somewhat, at least in academic literature, suggest that now separately, now a general term for a Stirling engine with a permanently gaseous working fluid is used to refer to the closed-cycle regenerative heat engine, in which the cycle is defined as a thermodynamic system in which the System The working fluid is permanently stop, reproducing a specific type of internal heat exchanger and a regenerator (regenerator) describes the use of known as a thermal store. In 1931, a working machine on the same principle was invented using a liquid instead of aerosol liquid, known as the Malone heat engine.
question: Who invented the Stirling engine?
answers.text: Robert Stirling