The Stirling engine was first developed and patented by Rev. Robert Stirling in 1816. The engine was further improved by many yet failed to gain significant market adaptation due to technical limitations. One of the major technical limitations with kinematic Stirling engines was the difficulty in maintaining low friction sealing surfaces and the reliability of the mechanical linkages. In 1964, while teaching a mechanical engineering class at Ohio University in Athens Ohio, William Beale conceptualized what would come to be known as the Free-Piston Stirling Engine (FPSE.) This new design eliminated the driving shaft sealing surface and most mechanical linkages, as well as opened the door for other technical innovations which would improve the efficiency and reliability of the Stirling engine.