Auguste Mouchout, French inventor of the first known device that directly converted solar energy into mechanical power (1865). Mouchout began his work with solar energy in 1860 after expressing grave concerns about his country’s dependence on coal. His initial experiments involved a glass-enclosed, water-filled iron cauldron, in which sunlight passed through a glass cover, heating the water. This simple arrangement boiled water, but it also produced small quantities of steam. Mouchout added a reflector to concentrate additional radiation onto the cauldron, thus increasing the steam output. He succeeded in using his apparatus to operate a small, conventional steam engine. Impressed by Mouchout’s device, Emperor Napoleon III offered financial assistance, which Mouchout used to produce refinements to the energy system. Mouchout’s work help lay the foundation for our current understanding of the conversion of solar radiation into mechanical power driven by steam.