John Leslie (April 10, 1766 - November 3, 1832) was a Scottish mathematician and physicist. In 1802 he gave the first modern account of capillary action. In 1804, he experimented with radiant heat using a cubical vessel filled with boiling water. One side of the cube is composed of highly polished metal, two of dull metal (copper) and one side painted black. He showed that radiation was greatest from the black side and negligible from the polished side. The apparatus is known as a Leslie cube. In 1805 he was elected to the chair of mathematics at Edinburgh. While there he published Elements of Geometry, Geometrical Analysis and Plane Trigonometry (1809). In 1810 he froze water using an air-pump which was the first artificial production of ice. In 1813 he published a follow-up to his previous book entitled, Geometry of Curve Lines. His main contributions to physics were made by the help of the differential thermometer. By adapting to this instrument to various ingenious devices, he was able to employ it in a great variety of investigations, connected especially with photometry, hygroscopy and the temperature of space. He published a famous book about multiplication table The Philosophy of Arithmetic in 1820. He died in 1832 at the age of 66.