Sir James Dewar (1842-1923) lecturing on liquid hydrogen at the Royal Institution in London in 1904. Dewar was born at Kincardine-on-Forth in Scotland and was educated at Dollar Academy and the University of Edinburgh. In 1875 he obtained a professorial position at Cambridge and, two years later, at the Royal Institution in London. He invented the Dewar flask (known domestically as the thermos flask) and used it for the storage of liquified gases in his research on low temperatures. Using the Joule-Thompson effect, Dewar was the first to build a large regenerative cooling machine, with which he was the first to liquefy hydrogen in 1898. This painting by Henry Brooks shows Dewar lecturing during one of the popular 'Evening Discourses' instigated by Faraday and which are still held to this day.