The invention fared little better at the hands of Professor Faraday, from whose efficient advocacy the most favorable results might have been anticipated. This gentleman had announced that he would deliver a lecture on the subject in London, in the spacious theatre of the Royal Institution. The novelty of the invention, combined with the reputation of the lecturer, had attracted a very large audience, including many individuals of eminent scientific attainments. Just half an hour, however, before he was expected to enlighten this distinguished assembly, the celebrated lecturer discovered that he had mistaken the expansive principle which is the very life of the machine. Although he had spent many hours in studying the Caloric-Engine in actual operation, and in testing its absolute force by repeated experiments, Professor Faraday was compelled to inform his hearers, at the very outset, that he did not know why the engine worked at all. He was obliged to confine himself, therefore, to the explanation of the Regenerator, and the process by which the heat is continually returned to the cylinder, and re-employed in the production of force. To this part of the invention he rendered ample justice, and explained it in that felicitous style to which he is indebted for the reputation he deservedly enjoys, as the most agreeable and successful lecturer in England. Other causes than the misconception of a Brunel and a Faraday operated to retard the practical success of this beautiful invention. The high temperature which it was necessary to keep up in the circulating medium of the engine, and the consequent oxidation, soon destroyed the pistons, valves, and other working parts. These difficulties the inventor endeavored to remedy, in an engine, which he subsequently constructed, of much larger powers, but without success. His failure in this respect, however, did not deter him from prosecuting his invention. He continued his experiments from time to time, as opportunity permitted, confident that he was gradually, but surely, approaching the realization of his great scheme.