THE subject of this address makes it perhaps a matter of interest to recall a few instances from past history bearing upon the association of physics with the advancements in the arts and sciences.
James Watt, whose great work was in engineering, was by such association led to discover more about the properties of steam, which were imperfectly known at the time; he had many friends among the physicists and chem!sts, but their knowledge of the subject, in which he was deeply interested, did not satisf); him. He, therefore, experimented himself and drew his own conclusions, which, though only approximate, were yet sufficiently correct to guide him to his epoch-making achievements. Then again, there can be no doubt that the work of Watt influenced physicists to direct their attention to the accurate determination of the properties and laws of steamwand not long afterwards to the establishment of the great laws of thermodynamics; for Joule's great work was in physics, although he began with an endeavor to improve an electromagnetic engine worked by the electrolytic consumption of zinc, which he at first thought would supersede the steam engine of Watt as a prime mover; in this work he showed the l{ighest skill as an electrical and mechanical *Address delivered Thursday, September :8, 1924, on the occasion of the centenary of the fotmding of The Franklin Institute.