Section A. -Mathematical and physical sciences. - Address of the President, Lord Rayleigh, O. M., D. C. L., at the anniversary meeting on November 30, 1906

On this list are to be found the names of veterans distinguished in many branches of science and in public affairs. One name is a household word in every physical and chemical laboratory. It would be difficult, indeed, to enumerate the investigations which have owed their success to the invention of the Sprengel mercury pump. In other cases, scientific careers still in full activity have, unhappily, been cut short. I allude especially to Joly, Marshall Ward, and Weldon. Even within my term of office our discussions have been enlivened by Weldon’s scientific enthusiasm and vigorous polemics. On the Foreign list are two distinguished names. Professor Ludwig Boltzmann, of Vienna, was perhaps the first Continental physicist to take up the ideas of Maxwell’s electric theory of light, of which he had early grasped the scope and became for many years one of its most emphatic supporters. One of his earliest series of experiments was a determination of the influence of the crystalline quality on the dielectric constant of sulphur, with a view to comparison with its optical double refraction. In the theory of gases he is to be classed along with Clausius and Maxwell as one of the creators of the dynamical theory, on which he became the highest authority. By developing an idea originated by Bartoli he placed Stefan’s law of intensity of natural radiation on a theoretical basis, and thus became the pioneer in the modern thermodynamics of radiant energy. He contributed to the advance of physical science by many other investigations, and by his books on Gas Theory, on Electrodynamics, and on Mechanics. I may perhaps be allowed to add that at the time of his unhappy death, Boltzmann’s name was before the Council as proposed for one of our medals.