THE sixteenth annual Exhibition of Electrical, o*o Optical, and other Physical Apparatus held by the Physical Society of London and the Optical Society on January 5, 6, and 7, was marked by a new departure which added greatly to its interest and popularity. In addition to the trade display of scientific apparatus, a number of demonstrations were provided in illustration of typical results of modern research and new or improved laboratory methods, together with lecture experiments and repetitions of famous historical experiments. After the admission of ticket-holders for the usual two days, the Exhibition was thrown open to the general public for a further day, and the available accommoda tion at the Imperial College of Science and Techno logy, South Kensington, was fully occupied through out. There can be no doubt as to the success of the new section, and it is to be hoped that in future years it may be greatly extended. It makes con siderable demands on the time of those who take part in it, as the experiments have to be carefully prepared, but public spirit of this kind has never been lacking amongst physicists. Prof. A. O. Rankine must be congratulated on the feat of organis ation which he achieved, and mention must be made of the excellent illustrated catalogue, containing brief descriptions of the more important exhibits, which is now printed in a form suitable for inclusion in the bound volumes of the Proceedings of the two Societies.