THE actual date of the centenary of this Society was February 1920. Prof. A. Fowler, who was then president, delivered an appropriate address on that occasion, recapitulating the circumstances of the origin and early history of the Society. It was felt, however, that the conditions of foreign travel were still too difficult to render the occasion suitable for a full celebration of the event. Early in the present year it was thought that it would be well to take advantage of the presence of a large number oi astronomers in Rome, at the meeting of the International Astronomical Union, many of whom, it was hoped, would be able to visit London on their way home. The end of May was therefore chosen as the date for the celebration, which was attended by a considerable number of associates.