Commission 25. (Stellar Photometry.)

The acting chairman read a letter from the President of the Commission, Mr F. H. Seares, calling the attention of the Commission to certain points of importance which might be taken up for discussion. In the course of this discussion Dr H. Shapley invited cooperation with the Harvard Observatory on the work of unification of the magnitude systems in the northern and southern sky. After a discussion on the problems of standardizing colour filters and photographic plates used in stellar photometry the recommendation suggested by Dr Shapley that all engaged in photometric research publish promptly the characteristics of their instruments, colour filters, etc., was adopted.