At the IPPF Bombay conference, Clarence was busily finding foreign doctors interested in testing and collecting data on the effectiveness of simple methods of contraception. In the 1930s he had attempted to do this, working with a list of missionary doctors supplied by his brother Sidney, who was a member of the Presbyterian Board of Foreign Missions. Little had come of that attempt: foreign customs levied large duties, the climate quickly reduced powder and sponge to paste and gum, and overworked missionary physicians had no time to keep the careful records Clarence needed for substantive clinical studies. The Bombay conference offered new contacts and new opportunities.