The world's largest bubble chamber, the 15‐foot device at the National Accelerator Laboratory, was operated successfully at the end of September, and in October it ran with its 30‐kG magnet at 86&percent; of full field, using the 300‐GeV repetition rate. Earlier this year the Big European Bubble Chamber (BEBC) began operating at CERN and is now being used for physics runs; it is a 3.70‐meter device. These machines, together with the Argonne 12‐foot chamber and the Brookhaven 7‐foot chamber, may be the last generation of big bubble chambers to be built, according to Charles Peyrou, who heads the track‐chambers division at CERN and Nicholas P. Samios of Brookhaven, who has many years of bubble‐chamber experience.