THE world's air altitude record was regained for Great Britain by the Royal Air Force on June 30, by a flight to an altitude of 53,937 feet (more than ten miles). The previous record of 51,362 feet was held by Lieut.-Colonel Mario Pezzi for Italy, who beat the then British record of 49,944 feet last autumn. The flight was made from the aerodrome of the Royal Aircraft Establishment, Farnborough, by Flight-Lieut. M. J. Adam, using the Bristol 138 experimental high altitude aircraft. This was the same machine as used by Flight-Lieut. Swain, R.A.F., for the previous record, but was fitted with a special Bristol Pegasus engine. It had various detail improvements as suggested by experience. The pilot wore the actual high-pressure suit that was prepared as a reserve for the previous record flight, with small improvements. These included precautions against 'frosting up' of the Celestroid windows of the headpiece, and an emergency breathing pipe to lead air direct from the outside when necessary, instead of having to slash open the front of the headpiece as did Flight-Lieut. Swain, upon landing, after his flight. The transparent material forming the cabin roof was observed to crack upon reaching an altitude of about 48,000 feet, but this was not serious enough to interfere with the continuation of the flight.