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Project Mercury pressure suit specialist Joseph W. Schmitt adjusts a respirometer attached to the helmet of astronaut Virgil I. Grissom during a dress rehearsal for the NASA's second manned suborbital flight, dubbed Liberty Bell 7, planned for the week of July 16. Respirometer enables ground medical personnel to monitor the pilot's breathing rate during the countdown and flight. Hose attached to the left side of the pilot's suit brings breathing oxygen into the suit.