China conducted its sixteenth nuclear explosion (fifteenth in the atmosphere) at Lop Nor (40¿N, 90¿E) on June 17, 1974. France also started its 1974 test series of nuclear explosions on the same date in the southern hemisphere near Mururoa Atolls (22¿S, 139¿W). Radioactive fallout samples from some of these nuclear explosions were collected by swiping certain exposed portions of the aircraft flying between Tokyo/Ōsaka and Bombay, New York and Bombay (for the Chinese test), and Sydney and Bombay (for the French tests). This paper gives some of our observations based on these studies for samples collected between June 15, 1974, and July 30, 1974. The study involved measurement of a number of radionuclides, i.e., 89Sr, 99Mo, 111Ag, 132Te, 140Ba, 237U, 239Np, etc. The observed activity ratios for some selected pairs of radionuclides have been interpreted in terms of fissile material used in the device and the type of explosion.