Tentative conclusions previously drawn from an analysis of seismic readings of four 1954 hydrogen bomb explosions are re-examined in the light of source data subsequently released on these explosions. The released data show that the authors' earlier computed origin-times for the four explosions were correct within 0�0, 0�4, 0�7, and 0�1 sec respectively. The re-examination shows that the J.B. P tables. need a correction of ?2�2 � 1�0 sec for surface epicentres in the mid Pacific and recordings at continental stations. It is confirmed that any difference between the P travel-times from Bikini to Australia and Bikini to the United States is not much more than 1/2 sec. The authors' previous inferences on the velocities of air waves from the explosions remain undisturbed. The re-examination confirms the occurrence of diffracted PKP waves in front of the 142� caustic, and confirms that these diffracted waves arrive at times significantly earlier than PKIKP waves.