In this letter we do not intend to repeat the presentation of the results obtained in French stations in connection with the world magnetic effects of the July 9, 1962, event. In two Notes at the Academie des Sciences de Paris, Roquet, Schlich, and Selzer [1962a, b] presented the essential parts of these results, at least in a schematic way, pending the publication of a more elaborated paper to appear in an early issue of the Annales de geophysique. This letter has a somewhat different purpose. It intends to draw the attention of our colleagues working on the same subject to some peculiarities that apparently have so far been overlooked. In the two Notes already cited we gave the exact times at which the first impetus due to the detonation was recorded in Chambon-la-Foret (France) and in Kerguelen Islands (South Indian Ocean), remarking that these two times (respectively, 0900:08.8±0.2 and 0900:08.7±0.5 UT) differed by less than a few tenths of a second. Later we found out that with the same approximation they were in fact coincident with the zero time of the detonation (0900:09.0 UT). From this we have concluded that the first impetus had traveled with a velocity far greater than the fastest that can be calculated for hydromagnetic waves, and that it had been propagated either by some electromagnetic means or by some other very fast process, such as extremely fast neutrons as suggested by Crain and Tamarkin [1961] and Field [1963]. The speeds involved are at least greater than one-twentieth the speed of light.