THE
ERUPTION
OF
PELÉE
43
at this time; on the other hand, the great earthquake of Guatemala, on April 18, was impressively registered by the seismographs at nearly all, or all, of the observatories. The most interesting magnetic notation is t h a t of Zi-ka-Wei, China, the observations pertaining to which were made by M. de Moidrey, and are published in the Comptes Rendus for August 11, 1902: "Ce jour-là, à 7 h. 58 m. [Martinique time], après une longue période de calme magnétique, notre bifilaire indique un accroissement brusque de la composante horizontale, qui reste agitée pendant huit heures environ" (p. 322). The duration and the great distance a t which the disturbance was felt are alike noteworthy. Zi-ka-Wei is situated almost exactly on the meridian opposed to Saint-Pierre—i.e., half round the world in distance from it. This record is specially significant as during the K r a k a t a o eruption it was considered doubtful if the instruments of this station recorded any disturbance t h a t could be correlated with the cataclysmic occurrences in the Sunda Straits.* The replies to the official inquiries sent out b y the K r a k a t a o Committee of the Royal Society would seem to indicate t h a t no particular magnetic disturbances were noted in Bombay, Melbourne or Toronto, and the perturbation was so slight and of so doubtful a nature in the European cities t h a t it m a y be questioned if they were in any way related to the eruption; at all events, there was nothing t h a t was a t all comparable with the magnitude of the disturbance registered a t the American stations. On the other hand, it seems t h a t some slight magnetic variation was noted a t Para, Brazil, on the day of the K r a katao eruption. Dr. Van der Stok, the Director of the Batavia Observatory, noted at the time of the K r a k a t a o eruption a marked magnetic oscillation, which he attributed to the influence of the magnetic iron contained in the falling ashes. Probably this disturbance was of the same nature as t h a t which I noted on the rim of the ancient basin of the Lac des Palmistes a t the time of m y first ascent to the summit of Pelée (May 31), when the compass-needle was deflected forty degrees or more to the eastward. The basin was still steaming extensively, and was largely filled u p with ejected material from the volcano, recently cast out.† I n discussing the problems t h a t are associated with this new form of magnetic disturbance, Bauer expresses himself as follows:‡ " The coincidence of the magnetic disturbance with the Mt. Pelée eruption was such a striking one as to suggest, as already stated, some physical connection. And the first thought might naturally be t h a t the displacement of masses in the earth's interior produced a redistribution of the electric currents inside
* M a r c Dechevrens: "Je ne sais si les irregularité magnétiques que j'envoie ont eu aussi une relation avec le bouleversement de Krakatao; les magnétogrammes ne montrent rien le 28."— R o y a l Society R e p o r t , 1888, p. 473. † See in this connection t h e suggestive p a p e r b y D a v i d : " L a stabilité de la direction d'aim a n t a t i o n de quelques roches volcaniques." Comptes Rendus, 1904 (138), pp. 41-42. ‡"The P r e s e n t P r o b l e m s of T e r r e s t r i a l M a g n e t i s m . "