Having collected the observations made at all the chief meteorological stations, General Strachey recently read a paper before the Royal Society which, in his opinion, conclusively shows that an immense air-wave started from Krakatoa at about thirty minutes past nine A.M. on August 27th. Spreading from this common centre, the wave went three and a-quarter times round the globe, and those parts of it which had travelled in opposite directions passed through one another ‘somewhere in the antipodes of Java.’ The velocity of the aërial undulations which travelled from east to west was calculated at six hundred and seventy-four miles per hour, those moving in the reverse direction at seven hundred and six miles per hour, or nearly the velocity of sound. But another effect of the eruption was a series of ‘tidal waves,’ so called—although the term is objected to because not strictly scientific—which, like the air-wave, passed round the world. Whether this was synchronous with the final explosion, it is not possible to say. The highest of these seismic sea-waves, which was over one hundred feet high, swept the shores on either side of the Straits, and wrought terrible destruction to life and property. More than thirty-five thousand persons perished through it; the greater part of the district of North Bantam was destroyed, the towns of Anjer, Merak, Tjeringin, and others being overwhelmed. The initial movement of this destructive agent was undoubtedly of the nature of a negative wave; but the best testimony to this is lost, since those who witnessed it were its victims. The sudden subsidence of so large an area of the sea-bottom in the Straits caused the sea to recede from the neighbouring shores. This negative wave was, however, seen by Captain Ferrat from his vessel, as she lay at anchor at Port Louis. He states that towards two P.M. he saw the water in the harbour roll back and suddenly fall four or five feet; and that, a quarter of an hour afterwards, the sea returned with great violence to its former level, causing his own and other vessels to roll terribly. The best witness of this remarkable phenomenon, however, is Captain Watson, of the British ship _Charles Ball_. His vessel was actually within the Straits, and he states that he and his helmsman ‘saw a wave rush right on to Button Island, apparently sweeping right over the south part, and rising half-way up to the north and east sides fifty or sixty feet, and then continuing on to the Java shore. This was evidently a wave of translation and not of progression, for it was not felt at the ship.’ This latter movement, beyond question, must have coincided with the great ‘tidal wave’ above mentioned, and which was felt at Aden, on the Ceylon coast, Port Blair, Nagapatam, Port Elizabeth, Kurrachee, Bombay, and half-way up to Calcutta on the Hooghly, the north-west coast of Australia, Honolulu, Kadiall in Alaska, San Celeto near San Francisco, and the east coast of New Zealand.