It was a clear day, and the islands were distinctly visible. Sight travels more swiftly than sound, and before any noise was heard, the immense mass of rock, crown shaped, from which the islands take their name, was seen by the gazers on the beach to leap from its place and fall into the sea. Other masses in swift succession followed; then came roars of sound, as if heaven and earth were coming together; roars of sound which rattled the doors and casements of the hotel as if shaken with a high wind. For twenty minutes this awe-inspiring exhibition continued, and when the tremendous cannonading ceased, the Coronada Islands—in the form in which they had previously existed—were no more. The work of resurveying and making new topographical maps was subsequently performed, as a part of the duty of those connected with the dynamic exposition, but it needed no measurements to demonstrate the awful power of the potentite. An area of solid rock a mile square was rent into fragments for a depth of one hundred feet. Many improvements in machinery and management were suggested to the officers of the _Petrel_, but the experiment was conceded by all the great engineers who witnessed it, to be so completely successful as to practically eliminate land warfare from the future of nations. “It is fortunate,” said the Marquis of Salisbury, who was one of the British delegation—“it is fortunate that the manufacture of even a small quantity of potentite requires months of time, great skill, and a costly and extensive laboratory, so that it will be not impracticable to prevent its preparation by private persons. But given a piece of land anywhere in the civilized world large enough to permit of the building of air ships and the manufacture of potentite, and sufficiently defended to afford to its garrison three months’ time in which to perfect the making of that explosive, and any power, however insignificant, could, with a hundred air ships, destroy in three days all the great cities in Europe.” “As it now appears,” continued the Marquis, “this method of warfare would not be so available against a moving object on the sea, such as a war ship. But if the submarine torpedo boat, whose operations we are to witness to-morrow, shall be anything nearly as effective as Mr. Morning’s air ship, it seems to me that a convention of civilized powers to adjust international relations and provide for a Congress and Court of Nations, to which all international differences must be submitted, will be an absolute necessity in the future,” “And how would the decrees of such a court be enforced, your lordship,” inquired Prince Bismarck, who was listening.