First come the oared Long Ships, the slave-manned galleys, the argosies of the Phoenicians, the Greeks, of Carthage, Rome, Byzantium, of Barbary, Norway, Venice, Genoa, Spain. They are human-wielded, sea-compelling engines. Then come the Great Ships, the device of Henry VIII. They shattered the galleons of Spain, they wrecked the Dutch Republic, destroyed the Empire of France, gave Britain the command of the sea. They explored the planet, they created the greater commerce. They come under sail, they need no slave-engines, these white-winged servants of the winds, winged conquerors of all seas. Then come the iron ships which laid the cables, peopled the lands, and narrowed down the world into a house for man; the steel ships, smoke-maned conquerors of both wind and sea, not man-driven galleys, but steam-driven carriers, racing cities, and cruising fortresses. They drove the white sails from the face of the sea, drove them to refuge in the skies. And so sweeps the majestic pageant of the ships into the golden age of seamanship. "There shall be no more sea," for man has taken wings to cleave the air. Poised on broad aeroplanes, alive with power flashed to them through space, the aerial battleships have claimed the very pathways of the eagles. Rolling down the cloud-seas come the snow-white, glittering giants of the electric age, England's dread Channel Fleet, surely the last supreme achievement of mankind. And far aloft, attended by white cirrii, hangs one small star-like speck in the blue zenith, an unarmed private yacht offering to meet the entire navy of Britain and all the fleets of Europe in single combat. There is a legend of John Brand I., that wandering on the moors by the Lands End, he came upon a dark and silent pool. Being in an idle mood he sat beside the bank throwing pebbles, and watched the little ripples spread away over still water. So the thought came to him of those small innumerable waves which constantly spread away from the earth's centre, the waves of gravitation. Thinking profoundly he took a pebble in his hand. What mighty chord of the celestial music thrilled in that stone pulling it down to the earth? What was its chord of mass--how many millions of waves to the second? Perhaps a million vibrations. Suppose then he made an engine which would sound that note exactly. The stone would fall off the planet, be whirled into space! Could he build a ship to carry such an engine, strike the great chord, and hurl the vessel off among the stars? Could he arrest its flight, create the ship into a planet, free from the earth, and driven at his will within the limits of the atmosphere?