ut it was not the open air again. They were beneath the gigantic dome! For as Norman and Hackett breathed deep, awe fell on their faces as they took in the scene. Far overhead stretched the dome's colossally curving roof, and far out on all sides. It was lit beneath that roof by a clear light that the two would have sworn was sunlight. The dome was in effect the roof of a gigantic, illuminated building, and upon its floor there stretched a mighty city.
The city of the frog-men! Their boats were rising up over it and Norman and Hackett saw it clear. Square mile upon square mile of structures stretched beneath the dome, black buildings often of immense size, varying in shape, but all of square, rectangular proportions. Between them moved countless frog-hordes, swirling throngs in streets and squares, and over the roofs darted thick swarms of flying-boats. And at the city's center, in a great, circular, clear space, lay a wide, round, green pool—the opening of the water-tunnel up through which they had come.
Norman pointed down toward it. "That's your answer!" he cried. "The only entrance to this frog-city is from the sea, up through that water-tunnel!"
"Good God, an amphibian city!" Hackett was shaken, white-faced.
The two boats were driving quickly over the city, through the swarming craft. Norman glimpsed towering buildings that might have been palaces, temples, laboratories. They slowed and dipped toward one block-like building not far from the water-tunnel's opening. Armed frog-guards were on its roof, and other boats rested there. The two came to rest and the two captives were jerked out, the guards seizing them.
Half-dragged and half-floating they were led toward an opening in the roof from which a stair led downward. They passed down thus into the building's interior, lit by many windows. Norman glimpsed long halls ending in barred doors, guards here and there. Tube-lines ran along the walls and somewhere machines were throbbing dully. They came at last to a barred door whose guard opened it at the croaking order of the frog-men who held the two, and they were thrust inside, as the door clanged. They turned, and exclaimed in amazement. The room held fully a half-hundred men!
They were men such as the two fliers had never seen before, like humans except that their skins were a light green instead of the normal white and pink. They were dressed in dark short tunics, and kept talking to each other in a tongue quite unintelligible to Norman and Hackett. They came closer, flocking curiously around the two men, with a babel of voices quite meaningless to the two. Then one of the men uttered an exclamation, and all turned.
