The two observers in the airplane, stricken with horror at what they had seen, flew mechanically back and forth. Once they passed within a few hundred feet of the standing giant. They saw its two hundred foot mooring mast for dirigibles rising above the eighty-five stories of the main structure. They saw the little observatory room up there in the mooring mast top, with its circular observation platform, a balcony around it. But they did not notice the figures on that balcony. Then, from the top of the Empire State Building--from the circular observation platform--a single, horribly intense green light-beam slanted out into the night! A new attack! As though all which had gone before were not enough destruction, now came a new assault. The spectral enemies were tangible now! * * * * * The single green light-beam was very narrow. But the moonlight could not fade it; over miles of distance it held visible. It struck first a passing airplane. The two observers in the monoplane were at this time down near the Battery. They saw the giant beam hit the airplane. A moment it clung, and parts of the plane faded. The plane wavered, and then, like a plummet, fell. The beam swung. It struck a warship lying in the upper bay. Explosions sounded. Puffs of light flared. The ship, with all its passengers vanished and gone, lay gutted and empty. The source of the light moved rapidly around the circular balcony. The light darted to every distant point of the compass. The surprised distant ships and forts, realizing that here for the first time was a tangible assailant, screamed shots into the night. But the green beam struck the ships and forts and instantly silenced them. Now the realization of this tangible enemy spread very far. Within a few minutes, planes and radio communication had carried the news. From distant points which the light could not or did not reach, long-range guns were firing at the Empire State. A moment or two only. The base of the building was struck. Then, frantically, observing planes sent out the warning to stop firing. The green beam had for a minute or two vanished. But now it flashed on again. What was this? The spectral wraiths of ten thousand of the enemy were staring. The observers in the planes stared and gasped. What fantasy! What new weird sight was this, stranger than all that had preceded it! CHAPTER XII _On the Tower Balcony_