It was on the fifth day out from Lakehurst. The Fury, with her sister ships spread out some thousands of miles to right and left, was cruising at five thousand miles per hour, at heliocentric elevation 93.243546, ecliptic declination 7°, 18' 46" north, right ascension XIX hours, 20 min., 31 sec. The earth was a little green globe beside her, and the moon a thin silver crescent beyond.
"Object ahead!" called a lookout in the domed pilot-house of the Fury, turning from his telescope to where Captain Brand and Bill stood smoking, comfortably held to the floor by the ship's acceleration. "In Scorpio, about five degrees above Antares. Distance fifteen thousand miles. It seems to be round and blue."
"The Prince, at last!" Brand chuckled, an eager grin on his square chinned face, light of battle flashing in his blue eyes.
He gave orders that set the heliographic mirrors flickering signals for all nine of the Moon Patrol fliers to converge about the strange object, in a great crescent. The black fins that carried the charging vitalium plates were drawn in, and the full power of the motor ray tubes thrown on, to drive ahead each slender silver flier at the limit of her acceleration.
Four telescopes from the Fury were turned upon the strange object. Captain Brand and Bill took turns peering through one of them. When Bill looked, he saw the infinite black gulf of space, silvered with star-dust of distant nebulae. Hanging in the blackness was an azure sphere, gleaming bright as a great globe cut from turquoise. Bill was reminded of a similar blue globe he had seen—when he had stood at the enormous telescope on Trainor's Tower, and watched a little blue circle against the red deserts of Mars.
Brand took two or three observations, figured swiftly.
"It's moving," he said. "About fourteen thousand miles per hour. Funny! It is moving directly toward the earth, almost from the direction of the planet Mars. I wonder——" He seized the pencil, figured again. "Queer. That thing seems headed for the earth, from a point on the orbit of Mars, where that planet was about forty days ago. Do you suppose the Martians are paying us a visit?"
"Then it's not the Prince of Space?"
"I don't know. Its direction might be just a coincidence. And the Prince might be a Martian, for all I know. Anyhow, we're going to find what that blue globe is!"