So that there had grown gradually the commerce that kept endless streams of ships moving between earth and moon--great and luxurious passenger-craft laden with the wealthy and powerful of earth; and sleek private ships bound like the others for the luxurious lunar cities. Bulky and battered cargo-rockets had their own space-lanes, carrying metals and minerals to the earth, and returning with loads of supplies and tanks of the liquid rocket-fuel to the moon. It was inevitable that all this traffic should need regulating, and so there had been formed the Earth-Guard, an organization corresponding to the old Coast-Guards of the nations, but controlled by an international commission of earth's powers. The Earth-Guard boasted five hundred gleaming rockets that patrolled ceaselessly the space between and around the earth and moon, enforcing peace with their electric-guns and guarding the lunar commerce. For there were those against whom it must be guarded--space-pirates who dashed forth from time to time from hidden bases on earth or moon to harry and hold up in the void the rich lunar commerce. The boldest and most dreaded of them all was that swift and flashing corsair of the void known to all on earth and moon alike as the Hawk, and who for years had been the despair of all the Earth-Guard. "Lord, if we can get him!" Evans was praying as he gazed out of a port hole from the hurtling ship's pilot-house. "I get so tired of jabs about him that I'd lose an arm to get him." "Well, everyone's turn comes sooner or later in that game," philosophized Calden. "It may be the Hawk's now." Evans pulled a speaking-tube toward him and shouted down into it over the roar of the rocket's explosions. "Hartley? Put full crews on all the electric-guns and have them stand ready for action. Yes. And tell them it's the Hawk we're after this time--it'll put them on their toes." Calden grinned as a moment later a muffled cheer came up from the gun-rooms beneath. "They're on their toes, evidently," he commented. "They're as crazy to get their hands on the Hawk as you are." Evans made no answer but started ahead with teeth clenched upon his lower lip, glancing over now and then at the dials that recorded the rocket's position between earth and moon. This recording was automatic, being dependent on the change in the gravitational power of the two bodies. Evans saw by them now that the rocket was hurtling into the very zone in which the _Pallas_ had reported itself. Missed! He reached to turn a knob and there clicked up into position against the lenses set in the pilot-house window two long metal tubes with eye-pieces that formed powerful binoculars. Gazing ahead through these he kept watch, while with fingers on the firing-levers of the rocket's tubes Calden kept them steady on their course. Minutes passed before Evans uttered a cry.