They stared at the meter in amazement. It was incredible, even after they had seen those heptagons in action, that at such extreme range any offensive beam could be driven with such unthinkable power--power requiring for its neutralization almost the full output of the prodigious batteries of accumulators carried by the _Sirius_! Yet for five, ten, fifteen, twenty minutes that beam drove furiously against their straining screens, and even Brandon's face grew tense and hard as that frightful attack continued. At the end of twenty-two minutes, however, the pointer of the meter snapped back to the pin and every man there breathed an explosive sigh of relief--the almost unbearable bombardment was over; the screen was drawing only its maintenance load. "Wow!" Brandon shouted. "I thought for a minute they were going to hang to us until we cracked, even if it meant that they'd have to freeze to death out here themselves!" "It would have meant that, too, don't you think?" asked Stevens. "I imagine so--don't see how they could possibly have enough power left to get back to Jupiter if they shine that thing on us much longer. Of course, the more power they waste on us, the quicker we can take them; but I don't want much more of that beam, I'll tell the world--I just about had heart failure before they cut off!" The massive heptagon was now drifting back toward Jupiter at constant velocity. The hexans were apparently hoarding jealously their remaining power, for their wall screens did not flash on at the touch of the visiray. Through unresisting metal the probing Terrestrial beams sped, and the scientists studied minutely every detail of the Vorkulian armament; while the regular observers began to make a detailed photographic survey of every room and compartment of the great fortress. Much of the instrumentation and machinery was familiar, but some of it was so strange that study was useless--days of personal inspection and experiment, perhaps complete dismantling, would be necessary to reveal the secrets hidden within those peculiar mechanisms. "They're trying to save all the power they can--think I'll make them spend some more," Brandon remarked, and directed against the heptagon a heavy destructive beam. "We don't want them to get back to Jupiter until after we've boarded them and found out everything we want to know. Come here, Quince--what do you make of this?" Both men stared at the heptagon, frankly puzzled; for the screens of the strange vessel did not radiate, nor did the material of the walls yield under the terrible force of the beam. The destructive ray simply struck that dull green surface and vanished--disappeared without a trace, as a tiny stream of water disappears into a partially-soaked sponge. "Do you know what you are doing?" asked Westfall, after a few minutes' thought. "I believe that you are charging their accumulators at the rate of," he glanced at a meter, "exactly thirty-one thousand five hundred kilofranks."