It was only a half-hour after that that the men at Mars Center realized perfectly what it meant. Their power was being drained just a little bit better than twice as fast as they generated during the day--and since Phobos spun so swiftly across the sky. Deenmor got the attack just about the time Mars Center was released. Deenmor immediately began seeking for the source of it. Somewhere on Phobos--but where? The Mirans were experts at camouflage. Deenmor Station, realizing the menace, immediately rayed the "projector." They tore up a great deal of harmless rock with their huge UV rays. But the bomb device continued to throw one bomb each five seconds. When Deenmor operated from Phobos' position, Mars Center was exposed to the deadly, constant drain. A day or two later, the bombs were coming one each second and a half, for more ships had joined in the work on Phobos. Gresth Gkae saw the work was going nicely. He knew that now it was only a question of time before those magnetic shields would fail--and then the whole fort would be powerless. Maybe--it might be a good idea, when the forts were powerless to investigate instead of blowing them up. There might be many interesting and worthwhile pieces of apparatus--particularly the UV beam's apparatus. XI Buck Kendall entered the Communications room rather furtively. He hated the place. Cole was there, and McLaurin. Mac was looking tired and drawn, Cole not so tired, but equally drawn. The signals were coming through fairly well, because most of the disturbance was rising where the signals rose, and all the disturbance, practically, was magnetic rather than electric. "Deenmor is sending, Buck," McLaurin said as he entered. "They're down to the last fifty-five tons. They'll have more time now--a rest while Phobos sinks. Mars Center has another 250 tons, but--it's just a question of time. Have you any hope to offer?" "No," said Kendall in a strained voice. "But, Mac, I don't think men like those are afraid to die. It's dying uselessly they fear. Tell 'em--tell 'em they've defended not alone Mars, but all the system, in holding up the Strangers on Mars. We here on Luna have been safer because of them. And tell--Mac, tell them that in the meantime, while they defended us, and gave us time to work, we have begun to see the trail that will lead to victory." "_You have!_" gasped McLaurin. "No--but they will never know!" Kendall left hastily. He went and stood moodily looking at the calculator machines--the calculator machines that refused to give the answers he sought. No matter how he might modify that original idea of his, no matter what different line of attack he might try in solving the problems of Space and Matter, while he used the system he _knew_ was right--the answer came down to that deadly, hope-blasting expression that meant only "uncertain."