"I check you to nineteen decimal places, Mart, and from your ideas I'm getting surer and surer that we can pull their corks. I can get into action in a hurry when I have to, and my idea now is to wait until they relax a trifle, and then slip a fast one over on them. One more bubble out of the old think-tank and I'll let you off for the day. At what time will their vigilance be at lowest ebb? That's a poser, I'll admit, but the answer to it may answer everything--the first shot will, of course, be the best chance we'll ever have." "Yes, we should succeed in the first attempt. We have very little information to guide us in answering that question." He studied the problem for many minutes before he resumed, "I should say that for a time they would keep all their rays and other weapons in action against the zone of force, expecting us to release it immediately. Then, knowing that they were wasting power uselessly, they would cease attacking, but would be very watchful, with every eye fastened upon us and with every weapon ready for instant use. After this period of vigilance, regular ship's routine would be resumed. Half the force, probably, would go off duty--for, if they are even remotely like any organic beings with which we are familiar, they require sleep or its equivalent at intervals. The men on duty--the normal force, that is--would be doubly careful for a time. Then habit will assert itself, if we have done nothing to create suspicion, and their watchfulness will relax to the point of ordinary careful observation. Toward the end of their watch, because of the strain of the battle and because of the unusually long period of duty, they will become careless, and their vigilance will be considerably below normal. But the exact time of all these things depends entirely upon their conception of time, concerning which we have no information whatever. Though it is purely a speculation, based upon Earthly and Osnomian experience, I should say that after twelve or thirteen hours would come the time for us to make the attack." "That's good enough for me. Fine, Mart, and thanks. You've probably saved the lives of the party. We will now sleep for eleven or twelve hours." "Sleep, Dick! How could you?" Dorothy exclaimed. CHAPTER V First Blood The next twelve hours dragged with terrible slowness. Sleep was impossible and eating was difficult, even though all knew that they would have need of the full measure of their strength. Seaton set up various combinations of switching devices connected to electrical timers, and spent hours trying, with all his marvelous quickness of muscular control, to cut shorter and ever shorter the time between the opening and the closing of the switch. At last he arranged a powerful electro-magnetic device so that one impulse would both open and close the switch, with an open period of one one-thousandth of a second. Only then was he satisfied.