Great liners of space were requisitioned and fitted with Dis rays, and with mighty attractor beam apparatus that would grip and hold anything short of another liner. Each of the ten-man-cruisers had a smaller attractor beam by which they could grip an adversary and hold to his tail with the tenacious grip of a bulldog and yet not weary the pilot with violent movement. These ships were exceedingly powerful, and their speed was limited only by the accelerations the passengers could stand. But all the scientists of the System were working desperately to design some new weapon, some new machine that was a little faster, a little more powerful; although with resistance in space and with the tremendous energies of matter at their disposal, there was little lack of power as far as the speed of the ships were concerned. Ten thousand times more powerful than the titanic energies of atoms, this energy had defeated the Martians that memorable day in May, 1947, and it was a full ten billion times more powerful than the energies of coal, of oil, of the fuels man had known before that day. But they needed a machine that could project the Dis ray farther. Twenty-five miles was the limit, beyond that the tremendous electrical field that was used to direct it must be built up to so high a voltage that there was no practical way of insulating it. They must be satisfied with the twenty-five mile range--but the scientists were working at increasing the range. They had two weeks before the Sirians would reach Mars, and in those two weeks much was done. There was a very carefully laid out system in all notices; the absolute truth was laid before the public, but there was also laid before them the evidences of Man's power. There were no panics. This was no weird thing to them, the landing of a fleet from another world; it was as commonplace to them as the landing of a fleet from the other side of the ocean had been a generation ago. The element of the unfamiliar was gone, and with it had gone the element that produces panic, that reduces the efficiency of a nation or of a System. New production machines had to be built, new designs worked out, new dies cut, but it was done with the quickness that a generation of mass production had made possible, it was not new to them, this change of design overnight. It required most of those two precious weeks to get the great machines working once more at their tasks, but at last a steady stream of ten-man cruisers was being poured out, 5000 an hour, night and day, from the factories of three planets. But there was only one day to work before the Invaders would reach Mars, and the fleet was gathered, 120,000 ten-man ships, manned by the volunteers of three worlds. But in the meantime Waterson had had built for himself a ten-man ship with triple strength of walls, and triple power plant installation, and an extra energy generator. He was experimenting with it, no one knew on what.