But the outlaws were not to win a foothold upon that inimical planet easily, nor were they to hold it without effort. Through the weird vegetation of the circle's bare edge there scuttled and poured along a horde of the metal-studded men--if "men" they might be called--who, ferocity incarnate, rushed the robot line. Mowed down by hundreds, still they came on; willing, it seemed to expend any number of lives in order that one living creature might once touch a robot with one out-thrust metallic stud. Whenever that happened there was a flash as of lightning, the heavy smoke of burning insulation, grease and metal, and the robot went down out of control. Recalling his remaining automatons, Roger sent out a shielding screen, against which the defenders of their planet raged in impotent fury. For days they hurled themselves and their every force against that impenetrable barrier, then withdrew: temporarily stopped, but by no means acknowledging defeat. Then, while Roger and his cohorts directed affairs from within their comfortable and now sufficiently roomy vessel, there came into being around it an industrial city of metal, peopled by metallic and insensate mechanisms. Mines were sunk, furnaces were blown in, smelters belched forth into the already unbearable air their sulphurous fumes, rolling mills and machine shops were built and equipped: and as fast as new enterprises were completed additional robots were ready to man them. In record time the heavy work of girders, members, and plates was well under way; and shortly thereafter light, deft, and multi-fingered mechanical men began the interminable task of building and installing the prodigious amount of precise machinery required for the vast structure. Roger was well content: but one day he was rudely awakened from his dream of complete isolation. Even though he had no reason to believe that there was anything dangerous within hundreds of millions of miles, it was Roger's cautious custom to release the screens from time to time, in order to allow his detectors to range out. This day, as he sent out his beams, his hard gray eyes grew even harder. "Mirsky! Nishimura! Come here!" he snapped, and showed them upon his plate an enormous sphere of steel, its rays flaming viciously. "Is there any doubt whatever in your minds as to the System to which that ship belongs?" "None at all--Triplanetarian," replied the Russian. "While larger than any I have seen before, its construction is unmistakable. They managed to trace us, and are testing out their weapons before attacking. Do we attack or do we run away?"