"Dunno. One of the little machines maybe. Look." Sherman peered cautiously round his side of the stump. In the valley beneath them, shining brilliantly in the pure white light it had released, was one of the metal fish--but a smaller one than the usual fighting machine, and without the projecting trunk. "We've been working on them for a while," the girl whispered. "I don't know what they're for, but they aren't fighting machines." Remembering how the vision plate of the fighting machine he had controlled had reflected every object within range, Sherman made himself small behind the stump. The machine below was probably trying to locate them in the light it had released. "Wonder they don't bring the birds out," he thought, and as if in answer to this idea, one of the four-winged creatures strutted around the machine, blinking in the light, then took off with a whir of wings, and spiralled upward. The light went out, reappeared as a beam, pointing down the valley and the machine moved off, slowly sweeping the sides of the hills with its pencil of illumination. He could see the multiple glow of the tubes at the stern, greenly phosphorescent, as the machine progressed. High above the bird screamed shrilly. CHAPTER XVII Marta's Sacrifice Progress up the hillside was slow. It had become completely dark; they were without any means of making a light and would not have dared to make one if they could. The mud was tenacious, the constant contact with stumps and rocks both irritating and difficult. But at last in their fumbling way, they reached a spot where the denudation gave place to a line of trees, looming dark and friendly overhead against the skyline, and after that they went faster. Where they were or what route to take neither had any idea. That portion of the Catskills is still as wild as in the days of the Iroquois, save for the few thin roads along the line of the valleys and these they dared not seek. They solved the difficulty by keeping to the hillcrest till it ran out in a valley, then rapidly climbing the next hill and proceeding along that in the shelter of the forest. Though they necessarily went slowly they did not halt; neither felt the need of rest or sleep, their metal limbs took no serious bruises, and the slip of the hill kept them from running in circles as people usually do when lost in the woods. Just as the eastern sky began to hold some faint promise of dawn they came upon a farmhouse in a clearing at the top of a hill. It was an unprepossessing affair with a sagging roof, but they burst in the door and went through it in the hope of finding weapons and perhaps an electric battery, for both were used to the bountiful electric meals of the Lassans and were beginning to feel the lack.