He faltered on the last word, as his blow landed and sent some of its force smashing back up his arm and body. But the Commander knew--as a smith knows--the feel of metal under his strength; and Jon McPartland knew his hunch had been right even before McTavish cried: "You--you _bent_ it!" "Right, Mister. I bent it. And I couldn't bend the steel that went into this ship's hull, could I, McTavish?" "Blasting right you couldn't, begging your pardon, sir. No man could." "Then it isn't steel any longer, McTavish--not near the edges of the spot their ray hit!" McPartland twirled the hammer in his hand, eager as a small boy just learning how to whip the neighborhood bully. "Where that ray hit there was disintegration at the center, transmutation at the edges." Understanding was spreading over the Engineer's face behind the transparent helmet of his space suit. "Then, man, that ray has one magnetic charge; positive or negative, proton or electron." "And your technicians will tell us which," ordered the Commander. "Get them busy cutting out samples. We want to know quickly. But you and I have enough to do while we wait, Mister." He led the way back to the bulkhead. Inside, McTavish gave orders, while shedding his space-suit and starting down the corridor to the control room. McPartland explained as they went. "Our magnetic screens, having electrons and protons, bent their ray. I saw it. That made me think they used a mono-charged stream of particles. Some of the particles in the screen attracted the ray charges, others repelled them. You know, of course," he went on, "how our screens diffuse our own type of duo-charge beam at long range and protect the ship against them." "Yes, man!" His Engineer agreed, excitedly now. "And beams from the screened ship go through on initial velocity. But they couldn't use a screen--the enemy: there'd be no balance of forces--they'd bend their own ray!" "The way we'll bend it, Mister, when we go back after those murderers!" Jon McPartland took a deep, triumphant breath, and his face lit up with a battle smile that made the Engineer's heart lift. "Mister McTavish, we're going to string a space lifeboat out behind us on about two miles of cable. You are going to rig up our dynamos to make this ship and the lifeboat the poles of an electromagnet. When your Technicians determine the polarity of the enemy ray, we'll make the ship the repelling pole." "Then, man, begging your pardon, sir, we go back and let them blast," cried the Engineer. "Their ray curves away from us--toward the lifeboat. By the time they figure the trick out, we'll be close enough to blast them wide open." "We'd better be," his superior concluded grimly. "Or the devils will blast away the lifeboat and the cable. Leave us without an electromagnet--right back where we started from." * * * * *