The homeward journey was accomplished even more swiftly than the trip northward as Sherman gained in experience at the controls of the machine. As it glided slowly to earth at the airport a little group of officers was waiting to meet them. "What in thunder have you been doing?" one of them greeted the Americans. "Your static, or whatever it was you let loose, burned out all the tubes in half the army radio sets in New Jersey." "By the nine gods of Clusium!" said Sherman. "I never thought of that. We're reducing matter pretty much to its lowest terms, and it's all a good deal alike on that scale--vibrations that may be electricity, magnetism, light or matter. Of course, when we let go that shot there was enough radiation to be picked up on Mars. I'll have to figure out a way to get around that. Those Lassans are no bums as electricians and after we've been at them once or twice, they'll be able to pick up our radiation whenever we're coming and duck us." "There's another thing," said Ben. "I thought the _Monitor_ vibrated a good deal when you let that shot go." "It did. We'll have to get more rigidity or we'll be shaking ourselves to pieces every time we shoot. But this, as I said, is an experimental ship. What we've got to do now is turn in and build a real one, with heavy armor and a lot of new tricks." "How are you going to know what kind of armor to put on her?" "That's easy. Steel will keep out any kind of material projectiles they're likely to have, if it's thick enough. It won't keep out the light-ray, but we'll put on a thin lead plating to take care of that, just in case, though I don't think they're likely to try it after the one failure. "Then inside the steel armor, we'll put a vacuum chamber. That will stop anything but light and maybe cosmic radiation, and I don't think they're up to that, although we'll get a little of the effect through the struts that support the outer wall of the chamber. What I would like though, is a couple of these Lassan thought-helmets. Not that you people are slow on the uptake, but we'd be a lot faster if we had them, and we're going to need all the speed we can get." They were crossing the flying field as they spoke, making for headquarters, where Sherman presently laid out the design for the second _Monitor_, embodying the improvements he had mentioned. The engineer who looked it over smiled doubtfully. "I don't think we can give this to you in less than three or four weeks," he said. "It will take a lot of time to cast that armor you want and to build the vacuum chamber. I assume your own workmen are going to make the internal fixtures." "Correct from the word go," Sherman told him. "But you better have it before three or four weeks are up. Ben, what do you say we run over to the lab and see if we can dig up something new." * * * * *