"I thought you'd be on the job," said Darrow, with satisfaction. "How's your instrument? Going, eh? We are in the wireless offices," he told the others. "Sit down, if you can find chairs. We'll wait until the sun is shining brightly, love, before we really try to get down to business. In the meantime--" "In the meantime--" repeated both Jack and Hallowell, in a breath. "Go on, my son," conceded the latter. "I bet we have the same idea." "Well, I was going to say that I'm not in the grammar-school physics class, and I want to know what you meant by your remark to Eldridge," said Jack. "That's my trouble," said Hallowell. "It's simple enough," began Darrow. "We have had, first, a failure of all electricity; second, a failure of all sound; third, a failure of all light. The logical mind would therefore examine these things to see what they have in common. The answer simply jumps at you: _Vibration_. Electricity and light are vibrations in ether; sound is vibration in air or some solid. Therefore, whatever could absolutely stop vibration would necessarily stop electricity, light and sound." "But," objected Jack, "if vibration were absolutely stopped, why wouldn't they all three be blotted out at once?" "Because," explained Darrow, "the vibrations making these three phenomena are different in character. Sound is made by horizontal waves, for example, while electricity and light are made by transverse waves. Furthermore, the waves producing electricity and light differ in length. Now, it is conceivable that a condition which would interfere with horizontal waves would not interfere with transverse waves; or that a condition which would absolutely deaden waves two hundred and seventy ten-millionths of an inch long would have absolutely no effect on those one hundred and fifty-five ten-millionths of an inch long. Am I clear?" "Sure!" came the voices of his audience. "That much Eldridge and any other man trained in elementary science already knows. It is no secret." "It hasn't been published," observed Hallowell grimly. "Well, go to it! The task of the independent investigator, of which we are some, is now to discover, first, what are those conditions, and, second, what causes them. With the exception of Mr. Hallowell, we all know what this guiding power is." "Don't get it," growled Simmons. "Now, look here, Simmons, you are very loyal to McCarthy, for whatever reason, but your loyalty is misplaced. For one thing, your man has disappeared, and will not return. That last message scared him out. For another thing, we're going to need you in our campaign, the worst way." "I'm from Copenhagen; you got to show me," said Simmons. Darrow laughed softly.