Suiting action to word, he took up his stopwatch and set the needle swinging. They watched it with strained faces as second after second went by and it still continued to swing. When it had come to rest Crane read his watch and made a rapid calculation.

"About three hundred and fifty million miles," he stated. "Clear out of our solar system already, and from the distance covered he must have had a constant acceleration so as to approximate the velocity of light, and he is still going with full...."

"But nothing can possibly go that fast, Mart, it's impossible. How about Einstein's theory?"

"That is a theory, this measurement of distance is a fact, as you know from our tests."

"That's right. Another good theory gone to pot. But how do you account for his distance? D'you suppose he's lost control?"

"He must have. I do not believe that he would willingly stand that acceleration, nor that he would have gone that far of his own accord. Do you?"

"I sure don't. We don't know how big a bar they are carrying, so we can't estimate how long it is going to take us to catch them. But let's not waste any more time, Mart. For Cat's sake, let's get busy!"

"We have only those four bars, Dick—two for each unit. Do you think that will be enough? Think of how far we may have to go, what we may possibly get into, and what it will mean to Dottie if we fail for lack of power."

Seaton, though furiously eager to be off, paused at this new idea, and half-regretfully he replied:

"We are so far behind them already that I guess a few hours more won't make much difference. It sure would be disastrous to get out near one of the fixed stars and have our power quit. I guess you're right, we'd better get a couple more—make it four, then we'll have enough to chase them half our lives. We'd better load up on grub and X-plosive ammunition, too."