"Dear God!" The exclamation was wrung from me as recollection returned with a rush. "Where? You can't have!" "Here." He thrust a bundle of letters into my hands. "You acted so strangely last night you caused me to suspect you of a serious crime. Also, you overlooked several important points. You got back from a trip only last night." Last night! Surely it was years. "You had left instructions to have your mail forwarded," the level voice went on. "These letters were evidently one day behind you. I picked them up at your rooms this morning. I took the liberty of opening them. Read this one." He selected it. * * * * * With trembling fingers I extracted from the envelope a single written page. I recognized the handwriting as the professor's. I read with feverish intensity, each single word burning itself into my consciousness: Dear Thornton: I am writing this in anticipation. I will see that it is mailed when my plans are completed. Too late, dear friend, for you to attempt, with the best intentions in the world, to frustrate them. You will, perhaps, recall that many years ago, when I gave you my full confidence, I told you that I felt sure that the law of compensation would atone in some measure for my loss. Thornton, old friend, I believe that, in more ways than one, my hour has arrived. Two days ago I completed the absolute zero. But even better! A man called here to-day. Although he did not recognize me, I saw through the veneer of added years with ease. Fate, call it what you will, my visitor is the man who wrecked my happiness. Under pretext I shall detain him. I shall induce him to enter the crystalline cage. I have already arranged a dual control which the power will destroy when I apply it from _the inside of the cage_. Please destroy the cage. It will have brought compensation to me before you read this. Good-by, dear friend! Wroxton. "I apologize, Mr. Thornton." The chief offered a hand which I clutched in mingled sorrow and relief. The world had lost a genius. I had lost a dear friend. But he was right. It was compensation. Tanks _By Murray Leinster_ ... The deciding battle of the War of 1932 was the first in which the use of infantry was practically discontinued ... --History of the U.S., 1920-1945 (Gregg-Harley). [Illustration: _Row after row of the monsters roared by, going greedily with hungry guns into battle._] [Sidenote: Two miles of American front had gone dead. And on two lone infantrymen, lost in the menace of the fog-gas and the tanks, depended the outcome of the war of 1932.]