Everything moved along smoothly after this. Walter and Edna were happy in their work and the Fall of 1928 rewarded them with a new and wonderful discovery. They had been able to perfect a machine which would reflect light in such a way as to make an airplane invisible and this, together with Robert's noiseless invention, solved the problem. He knew now that in time of war, the plane could be used to sneak upon the enemy and that they would be unable to see or hear it. After holding a conference, they decided that this invention, as well as "The Demon of Death" should not be patented or offered for sale to any Government, that they would test it out and keep it a secret. Here Robert's great generosity showed itself again when he decided that this invention should be used in time of greatest need for the benefit of the United States. Walter said, "Robert, love indeed does make a great man, makes him unselfish, causes him to think of his country, of his mother, his sweetheart and everything else before himself. No wonder you are making a success and always will, because you are doing right." The completion of the great machine, "The Demon of Death," which Robert had worked on untiringly day and night, was a great triumph for him, but his wonderful energy had been exhausted. Walter had noticed before the machine was completed that Robert looked tired and worn. His mind lacked its old-time quickness and he feared for his health. Robert began to reach the office late and ceased to take an interest in his work. He was moody and despondent. Thanksgiving Day, Walter and Edna arranged a big dinner and invited Robert. He appeared very much worn and ate very little dinner. Both Walter and Edna noticed that he was less talkative than ever before. About an hour after dinner was over Robert fell in a faint. A doctor was called immediately and after making a careful examination pronounced it a case of nervous breakdown. Said there must be something preying on his mind or that he had been under a long strain. Walter explained the disappearance of Marie and how Robert had worried over the love affair; his long, strenuous campaigns in the stock and commodity markets and his work upon his inventions; that up to a few months previous Robert had been able to work almost day and night without showing any fatigue, but that in recent weeks he had noticed a great change in him. After the doctor had heard the story of the love affair and Marie's disappearance, he was sure that a long and needed rest was necessary to restore Robert to his normal health. He ordered him to remain absolutely quiet and not attempt to look after any of the details of his business. A few days later Walter persuaded Robert to go to Atlantic City, which he did, and after remaining there and resting a couple of weeks, he returned apparently well and showed his old-time strength and vigor. Was anxious to get back to work and look after his speculative deals in the market. CHAPTER XX