So with you. You are in the same position with respect to the prophecies in this work as your remote ancestor. Your descendants, picking up this book 750 years hence,--or at the time in which this story is laid,--will ridicule the author for his lack of imagination in conceiving the obvious developments in the first half of the next century. It may be of passing interest to note that several of the predictions made by the author when this story was written have already become verities. Notable among these is what the author termed the _Hypnobioscope_, the purpose of which is to acquire knowledge while asleep. The author was greatly astonished to read the results obtained by J.A. Phinney, Chief Radioman, U.S. Navy, who, having tried the system himself, in 1923, introduced it at the Pensacola, Florida, Naval Training School. Here one may see naval students stretched out on long benches asleep with casket-like coverings over their heads. The caskets contain two telephone receivers through which radio code is sent to the sleeper. It has been demonstrated that the sleeping student can be taught code faster than by any other means, for the sub-conscious self never sleeps. Students who have failed in their studies have passed examinations after being taught by this method. The scientific conception or vision of the world of 750 years hence, represents the author's projection of the scientific knowledge of today. Scientific progress is moving at an accelerating pace, and if that pace is maintained, it seems fair to assume that the conception herein described will, 750 years hence, be found to have fallen far short of the actual progress made in the interim. Hugo Gernsback _September 3, 1925_ FOREWORD BY LEE DE FOREST, Ph.D., D.Sc., D.Eng. _Father of Radio_ No book in two generations, no book since Jules Verne, has undertaken to do what Hugo Gernsback in the first decade of our century has here so outstandingly achieved. He is gifted with a mind eternally alert, trained from childhood to observe and think. His unbridled imagination has ever fed on the facts of science and technology which his habit of omniverous reading has been continually storing within his brain. As result of this unusual combination his tireless energies have been directed, since childhood in Luxembourg, to writing popular science in a fashion peculiarly attractive to young men and boys who, like himself, possess a keen interest in all realms of physical Nature.