These learned elements in the imaginary voyages point definitely to our modern stories. The difference lies in the emphasis: our modern stories are severely and consistently logical, and interest centers in the machine or the scientific theory. The reader does not ask to go on long journeys to see chimeras, but he asks to see ultra-logical man. He does not encourage the author in being satiric; he wants him to be inventive, to be more ingenious than the race has been. The reader wants the author to show him what man would be if he were consistently progressive and wise, what he would come to if he worked day and night at his science and applied what he learned,--indeed, what he already knows. For it is an open secret in the scientific world that there is hardly a wonderful modern machine that is not an almost foolishly simple application of a well-known law. Take our marvelous future trains, for instance, that are to run on one rail and be as wide and commodious as houses--they are but to follow a principle that every school-boy sees in operation when he spins a top. I dare say, if some person would only write a story telling us where to affix the wheel and the balance, we might convert our present houses into private Pullmans, as it were, that could at any time transport us, family and all, with everyone of our personal and familiar conveniences intact therein, to any spot we chose, the only extra expense to us for each trip being a slight rent for wheel space for the time that we were running over the single-rail track that led thitherward. [Essential elements] Shading off from the imaginary voyage type, therefore, is this modern one which I have designated by the somewhat long title, tales of scientific discovery and mechanical invention. By this title I mean to distinguish stories in which the occurrences, though startling, are perfectly logical in sequence, granted the premise--extraordinary, but not improbable under the conditions set forth. The words discovery and mechanical express the fact that the sustaining structure of a story such as these is often some invention superimposed upon modern science. In the use of electricity, for instance, the characters in the narrative go one step further than Mr. Edison; in the construction and operation of the flying-machine, several steps further than the Wright brothers; in the discovery of elements, someone finds something more useful and of greater power than radium; or, after long experimenting, he mixes a paint so black or so white that the object beneath it becomes invisible; and so on and so on--but all plausible, all with precise truth-likeness. [Stories of this type]