The Invisible Master By EDMOND HAMILTON Author of _The Hidden World, Cities in the Air, etc._ _Illustrated By RUGER_ [Transcriber's Note: This etext was produced from Scientific Detective Monthly April 1930. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] _A thousand alarms are pouring into Police Headquarters! The Invisible Master broods over the city! Who is He? We defy any reader to guess the secret! Even the editorial staff of SCIENTIFIC DETECTIVE MONTHLY was astounded at the conclusion of this scientific yarn. Write and tell us if you were able to foretell the ending._ _If you were to ask us which, in our opinion, is the greatest scientific detective story of the year, we certainly would pronounce the present story to be that unusual gem._ _Here is a story that will keep you fascinated, not only in connection with its excellence of science, understandable by everyone, but by the fast-moving action for which this well-known author is famous._ _Invisibility in this sort of story is perhaps not a new idea; but we venture to say that no one can foretell the O. Henry-like ending, which is as unexpected as it is dramatic._ CHAPTER I Carton Earns His Salary "And to think," Charlie Carton exclaimed, "that they pay you a city editor's salary for ideas like that!" The other looked up from his desk, nettled. "I didn't say I took any stock in the thing, Carton," he pointed out. "But I got the tip that the _Courier_ and the _Sphere_ have their men hurrying out to the university, and we can't afford to miss anything." "And I'm to write a breath-holding tale of how Dr. Howard Grantham, the super-physicist, has discovered the secret of invisibility?" demanded Carton. The city-editor smiled. "Write it any way you please," he said, turning to the papers on his desk. "But whatever you get out of it, see that the _Courier_ and _Sphere_ men don't get more!" "I'll get out of it some pointers on the methods of publicity-crazy scientists, if nothing else," was Carton's parting shot. It was with this skepticism strong in him that he rode uptown on the west-side subway, nor had his mood changed by the time he emerged again into the morning sunlight. East and northward from him stretched the campus of America University, a sweep of green from which rose the great gray buildings. Carton walked quickly toward the building, one of the nearest to him, that held the university's world-famed department of physical science.