Cover by Howard V. Brown. Science Fiction stories by John W. Campbell Jr ("The Mightiest Machine" part 1 of 5), Donald Wandrei, Raymond Z. Gallun, Howard W. Graham PhD, John W. Campbell Jr - as (Karl Van Campen), Don A. Stuart, Stanton A. Coblentz, and Edward E. Smith PhD "The Skylarks of Valeron-Part 5 of 7".
