Contents: Invention and Imagination - essay by John W. Campbell, Jr. [as by The Editor ] The Luck of Ignatz - novelette by Lester del Rey The Analytical Laboratory: June 1939 (Astounding, August 1939) - essay by The Editor In Times to Come (Astounding, August 1939) - essay by The Editor Heavy Planet - shortstory by Milton A. Rothman [as by Lee Gregor ], artwork by Koll General Swamp, C.I.C. (Part 1 of 2) - serial by L. Ron Hubbard [as by Frederick Engelhardt], with artwork by Isip Isotope 235 - essay by John W. Campbell, Jr. [as by Arthur McCann ] Space War - essay by Willy Ley Life-Line - shortstory by Robert A. Heinlein, with artwork by Isip Brass Tacks and Science Discussions (Astounding, August 1939) - essay by The Editor Stowaway - shortstory by Nelson S. Bond, with artwork by Cartier There's Just as Good Fish— - essay by L. Sprague de Camp The Blue Giraffe - novelette by L. Sprague de Camp, with artwork by Koll An Ultimatum from Mars - shortstory by Ray Cummings, with artwork by H. W. Wesso [as by Wesso ] Pleasure Trove - novelette by P. Schuyler Miller, with artwork by Koll