Contents:"We Have with Us—" / essay by John W. Campbell Jr.Methuselah's Children (Part 1 of 3, Lazarus Long series) / serial by Robert A. Heinlein; interior artwork by H. RogersIn Times to Come / essay by The EditorThe Analytical Laboratory: May 1941 (/ essay by The EditorSpaceship in a Flask / Clifford D. Simak; interior artwork by Frank KramerThe Seesaw (Weapon Shops of Isher series) / by A.E. van Vogt; interior artwork by Charles SchneemanThe Probable Man / Alfred Bester; interior artwork by Frank KramerVermin of the Sky / essay by R.S. RichardsonThe Geometrics of Johnny Day / by Nelson S. Bond; interior artwork by Charles SchneemanWe Also Walk Dogs (Future History series) / Robert A. Heinlein (as by Anson MacDonald]; interior artwork by KollikerMore Than Giant Mirrors Needed / essayBrown / by Frank Belknap Long; interior artwork by Frank KramerBrass Tacks / essay by The EditorLetter / essay by Allan Ingvald BensonLetter / essay by L. Sprague de CampLetter / essay by Harry Warner Jr.