3" non-yellowing library tape reinforcing spine. Top 1" of back cover shows a light spatter-trace where I would guess something was spilled but blocked from the rest. This is very tight and square with some very light shelfwear - probably unread.

These originally appeared from 1935 to 1939 - all in Astounding, and all as by "Don A. Stuart" (the pseudonym Campbell used for stories more thoughtful or experimental than the Super-Science or Space-Opera he was known for in the early Thirties.) Stories 3-5 are grouped as "The Story of the Machine" and the last 2 stories are grouped as "The Story of Aesir."